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BIOL 2210 > Midterm 2 (Lectures 13-24) > Flashcards

Midterm 2 (Lectures 13-24) Flashcards

1
Q

What are some requirements for locomotion on land?

A
  • streamlining not important in air
  • can’t generate thrust by pushing against air
  • use legs and feet to transmit backward force to substrate
  • gravity requires that skeleton supports body
  • limbs must be able to lift body off the ground
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2
Q

Skeletal support adjusts to various conditions due to what capability?

A

Remodeling capacity of bone is important to allow bones to mend and adjust to conditions.

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3
Q

External vs internal layers of bones?

A

External layers: dense and compact (lamellar), strong

Internal layers: porous, light, spongy

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4
Q

What is the function of the axial system in fish vs tetrapods?

A

Axial system: ribs and vertebrae

Fish: for muscle attachment
Tetrapods: for support

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5
Q

What is the function of appendages in fish vs tetrapods?

A

Fish: for steering
Tetrapods: for locomotion

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6
Q

Zygapophyses

A
  • on neural arches of vertebrae
  • helps lock vertebrae
  • articulate to support weight of viscera
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7
Q

Which have lost the zygapophyses?

A

Aquatic tetrapods have lost zygapophyses

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8
Q

What is the role of the ribs in skeletal support?

A
  • help retain volume of body cavity in amniotes

- when animal lies down, weight against ground would affect breathing and heart beat

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9
Q

What is the role of the pelvic girdle in skeletal support?

A
  • Bears weight of the animal
  • connects directly with vertebral column
  • connects axial and appendicular skeletons
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10
Q

What allowed for a distinct neck region in tetrapods?

A
  • loss of opercular bones
  • cervical vertebrae allow independent head movement
  • pectoral girdle loses connection to skull*
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11
Q

Which costs more energy, locomotion on land or water?

A

On land is energetically more costly.

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12
Q

How did evolution of tetrapod locomotion come about?

A

1) primitive tetrapod locomotion is still seen in salamanders:
- force from trunk muscles (body undulation)
- feet primarily to provide frictional contact with ground
2) use of limbs more derived trait
- trunk muscles become more important in ventilation
- limbs become more important for locomotion

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13
Q

How is eating on land different than eating in water? What is the difference of snouts in fish vs tetrapods?

A
  • in water, food is nearly weightless
  • fish: short snouts for suction feeding
  • tetrapods: longer snouts to capture prey
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14
Q

What was a key innovation for eating on land?

A

Muscular tongue:

  • support from hyoid arch (vs gills in fish)
  • manipulate food for chewing and transport
  • prey capture in some (projectable tongue evolved independently in frogs, salamanders and chameleons)
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15
Q

What is the role of the salivary glands in eating on land?

A
  • moisten food
  • saliva with enzymes to begin chemical digestion
  • some with venomous secretions (lizards and snakes)
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16
Q

What is an example of a venomous mammal?

A

Northern short-tailed shrew

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17
Q

Best breathing methods in water vs air?

A

Water: gills very efficient, flow through ventilation
Air: gills collapse, tidal ventilation (now possible due to low density and viscosity of air, and high oxygen content)

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18
Q

The lung comes from where?

A
  • “Inherited” from fish

- ventral in sarcopterygians (and bichirs)

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19
Q

The internal moist membranes in the lungs has what function?

A
  • permits gas exchange

- limits dehydration

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20
Q

How are the lungs different in non-amniotic tetrapods (amphibians) vs amniotes?

A

Non-amniotic tetrapods (amphibians):
-lung ventilation
-positive-pressure buccal pump
-suck air into mouth by expanding oral cavity
-push air into lungs by raising floor of mouth
Amniotes:
-negative-pressure aspiration pump
-create negative pressure in abdominal cavity by expanding rib cage
-draw air into lungs

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21
Q

What is the internal structure of the lungs?

A
  • simple sacs in amphibians (supplemented by cutaneous respiration)
  • subdivided in amniotes (lobes, alveoli) to increase surface area
  • cartilaginous trachea (permits longer necks) and larynx in amniotes
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22
Q

What is the difference between blood pumping in fish vs tetrapods?

A
  • fish: in water, blood only needs to overcome fluid resistance to move
    tetrapods:
  • require higher blood pressure to push blood upward against gravity, like giraffes with long necks
  • higher blood pressure also forces some of the plasma out of vessels into intercellular spaces that is then recovered and returned to circulatory system by lymphatic system
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23
Q

How did tetrapod circulation evolve?

A
  • evolution of double circulation
  • pulmonary circuit takes deoxygenated blood to lungs
  • systemic circuit supplies oxygenated blood to body
  • atrium always completely divided
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24
Q

What is different about amphibians’ circulation compared to tetrapods?

A
  • atrium always completely divided
  • amphibians have no ventricular division, oxygenated blood received in both atria since skin also a major site of gas exchange
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25
Q

In the double circulation of blood in amniotes, how is the system divided?

A
  • ventricle divided by a fixed barrier (crocodiles, birds, mammals) or transiently/temporarily separate chambers when heart contracts (turtles, lizards)
  • deoxygenated blood in right side of heart
  • oxygenated blood in left side of heart
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26
Q

How is oxygen supplied to the heart muscle in amphibians and non-avian reptiles? In mammals and birds?

A

amphibians and non-avian reptiles: enough oxygen diffuses from blood in ventricle
Mammals and birds: thick ventricular muscles, right ventricle with deoxygenated blood

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27
Q

What can be said about the evolution of coronary arteries in mammals and birds?

A

Coronary arteries evolved independently

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28
Q

How are the sensory systems in air different than those for water?

A
  • air not dense enough to stimulate lateral line like water does
  • air does not conduct electricity like water does
  • air is good for vision, hearing, olfaction of small molecules
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29
Q

Sensory systems in air: Vision

A
  • light can be transmitted through air with little disturbance
  • can be used to sense distance
  • cornea involved in focusing light on retina
  • need eyelids and lubricating glands for eyes (due to exposure to air)
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30
Q

Sensory systems in air: hearing

A
  • airborne sounds detected by inner ear
  • fluids in inner ear set in motion by sound waves, stimulate hair cells
  • middle ear amplified sound with outer membrane (tympanum)
  • transmits to inner ear through series of bones (stapes)
  • connected to mouth with Eustacian tube (derived from spiracle)
  • in Ostariophysan fish, they have Weberian apparatus for hearing
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31
Q

Sensory systems in air: olfaction

A
  • airborne molecules that we can detect with our noses
  • receptors restricted to nasal passage (moist membrane) vs body surface in fishes
  • mammals have greatest olfaction sensitivity
  • area of olfactory epithelium increased by turbinates
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32
Q

In general mammals have the greatest olfactory sensitivity. What can be said about primates?

A
  • primates have relatively poor sense of smell
  • short snout
  • less extensive olfactory epithelium
  • humans and chimps have poor sense of smell vs dogs who have a really good one
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33
Q

What is different about olfaction in snakes?

A
  • Vomeronasal organ on roof of mouth
  • detects non air-borne molecules
  • snake flicks tongue to transfer molecules to organ
  • greatly reduced in primates (humans and chimps)
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34
Q

In marine teleosts, how is water lost? What was used to conserve water?

A
  • water lost through body and respiratory surfaces, kidneys

- scales were used to prevent water loss in fish

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35
Q

In tetrapod evolution, what happens to scales?

A
  • scales were lost early in tetrapod evolution except for scales on belly
  • scales were used to prevent water loss in fish
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36
Q

How do tetrapods control water conservation?

A
  • epidermis of early tetrapods resembled extant amniotes
  • keratin produced by epidermal cells
  • outer layer (stratum corneum) several layers deep to protect against abrasion and some water loss
  • most water loss reduced by lipids in skin
  • thin glandular skin of amphibians likely derived
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37
Q

Other than dehydration, why is it important for tetrapods to control water loss? How does it compare to aquatic organisms?

A
  • water also needed to get rid of ammonia, a toxic waste product of digestion
  • kidneys adopt additional role of nitrogen excretion
  • aquatic organisms get rid of ammonia via gills
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38
Q

How does temperature regulation on land differ to water?

A
  • Temperature not as stable on land
  • But patchier, better for organisms to find different patches of microhabitats (like shade, cave)
  • And lower heat conductivity means animals can maintain body temperatures different from air (in water, heat is whisked away from body)
  • Behavioural control of temperature in ectotherms (lizards)
  • Independent evolution of endothermy in birds, mammals
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39
Q

How did tetrapods originate (their precursors)?

A
  • precursors=tetrapodomorph fishes or fishapods
  • related to sarcopterygian fishes
  • fishapods=intermediate
  • With new discoveries, gap between extant fishes and tetrapods narrowing
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40
Q

What does “tetrapod” mean?

A

four feet

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41
Q

What are synapomorphies of tetrapods?

A
  • hands and feet with digits

- fin rays lost

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42
Q

Name two subdivisions of the “Fishapods.” What do they both have in common?

A
  • Osteolepiforms
  • Elpistostegalids (Panderichthys)
  • still very fish-like
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43
Q

Which has more derived characters, Panderichthys or Osteolepiformes?

A

Panderichthys more derived due to:

  • Loss of dorsal and anal fins
  • reduced caudal fin
  • Flat heat, long snout with eyes on top of head
  • Stronger “forelimbs”
  • Likely shallow water predators
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44
Q

Elpistostegalids: characteristics

A
  • likely sister group to tetrapods, not direct ancestor
  • Still with fin rays, well-developed gills, poorly ossified vertebrae
  • Loss of operculum (could raise its head)
  • Lungs and gills still well developed, but no opercular bones
  • Long snout
  • Large ribs (could likely support body at least partially on land)
  • Pectoral fin could bend in middle
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45
Q

What is Tiktaalik?

