Exam 1 Flashcards
Current classification order for herps
1) Kingdom: Animalia
2) Phylum: Chordata
3) Subphylum: Vertebrata
4) Class: Amphibia and Reptilia
Monophyletic lineage (clade)
- composed of an ancestor and all of its descendants
- Amphibians (frogs, salamanders, caecilians)
Paraphyletic group
- includes all of the descendants of a common ancestor minus one or more monophyletic groups
- Reptilia is an example if birds are excluded
-Polyphyletic group
-consists of distantly related taxa whose last common ancestor is not a member of the group
Sister group
-adjacent branches on the cladogram
Outgroup
-outside of the reptile clade
The devonian opportunity
- about 375 mya
- there was a diversity of shallow aquatic habitats which generated a variety of unexploited microhabitats
What was the driving force behind the evolution of the tetrapods
-exploitation of new habitats during the late devonian
Tiktaalik
-missing link between fishes and walking land creatures
how do we know tetrapods are descended from lobe-finned fish
- labyrinthodont teeth (moze or labyrinth pattern of tooth surface)
- this is a characteristic not shared with other fishes
Ichthyostega
- a stem tetrapod
- basically a fish with legs
- tiktaalik
Transitioning from fish to tetrapod
1) Lungs already present for air breathing
2) Passive pump mechanism replaced by buccal-force pump
3) Joints formed (fins to limbs)
4) No more suction feeding
5) Developed elongated jaws, rudimentary ears, nasal passages, thicker skin
Morphology - fins to limbs
- joints formed in “legs” and digits formed from fin rays
- no longer supported by buoyancy in water
How did feeding change from fish to tetrapods
- skull and vertebral column become mobile
- elongated jaws develop
Origin of modern amphibians
-250-300 mya
Primitive amphibians: Lepospondyls
- labyrinthodont teeth
- simple, spool-shaped vertebrae
- primitive amphibians
- similar niches to salamanders, caecillians, lizards
Primitive amphibians: Temnospondyls
- labyrinthodont teeth
- resemble large salamanders, crocodiles
- sharp, conical teeth, l
- large fangs suggest they were predators
Carboniferous
- Age of giant amphibians
- increasingly warm, with moist terrestrial env
- this env is highly favorable for amphibians
- 360-286 mya
Gerobatrachus
- earliest fossil that can be clearly assigned to an extant modern amphibian clade
- could be link to modern salamanders
- frogmander
Triadobatrachus
- sister taxon to anura
- early triassic 245 mya
- protofrog
What generated many of the extant amphibian families
=radiation later in the Cretaceous and Paleocene
- many of these familes are essentially unchanged for epochs
- red spotted newt is example
Subclass Lissamphibia
- living amphibians
- extant amphibians fall into one of three orders (anura, caudata, gymophiona)
Traits of Lissamphibia
- smooth skin
- Pedicellate teeth
- containts poison, pheromone, and mucous glands
- shell-less eggs
- three chambered heart
- ability to elevate the eye
Anuran traits
- fore and hind limbs usually of unequal size
- usually no parental care
- external fertilization
- fused bones (tibiofibula, raidioulna)
Anuran ancestral mode
- typicall have external fertilization and lay eggs
- there is a wide diversity of reproductive modes
Typicall less than ___% of tadpoles reach metamorphosis
- 10
- due to predation
Traits of caudates
- have four limbs of equal size usually (sirens are exception)
- generally fossorial or aquatic
- internal fertilization
- aquatic or terrestrial eggs
Characteristics of gymnophiona
- eyes covered with skin or bone
- chemosensory tentacles - detects prey
Reproductive strategy of caecilians
-all have internal fertilization via phallodeum
Parental care for caecilians
- dermatophagy - young feed on mothers enriched skin cells
- grow in length x10 in one week
Devonian was the ____
- ago of fishes
- and also first tetrapods
Amniotic egg
- shared, derived character of amniotes
- shell protects against desiccation and reduces predation
What are the synapomorphies that distinguish the Amniotes?
