Lecture Final Flashcards
How are foraging modes defined? What are the two major foraging modes we talked about in class?
Foraging modes traditionally defined based on behavioral patters of locating and capturing prey. Two foraging modes talked about were 1.) Sit-and-wait foraging (ambush foraging) and 2.) Active foraging (wide foraging).
Compare and contrast Sit-and-Wait foraging with Active foraging.
Sit-and-Wait Foraging Use little time and energy searching for prey items Stationary behavior and attack mobile prey when detected within field of vision Most energy spent on capturing and handling prey items **often more territorial and generally wait for food to come into territory. **generally seen in Iguanians Movement times, rates, & percentages are lower in sit-and-wait foragers Lower/limited endurance & higher sprint speeds in sit- and-wait foragers Daily energy use & intake lower in sit-and-wait foragers Active Foraging Actively move through environment searching for prey items Much energy used during searching phase Little energy used in capture of prey item **generally smaller prey so they don’t have to wrestle with it to catch and eat it. **generally seen in non-iguanian squamates Activity body temperatures higher in active foragers BOTH are foraging modes exhibited in reptiles and amphibians.
What is the Optimal Foraging Theory?
Traditional explanation for the evolution of foraging modes In presence of competition, individuals best able to exploit resources should have selective advantage Fine-tuned by natural selectionultimate pay-off should be greater reproductive success Overly simplistic theoryforaging is complex Few studies support associated predictions
What are some factors that influence foraging behavior?
External factors include prey availability, predation risk, social interactions (e.g.. competition), habitat structure, and opportunities for thermoregulation. Internal factors include hunger, learned experiences, age, sex and reproductive state, etc. Historical factors include sensory limitations, morphological characteristics (e.g. mouth shape, head size), physiological constraints (sprint speed), and behavioral set (conservative foraging mode)
What are the different ways that amphibians and reptiles can detect prey? Specifically, how do Caecilians, Batrachians, Crocodylians, Chelonians, and Squamates detect?
Prey may be detected by visual, chemical, tactile, and/or thermal signals May have reliance on a single system or used in combination Caecilians: Tentacles for chemosensory cues Batrachians: Visual cues Crocodylians: Visual and tactile cues Chelonians: Visual, tactile, & chemical cues Squamates: Use all forms Subgroups may primarily use one sense
Define and describe Visual Prey Detection.
Primarily important for the sit-and-wait predators Common in iguanians and cordylids; also most anurans Success in prey capture generally requires binocular perception of prey item Align head (and body) with prey Exceptions: Chameleons Large and well-developed eyes Prey movement often required
Define and describe Chemosensory Prey Detection.
Three avenues for detecting chemical cues from the environment 1. Olfaction: Nasal chamber 2. Vomerofaction: Vomeronasal (Jacobsonʼs) organ 3. Taste (gustation): Oral cavity Olfaction and vomerofaction rely on airborne and/or surface chemical cues Olfaction: Long-distance detection; Presence of food and general location Vomerofaction: Short-distance detection Gustation: Primary function is food discrimination Involves taste buds of oral cavity
In what groups is chemosensory prey detection found in amphibians and reptiles? What is the traditional and new view of how this was derived in squamates?
Olfaction and vomerofaction: Important in “scleroglossan” squamates and plethodontids salamanders Fine-tuned vomerofaction in snakes and other deeply fork- tongued squamates Recent evidence in crocodylians and aquatic turtles; Historically thought to be primarily visual and tactile focused The “Squamate Story” Traditional theory relating squamate diversification; Evolution of vomerofaction-based foraging system in “scleroglossans” from ancestral visual-based system as seen in iguanians Now: Iguanian condition is derived and vomerofaction is ancestral Did evolution of sit-and-wait foraging aid in iguanian diversification? Evolution of vomerofaction may still have allowed for the diversification of squamates
Define and Describe Auditory Prey Detection.
All amphibians and reptiles can hear and/or sense vibrations Generally, not thought to be important for foraging; Recent anecdotal evidence suggestions prey may be detected by auditory or vibration related cues in some groups
Define and describe Thermal Prey Detection.