A
  • an Elpistostegalid (a fishapod subdivision)
  • “Spectacular new find” from Ellesmere Island (2006), transitional fossil
  • Tiktaalik=“a large freshwater fish seen in the shallows” (Inuktitut)
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46
Q

What can be said about the earliest tetrapods and the discoveries made about them?

A
  • with limbs
  • from late Devonian Trackway
  • stride length suggests body 85 cm long
  • no drag marks from tail
  • ripple marks indicate shallow water
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47
Q

Name two Stem Tetrapods.

A

1) Acanthostega

2) Ichthyostega

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48
Q

Acanthostega: facts

A
  • Stem Tetrapod (not a single lineage; these “fishapods” did not evolve directly into tetrapods)
  • Likely primarily aquatic
  • MOST fish-like
  • Transitional form from water to land
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49
Q

Acanthostega: fish-like characteristics

A
  • Caudal fin with dermal rays
  • Lateral line
  • Scales
  • Gills likely internal and covered with soft-tissue operculum
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50
Q

Acanthostega: other transitional characteristics

A
  • Had lungs but ribs too short to support chest cavity on land
  • Scales only on belly
  • Perhaps some cutaneous respiration
  • More muscular neck
  • Morphology of teeth and skull suggest ‘terrestrial-style’ feeding
  • Webbed digits on each hand and foot
  • But front foot could not be brought into weight-bearing position, likely more for paddling
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51
Q

Ichthyostega: facts

A
  • Stem Tetrapod (not a single lineage; these “fishapods” did not evolve directly into tetrapods)
  • less fish-like than Acanthostega
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52
Q

Ichthyostega: fish-like characteristics

A
  • Caudal fin with dermal rays but reduced
  • Traces of lateral line and scales
  • Ear specialized for underwater hearing
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53
Q

Ichthyostega: other transitional characteristics

A
  • Limbs likely weight bearing
  • Pectoral and pelvic girdles better adapted to land (pectoral girdle free of skull)
  • More supportive ribs, stronger vertebrae with more developed zygapophyses
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54
Q

How did tetrapods evolve characteristics in an aquatic environment?

A
  • Tetrapods predated terrestrial vertebrates
  • Anatomical changes could have been advantageous in shallow water (Air-breathing, Limbs for support and lunging at prey in weedy water, Development of distinct neck and longer, flatter snout)
  • Ability to migrate overland between adult and juvenile habitats or to deal with drought, bask in sun, etc.
  • Not “preadaptations” that occurred in anticipation of life on land
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55
Q

Who are the non-amniotic tetrapods?

A
  • Extant non-amniotic tetrapods = amphibians
  • But non-amniotic tetrapods once much more diverse
  • Larger, more crocodile-like with dermal scales
  • Uncertain relationships among lineages
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56
Q

Why is there uncertainty in the relationships among lineages of the non-amniotic tetrapods?

A
  • Missing critical piece of fossil record for 20–30 my (“Romer’s Gap”)
  • When major tetrapod groups were undergoing rapid diversification
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57
Q

What are the two major lineages of the tetrapods 350 mya?

A

1) Batrachomorphs

2) Reptiliomorphs

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58
Q

Batrachomorphs

A
  • Major lineage of non-amniotic tetrapods
  • “frog form”
  • Flat, immobile (akinetic) skulls
  • Includes temnospondyls = -Largest and longest-living group of extinct non-amniotic tetrapods
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59
Q

Reptiliomorphs

A
  • Major lineage of tetrapods 350mya, both non-amniotes and amniotes
  • “reptile form”
  • Taller, narrower (domed) skull and cranial kinesis
  • Includes “stem amniotes” which were non-amniotic
  • First possible amniotes in fossil record only 20my after first known tetrapod
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60
Q

What are the lepospondyls and what is their relationship with other Tetrapod groups?

A
  • Mostly small, elongate, primarily aquatic tetrapods
  • Some lizard-like, many limbless
  • relationship with other tetrapods uncertain
  • Intermediate characteristics between temnospondyls and “stem amniotes”
  • Origin of modern amphibians (Lissamphibia) debated
  • Some suggest that frogs and salamanders derived from temnospondyls and caecilians are derived from lepospondyls
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61
Q

Lissamphibians

A
  • Salamanders, anurans (no tail), caecilians
  • extant amphibians -“Liss=smooth”
  • Smooth, permeable skin=apomorphic (derived) trait
  • Many extinct non-amniotes with bony scutes
  • > 6000 extant spp.
  • Monophyly doubted by some
  • But generally identified as monophyletic due to presence of several synapomorphies
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62
Q

Which of the Lissamphibians based on characteristics is often the “odd man out”?

A

Caecilians

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63
Q

Identify amphibian synapomorphies.

A

1) thin glandular skin used in cutaneous respiration
2) structural characteristics of inner ear
3) retinal cell (green rods) in eyes
4) levator bulbi muscle of the eye

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64
Q

Amphibian synapomorphy: thin glandular skin

A
  • used in cutaneous respiration (gas exchange through skin)
  • temperature regulation
  • osmoregulation
  • escape from predators
  • but lungs more important when temperatures and activity levels are high
  • Mucous glands keep skin moist since dry skin less permeable to gases
  • Only some caecilians with residual scales
  • Moist skin also important for temperature regulation (overheat if skin dries out=can’t osmoregulate)
  • sodium uptake at skin (for osmoregulation in freshwater)
  • Most require moist micro environments
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65
Q

Amphibian synapomorphy: structural characteristics of inner ear

A

a. Papilla amphibiorum
- Patch of specialized hair cells in inner ear sensitive to low frequencies
b. Operculum-columella complex (equates to Weberian apparatus)
- Bones involved in transmitting sounds to inner ear
- Connection to pectoral girdle allows low-frequency sounds to be transmitted from ground via forelimbs (frogs and salamanders)
* This connection absent in limbless caecilians

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66
Q

Amphibian synapomorphy: Retinal cell (green rods) in eyes

A
  • in frogs and salamanders

- lacking in mostly-blind caecilians

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67
Q

Amphibian synapomorphy: Structure of levator bulbi muscles of the eye

A
  • Modified in caecilians to retract tentacles

- Outward bulging eyes cause buccal cavity to enlarge

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68
Q

Name the three groups of Lissamphibians.

A

1) salamanders
2) anurans
3) caecilians

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69
Q

Class Lissamphibian: Order Caudata or Urodela: Salamanders

A

-All elongate, most with long tail
-caud, uro=tail
-Almost all with 4 limbs (exception: some Sirenidae)
-Locomotion likely similar to ancestral Tetrapod = undulation of trunk
-600 species
Ex) Rusty mud salamander

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70
Q

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Family Sirenidae

A
  • 4 species
  • Aquatic salamanders
  • External gills
  • Lack pelvic girdle and hind limbs
  • Have forelimbs
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71
Q

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Family Cryptobranchidae

A
  • “hidden gills”
  • Includes Japanese and Chinese giant salamanders (largest) and North American hellbenders
  • All are permanently aquatic and paedomorphic (don’t undergo metamorphosis)
  • have lateral line (only useful in water), no eyelids in adults (only terrestrial)
  • But without external gills
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72
Q

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Family Proteidae

A
  • mudpuppies and European olm (cave dweller)
  • One in Manitoba, the common mudpuppy
  • Aquatic, paedomorphic, with external gills
  • Large due to being aquatic
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73
Q

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Congo eels

A
  • 3 species
  • Aquatic but adults without gills due to well-developed lungs
  • Can estivate (dormancy during hot or dry periods) for up to 2 years
  • Have tiny limbs
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74
Q

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Mole salamanders

A

-3 species in Manitoba

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75
Q

Class Lissamphibian: Order Caudata or Urodela: Salamanders: Family Plethodontidae

A
  • “Lungless” salamanders
  • Cutaneous respiration only
  • 400 spp.
  • Most fully terrestrial, Some aquatic, Some cave-dwelling, arboreal
  • Some can drop tail as predator-defense mechanism
  • Many plethodontids can protrude tongue considerable distances
  • Have adapted hyobranchial apparatus for feeding (Essential part of buccal pump in other salamanders, Elongated and lightened for protrusion of tongue, Conflicting needs for respiration vs feeding)
  • good vision to catch moving prey (binocular vision)
  • Some with direct development
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76
Q

How are different families or divisions of Anurans organized?

A

-organized by their abilities, locomotion, structure, habitat, but NOT based on ancestry

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77
Q

Class Lissamphibian: Order Anura: Anurans

A
  • 5400 species
  • all continents except Antarctica
  • different groups often distinguished by locomotory specializations
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78
Q

Anurans are organized into what subdivisions?

A

1) frogs
2) toads
3) semi-aquatic frogs
4) tree frogs

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79
Q

Class Lissamphibian: Order Anura: Anurans: “Frogs”

A
  • 8 species
  • specialized for jumping
  • Long hind legs; tibia and fibula fused
  • Pelvis attached to stiffened vertebral column
  • Pelvis and urostyle keep posterior trunk rigid
  • Forelimbs and pectoral girdle absorb impact
  • Often sedentary ambush predators
  • Camouflaged, generally lack chemical defenses
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80
Q

Class Lissamphibian: Order Anura: Anurans: “Toads”

A

-4 species
-Not monophyletic
-Convergent adaptations to dry environments
-Shorter legs, heavy bodies, leathery skin
-Wide-ranging predators
-Many with poison glands
(Cane toad or psychoactive toad)

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81
Q

Class Lissamphibian: Order Anura: Anurans: Semi-aquatic frogs

A
  • Streamlined, webbed toes, lateral line in adults
  • e.g., African clawed frog
  • Use section to engulf food
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82
Q

Class Lissamphibian: Order Anura: Anurans: Tree frogs

A
  • Over 1000 species in many different families
  • Not monophyletic
  • Often walk and climb on 4 legs
  • Enlarged toe disks with mucous glands for adhesion
  • Surface tension and viscosity
  • 4 species in Manitoba
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83
Q

Class Lissamphibian: Caecilians

A
  • Caecus = blind
  • Skin or bone over eyes, sometimes without eyes
  • a.k.a. Gymnophionans (“naked snake”) or apodans (“without feet”)
  • 170 species
  • Tropical, generally burrowing
  • Some species with scales in dermal folds (annuli)
  • Protrusible tentacles also unique to amphibians
  • Structures associated with eyes of other amphibians associated with tentacles (Retractor muscles and Lubricating gland)
  • Feed on small or elongate prey (e.g., termites, earthworms)
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84
Q

What are the origins of modern amphibians like the anurans, urodela and caecilians?

