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Herpetology Exam Questions

Terms in this set (58)

Define paraphyletic and describe how it applies to herpfauna
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Which living amphibian order contains most families and species?
Anura
why SA has such high amphibian diversity; 2 reasons for SA salamander diversity
Amphibians are most successful where warm temperatures and rainfall coincide
1. Isolation results in speciation
2. Elevation gradient (in Southern Applachia)
3. Salamanders require cool, wet environments to live and most species need a water source in which to lay their eggs. The high elevation and humid conditions of the Appalachians provide a perfect climate for salamanders to thrive in.
4. microhabitats
why reptiles lack same diversity in SA
Limiting factors for reptiles + Adaptations that let reptiles live in more arid areas
•Temperature
•Impermeable skin
•Scales covered with keratin (fibrous structural protein)
•Water loss is much less of a problem
•Reptiles dominate warm areas, but also dry areas
Why do dryer areas often have higher reptile diversity?
•Less competition with mammals, birds and amphibians
*why continental drift can be used to explain distribution of amphibians but less so with reptiles
Reptiles are not as restricted in movement. Many families of reptiles have distribution patterns that are not restricted by their origin.
Frogs and salamanders both predate the separation of the continents
how amphibian heart differs from reptile hearts
Amphibian heart
•3 chambered heart
•2 atria, 1 ventricle
•Much less efficient than the 4 chambered hearts of mammals, birds and some reptiles
•Oxygenated and deoxygenated blood mix in the ventricle
•Limits activity

Reptile heart
•3 chambered in lizards turtles and snakes
•Incomplete ventricle septum reduces mixing of oxygen and deoxygenated blood
•4 chambered in crocodilians: no mixing, most efficient, evolved due to:
-Large size
-Active lifestyles
-Evolutionary link with dinosaurs and birds
*compare amphibian eggs to reptile eggs
Amphibian eggs:
-membranous
-Prone to desiccation
-Many species rely on standing water
-Aquatic larval stages

Reptile eggs:
-hard shelled eggs that are usually laid on land.
-embryo develops in a fluid filled sack called the "amnion" - they are "bringing the ocean with them"
-amniotic egg allows them to colonize and reproduce in arid environments (Along with birds and mammals).
- freed reptiles from water reproductively
- egg tooth - hardened tip on the end of their snout, which helps them break free of their egg. The tooth drops off afterwards.
amphibian lungs
What group evolved lung first? Ancient fish groups, one of which was the ancestor to all of the amphibians
How do amphibian lungs work?
•Very simple sack-shaped structures
•Inefficient
•No diaphragm
•Lungs an out pocket of gut
•Use a buccal pharyngeal pump to force air into lungs
•Skin breathing for gas exchange (May be the reason modern amphibians lost the scales of their ancestors)
•Cool temperatures facilitate better oxygen uptake
•Salamanders are more abundant in cool mountain streams
reptile lungs
Compare reptile lungs and respiration to amphibian lungs and respiration
•More developed than amphibian lungs
•More branching and vascularized the increase surface area and oxygen uptake
•More efficient
•Greater surface area for the exchange of gases
•Inflated and deflated by the bellowslike expansion and contraction of the rib cage.
how some desert frog species able to survive and reproduce in harsh arid environments
•Nocturnal
•They either live around permanent bodies of water or stay buried in the soil and only emerge when the ground is wet
•Many desert amphibians come to the surface, breed and lay eggs during short periods of rain
•Usually have very short larval periods and metamorphose in 2 week or less
2 examples of how amphibians can increase SA-V ratio
• Increasing surface area: flattened bodies (Surinam toad), heavily folded skin, long slender bodies
*how cloacal breathing works and group that uses this strategy
Some aquatic turtles can pump water in and out of their cloaca to aid gas exchange
2 functions of axial muscles in snakes and lizards, as well as how those functions are limiting
Axial muscles cause lungs to expand and contract to help them run involved in movement power the lungs of squamates
-Unable to breath during intense running
-Monitors use buccal pumping during high activity to supplement breathing
how temperature, metabolism, and longevity related
Species in colder regions exhibit lower activity levels, lower metabolisms, and slower growth rates (cold inhibits and delays metamorphosis = longer larval stages), meaning they conserve more energy in the long-term and live longer. Tropical species consume at higher rates and exhibit rapid growth rates, high activity levels, and high metabolisms, thus living shorter lives. (also experience more mutations/speciation)
how latitude and altitude affect pigmentation in herpfauna populations
colder climate --> darker pigmentation
how air breathing herpfauna can hibernate underwater
• Many aquatic turtles and amphibians hibernate under water
• The mud in the bottom of a pond is highly unlikely to freeze
• Metabolism drops low enough and water oxygen levels are high enough for skin breathing to meet metabolic needs
define parietal eye and its role in hibernation
Changing light levels perceived by the pituitary
• Parietal eye: photoreceptive area on head associated with pineal gland (in reptiles and amphibians)
• Pineal gland: send signals to the pituitary, which regulates hormone production)
• External light cues affect the production of hormones associated with breeding and hibernation
*how antifreeze compounds work in hibernating herps / how nucleating compounds work and differ
• Antifreeze compounds like glycogen and urea lower freezing point of body
• Nucleating proteins:
-Body freezes from the outside inward
-Circulation stops, heart stops and the metabolism drops to zero
-Nucleating proteins keep ice crystals in the body small and prevent tissue damage
-Glucose released by the liver also plays a role
features unique to Plethodons and why the group is successful
Lungless salamanders:

-most species rich family

Features:
-no lungs
-slender body
- small legs

-aquatic, terrestrial, arboreal

• Cold water and turbulence result in very high oxygen levels in mountain streams
• Plethodontidae breath through their skin
• No lungs, no drowning
2 different reproduction strategies used by amphibians in vernal pools
Marbled Salamander:
-lay eggs before pool fills up, guards eggs until water/rain comes, eggs hatch when water is present

Spotted Salamander:
-breeding migrations to pools in spring ( rain)

Spadefoot Toads:
-reproduce in temporary pools, fast growth, go underground when not reproducing
what family newts belong to and how some of their life cycles differ from those of other salamanders
Salamandridae: terrestrial juvenile stage (less competition with aquatic adults for food)
salamander family with most species that utilize vernal pools
Ambystomatidae (mole/marbled salamanders)
*physical features that indicate salamanders are cannibalistic
Cannibalistic species are not only larger, but have a proportionately larger/wider head with larger teeth
2 chemosensory organs that occur in salamanders and 3 possible uses of chemosensory in salamanders
• Salamanders rely heavily on chemosensory to detect chemical clues in the environment, for prey detection and predator avoidance, and for social interactions (mating)
1. Naso-labial grooves: Plethodontidae; grove under the nares that is lined with chemoreptors for prey detection and predator avoidance
2. Mental gland: gland on the underside of the mouth of male salamanders that releases pheromones to encourage females to mate
3. Cirri: long protrusions on the snout of male salamanders that detect pheromones given off by females
5. Long tongues: some salamanders use long tongues capture prey
predator avoidance strategies used by woodland salamanders and how they work (3 asked for)
• Warning colors: More likely to encounter visually oriented predators like birds → Many species advertise their toxicity
• Glue: Some species employ glue-like mucous; very difficult to remove from skin; most likely evolved to discourage garter snakes
• Polymorphism to confuse visual predators like birds
how caecilian lungs differ from those of other amphibians; herpfauna group with similarly evolved lungs
• Left lung greatly reduced
-Same modification seen in snakes
-Elongate body shape has limitations
-Burrowing adaptation
define phallodeum, what it is used for, and in which group it occurs
tube-shaped reproductive organ in male caecilians that penetrates female cloaca
define paratoid gland and in which anuran family it occurs
external skin gland on the back, neck, and shoulder that secretes a milky alkaloid substance to deter predators; bufotoxin acts as a neurotoxin; Bufonidae
*how Pipidae differs from other anurans
Tongueless Frogs:

Features:
-webbed feet
- flattened body w/ legs on side (swimming)
- no tongue
-unique way of making sound

Lifestyle:
-all fully aquatic
3 unusual reproductive methods used by frogs
1. Amplexus - exhibited by some externally fertilizing species (chiefly aquatic) in which a male grasps a female with his front legs as part of the mating process, and at the same time or with some time delay, he fertilizes the female eggs as they are released from the body
2. Mass spawning
3. Internal fertilization
why amphibians have highest extinction rate, all contributing factors, and some possible ecological consequences
-Habitat Loss (deforestation, dams)
-Road Mortality
-Pollution
-Overharvest (dissections, pet trade, food, bait, etc.)
-Climate Change (global temp and rainfall patterns changing, precipitation changes: interferes with amphibian reproduction)
-Invasive Species (cats, rats, mongoose, fish, amphibians with diseases, etc.)
-chytrid fungus ( main cause of amphibian decline)
physiological adaptations that freed reptiles from dependence on water
1. scales: keratin scales makes skin impermeable to water; reduces water loss from evaporation/osmosis, can occur in very dry areas (unlike amphibians)
2. paired kidneys: more complicated and efficient than amphibians, don't urinate, uric acid (waste), requires less water
3. amniotic egg
4. improved lungs: more efficient than amphibian; cant breathe through skin, need better lungs
What are the four main modern groups of reptiles?
• Crocodilia - alligators and crocodiles (26 species)
• Testudines - turtles and tortoise (400 species)
• Sphenodontia or Rhynchocephalia - tuataras (2 species)
• Squamata - snakes and lizards (9,300 species)
reasons why reptiles might shed skin
growth, injury, infection
*Alligators exist in North America and in China. How would you explain this geographical distribution?
American and Chinese alligator evolved together back before Pangea split about 200 million years ago.
*Describe the evolution of turtle shells. What animal was the probable ancestor?
Turtles evolved about 250 million years ago. Eunotosaurus = likely ancient ancestor. Had very broad rib bones, resembling what we see as the turtle shell today. Turtles share a common ancestor with crocodilian, birds and dinos.
What are the 2 main turtle lineages, how do they differ from one another, and which is most versatile?
Hidden Neck:
-neck folds down when withdrawn
-most turtles
-only have hidden neck in N. America

Side Neck:
-neck curves to side when head is drawn into shell
-some have very long necks
how 2 turtle groups in Emydidae (box and pond turtles) are anatomically different from one another and adaptive advantages of differences
Pond turtles Features:
-dome shaped shell, flattened
-large plastron
-mostly all aquatic

terrestrial: box turtle

pond turtles aquatically adapted with flattened shell (hydrodynamic) and flipper-like limbs, while box turtles are more terrestrially adapted with domed shell and terrestrial clawed legs (both with large plastron for less mobility but more protection)
plastrons of mud turtles vs. musk turtles and the adaptive advantages (Kinosternidae)
Mud:
-hinged plastron, to protect head from predators
-slow water adaptation

Musk:
-reduced plastron, better movement on rough terrain
-stream adaptation
why most of Testudinidae evolved heavily domed shell
Dome Shaped Shell
-terrestrial
-harder to break, keeps from getting stuck on back
why gigantism evolved in so many island tortoise species and why so many have gone extinct
Island Gigantism:
-giant tortoises developed on many dif islands
-evolved large size to fill niche of large grazers