Infrared (long wavelength light) receptors evolved multiple times in boids and pythonids, and once in Crotalinae Multiple labial pits in boid and pythonids Single pit (=loreal pit) between eye & nostril in pit vipers Organ consists of thin, highly enervated membrane stretched across open cavity Structure allows precise detection of distance & direction In rattlesnakes, head cooled when snake is excited Allows even more precise thermal differentiation (0.003o C) Pit organs are enervated by trigeminal nerve” Wired to visual cortex Thermal images are integrated with visual images Snakes see the thermal profile of infrared source superimposed on visual image
Define and Describe Tactile Prey Detection.
Known method of detection, but still poorly understood Mechanoreceptors in skin Lateral line system in aquatic amphibians Crocodylians? Enervated epidermal appendages Barbels around lower jaws in many aquatic turtles Lure-like tongue of Alligator Snapping Turtle (Macrochelys temminckii) Head tentacles in the Tentacled Snake (Erpeton tentaculatum)
Where in amphibians and reptiles did the projectile tongue feeding evolve?
Projectile tongue independently evolved in different groups of amphibians and reptiles Amphibians: anurans and some salamanders Reptiles; within Chamaeleonidae
Describe projectile tongue feeding in Caudata.
Most terrestrial salamanders feed by capturing prey with a large, moist/sticky tongue Tongue barely protrudes from the mouth (only a few millimeters) (Non-chamaeleonid iguanians & Sphenodon are similar) More substantial tongue projection evolved in several lineages: Salamandridae; Chioglossa & Salamandrina Plethodontidae; several groups All forms are lungless; Buccal floor freed from respiratory function (=buccal pump) & removes constraint on hyobranchium
Describe the typical feeding sequence of projectile tongue feeding in Caudates.
Typical feeding sequence in Caudata: 1. Tip of mandible often placed in contact with substrate 2. Muscle contraction raises skull 3. Contraction of the paired muscles draw hyobranchium (=hyobranchial skeleton or hyoid apparatus) forward; Tongue supported by hyobranchium; Pushes tongue out of mouth. 4. Tongue generally changes shape; Well defined ridge anteriorly, with central depression; Prey adheres to sticky secretions of tongue 5. Tongue retracted by contraction of separate muscle Net result: tongue protruded only a few millimeters from mouth
How does the typical feeding sequence of Caudates differ in Plethodontid Salamanders?
Plethodontid Salamanders
Most pronounced in bolitoglossines
Some project tongue up to half their body length
Same muscles are involved as in other caudate “minimal” projectile tongue feeding
Muscles and hyobranchium more greatly modified
Prey adheres to sticky surface of tongue and is drawn back into mouth
Feeding sequence takes only 4-6 milliseconds
Main components of projectile tongue: Y-shaped hyobranchial skeleton; Long, tapering epibranchial cartilages; Paired ceratobranchial cartilages; Basibranchial cartliage (Supporting base of tongue; tongue not attached to floor of mouth); & Specialized muscles: Subarcualis rectus I (Tightly coiled around epibranchials) & Retractor muscle
Describe Projectile Tongue Feeding in Anurans.
Most species feed via a projectile tongue
May be combined with lunging body toward prey
Tongue essentially flipped out of the mouth
Anterior end of tongue attached to floor of mouth;
posterior portion is free
Tongue supported by genioglossus muscles
Tongue projection not as rapid as salamanders Takes ~ 35-40 milliseconds
Not all anurans rely on projectile tongue; Rhinophrynus: Feeds on ants and termites (Relies on tongue protrusion) & Pipidae: Tongueless (suction feeding)
What is the feeding sequence of projectile tongue feeding in Anurans?
Feeding sequence:
- Genioglossus contracts & stiffens forming a stiff rod
- Submentalis muscle also contracts; Short, transverse muscle at front of mandible; Contraction causes muscle to bulge upward
- Submentalis pushes on stiffened tongue; Propels tongue upward and forward
- Free posterior end of tongue flipped forward and downward onto prey; Prey adheres to sticky tongue surface
- Contraction of hyoglossus muscle retracts tongue

Describe projectile tongue feeding in Chameleons.