A
  • caecilians diverged from anurans and urodela more than 300 mya
  • clade is consistent with polyphyletic origins from spearated groups of Paleozoic tetrapods
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85
Q

Biphasic

A

has two life stages (one aquatic, one terrestrial)

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86
Q

Indirect development vs direct development

A

Indirect development: has complete metamorphosis in life cycle, has larval stage
Direct development: skip larval stage

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87
Q

In general. most amphibians have what type of life cycle and reproduction method? However, some amphibians show what other reproductive lifecycles or reproduction method?

A

general: biphasic lifecycle with indirect development, oviparous
others: direct development, paedomorphic, viviparous

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88
Q

Paedomorphic

A
  • retain larval characters

- skip metamorphosis

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89
Q

Oviparous vs Viviparous

A

Oviparous: lay eggs on land or in water
Viviparous: live birth, retain egg and give birth to metamorphosed young

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90
Q

True or false? Some amphibians show sign of parental care?

A

True. Some carry or guard their eggs or hatchlings

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91
Q

What kind of reproduction is seen in Anurans?

A
  • biphasic lifecycle, indirect development
    1) aquatic tadpole
    2) metamorphosis
    3) half tadpole-half frog stage
    4) terrestrial adult frog
  • 20% of anuran species are direct developers
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92
Q

How are the tadpoles of Anurans different than the adult frog?

A
  • Aquatic tadpole morphologically, ecologically very different from adult terrestrial frog
  • Tadpoles of most species filter feeding herbivores, adults carnivores
  • Exploit seasonal spring bloom of primary productivity, but ponds/algal blooms not reliable year-round
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93
Q

How is metamorphosis in Anurans different than lampreys?

A

Anurans:

  • stimulated by thyroid hormones
  • tadpole structures broken down and rebuilt
  • legs appear, tail regresses
  • small mouth replaced with large mouth
  • long gut of herbivore replaced with short gut of carnivore
  • rapid
  • indirect development
  • lay eggs in ponds and then live on land

Lamprey:

  • very slow
  • Ammoceote larva, so indirect development
  • lay eggs in freshwater but live in salt water (anadromous)
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94
Q

In which phase of the Anuran lifecycle is the organism most vulnerable to predation?

A

-shortest phase and most vulnerable is the half-tadpole half-frog phase

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95
Q

Anuran reproduction: Internal vs external fertilization

A
  • External fertilization in most species since not as successful on land, it relies on water
  • Internal fertilization in some (on land, ex=tailed frog)
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96
Q

Lecithotrophic

A

Embryo receives no additional nutrition other than that provided by the yolk of the egg

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97
Q

Matrotrophic

A

embryo receives additional nutrition from the mother and yolk of the egg

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98
Q

How many Anuran species are known to be matrotrophic?

A

only two known species

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99
Q

In which situation is breeding in Anurans prolonged or explosive?

A

explosive=in temporary ponds

prolonged=males establish territory and compete for mates by vocalizing

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100
Q

Anurans generally produce larger eggs. What advantages and disadvantages come with this?

A

advantages: better survival
disadvantages: require longer to hatch and have greater exposure to predators

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101
Q

Anurans have evolved what type of behaviours to protect the eggs and tadpoles?

A
  • tree frogs laying eggs on leaves overhanging water
  • foam nests produced during amplexus (mating method for external fertilization), tadpoles secrete enzymes that dissolves the foam
  • in bromeliads (in plants)
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102
Q

What are some examples of male Anurans showing parental care?

A
  • African bullfrogs guard eggs and tadpoles
  • midwife toads gathers strings of eggs around hind legs
  • Darwin’s frog carries eggs and embryos in vocal pouches; emerge fully-developed
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103
Q

What are some examples of female Anurans showing parental care?

A
  • many tree frogs carry eggs on back
  • eggs covered over by skin of Surinam toad; emerge post-metamorphosis
  • in stomach of two Australian species (gastric brooding), Both extinct?Possibly because can’t feed while brooding
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104
Q

Most salamanders have what type of reproduction? Some others like the Cryptobranchidae and Sirenidae have what type of reproduction?

A

most: internal fertilization

some like Cryptobranchidae and Sirenidae: external fertilization (due to being aquatic)

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105
Q

What method of reproduction do salamanders have that we haven’t seen yet?

A
  • use of spermatophores
  • no intromittent/ external male organ
  • Females may pick up spermatophore with cloaca
  • Or male may insert spermatophore into cloaca with feet
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106
Q

What are important concepts when salamanders reproduce with each other?

A
  • Courtship patterns, secondary sexual characteristics, and pheromones important
  • Involves male rubbing pheromones onto nose of the female
  • Sexual dimorphism within species
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107
Q

Sexual dimorphism

A

the differences in appearance between males and females of the same species, such as in colour, shape, size, and structure

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108
Q

Spermatophore

A

a protein capsule containing a mass of spermatozoa, transferred during mating

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109
Q

What are the differences in the aquatic larvae of salamanders who do indirect vs direct development?

A

Indirect development: Most salamanders lay eggs in water which hatch into gilled aquatic larvae prior to metamorphosis
Direct development: Although some families (e.g., Plethodontidae) bypass aquatic larval stage, Gills reabsorbed before hatching, Conflict between larval feeding (suction) and adult feeding (projectile tongue) so loss of the lung

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110
Q

Are most salamanders oviparous or viviparous?

A
  • most are oviaprous

- few are viviparous (ex-genus Salamandra)

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111
Q

Which paedomorphic (larval characteristics) are retained in a number of salamanders?

A
  • gills

- lateral line

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112
Q

What are some examples of obligate and facultative paedomorphic salamanders? What is this dependent on?

A
  • Obligate in Cryptobranchidae, Proteidae, and most cave species
  • Facultative in some, e.g., mole salamander
  • depends on environment!
  • Metamorphic phenotype predominates in temporary ponds
  • Paedomorphic phenotype in permanent, fishless ponds
  • Same species = developmental plasticity
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113
Q

How do Caecilians reproduce?

A
  • All with internal fertilization with intromittent (external male) organ
  • Some species lay eggs and females brood the eggs
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114
Q

Are Caecilians oviparous or viviparous?

A
  • 25% oviparous

- 75% viviparous

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115
Q

How do the young caecilians receive nutrition? How do they develop inside the mother?

A
  • Young feed on special outer layer of mother’s skin = matrotrophic
  • Embryos get nutrition by scraping oviduct walls with specialized teeth; epithelium produces ‘uterine milk’
  • oviduct walls highly vascularized
  • Gas exchange through close contact with fetal gills and vascularized ovarian walls of the mother
  • Gills absorbed before birth
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116
Q

Caecilians are direct or indirect developers?

A

all direct developers (no larval stage)

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117
Q

Why do amphibians have mucus on the skin and mucous glands?

A
  • to keep skin moist for cutaneous respiration
  • Antibacterial activity (eg. Xenopus skin secretions)
  • May make skin slippery (to protect from being captured)
  • Some species with adhesive mucus (Eg. Some salamanders)
  • Deters predation
  • Some species with toxic or irritating mucus secretions
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118
Q

Where are poison glands located and what are their functions in amphibians?

A
  • Concentrated on dorsal surface
  • Primary chemical defense
  • Some extremely toxic
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119
Q

Which is the most toxic amphibian?

A

-poison dart frogs
family Dentrobatidae
Golden Dart Frog
-Diurnally-active, brightly-coloured frogs
-has batrachotoxin (alkaloids)
-Single frog with enough poison to kill 10 people if enters body through cut or if eaten raw
-Captive-bred animals without significant levels of toxins when fed different diet

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120
Q

How are some frogs poisonous?

A
  • over 200 different alkaloids
  • batrachotoxin from golden dart frog
  • most alkaloids obtained from prey (ex-ants)
  • sometimes modified to make more toxin
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121
Q

What kind of habitats do most amphibians live in?

A
  • Most amphibians in moist habitats, microhabitats
  • But some amphibians (especially anurans) in arid habitats
  • Different families with convergent adaptations
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122
Q

What kind of habitat adaptation was taken up by the spadefoot toad in Sonoran and Chihuahuan deserts for water conservation?

A
  • burrowing toads
  • Spend 9-10 months of year in moist underground
  • Emerge only during rainy season to feed, grow, reproduce
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123
Q

What kind of adaptation was taken up by the tree frogs for water conservation?

A
  • In more humid understory vegetation
  • many species with skin 1/10th less permeable to water than most other frogs
  • Some use legs to spread lipid secretions from dermal glands over body (“frog wax”)
  • Behavioural control of evaporative water loss: water-conserving posture of tree frogs, during dry conditions, they get into smaller posture to reduce surface area and lower the amount of water lost
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124
Q

How many amphibian species in Manitoba exist that have overwintering habits?

A

16 species=
4 Salamanders
12 anurans

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125
Q

A manitoban salamander, the Mudpuppy survives the winter how?