extinction:
-humans: overexploitation
-would take turtles for food on long ship journeys
Methods of internal thermoregulation and temperature control in leatherback sea turtles
- Counter current exchange - the warm blood leaving the heart (artery) warms the blood coming back to the heart (vein) after all heat is lost in the extremities. The atery and vein are side by side and exchange heat.
- Insulation - have a thick fat layer
- Activity - highly active! Been documented to swim up to 12,000 miles in 647 days.
features of sexually dimorphic turtles to help distinguish between genders
• Size - Females tend to be larger as they have to produce and carry and lay eggs.
• Plastron - females have a convex or flat plastron, males have a concave plastron so they can sit on top of females without rolling off.
• Tail length - females have short(er) tails, where males have longer tails with their cloaca farther down from the base of the tail. (Gotta reach it around to the female's cloaca.
arribada definition and why sea turtles evolved this strategy
Sea turtles all nest on the same stretch of beach at the exact same time. Advantages are they have the greatest chance of a few of their offspring making it back to the ocean if they all hatch at the same time and same place. Now, they face risks of humans overharvesting...basically a free-for-all.
anatomical ways tuataras differ from lizards
1. quadrate bone is fused to the skull (mouth can't open as wide like in lizards' moveable quadrate bone)
2. 2 top and 1 bottom row of teeth (like snakes)
3. more primitive hearts
4. no external ears
*where tuataras occur globally and why distribution is so limited
-temperate forests on over 30 islands off the coast of New Zealand
-more cold tolerant than other reptiles, but not tolerant of warm temps
*why herbivory selects for larger body sizes in lizards; name families with large numbers of herbivorous members
Iguanidae - Herbivory selects for larger body sizes because plants are really common and easy to find in their region (mostly in the America, islands)
how chameleon feet differ from feet of other lizards and why they evolved these unusual feet
Fused Toes:
-pincher grip
-to be able to climb on tiny branches to get away from predators
how adhesive pads on gecko feet work at molecular level
species specific toe pads with microscopic hairs molecularly interact with climbing surface; lots of friction! (Terrestrial specie lack toe pads)
life history traits that make some gecko species so good at island hopping
• Hard shelled eggs - incubate without moisture in most species. Eggs also have adhesive parts, can stick to most anything and travel long distances.
• Parthenogenesis - some gecko species use this. Easy to reestablish a population even she's the only one!
define a dewlap and how is it used
in anoles, longitudinal flap of skin that hangs beneath the lower jaw or neck
- for courting displays, competition, different species have different size and color dewlap...prevent hybridization.
*interesting hunting method of komodo dragons
Hunting strategy - ambush and bite big prey. Venom and 57 different strains of bacteria in mouth prevent wound from healing. Wound gets infected from so much bacteria. Komodo dragon stalks prey till it become too weak from the bite and/or dies. May take several days.
2 theories of origin of snakes and the accompanying physical features
2 theories for the origin of snakes - evolved from burrowing lizards or aquatic lizards?
• burrowing: lost limbs to facilitate burrowing, lost eyes to keep dirt out, revolved them when they returned to the surface and they came back more primitive. Lots of lizards are limbless. Eyes are indeed more primitive and all earliest fossils are terrestrial.
• aquatic: limblessness may facilitate better swimming, eye scales work like goggles, evolved eyes like a fish, lack of ears to keep water out. Early fossils of snakes had limbs! Also their eyes are eerily similar to a fish.
*why some arboral boas and pythons (non-venemous) evolved enlarged fang-like front teeth
Bird feeding adaptations - enlarged teeth to penetrate feathers and prevent escape.
*2 ways viper teeth differ from teeth of other snake families
Fangs:
-hinged
-replaceable (because large size, more likely to fall off)
-hollow for venom injection
most venomous snakes cryptically colored but coral snakes use warning colors --> why more adaptive
Cryptic Coloration:
-common in ambush hunters
-typical of most snakes
-camouflage
Coral snakes and warning colors - advertise toxicity to highly visual, non-snake predators (birds, mammals) without hindering own hunting ability, as their primary prey (fellow snakes) are not highly visual and rarely detect coral snakes' colors until it's too late
physically compare/contrast active vs. ambush hunters (snakes)
Ambush Hunting: (vipers, boas)
-cryptic coloration
-large head, thick body
-often venomous
-low metabolism


Active Hunting:(colubrids, elapids)
-slender bodies
-large eyes
-high metabolism
circumstances when balanced polymorphism is adaptive --> from both predation and prey standpoint?
snakes of the same clutch can look completely different. Visual hunters will catch one and spend their lives looking for that pattern. In the meantime they pass right over the same kind of snake.
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