Represents a clade within the Chamaeleonidae
Capable of projecting tongue ~1.5-2X their snout-vent length
Main components of projectile tongue:
Tip: external sticky pad and powerful circular muscle (=accelerator muscle)
Accelerator muscle wrapped around anterior extension (=processus entoglossus) of hyobrancial skeleton; Accelerator muscle constricts on processus entoglossus
Hyoglossus muscle attached to posterior end of tongue tip; At rest, loosely pleated behind tongue; Retracts tongue to mouth
What were the two different feeding environments mentioned in class?
What are the advantages and disadvantages of each?
Two feeding environments are Terrestrial and Aquatic.
Methods of feeding in aquatic and terrestrial environments differ
Advantages of aquatic feeding & disadvantages of terrestrial feeding:
- ) Food manipulation accomplished without much effort in aquatic environment & effort required in terrestrial
- ) Saliva not required for food lubrication in aquatic but required in terrestrial
Disadvantages of aquatic feeding and advantage for terrestrial:
1.) Predator movement generates pressure waves & moves prey away in aquatic but not in terrestrial
Define and describe suction feeding in aquatic environments.
Aquatic salamanders (adults&larvae), aquatic frogs, tadpoles, some turtles use suction feeding
Essentially Sucking/drawing food into mouth
Two main factors must be overcome: 1.) Initial inertia 2.) Water viscosity **Requires great deal of force
Involves negative pressure in the buccal cavity via expansion of buccal cavity
Generate enough pressure to draw prey into mouth
Must be rapid to prevent prey escape

Suction Feeding
Mouth opening usually small which allows directional suction;
EITHER 1.)** Unidirectional** flow of water through buccopharyngeal cavity; Only possible when gill slits present
2.) If no gill slits, depends on bidirectional flow
Define and describe unidirectional flow suction feeding in aquatic environments.
Aquatic Salamanders; Larval and highly paedomorphic salamanders possess gill slits
Two phases involved with suction feeding
- ) Expansive phase: Jaws open, hyoid apparatus drops, and buccopharyngeal cavity expands; Rapid flow of water into and through the buccopharyngeal cavity (negative pressure)
- ) Compressive phase: Rapid elevation of mandibles (=closing mouth), hyoid apparatus elevated; Water ejected through gill slits (positive pressure
Tadpoles: Employ different mode of suction feeding; Unidirectional flow of water & continuous suction feeding by continuous pumping of buccal cavity (not in bursts)
Define and describe bidirectional flow of suction feeding in aquatic environments.
What are the different ways this is made more efficient in Anurans, Turtles, and Tadpoles?
Bidirectional flow is when food is pumped into the mouth, but then the water must go back out of the mouth; less efficient because loss of prey item more likely
Anurans; Adult Pipid frogs; Xenopus and Pipa also use forelimbs to place food in mouth.
Turtles; Some aquatic turtles employ suction feeding; No gill or pharyngeal slits = bidirectional flow; Before opening mouth (=dropping lower jaw), hyoid is elevated in order to maximize the amount of negative pressure generated
Tadpoles; Water continuously passed across a filter; Most tadpoles feed on suspended phytoplankton or scrape algae from substrate; Alternating dropping and elevating the buccal floor (=floor of mouth) of buccal cavity moves water through system = buccal pump; Suspended food particles trapped by filter; Particle filtration takes place in pharyngeal cavity; Sieving through branchial filters or entrapment by mucus filaments (mucus entrapment); Mouth parts generally have several rows of small keratinized structures on oral disk surrounding mouth or labial teeth (labial tooth rows)
Explain in detail the suspention feeding by bidirectional flow in tadpoles.
What are the different mechanisms that have evoloved for terrestrial feeding?
Different mechanisms have evolved for terrestrial feeding
Major specialized mechanisms involved:
Tongue protrusion (including projectile tongue)
**Cranial kinesis; **squamates (particularly snakes!)
Constriction
Venom delivery
Akinetic skulls and nonprojectile tongue feeding
General characteristics are rigid skull and hinged mandible
Describe Akinetic Skull and Nonprojectile Tongue Feeding in Caecilians.