A
  • Paedomorphic
  • Remains active in permanent bodies of water
  • One that doesn’t freeze to the bottom during the winter
126
Q

How do other amphibian species survive the Manitoba winters?

A

1) freeze-avoidance:
- Aquatic hibernators (northern leopard frog, green frog, mink frog)
- Rely on cutaneous respiration all winter in the water
- Skin pinker=more blood to skin
- Eyes protected by nictitating membrane
- Terrestrial hibernators beneath the frost line (salamanders and toads)
2) freeze-tolerance:
- 4 frog species (e.g., gray treefrog, wood frog)
- Allow ice to form within body wall
- But glucose or glycerol prevent vital organs from freezing
- Can withstand temperatures as low as -6oC

127
Q

What can be said about the evolution of the first possible amniote?

A
  • in fossil record only 20my after first known tetrapod
  • small animals
  • carnivorous on insects
  • timing of evolution of amniotic eggs (synapomorphy) inferred from branch time between two main amniotic lineages: saurospida (reptiles and birds) and synapsida (mammals)
128
Q

What are the two main amniotic lineages?

A

1) saurospida (reptiles and birds)

2) synapsida (mammals)

129
Q

What are some synapomorphies of amniotes?

A
  • amniotic egg
  • three additional membranes that form outgrowths of embryo body wall (all vertebrates have extraembryonic membranes enclosing yolk sac)
  • produced by female reproductive tract
130
Q

What are the three additional membranes that form around the embryo body wall in amniotes (egg-laying and viviparous animals)?

A

1) chorion: outer membrane surrounds entire contents of egg
2) amnion: inner membrane surrounds embryo only
3) Allantois: develops as outgrowth of hindgut, storage for nitrogenous wastes, urinary bladder grows from the base, serves as respiratory organ during later embryonic development, vascularized

131
Q

True or false? Embryonic membranes of placenta in livebearing mammals are analogous with those in amniotic egg.

A

False. Embryonic membranes of placenta in livebearing mammals are homologous with those in amniotic egg.

132
Q

What are the advantages of amniotic eggs over the amphibian eggs?

A
  • not necessarily essential for development on land but may have allowed for larger egg and embryo size
  • shell provides mechanical protection while porous for gas exchange and water vapour
  • albumin and yolk provide water, protein and energy
  • membranes improve gas exchange and nutrition
  • intra-egg transport of food and gases allows for larger eggs
133
Q

The three additional membranes in amniotes is a huge advantage in what sense when talking about their overall function?

A
  • membranes improve gas exchange and nutrition

- intra-egg transport of food and gases allows for larger eggs

134
Q

The leathery and flexible shelled eggs are seen in which amniotes? What about the calcified and rigid shells?

A
  • leathery and flexible=lizards, turtles, monotreme

- calcified and rigid=birds and crocodiles

135
Q

What other features are seen in amniotes?

A
  • waterproof skin: thicker skin with keratin and lipids in epidermis, not used for respiration, more skin elaborations (scales, feathers, hair)
  • costal (rib) ventilation of lungs: negative pressure aspiration pump draws air into lungs, permits longer neck, provides space for elaboration of nerves to forelimb, improves control of forelimbs and ability for manipulation
  • direct development: no external gills at any point, no lateral line
136
Q

How are amniotes classified?

A
  • classified by patterns of temporal fenestration
    1) anapsid
    2) diapsid
    3) synapsid
137
Q

Anapsid

A
  • “without junction”
  • solid skull with no temporal fenestrae
  • in primitive amniotes and turtles
  • secondary loss of temporal fenestrae in turtles
138
Q

Diapsid

A
  • “two junctions”
  • two temporal fenestrae
  • birds and other reptiles
  • many modifications associated with increased flexibility in snake skull and birds with heavily restructured skull
139
Q

Synapsid

A
  • “shared or joined junction”
  • single temporal fenestra
  • mammals and their relatives
140
Q

What is the function of the temporal fenestrae? How did it likely arise?

A
  • provide increased attachment area for jaw musculature
  • likely arose independently in diapsids and synapsids
  • different forms likely related to different feeding styles
141
Q

The early division of amniotes resulted in what two lineages?

A

1) synapsids (mammals)
2) sauropsids (reptiles, dinosaurs, birds)
- parallel independent evolution

142
Q

What amniote characteristics had independent parallel evolution during the early division of synapsids and sauropsids?

A
  • rapid, sustained locomotion
  • powered flight
  • complex social behaviour
  • endothermy
  • but often with different solutions to same challenges of life on land
143
Q

What is the challenge in sustaining locomotion on land?

A
  • need steady supply of oxygen
  • anaerobic for short sprints
  • use of axial muscles for bending trunk conflicts with ability to compress rib cage to ventilate lungs
  • need to keep trunk rigid and use limbs for propulsion
144
Q

What are the solutions in sustaining locomotion on land for synapsids?

A

1) limbs underneath trunk
2) development of diaphragm (contraction increases volume of pulmonary cavity to draw in air, complements rather than conflicts with locomotion, aided by movement of viscera)

145
Q

Where are the limbs underneath the trunk for locomotion on land first seen?

A

-first seen in theraspids, non-mammalian synapsids

146
Q

What are the solutions in sustaining locomotion on land for sauropsids?

A

1) no diaphragm
2) use pelvic movements (crocodilians, movement of liver also helps change volume of trunk, anterior movement of viscera forces air out of lungs)
3) bipedalism (birds, dinosaurs) minimizes trunk movement

147
Q

Bipedalism

A

-movement on the two rear limbs or feet

148
Q

What are challenges in increasing gas exchange for locomotion on land?

A
  • simple lungs in amphibians so rely on cutaneous respiration for additional supplement of oxygen
  • due to high levels of activity on land, need more oxygen
149
Q

What are some solutions to increase gas exchange for locomotion on land for synapsids?

A
  • alveolar lungs
  • tree-like pattern of branching airways ending in alveoli to increase surface area
  • still tidal ventilation since air is so much less dense than water
150
Q

What are some solutions to increase gas exchange for locomotion on land for sauropsids?

A
  • faveolar lungs
  • small chambers lining airway
  • simple in most lizards, although extensive faveolar subdivisions in active monitor lizards
  • still tidal ventilation
151
Q

How do birds increase gas exchange for locomotion in the air?

A
  • High activity and high altitude (low oxygen content) needs to be more efficient
  • Pneumatic bone (due to air sacs) makes bones lighter
  • have system of air sacs
  • poorly vascularized
  • store air during parts of respiratory cycle
  • two cycles required to move unit of air through lung
  • one way air flow through lung
  • air capillaries run opposite direction to blood flow =crosscurrent or countercurrent exchange to increase efficiency of gas exchange and allows birds to breathe at high altitudes
  • one way flow of air through lungs also minimizes dead space or residual air (stale air left in system with each breath)
  • maintains gradient of oxygen still higher in air than blood (makes it more efficient)
152
Q

Crosscurrent or countercurrent exchange

A
  • air capillaries run in opposite direction to blood flow
  • increases efficiency of gas exchange
  • allows birds to breathe at high altitudes
  • maintains oxygen gradient higher in air than in the blood, making it more efficient
153
Q

What allow birds to breathe at high altitudes?

A

-crosscurrent or countercurrent exchange (air capillaries run in opposite direction to blood flow)

154
Q

The pneumatic spaces in the saurischian dinosaur fossils suggests that “longnecks” also had what time of respiratory system?

A
  • one-way air flow

- due to amount of dead space that increases with a longer neck, this system minimizes the dead space

155
Q

Which other organism has one-way flow of air like birds and dinosaurs?

A

crocodilians

156
Q

Why would sauropsids have developed the one-way air flow system?

A

-sauropsids likely evolved when oxygen levels were low

157
Q

What is a challenge with transporting oxygen to muscles on land?

A
  • high blood pressure needed

- forces plasma from capillaries into air spaces, which reduces gas exchange

158
Q

What is a solution for transporting oxygen to muscles on land by amniotes in general?

A
  • maintain different blood pressures in systemic and pulmonary systems by separation of the ventricle
  • blood pressure in the left ventricle is higher
159
Q

What is a solution for transporting oxygen to muscles on land by primitive amniotes?

A

-blood flow likely directed by internal structure (spiral valve)

160
Q

What is a solution for transporting oxygen to muscles on land by extant amniotes?

A
  • transient (short time) separation of oxygenated and deoxygenated blood when heart contracts (turtles and lizards)
  • fixed barrier (crocodiles, birds, mammals)
  • anatomical differences in heart suggest that this solution independently derived in two lineages
161
Q

The embryos of both the synapsid and sauropsid lineages have two systemic arches. They are derived from what?

A

Synapsid: principal systemic arch derived from left aortic arch
Sauropsid: derived from right aortic arch

162
Q

Compare the sensory systems and social behaviours of synapsids vs sauropsids.

A

synapsids:
-good olfaction and poor vision (primates are an exception)
-reflected in behaviours like scent-marking territorial behaviours in mammals
Sauropsids:
-good vision but poor smell
-territorial displays use colour and pattern (lizards, birds)

163
Q

Why is the class “reptilia” or “reptiles” considered paraphyletic?

A
  • Because it excludes birds
  • birds also a descendant from common ancestor to all reptiles
  • crocodiles and birds are sister taxa
164
Q

Sauropsid: Order Testudines: How many turtle species are there?

A

300 species

165
Q

Sauropsid: Order Testudines: What are the two extant lineages?

A

1) Pleurodira

2) Cryptodira

166
Q

Sauropsid: Order Testudines: What is the difference between Pleurodira vs Cryptodira?