-skull fenestrae
Some unifying characteristics of the class Reptilia
- shelled amniotic egg
- scales of epidermal origin made from keratin
- internal fertilization through a copulatory organ
- 3 chambered heart (except croc)
Reptile heart:
- occurs in all reptiles except crocodiles
- ridges on heart help oxygenated and deoxygenated blood stay separate
- 3 chambers to allow thermal flexibility
Subclass Anapsida, stem reptiles
- developed shells and attained huge sizes
- led to the modern chelonians
- includes turtles
Turtles
- only living anapsids and one of the earliest reptile lineages
- highly motile neck
- origins 220 mya
Three hypotheses of turtle origins
1) Anapsid hypthesis
2) Archosaur hypothesis
3) Lepidosaur hypothesis
Subclass Diapsida
- most species rich extant group of amniotes
- two extant groups are lepidosaurs and archosaurs
- have hemipenes, ecdysis, and transverse cloacal slit
(lepidosaurs) Order: Rhynchocephalia
- also called tuatara
- sister group to all lizards and snakes
- series of spines on nape and back
- teeth fused to jaw
- vestigial eye
(Lepidosaurs) Order: Squamata - Suborder: Lacertilla
- True lizards, squamates
- egg bearing
- most are small and insectivorous, larger species are usually herbivorous
(Lepidosaurs) Order: Squamata - Suborder: Ophidia
- Snakes
- No limbs, eyelids, or external ear
- left lung is reduced or absent
- all are carnivorous
(Lepidosaurs) Order: Squamata - Suborder: Amphisbaenia
- named after a mythical ant-eating serpent
- “to go both ways”
- mostly legless, burrow, eat inverts
Jurassic/Cretaceous (Mesozoic era)
- Age of the Reptiles
- originated ~250 mya in the Permian
End of the age of reptiles
~65 mya
- The K-T (Cretaceous-Tertiary) event
- Mass extinctions correlate with the catastrophic impacts of extra-terrestrial objects
- 70% of all species on earth went extinct
Archosaurs gave rise to the ________
- Crocodylia
- originated ~200 mya in the Triassic
- only ~23 spp today
Order Crocodylia
- eyes and nostrils set high on head
- organs remain on surface while the rest of its body is submerged
- four-champered heart
- Thecodont teeth
How to crocodiles feed
- rotational feeding on large prey
- ingest stones to help grind hard food items
- dispatch food by drowning it
Crocodile skin
-armored by sheets of abutting osteoderms
Crocodylia heart
- four chambered
- cogged valve allows blood to be shunted from right side of heart, allows intro of deoxygenated blood
Subclass Synapsida
- originated 315 mya in the Carboniferous
- Eventually led to the modern mammals
- “proto-mammals”
Crocodiles in mythology
-Sebek who symbolized viscous passions, decit, treachery, hypocrisy
Crocodile reproduction
- build nests either as mounds of rotting vegetation or in friable soils
- guard nests and may assist young
Secondary palate in Crocodylia
- Separation of the oral and nasal cavities
- allows crocs to breathe even when submerged under water
Transoceanic dispersal
- dispersal by crossing an ocean
- more common in reptiles
- rafting
Green iguana dispersal
- Rafted several hundreds of km
- Began in Guadelope and traveled to Carribean
Tortoise dispersal
- rafting
- barnacle growth after 6-7 weeks
- capable of long-term sperm storage
Transcontinental dispersal
- dispersal by crossing a continent
- land bridges
ex: ratsnakes: land bridge was mostly composed of deciduous and coniferous forests then
human-mediated dispersal
- invasive species
ex: trade, traveling vehicles
ex: cane toads, red eared sliders, bullfrogs
Vicariance
the geographical separation of a population
-creation of a geographical barrier (i.e mountain)
Reasons for different species distribution
- Pangea
- cooling/warming periods
Island gigantism
-less predators and more food
Island dwarfism
-easier to hide and less food required
Adaptive radiation
-the diversification of a group of organisms into forms filling different ecological niches
Ectotherm
- rely on solar radiation to raise body temps to a functional level
- more energy efficient
-Endotherm
-regulate body temp by metabolizing the food them eat
Pros of ectotherms
- use a fraction of the amount of energy a mammal uses
- can convert a greater percentage of the enrgy they consume into body tissue
- small body niche is efficient
Cons of ectotherms
- difficult to maintain body temps in cold climates
- predation risk
- go into torpor when food is scarce
Brumation
- hibernation for ectothermic animals
- seek thermal refuges to avoid freezing
Hibernations
- state of dormancy of endotherms
- deep sleep triggered by env conditions
Estivation
- dormancy during very hot and dry conditions
- also seek thermal refuges to avoid overheating
Reptile skin and thermoregulation
- highly impermeable skin permits direct exposure to sunlight without excessive water loss
- temp control is much more common in reptiles for this reason
Activity temp range
-temp range over which an individual is active
Optimal temp range
-temp at which performance of some biochemical reaction or behavior is maximized
Critical thermal maxima and minima
-higher and lower temps at which locomotion is impaired
Inertial homeothermy
-large reptiles are able to maintain a mostly constant body temp
Qabs = (S)(A)(vfs)(a)
-rate of absorption of solar energy by animal
-S=intensity of the radiation
A = surface area of the animal
vfs = proportion of the animals surface that is exposed to radiation
a = proportion of the energy that is absorbed rather tha reflected
Basking
- heliothermy
- extensive in reptiles and some amphibians
- varies by life stage
Regional endothermy
-the ability to generate heat in the viscera, brain, eyes, and slow twitch muscle fibers
Producing metabolic heat
- leatherback sea turtle
- heat is generated through muscular activity
- retained by insulative, thick, oil-filled skin
Convection
-heat exchange between the solid (animal) and movement of the medium (air or water)
Thigmothermy
- drawing heat into body from contact with a warm object in the env
- exchange from solid to solid
Evaporative cooling
- water passes across skin, vaporizes on surface
- involves large loss of heat to convert water from liquid to gass
Why is evaporative cooling a mjor issue for amphibians
- skin is so permeable that high water loss is continuous
- only few have any control over evaporative hear loss
Amphibians in freshwater
- hyperosmotic
- actively sequester ions via gills and skin
Amphibians in brackish water
- Hypo-osmotic
- most amphibians would dehydrate in ocean water
How do spadefoots survive by being underground for 9 months a year
- start with a full bladder of dilute urine
- for first 7 months, their plasma and urine conc dont change
- for las 2-3 months, soil dries, toads ramp up their plasma osmolality and continue to extract moisture from soil
Cutaneous drinking
- dermal absorption of water
- primarily through the seat patch or pelvic patch or venter
- amphibians
Salamander grooves and annuli
- Costal grooves
- grooves and wrinkles on ventrum draw water from a wet surface up onto animal through capillary action
Water gains
- liquid water
- performed water
- metabolic water
Water loss
- evaporation
- urine and feces
- salt glands
Ammonotelic
-in aquatic env
Ureotelic
-in moist terrestrial env
Uricotelic
-in arid env
Aestivation
-dormancy and cocoon formation of dead epidermis or encapsulating dried mucous
Biogeography
-past and present distribution of animals
What is preformed water
-what that is derived from dietary components like starch, fat, protein