Compact and rigid skulls; Adaptation for burrowing; Some lineages have limited cranial kinesis
Well developed (relatively large), recurved teeth; Assists with prey capture and restraint/retention
Tentacle: Chemosensory function
Describe Akinetic Skull and Nonprojectile Feeding in Turtles.
Generally, heavily built skulls (Retained, primitive condition)
Absence of cranial kinesisis likely a secondary loss (=derived condition); Occurred early in turtle evolution
Extant taxa lack teeth; Upper and lower jaws covered with sheaths = rhamphothecae (Composed of keratin)
Jaws often modified for different diets
Broad crushing jaws for feeding on hard-bodied prey (=durophagous) like mollusks and crustaceans U.S. taxa: Graptemys, Malaclemys
Narrow jaws with sharp rhamphothecae for Slicing/dismembering soft-bodied prey; “chopping” U.S. taxa: Apalone, Chelydra
Sharp rhamphothecae & rearward motion of lower jaw; Primarily seen in testudinids; Herbivorous diet so rhamphotheca modified for slicing plant material
What are the different jaw modifications found in terrestrial feeding turtles and what is each modification for?
Jaws often modified for different diets
Broad crushing jaws for feeding on hard-bodied prey (=durophagous) like mollusks and crustaceans U.S. taxa: Graptemys, Malaclemys
Narrow jaws with sharp rhamphothecae for Slicing/dismembering soft-bodied prey; “chopping” U.S. taxa: Apalone, Chelydra
Sharp rhamphothecae & rearward motion of lower jaw; Primarily seen in testudinids; Herbivorous diet so rhamphotheca modified for slicing plant material
Describe Akinetic Skull and Nonprojectile Tongue Feeding in Crocodilians.
Heavily built and rigid skulls
Open mouth by lifting the skull (unlike caecilians
& turtles); Extensive muscles allow a very forceful, downward bite
Primarily carnivores
Broadest skulls are generalists; Assists feeding on large, hard-bodied prey
e.g., Alligator mississippiensis
Slender jaws feed primarily on fish
Some species of Crocodylus
Gavialis & Tomistoma exhibit the greatest specialization
All lack “slicing” teeth and exhibit “rotational feeding” that allows them to pull off larger chuncks of food for feeding instead of swallowing the whole prey item; More important for larger prey items
Possess a pyloric gizzard; A muscular posterior region of stomach; Aids in digestion of large and bony prey via grinding
Describe Akinetic Skull and Nonprojectile Tongue Feeding in Sphenodon.
Generalist; feeds on small vertebrates and invertebrates
Acrodont dentition, with complex pattern; (Pair of enlarged incisor-like teeth at front of upper jaw; Pair of canine-like teeth at front of lower jaw; Smaller marginal teeth along maxilla and dentary; Palatine teeth are parallel to maxillary teeth)
Prey capture and manipulation
Small inverts captured with sticky tongue (slightly
protrusible)
Larger prey are impaled on enlarged anterior teeth; Crushing and shearing of prey within mouth
Describe Akinetic Skull and Nonprojectile Tongue Feeding in Amphisbaenians (long, legless lizards).
Compact and rigid skulls; Secondarily derived condition
associated with burrowing
Diet of invertebrates & small vertebrates; Some have sharp, recurved teeth; Pleurodont or acrodont dentition
Some species actually tear or shear off pieces of prey items which requires twisting of body and/or head.
What is the primary purpose of the evolution of venom delivery systems in squamate reptiles?
Venom delivery systems present only in some squamate reptiles
Multiple (=independent) origins
Primary purpose is prey capture & digestion
Ancestral function was more likely related to digestion
Defense is a current secondary role
What are the traditional views on venomous squamates and derived morphology?
What was evidence for this idea?
Traditionally, all extant “venomous” squamates belong to the Anguimorpha & Serpentes
Only one extant “lizard”: Heloderma
Slightly grooved mandibular teeth in extinct Estesia mongoliensis
All others are snakes (i.e., viperids, elapids, and some “colubrids”)
Discuss envenomation in Heloderma.