A

Pleurodira:

  • “side neck,” bend neck horizontally to retract head
  • now only in Southern Hemisphere
  • ex) Australian snake-necked turtles, South American matamata (lacks horny beak, flaps of skin sensitive to minute vibrations, feeds by suction due to being aquatic)

Cryptodira:

  • “hidden neck”
  • bend neck in vertical S shape to retract head, contract it under the spine
  • only Australia without Cryptodires
  • ex) tortoise=land turtles, Galapagos turtles, Gopher tortoise, pancake tortoise, western painted turtle (Manitoba), snapping turtle (Manitoba, soft shelled turtles (reduced ossification of shell and webbed feet), sea turtles (secondary return to aquatic environment, do migration), Cheloniidae (6 species, retain epidermal scales on shell=loggerhead and green turtles), leatherback turtle (largest extant turtle, dermal ossification reduced to bony platelets in skin, wide distribution, can dive to over 1000m deep, feed largely on jellyfish)
167
Q

Sauropsid: Order Testudines: Cryptodira: What is special about sea turtles?

A
  • particularly specialized for aquatic life (flippers)
  • Cheloniidae has 6 species like loggerhead and green turtles
  • retain epidermal scales on shell
  • secondary return to aquatic habitat
  • do migration
168
Q

Sauropsid: Order Testudines: Cryptodira: Which is the largest extant turtle?

A
  • A Cheloniidae called the leatherback turtle
  • dermal ossification reduced to bony platelets in skin
  • wide distribution
  • can dive deeper than 1000m
  • feed largely on jellyfish
169
Q

What is the phylogenetic relationship of Testudines?

A
  • testudines is monophyletic
  • shell and post-cranial skeleton unique
  • earliest turtles with shell and beak of derived turtles
  • 220 million year old fossil turtle found in 2008 with a half-shell, fully formed plastron=lived in water, underside exposed to predators, with teeth)
  • neck vertebrae specialized for retraction of head
  • evolved independently in Pleurodira and Cryptodira
  • relationship with other vertebrates not clear
170
Q

What is the conflict with placing the Testudines on the phylogenetic tree?

A
  • due to anapsid skull, originally thought to be early amniote offshoot
  • but likely secondary loss of temporal fenestrae
  • origin from within diapsid reptiles more likely due to molecular data
  • exact placement within Diapsida uncertain but complete genome suggests turtles sister to birds/crocodilians
171
Q

Is this statement true or false about turtles? Covered in bone, with limbs inside the ribs and teeth.

A

False. Covered in bone with limbs inside the ribs and horny beaks instead of teeth.

172
Q

Describe the shell and skeleton of the turtle.

A
  • carapace (dorsal shell) consists of dermal bone growing from 59 centres of ossification
  • 8 dorsal plates fused to neural arches of vertebrae
  • 8 pairs of costal bones fused to ribs
  • ribs external to pelvic and pectoral girdles
  • carapace bones covered by epidermal scales
  • plastron (ventral shell) formed mostly from dermal ossification
  • entoplastron and epiplastron derived from interclavicle and clavicle
  • processes form rigid connection between carapace and plastron
  • shell kinesis by hinges that allow lobes of plastron to close off openings (evolved many times)
173
Q

What modifications of shells can be seen in different turtles?

A
  • soft-shelled: soft for better swimming in water
  • leatherback: greatly reduced ossification
  • pancake: can squeeze in small spaces
174
Q

Carapace vs Plastron

A

Carapace: dorsal shell that consists of dermal bone (ossification) and covered by epidermal scales
Plastron: ventral shell formed from dermal ossification

175
Q

Processes of the turtle’s shell

A

processes form rigid connection between carapace and plastron

176
Q

Shell kinesis of turtles

A
  • hinges allow lobes of plastron to close off openings

- evolved independently many times

177
Q

What two circulatory circuits are seen in turtles?

A
  • pulmonary and systemic circuits (separate systems)
  • must flow in series in derived sauropsids, synapsids
  • turtles and lepidosaurs able to shift blood between pulmonary and systemic circuits
178
Q

How is the heart organized in turtles?

A
  • single ventricle with three compartments: cavum pulmonale, cavum venosum and cavum arteriosum
  • muscular ridge divides cavum pulmonale and cavum venosum when ventricle contracts
  • cavum venosum and cavum arteriosum connected by intraventricular canal
179
Q

Pulmonale

A

associated with lungs

180
Q

Describe what happens to the heart of a turtle when the atria contracts.

A

1) atria contracts
2) atrioventricular valves open (flaps of tissue cover the entry when not contracting)
3) deoxygenated blood (from body) from right atrium flows in cavum venosum
4) oxygenated blood from left atrium flows into cavum arteriosum
5) flaps from atrioventricular valves close intraventricular canal
6) oxygenated blood confined to cavum arteriosum
7) deoxygenated blood in cavum venosum passes over muscular ridge into cavum pulmonale

181
Q

Describe what happens to the heart of a turtle when the ventricle contracts?

A

1) ventricle contracts
2) blood pressure within heart increases
3) deoxygenated blood in cavum pulmonale flows first into pulmonary circuit where resistance is lower (path of least resistance)
4) muscular ridge closes off passage between cavum venosum and cavum pulmonale
5) right atrioventricular valve closes and no longer blocks intraventricular canal
6) oxygenated blood flows from cavum arteriosum into cavum venosum
7) then into aortic arches
8) blood then goes to body
9) cavum venosum alternately with deoxygenated, then oxygenated blood

182
Q

Turtles can shift blood between pulmonary and systemic circuits. How?

A
  • increase resistance in pulmonary circuit using muscles that narrow blood vessel diameter
  • some deoxygenated blood bypasses lungs
183
Q

Turtles can shift blood between pulmonary and systemic circuits. Why?

A
  • adjust to changes in respiratory needs
  • bypass lungs during breath-holding (“ration” out oxygenated blood)
  • ex) during underwater diving and when drawn into shell
184
Q

How do land turtles do respiration?

A
  • ribs not used to ventilate lungs since they are fused to rigid shell
  • use contraction of abdominal muscles
  • lungs attached dorsally and laterally to carapace, and ventrally to connective tissue sheet and viscera (weight of viscera keeps sheet stretched downward)
  • muscle contraction allows viscera to settle downward, drawing air in
  • muscle contraction forces viscera upward and air out
  • but can’t inflate lungs when head and legs inside shell (can only do it for so long before they have to breath in again)
185
Q

How do aquatic turtles do respiration?

A
  • hydrostatic pressure helps ventilate lungs
  • some gas exchange directly from water
  • especially in pharynx and cloaca
  • ex) Fitzroy river turtle: rarely surfaces to breathe, fimbriae and microfimbriae give huge surface area
186
Q

Are turtles short or long-lived?

A

long lived, especially larger species

187
Q

How do terrestrial turtles regulate temperature?

A
  • behaviour helps stabilize body temperature
  • terrestrial turtles move between shade/sunlight
  • large turtles heat and cool more slowly (thermal inertia)
  • can be harder to find large enough microhabitats for them since when hot and dry there can be competition for shade
188
Q

How do freshwater turtles regulate temperature?

A
  • behaviour helps stabilize body temperature
  • bask on rocks and trees
  • UV light helps activate vitamin D, necessary for Ca deposition
  • ex) musk turtles have reduced plastron for climbing
189
Q

How do large marine turtles regulate temperature?

A
  • can maintain body temperature considerably above ambient
  • ex) green turtles up to 37 in 20 degree water
  • ex) leatherback turtles with countercurrent arrangement of blood vessels in flippers
190
Q

How do turtles do social behaviour and courtship?

A
  • visual, tactile, olfactory and auditory signals important
  • species specific colour patterns (species recognition during courtship)
  • pheromones produced by subdentary glands of tortoises
  • fecal pellets may serve as territorial markers
  • biting, ramming, hooking and head movements establish dominance
  • epiplastrin on males used as a hook to flip over other males
191
Q

How do turtles eat?

A
  • no teeth, have horny beak
  • can’t sick out tongue
  • good night vision
  • omnivorous generally but juveniles more carnivorous than adults
  • Hawksbill turtles feed on sponges
  • Leatherbacks largely on jellyfish
  • green turtles only herbivorous sea turtles
192
Q

Are turtles oviparous or viviparous, and indirect development or direct development?

A
  • oviparous, large eggs with 40-60 days to hatch
  • eggs can have rigid shells (tortoises, softshell turtles) or soft flexible shells (sea turtles, snapping turtles, have faster development)
  • direct development
193
Q

Diapause

A

a period of suspended development especially during unfavorable environmental conditions.

194
Q

Diapause in turtles?

A
  • some do

- breed in the fall and hatch during the spring

195
Q

What affects the development of young turtles?

A

temperature and soil wetness

196
Q

What is temperature-dependent sex determination (TSD) in turtles?

A

three patterns:

1) males at higher temperatures
2) females at higher temperatures (constant or cycling)
3) females at low and high, males intermediate
- can shift from 100% males to 100% females within a narrow range of temperature

197
Q

Why do turtles do temperature-dependent sex determination (TSD)?

A
  • pattern may be related to sexual size dimorphism
  • higher incubation temperatures produce larger sex
  • better growth conditions produce sex that benefits more from being large (higher fecundity of females or territorial males)
  • poorer conditions produce sex penalized less from being small
  • temperature during middle third of development most critical (second trimester)
  • narrow range so that both sexes produced in a population under natural conditions (some warmer nests, some cooler nests)
  • soil moisture can modify temperature effect
198
Q

Which of the following is false?
A) The ventricle in the heart of turtles is divided into three compartments, the cavum pulmonale, the cavum venosum, and the cavum arteriosum.
B) When the atria contract, a muscular ridge divides the cavum pulmonale and the cavum venosum.
C) The cavum venosum and cavum arteriosum are connected by an intraventricular canal; this canal is open when the ventricle contracts.
D) Under normal conditions, deoxygenated blood in the cavum pulmonale flows into the pulmonary circuit when the ventricle contracts.
E) During diving, increased resistance in the pulmonary circuit causes some deoxygenated blood to bypass the lungs.

A

B) False. When the VENTRICLE contracts, a muscular ridge divides the cavum pulmonale and the cavum venosum.

199
Q

Why did some conservation efforts of turtles not work in some species?

A

initial conservation efforts failed when eggs incubated under uniform temperature conditions producing 100% males or females

200
Q

What behaviour is seen in baby turtles?

A
  • no parental care
  • emergence synchronized to swamp predators, stimulated by vibrations from first hatchlings
  • “run gauntlet” of predators at night
201
Q

Sexual dimorphism

A

condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs

202
Q

What behaviours are seen in females during reproduction?

A
  • females may disguise nest site
  • major breeding sites of sea turtles on isolated islands
  • often upcurrent from feeding grounds
203
Q

How do sea turtles (green turtles) navigate and migrate in the Carribean and Atlantic Sea?

A
  • move long distances between feeding and breeding areas every 2-3 years
  • four major nesting sites
  • no predators on volcanic island, but no food either, so good for nesting site
  • then females return to their natal beach (Ascension Island 2200km from Brazil
  • use variety of cues but chemosensory most important (smell of water)
  • South Atlantic equatorial current flows past Ascension Island toward Brazil
  • adults swim upstream, up odour gradient to island (hard journey but predator free zone)
  • piloting (to familiar landmarks) rather than true navigation
  • back to feeding grounds
  • newly hatched turtles may drift in current to feeding grounds (takes longer, but downcurrent so less difficult)
204
Q

How do adult loggerhead turtles migrate in the Pacific Ocean?

A
  • 6000 miles
  • journey may take up to 6 years for hatchlings
  • adults navigate back to natal Japanese beaches
  • perhaps in Southern Hemisphere also
205
Q

How do juvenile loggerhead turtles navigate?

A
  • round trip takes approximately 5-7 years
  • newly hatched turtles in Carribean use at least three cues for orientation: light, wave direction and magnetism
    1) light: crawl toward brightest light on emergence, some get confused due to lights of large cities
    2) wave direction: swim into waves to lead them into Gulf Stream, drift North along US Coast then east across Atlantic, need to decide which way to go when Gulf Stream divides because don’t want to go to cold North Sea
    3) Magnetism: to know when to turn to catch southern Gulf Stream, use 3D orientation of Earth’s magnetic field to determine direction and latitude
206
Q

Sauropsids: Superorder Lepidosaurs: facts

A
  • 8800 species
  • “scaly reptiles”
  • Tuatara (1 species)
  • Squamata: lizards (5500 species) and snakes (3300 species)
  • predominantly terrestrial
  • similarities to ancestral amniotes
207
Q

Sauropsids: Superorder Lepidosaurs: derived characters

A
  • water-impermeable, overlapping epidermal scales

- transverse (horizontal) cloacal slit

208
Q

Sauropsids: Superorder Lepidosaurs: Evolutionary relationships

A
  • monophyletic
  • traditionally sister group to archosaurs (crocodilians and birds)
  • but molecular data suggesting that turtles and archosaurs may be sister taxa
  • turtles are NOT lepidosaurs or squamates (should be in between Archosaurs and Lepidosaurs)
209
Q

Sauropsids: Superorder Lepidosaurs: Tuatara: facts

A
  • maori=”spines on back”
  • once diverse group in Mesozoic
  • only one species
  • most unspecialized extant amniote
  • only on small islands off coast of New Zealand
  • extirpated from mainland 800 years ago
  • protected in New Zealand, reintroduced into Karori Sanctuary in 2005
  • first wild hatchling discovered in sanctuary in 2008
210
Q

Sauropsids: Superorder Lepidosaurs: Tuatara: characteristics

A
  • one row of teeth on lower jaw
  • fits between two rows of teeth on upper jaw
  • parietal (third) eye=photoreceptive, involved in setting circadian and seasonal cycles
  • feeds on invertebrates, frogs, lizards and seabirds
  • nocturnal so have limiting ability to raise body temperature (most lizards are diurnal)
  • territorial
  • can live more than 100 years
  • slow metabolic rate, slow growth rate
211
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: facts

A
  • lizards and snakes
  • squamates are sister to tuatara
  • lizards are paraphyletic
  • lizards are sometimes placed in suborder Lacertilia but it is not monophyletic
212
Q

How do you distinguish a lizard from a snake?

A
  • lack of legs or limbs in the snake is not a good way to distinguish lizards from snakes
  • since there are legless lizards too
  • biggest difference is in the skull specializations that allow snakes to swallow prey larger than themselves
213
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”

A
  • 5500 species
  • sizes range from 3cm (gecko) to 3m (Komodo Dragon)
  • families: Iguanidae, Agamidae, Chamaeleonidae, Scincidae, Gekkonidae,Varanidae
214
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”: Iguanidae

A
  • 900 species
  • green and black iguanas
  • Anolis lizards (400 species, HUGE diversity!)
  • many arboreal in South and Central America (in presence of terrestrial predators)
  • large terrestrial iguanas in West Indies and Galapagos=marine iguana (absence of predators)
  • Galapagos marine iguana unique
215
Q

What diet do most lizards have?

A
  • most large lizards herbivorous (Marine and black iguanas)
  • rich gut microflora for digesting cellulose
  • exception: monitor lizards are carnivorous
  • small lizards insectivorous (geckos, chameleons)
216
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”: Agamidae

A
  • not monophyletic
  • dragon lizards, flying lizards (have extended rib cage and no powered flight like birds do), bearded dragon
  • scales modified into crests, spines, frills
  • both temperature-dependent sex determination (TSD) and genotypic sex determination (GSD)
217
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”: Chamaeleonidae

A
  • Chameleons
  • mostly arboreal
  • zygodactylous feet
  • most small lizards insectivorous
  • prehensile tails
  • projectile sticky tongue
  • specialized hyoid apparatus (bones that suspend tongue and larynx)
  • good vision (360 degree field view), eyes can move independently, gauge distance
218
Q

Zygodactylous feet

A

feet are arranged in pairs where two toes point forwards, and two to the rear

219
Q

Prehensile tail and tongue prehension and jaw prehension

A
  • tail capable of grasping to tree branches when climbing
  • tongue used to capture prey (grasp them with tongue)
  • jaw used to capture prey
220
Q

Which lizard families use tongue prehension vs jaw prehension

A

Tongue prehension: Iguanidae, Agamidae, Chameleonidae (rely on vision for prey detection, tongues for prey capture)
Jaw prehension: Varanidae, Scincidae, Gekkonidae (frees up tongue for chemoreception instead of prey capture, able to become nocturnal, invade subterranean habitats)

221
Q

The evolution of legless lizards and snakes evolved how?

A
  • evolved independently

- limb reduction evolved independently 60X in lizards

222
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”: Scincidae

A
  • Skinks
  • many with reduced limbs (evolved independently several times)
  • caudal autotomy well-developed
  • most are terrestrial insectivores
  • Northern prairie skink (only lizard in Manitoba)
223
Q

Caudal autotomy

A

dropping of the tail when scared

224
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”: Gekkonidae

A
  • Geckos
  • 2000 species, wide distribution
  • smallest lizard, only 16mm long
  • has species with reduced or no limbs
  • show caudal autotomy
  • many nocturnal
  • use vocalizations rather than visual displays
  • have vertical pupils
  • toe pads for climbing
  • ex) Legless gecko
225
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”: Varanidae

A
  • Komodo dragon and Gila monster
  • 40 species of monitor lizards
  • largest lizards, can go up to 3 metres in length
  • predatory on invertebrates and vertebrates (water buffalo, deer, goats)
  • hunting shows familiarity with prey’s behaviour and local geography, cooperation
  • lightweight skull (compared to crocodilians)
  • slashing bite delivers venom (causes hemorrhaging and shock)
  • uses positive pressure gular pump to supplement negative aspiration using axial muscles to ventilate lungs (pushes and pulls air into lungs)
  • have higher metabolic rate so need better respiratory system to be more effective in circulating oxygen
226
Q

What is special about the Gila Monster?

A
  • Family Varanidae (Lizards)
  • venomous
  • neurotoxin in saliva used medically to treat Type 2 diabetes
  • feed on rodents, eggs, juvenile birds
227
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”: Mosasaurs

A
  • extinct
  • Mesozoic lineage of marine lizards
  • Varanidae lizards or sister groups to varanidae
228
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: “Lizards”: Amphisbaenians

A
  • “worm lizards”
  • amphi=”double” and baen=walk
  • elongate legless burrowing (fossorial) lizards (squamates, NOT snakes!)
  • reduced right lung
  • capable of caudal autotomy
  • reduced pelvic and pectoral girdles, reduced eyes, heavily ossified skull for burrowing / tunneling
  • rectilinear locomotion using unique integument (skin)
  • visible annuli (rings)
  • little connection to trunk
  • skin telescopes increasing body diameter
  • used to push again and anchor against wall of tunnel
  • body can slide back and forth within integument
229
Q

How does the lung of Amphisbaenians (legless lizards) and snakes compare?

A

Amphisbaenians=reduced right lung

snakes=reduced left lung

230
Q

Fossorial

A

burrowing

231
Q

Integument

A

tough outer protective layer = skin

232
Q

How do you distinguish between a lizard and an amphibian?