2 extant species of Heloderma:
- Gila Monster (H. suspectum)
- Beaded Lizard (H. horridum)
Large venom gland associated with mandible; Located on lateral side; Gland homologous to mandibular gland (=gland of Gabe) of varanid (and other toxicoferan) lizards; Venom travels to labial side of mandibular tooth row via 1-5 ducts
Posterior mandibular teeth possess anterior and posterior grooves
Must maintain bite on prey for envenomation
Prey: Small mammals, ground nesting birds & eggs, small reptiles
Discuss venom delivery in snakes.
Most snakes lack complex venom delivery systems; No modification of teeth (=aglyphous condition)
Venom delivery shows various degrees of specialization and has multiple origins
Venom glands have a maxillary location; “Well developed”, secretory gland found in 30-40% of
colubrids
Usually placed into 2 traditional morphological groups:
- Rear-fanged: Opisthoglyphous condition
- Front-fanged: Proteroglyphous and solenoglyphous conditions
Discuss venom delivery in Opisthoglyphous.
REAR FANGED CONDITION: Seen within the “Colubridae”
Enlarged, grooved posterior maxillary teeth
Two traditional competing hypotheses
1. Many independent origins, or 2. evolved early in colubrid history with many secondary losses

Venoms of most rear-fanged snakes are weak and delivery system is inefficient; Venoms likely play a bigger role in prey digestion
Local examples: Trimorphodon, Hypsiglena
Some are quite dangerous (Africa & Asia); ie. Boomslang (Dispholidus typus) and Rhabdophis
Discuss venom delivery in Proteroglyphous.
ONE OF THE FRONT-FANGED CONDITIONS: Exhibited by elapid snakes
Hollow fangs anteriorly located
Relatively short (compared to vipers) and fixed in an erect position
Other maxillary teeth located posteriorly

Discuss venom delivery in Solenoglyphous.

ANOTHER FRONT-FANGED CONDITION: Exhibited by viperids
Hollow fangs anteriorly located
Relatively long (compared to elapids)
Fangs are hinged; Fold back when mouth is shut & erected when mouth is opened = rotation of short maxilla; Other maxillary teeth generally absent

Discuss venom delivery in Atractoaspis.
Atractaspis (Lamprophiidae)
The stiletto snakes or burrowing vipers
Odd group of venomous snakes with unique dentition condition (similar to solenoglyphous with front-fanged condition)
Relatively long, hollow fangs on short maxilla
Fangs swing outward
Discuss venom delivery in snakes in terms of efficiency.
Anteriorly located and hollow fangs generally more efficient at venom delivery
50-60% in rear-fanged vs 80-95% in front-fanged snakes
Discuss the evolution of venom and compositino of venom.
Traditionally, elapid venom is largely neurotoxic, while viperids possess largely hemotoxic venom
Finding many exceptions to this rule
Venoms a mix of a large number of polypeptides/ proteins (toxins) with varying biological activities
Toxins in snake venoms recruited from body proteins and then incorporated into venom system
Many toxins first originated in common ancestor of Iguania, Serpentes and Anguimorpha (Toxicofera; =Venom Clade)
Toxins produced by maxillary and mandibular glands
Subsequent evolution of more potent toxins in Serpentes and helodermatids
Also loss of maxillary (helodermatids) and mandibular (snakes) glands; elaboration of venom producing glands
Discuss the evolution of fangs.
Where did the enlarged, anteriorly placed fangs come from?
Derived from the enlarged posterior fangs from “colubrids”
Future studies need to continue developmental studies from a wider range of colubroid taxa exhibiting varying dentition conditions
What is the theory of sexual selection?
Who originally formulated the idea?
What does it lead to?
Originally formulated by Charles Darwin
Explains evolution of secondary sex characteristics
It is a special type of selection that favors traits/phenotypes that increase the probability of mating
(vs. Natural selection that affects overall survival & acts upon traits that adapt an individual to itʼs environment
Sexual selection leads to differences between the sexes; Secondary sexual characteristics (E.g., larger body size, crests, bright/showy coloration)
Specie that exhibit secondary sexual characteristics have sexual dimorphism
What are the general outcomes of sexual selection?
Two general outcomes of sexual selection:
- Selection upon traits that allow males to better compete with other males (male-male competition); Examples: Larger body sizes, loud mating calls
- Selection upon traits that lead females to prefer one male over another (female mate choice); Examples: Ornamental structures, bright colorations, mating calls
Favored explanation: Signal of health & quality
Often responsible for evolution of “extravagant” traits
“Fisherʼs runaway selection”
Which sex is generally under more intense sexual selection? Why?
What is a common mating system because of this?
Males generally under more intense sexual selection
Reproductive success of females limited by energy intake for clutch/brood; Limited number of eggs and/or clutches; Most reproductively active females successfully mate
Reproductive success of males limited by number of mates; Sperm is cheap
Polygyny (multiple females) is common when males contribute little or nothing towards parental care
Discuss how there may be conflict between sexual selction and natural selection acting on an organism.
At times they may be opposed; Trait that may increase probability of mating may decrease probability of survival
Example: Loud/ conspicuous advertisement call may increase probability of predation
There are always trade-offs Need to survive and reproduce
What type of mating system do the majority of herps have?
What are two things that dictate male mating strategies?
Majority of herps display polygynous mating systems (many females with one male)
Various behavioral tactics utilized by males
Male strategies dictated by:
- Spatial distribution of females (aggregated vs dispersed)
- Temporal receptivity (short vs long period)
Explain Explosive Mating Aggregations seen by many anurans.
Explosive Mating Aggregations
Often in temporary ponds and during early spring
Short breeding period (one to several nights) with large number of individuals with males competing for mates
Strong selection pressure for short breeding period; Ephemeral nature of breeding pond; Cannibalism & predation
Males arrive first & are more abundant
While calling, males move around searching for potential mates
EXAMPLE OF THIS: Wood Frog, Lithobates sylvatica
Explain Explosive Mating Aggregations seen by salamanders.
Characteristic of Ambystomatid salamanders
Winter and/or early spring breeding
Males court females; deposition of multiple spermatophores
Hynobiid salamanders
Males form mating balls around deposited egg sacs (a bunch of salamanders joined on top of the eggs to fertilize them)
Explain Explosive Mating Aggregations in Reptiles.
Rare among reptiles
Occurs in some Thamnophis and European natricine snakes
Form large communal hibernacula during winter & in spring, males emerge first, then intercept and mob females
Successful males deposit waxy sperm plug

What are some generalities about Explosive Mating Aggregations?
- Males outnumber females (Possibly because greater mortality in females, delayed sexual maturity of females, or annual mating by males, but not by females)
- Successful males generally mate only once or few times & many males do not mate
- Male-male competition driving sexual selection (rather than female mate choice)
What are some tactics for mate searching?
Mate searching done because individuals largely solitary and potential mates are widely dispersed
Mate searching is common in many aquatic turtles, lizards, snakes, and
some salamanders
1. Individuals have large overlapping home territories; During breeding season males are more active & females often produce pheromones; Even with this most males never find mates in given breeding season, and there is little male-male competition (nor female mate choice)
- Multiple males aggregate around female; Males remain with female for extended periods of time and multiple matings are common; there is male-male competition, but no combat (mate guarding); Overall, multiple males per female; females involved with multiple aggregates
- Males fight over females; Prolonged searches generally absent; no large aggregations & males spend short time with females
- Males search for females in aquatic medium (Some salamandrids); Females may release water borne pheromones; amplexus prevents other males from mating (mate guarding)
Discuss mate guarding as seen in salamanders and anurans.
Is it common in any other groups?
If so, which ones?
Males remains with female to defend and prevent other males from mating
Amplexus behavior assists in guarding females; This consists of attendance, prolonged copulation, chasing off other males (active combat).
Mate guarding before and/or after copulation; Male-male competition generally occurring
This causes polygyny to be less prevalent
Weaker sexual selection
Frequent among emydid turtles and some tortoises; they have aggressive contests
Common in many non-territorial lizards; Lacerta (guard females for hours to days) & Scincid lizards
Less common in snakes; but they have prolonged copulation that may last hours to days or male-male combat in some pythons, viperids, elapids, and colubrids
What is a lek?
What group has this as their general mating system?
What other groups do this?