A
  • absence of scales in amphibians, have thin permeable mucous skin
  • a lizard is an amniote
233
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: “snakes”: facts

A
  • monophyletic
  • phylogenetic relationship debated
  • earliest fossils from Cretaceous but snake skeletons fossilize poorly
  • hypothesis that snakes evolved from burrowing lizards (with reduced limbs and eyes)
  • ex) blind snakes, thread snakes (small burrowing (fossorial) snakes with reduced eyes, traces of pelvic girdle,snakelike braincase, represent ancestral condition, suggests that eyes of extant surface dwelling snakes redeveloped so why snakes and lizard eyes are so different)
234
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: “snakes”: Genus Titanoboa

A
  • ancient snake as long as a bus

- estimated to be 43 feet long

235
Q

What are the different families of snakes?

A

1) boidae
2) pythonidae
3) viperidae
4) elapidae
5) colubridae

236
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: “snakes”: Boidae

A
  • Boas (ex-Boa constrictor, Red tail boa, Emerald tree boa)
  • New world
  • mostly terrestrial
  • largest ones are usually aquatic or semi-aquatic since water can hold their weight (Anaconda is semi-aquatic)
  • some arboreal (Amazon tree boa)
  • more ancestral
  • a constrictor
  • vestigial pelvic girdle and residual hind limbs
237
Q

Which is the largest extant snake?

A

Anaconda

  • semi-aquatic
  • from family Boidae
238
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: “snakes”: Pythonidae

A
  • Old world pythons
  • ex) reticulated python
  • ancestral
  • vestigial pelvic girdle and residual hind limbs
  • many use both lungs
  • have python spurs (remnants of ancestor’s limbs)
  • constrictors
239
Q

What are some derived characteristics for more recent snake families?

A
  • reduced left lung
  • lost all traces of pelvic girdle
  • highly kinetic skull
  • single carotid artery
240
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: “snakes”: Viperidae

A
  • ex) pit vipers (have heat sensing pits to sense their prey in the dark), puff adders (heavy-bodied with blunt heads for burrowing), red diamondback rattlesnakes
  • venomous
  • erectable long hollow fangs
241
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: “snakes”: Elapidae

A
  • ex) Cobras, kraits, mambas, coral snakes, sea snakes ( a terrestrial tetrapod that secondarily loses its limbs and returns to the water, highly specialized for aquatic life)
  • venomous
  • hollow fangs
  • maxillae relatively immobile
242
Q

Some non-venomous snakes mimic the appearance of venomous snakes to confuse predators. How do you know if the snake is venomous or not?

A

red touching yellow=venomous

243
Q

How are sea snakes so highly specialized for aquatic life?

A
  • tail laterally flattened
  • ventral scales reduced or absent
  • dorsal nostrils with valves
  • lung extends to cloaca, involved in buoyancy regulation
  • oxygen uptake through skin
  • most viviparous rather than laying eggs on land
244
Q

Sauropsids: Superorder Lepidosaurs: Order Squamata: Suborder Serpentes: “snakes”: Colubridae

A

-1700 species
-venom glands without specialized hollow fangs
-on all continents except Antarctica
-consists of all other snakes we don’t know where to put
-ex) grass snakes, garter snakes,
king snakes, milk snakes (trunk musculature secondarily adapted for constriction, crawl slowly, rely on chemoreception),
whip snakes, racers (move quickly, visual predators),
parrot snakes (elongated arboreal snakes, large eyes)

245
Q

Snakes vs legless lizards (Amphisbaenians): Physical differences?

A
  • snakes have elongation of the body and reduction in diameter due to changes in internal anatomy
  • left lung reduced in snakes (right lung reduced in lizards)
  • gall bladder is posterior to liver (lined up instead of side to side like in lizards)
  • right kidney and gonad anterior to left
  • snakes have scales
246
Q

Snakes vs legless lizards (Amphisbaenians): Feeding differences?

A
  • legless lizards limited to eating small prey

- snakes have morphological specializations for swallowing prey larger than own diameter

247
Q

What seems to be the trend in Squamata regarding temporal arches?

A
  • first reduction and eventual loss of lower temporal arch (quadratojugal)
  • after that, further loss of upper temporal arch (squamosal and postorbital) in some lizards and snakes
248
Q

What allowed snakes to open their mouth wider?

A
  • lower and upper temporal arches are lost
  • creates streptostylic jaw suspension (strepto=twisting)
  • allows for bigger gape, speed of jaw closure, increases biting force
  • coupled with more hinge-like suture between frontal and parietal bones (humans have no hinge)
  • top of head can also bend=cranial kinesis (mesokinesis)
  • allowed switch to jaw prehension (most extreme in snakes)
249
Q

Mesokinesis

A

-or cranial kinesis
-middle of the skull in snakes can move
-allowed switch to jaw prehension
-kinesis=movement
meso=middle

250
Q

Jaw prehension is seen at the extreme in what organism? But also seen in what other organisms?

A
  • snakes most extreme

- also seen in monitor lizards, skinks, geckos

251
Q

List the organisms in order from least to most amount of motion of the jaw and head.

a) gecko
b) tuatara
c) chameleon
d) snake

A

tuatara (both temporal arches), chameleon (lost lower temporal arch), gecko (lost lower temporal arch and has mesokinesis), snake (lost both temporal arches and has mesokinesis)

252
Q

When a snake closes its mouth, how is this done so that the prey does not come shooting out of the mouth?

A
  • when closing mouth, brings tooth rows parallel

- has a 180 degree gape

253
Q

How many points of movement are in a snake’s skull?

A

8 points

254
Q

What is special about the jaws of a snake?

A
  • left and right of upper and lower jaws attached only by muscles and skin
  • both sides can move independently from each other
  • alternately holding and “walking over” prey since have no hands to push their food into mouth
  • can ingest really large prey!
255
Q

What feeding specializations are seen in snakes?

A
  • usually swallow prey headfirst
  • presses limbs against body
  • able to breathe while swallowing (like adult lamprey where it is important to breathe while attached to prey)
  • contraction of neck muscles moves food toward stomach (bending head sharply pushes prey along)
256
Q

How does a snake eat an egg?

A

1) wrap their mouth around it
2) draws it into throat
3) flexes muscles to push egg into the bony protrusions on their vertebrae
4) protrusions cause egg to collapse in on itself
5) snake carefully squeezes liquid out of egg
6) regurgitates the crushed egg shell
* very efficient and little content of egg is wasted

257
Q

What is the major difference between legless lizards (Amphisbaenians) and snakes?

A

difference in their skulls!

258
Q

What are two methods used by snakes to immobilize prey?

A

constriction and venom

259
Q

What features do snakes have to protect themselves from struggling prey?

A
  • rigid braincase

- frontal and parietal bones extend downward to entirely enclose brain

260
Q

Which snakes use constriction? How do they achieve this?

A
  • boas, pythons, some colubrids (secondary development of constriction, lost venom gland)
  • this is ancestral
  • hold prey in jaws
  • wrap one or more coils around it
  • take up slack, tightening loops each time prey exhales
  • suffocates or causes heart to stop (doesn’t squish it!)
261
Q

What is a consequence for snakes using constriction?

A
  • have short vertebrae and trunk muscles to produce loops of small diameter
  • will only produce small radius curves during locomotion
  • slow moving
262
Q

What was a conflict between locomotion and lung ventilation in ancestral amniotes?

A
  • trade off

- use of trunk muscles for lung ventilation conflicted with use for locomotion so started to use legs instead

263
Q

What was a conflict between feeding and lung ventilation in lungless salamanders?

A
  • adaptations to hyobranchial apparatus for feeding using projectile tongue conflicted with its use in lung ventilation
  • therefore, got rid of lungs and use only cutaneous respiration
264
Q

What is the Mexican black kingsnake?

A
  • a constrictor
  • powerful body
  • asphyxiates its prey
  • lacks venom
265
Q

What are the various venom-delivery systems?

A

a) opisthoglyphous
b) proteroglyphous
c) solenoglyphous
d) aglyphous

266
Q

Opisthoglyphous snake

A
  • fangs at rear of maxillae
  • solid fang or with groove
  • opistho=rear
  • glyph=sword
  • hold prey in mouth until it stops struggling
  • ex) African boomslang (Colubridae*), false viper
267
Q

Which was the first snake family to develop venom?

A

Colubrids

268
Q

Which is better to have in open habitats in North America, constriction or venom?

A

-venom because you have a faster-moving body type which is more advantageous out in the open compared to the slow moving constrictor boas that live in jungles

269
Q

How was it discovered that the African boomslang is actually venomous?

A
  • Karl Schmidt died from snake bite of the African Boomslang
  • was thought to be harmless so when it bit him, he didn’t think anything of it
  • rear-fanged snakes were not considered to be dangerous at the time
  • he made notes on the effects of the snake’s venom as they developed
  • Schmidt was found dead from respiratory arrest and cerebral hemorrhage
  • it is now found to be more toxic than front-fanged snakes
  • one of Africa’s most venomous snakes
270
Q

Proteroglyphous snake

A
  • hollow fangs
  • front of maxillae
  • protero=front
  • permenantly errect
  • short fangs
  • neurotoxin=fast acting
  • family Elapidae (cobras, African green mambas, coral snakes, sea snakes)
271
Q

Solenoglyphous snake

A
  • hollow fang
  • rear of maxillae
  • erected quickly during strike (swings forward)
  • soleno=pipe
  • longer fangs that inject venom deep into tissues
  • prey runs off and dies
  • follow scent of injured prey
  • hemotoxin=slower acting venom
  • family Viperidae (Red Diamond Rattlesnake)
272
Q

Hemotoxin vs Neurotoxin

A

Hemotoxin=slower acting venom, inject deep and find prey later (Viperidae=Solenoglyphous)
Neurotoxin=fast acting venom, short fangs, hold prey (Elapidae=Proteroglyphous)

273
Q

Aglyphous snake

A
  • have teeth, may have venom but without specialized fangs
  • unspecialized teeth for holding prey
  • ex) African pythons, blind snakes, some colubrids
274
Q

What are the contents of venom?