Lek: Aggregation of males on a traditional site to attract females
General mating system of anurans
Males gather in common area (may or may not be aquatic)
Variety of calling sites
Chorus may not be located at site of oviposition

Often strong sexual selection to increase rate, intensity, and/or complexity of call; Male-male competition via vocal interaction (Out-signal neighboring competition)
Greater amount of female mate choice; Females selecting based on call types/characteristics
Other lekking taxa: Some salamandrids in ponds, some iguanids (Iguana iguana in dead trees & Amblyrhynchus at basking sites near shore), & some crocodilians
What fields study multispecies patterns and the processes and mechanisms that generate such patterns?
Biodiversity biology &/or Macroecology
What is studied in biodiversity biology and macroecology?
Be sure to define what is meant by each segment of the answer.
Study of multispecies patterns and the processes and mechanisms that generate such patterns
Multispecies patterns: Number of species, population densities of the species, patterns of resource use, species distribution sizes
Processes and/or mechanisms: Competition, predation, environmental/physiological tolerances, historical factors
What is a community composed of overall?
What do biologist often focus on?
Why?
Overall, community is composed of all plant and animal species at a given locality or area
biologists often focus on a selected subset (=assemblage)
because communities are very diverse
Discuss the differences in changes over time in a community short term vs long term.
Communities and their various assemblages are usually dynamic
Short term: Changes not usually as dynamic
Long term: Species assemblages change and move; Speciation, extinction, and immigration/emigration
What is one of the first and most basic tasks when studying a community?
Determine species diversity
How many species are present = Species richness
Requires long-term and/or extensive
sampling for accurate estimates
Rare species found less frequently and may go un-noticed with small sample sizes
“Ecologically specialized” species may also be sampled infrequently
Species diversity and richness vary from place to place, but what are some general patterns that do exist?
Just list them, not discuss them.
Latitudinal variation; North/south gradient
Elevational variation
Climatic patterns
Discuss the latitudinal patterns that are seen in species diversity gradients.
Which groups fit this pattern and which do not?
Latitudes further north and south of equator generally have lower species diversity (Pattern long known and evident in many plants and animals)
Increases in latitudes = decreases in mean temperature and increase in seasonality
Overall, anurans, crocs, and snakes fit pattern. Lizards also, but extremely diverse in Australia.
Turtles and salamanders do not fit this pattern as well (=more restricted areas of high diversity)
Turtles: Eastern North America and SE Asia
Salamanders: Eastern North America, southern Mexico and Guatemala
Discuss elevation patterns seen in species diversity gradients.
What groups display this type of pattern?
Species diversity decreases with increase in elevation
Increases in elevation = decrease in temperature, increase in moisture, increase/decrease in habitat complexity
** Most amphibians and reptiles** display this pattern, but there is an** Exception**: Plethodontid salamanders of Nuclear Central America (Few lowland tropical species, but many montane species)
What is the main determinant of climate?
Why does climate matter?
In general, main determinant of climate is latitude
As latitude increases the mean temperature decreases & magnitude of change between seasons (=seasonality) increases (Moisture generally decreases).
Climate has a big affect on species diversity
Big variables are temperature and rainfall
What is the one of the most cited studies for amphibians and reptiles species diversity?
What did it study?
What were the results?
For amphibians and reptiles, one of the most cited studies is Schall and Pianka (1978)
It was a comparative study of U.S. and Australian herpetofauna
RESULTS:
Anuran and turtle diversity; Highly and positively correlated with mean annual rainfall & Negatively correlated with mean annual sunshine
Lizard diversity; Highly and positively correlated with mean annual sunshine; Negatively correlated with mean annual rainfall
Snakes diversity; Positively correlated mean annual sunshine (U.S.) Opposite in Australia; Positively correlated with mean annual rainfall
What does historical biogeography use to explain geographic distribution of species and clades?
Historical biogeography uses phylogenetic information to help explain geographic distribution of species and clades.
Aswer questions like:
Why have certain clades dispersed to some areas, but not others?
Primary focus has been on the geological connections between areas
What paper advocated for the consideration of interplay between niche conservatism and niche evoltion and clade ages?
Wiens and Donoghue (2004): Advocated the consideration of the interplay between niche conservatism and niche evolution, & clade ages
“Time-for-Speciation Effect” (TSE)
30-50 mya major speciation events in certain geographical areas