A
  • modified saliva
  • mixture of enzymes and other components
  • all venom with proteolytic enzymes to help speed digestion of proteins
275
Q

Most colubrids have small venom glands with venom that isn’t fatal to humans. What is the exception to this?

A

-African boomslang (Opisthoglyphous) that has a potent hemotoxin (slow acting)

276
Q

How is venom injected into the prey of elapidae snakes?

A
  • venom glands are large with tubes that empty into the hollow fangs
  • compression of adductor superficialis muscle forces venom out
  • proteroglyphous
  • spitting cobra can spit out venom at considerable distances (more than a meter), has good aim with help of spiral grooves for greater accuracy (like rifling in barrel of gun)
277
Q

What is used by snakes to detect their prey?

A
  • chemoreception
  • olfactory epithelium for airborne chemical stimuli
  • Vomeronasal organ for non-airborne (scent from wounded prey on ground) molecules that is carried to mouth by tongue
  • forked tongue helps determine direction
  • no connection between nasal passages and vomeronasal organ
  • some rely on vision (tree snakes, ambush predators where sticking out the tongue could give you away)
  • some with pit organs (pit vipers and pythons) that are infrared heat receptors for 180 degree thermal profile of prey, like night vision goggles
278
Q

How do snakes get traction for locomotion on land?

A

-ventral scales provide traction

279
Q

What are the different types of locomotion seen in snakes?

A

a) Lateral undulation (serpentine locomotion)
b) rectilinear locomotion
c) concertina
d) sidewinding

280
Q

Locomotion in snakes: Lateral undulation (serpentine locomotion)

A
  • body makes series of curves

- each curve pushes backward to move snake forward

281
Q

Locomotion in snakes: Rectilinear locomotion

A
  • alternate sections of ventral integument lifted off the ground and moved forward
  • Bends body, lifts off the ground, inches forward = like an inch worm
  • Much slower than the wide loops in lateral undulation
  • slow but effective especially on smooth surfaces
  • used mostly by heavy-bodied snakes (vipers, boas, pythons)
  • used by some to stalk prey (inconspicuous)
282
Q

Locomotion in snakes: Concertina

A
  • in narrow passages (rodent burrows)
  • presses loops in posterior part of body against wall to anchor itself
  • extends anterior part of body forward
  • best where there is insufficient space to move
  • forms smaller loops than lateral undulation
  • much slower
283
Q

Locomotion in snakes: sidewinding

A
  • primarily in deserts where sand substrate slips away during serpentine locomotion
  • raises body in loops, resting weight on 2 to 3 points
  • force is exerted downward rather than laterally so snake does not slip sideways
  • body is extended nearly perpendicular to line of travel
  • good only for small snakes in areas with few obstacles
284
Q

What is the main mode of reproduction in squamates?

A

-80% oviparous
-oviparity ancestral
-produce large eggs relative to non-amniotes
-vestigial egg tooth in some livebearers (to break out of the egg)
squamates
*in manitoba, three of five snakes are vivparous

285
Q

What can be said about the evolution of reproduction in squamates?

A
  • viviparity (with lecithotrophy and matrotrophy) evolved independently more than 100x in squamates
  • 65x where both egg-layers and livebearers in single genus
  • *10x where both single species
  • lecithotrophy and matrotrophy (true viviparous with chorioallantoic placenta)
286
Q

What are some advantages of viviparity in squamates?

A
  • female behaviour can control developmental temperature
  • particularly in cold climates since mother just has to move herself to warm her young (otherwise if Oviparous, then would have to move all her eggs)
  • In Manitoba, three of five snakes are viviparous
287
Q

What are some disadvantages of viviparity in squamates?

A
  • generally fewer clutches per year (but if oviparous then there are long incubation times that limit the clutch frequency anyway in cold climates especially
  • reduced agility of pregnant female
288
Q

Name the squamates that are egg layers.

A
  • most iguanids
  • most chameleons
  • almost all geckos
  • 55% skinks
  • most amphisbaenians
  • monitor lizards
  • Gila monster
  • *all pythons
  • milk snakes
  • rat snakes
289
Q

Name the squamates that are livebearers.

A
  • some iguanids
  • some chameleons
  • some geckos
  • 45% skinks
  • some amphisbaenians
  • *all boas
  • *all vipers
  • *some sea snakes
  • *garter snakes
290
Q

All amniotes have direct or indirect development?

A

direct development

291
Q

All squamates have external or internal fertilization? Why?

A
  • internal fertilization (fertilization necessary before shell deposition)
  • no external genetalia but males with 2 hemipenes (blind inverted cylinder exerted through vent, stored in base of tail when not in use)
  • sperm can be stored up to 6 years
292
Q

What are some examples of secondary sex characteristics seen in some squamates?

A
  • Femoral or praenal pores in many male iguanids and geckos
  • Spurs (vestigial hind limbs) in male boas, pythons (reduced or absent in females)
  • Chameleon male has horns
293
Q

Is parental care seen in squamates? What are the exceptions?

A
  • no it is rare
  • female python coils around eggs for protection and temperature regulation by shivering her trunk musculature to generate heat (up to 30 degrees celsius)
  • parental care in some livebearers like skinks where they are helping neonates escape from birth sacs
294
Q

What can be said about the reproduction of red-sided garter snakes?

A
  • good example of why storing sperm is important in females
  • not in good physiological state when fasting all winter
  • hibernate in large numbers in dens
  • best mating opportunity is when they emerge in spring
  • males rely on sperm produced in the preceding summer
  • females store sperm since eggs not yet mature
  • females mature eggs after they start feeding again following migration to feeding areas in marshes
  • females bask to increase gestation rate or young born too late in summer would be too small to survive winter
  • not known where young of year spend first winter
  • live births late July-October
295
Q

Parthenogenesis

A
  • “Virgin birth”=don’t need to reproduce with male to have young
  • seen in six lizard families and one snake
  • viable eggs without fertilization
  • produces diploid clones of mother (not a haploid egg!)
296
Q

How does parthenogenesis originate?

A
  • originate by hybridogenesis
  • two species similar enough to permit successful development
  • dissimilar enough ti disrupt meiosis and genetic recombination
  • each species may arise independently multiple times
  • most populations require pseudo-copulation to initiate egg development and maturation
  • non-gravid (not pregnant) females will assume male role
297
Q

Pseudo-copulation

A

describes behaviors similar to copulation that serve a reproductive function for one or both participants but do not involve actual sexual union between the individuals

298
Q

Name some advantages of parthenogenesis seen in some squamates.

A
  • reproductive potential twice that of parental species
  • single female able to colonize new habitat
  • may also show hybrid vigour (=heterosis) and be superior in intermediate habitats (like rats and raccoons)
299
Q

Heterosis or hybrid vigor

A

phenomenon that progeny of diverse varieties of a species or crosses between species exhibit greater biomass, speed of development, and fertility than both parents

300
Q

Facultative parthenogensis was seen recently in what squamate?

A
  • Komodo dragon

- given sex-determing system of this species, parthenogenetic offspring are all males

301
Q

If humans were capable of parthenogensis (“virgin birth”) the offspring would be all of which gender?

A

all females

302
Q

Temperature-dependent sex determination is seen in which squamates?

A
  • in skinks, geckos and agamids

- less widespread than what was seen in turtles and crocodilians

303
Q

How does temperature-dependent sex determination seen in the tuatara (a lepidosaur, NOT squamate) have implications in the conservation of its species?

A
  • attempts to establish populations on south end of South Island problematic
  • cool soil temperatures produce only females
  • but may benefit from global warming!
304
Q

What are some social behaviours commonly seen in squamates?

A
  • dominance hierarchiesm territorial, courtship
  • variety of visual (iguanids, chameleons, geckos since more brightly coloured), auditory (geckos), chemical (pheomones) and tactile signals
305
Q

How does the Anolis (Iguanidae) show social behaviour?

A
  • males have brightly coloured gular fans (throat fans)
  • species-specific colours and head and body movements
  • similar male territorial and courtship behaviours (Response=Aggression from male or submission from female)
  • Pheromones important in some iguanids
  • Femoral pore secretions
  • Secretions also absorb light in UV spectrum
306
Q

Caudal autotomy

A
  • self-amputation, can cut off their own tail
  • tuatara, some lizards (geckos and skinks), snakes
  • at distinctive fracture planes in all but 4-9 anteriormost caudal vertebrae
  • perforations for easy breaking
  • contraction of caudal muscles fracture vertebra
  • arterial sphincter muscles and venous valves close
  • severed tail twitches (anaerobic metabolism)
  • usually occurs as far posterior as possible
  • vertebrae in regenerated tail cartilaginous
  • without fracture planes
  • subsequent ruptures only possible anterior to original site
307
Q

What are some costs to autotomy of the organism’s tail?

A
  • social: lower in hierarchy

- energetic: tail is site of fat storage

308
Q

What are some adaptations made by desert lizards due to living in an extreme habitat?

A
  • dry and wide temperature fluctuations in the desert
  • chuckwalla = herbivorous iguanid
  • relies on water from plants and metabolic water
  • hibernates during winter in humid crevices
  • emerges in April to feed on annual plants
  • gains weight and stores excess water
  • maintains an osmotic concentration with nasal salt glands
  • less active in June, July (perennial plants)
  • some years, weighs less in fall than in April
309
Q

How does the Namib Desert Lizard live in its extreme habitat?

A
  • when moist air blows in from sea

- collects fog droplets off vegetation

310
Q

How does the Namib viper live in its extreme habitat?

A
  • fog forms water beads on snake’s body surface

- limited to coastal locations

311
Q

How does the Thorny devil live in its extreme habitat?

A
  • collects dew on body surface

- funnels water between scales to corners of mouth

BIOL 2210 (8 decks)

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