Herpetology Lecture Exam Final

Two clades of turtles

Two clades of turtles

1. Pleurodira=“side necked turtles” (horizontal retraction)

2. Cryptodira = “hidden-necked turtles” (vertical retraction)

chelidae family

15 genera, 69 species

Turtle

• Found in Australia and New Guinea and South America

• Aquatic, mostly freshwater

• Omnivorous

-only major freshwater turtle in australia

-most species rich family in SA

Pelomedusidae

Pelomedusidae

turtle

• 2 genera (Pelusios, Pelomedusa), 27 species

• Africa, Madagascar (most species-rich turtle family in Africa)

• Aquatic, freshwater

• Carnivorous

Podocnemidae

Podocnemidae

-turtle

• 3 genera, 8 species

• 2 genera in South America (Peltocephalus, Podocnemis)

• 1 genus with 1 species in Madagascar (Erymnochelys)

• Herbivorous, aquatic, freshwater (rivers and lakes)

-biggg

• Many extinct genera; extinction

probably explains strange distribution

in Madagascar and South America

• One extinct genus (Stupendemys)

may have been largest turtle that

ever lived (2.3 m shell length)

Trionychoidea

• Clade that unites the Carretochelyidae and Trionychidae

• Share many distinctive morphological characters not found in any other turtle families

Synapomorphies of Trionychoidea include

• Snout has fleshy proboscis

• No keratinized scutes on shell

• Hard parts of carapace covered by leathery skin

• Shell is more flattened than other turtles (more streamlined for

faster swimming?)

Trionychidae

-turtle family

(soft-shelled turtles)

• 13 genera, about 36 species

• Found in North America, Asia, Africa

• Aquatic, carnivorous

• 3 species in the U.S. (genus Apalone) found in the east(ish)

Carettochelyidae

-turtle

• 1 genus, 1 species (Carettochelys

insculpta)

• Found only in New Guinea and

northern Australia

• Aquatic (freshwater, brackish), omnivorous

• Flipper feet, move like sea turtle

9 families of cryptodira in OK

Kinosternidae

Dermatemydidae

Geoemydidae

Testudinidae

Emydidae

Platysternidae

Chelydridae

Cheloniidae

Dermochelyidae

Kinosternonidae

(mud and musk turtles)

found in OK

• 4 genera, 33 species

• North America to South America (most species in eastern U.S.

and Mexico)

• Aquatic (freshwater), mostly carnivorous

-poor swimmers, walk on bottom

-many have hinged plastron

Yellow mud turtle

(Kinosternon flavescens)

Chelydridae

(snapping turtles)

• 2 genera, 6 species

• North America to northwest South America

• Big, aquatic (freshwater or brackish), omnivorous

• Poor swimmers, walk on bottom

• Eastern North America to northwest South America

• Will eat anything, live anywhere; very common

Cheloniidae and Dermochelyidae

Cheloniidae and Dermochelyidae

(sea turtles)

• Share well-developed, paddle like forelimbs

• Only primarily marine turtles

• Fully aquatic (can barely move on land)

• Females come ashore to nest on (mostly) tropical beaches

Cheloniidae

• 5 genera, 6 species; range in size from 70 cm to 1.5 m

• Found in oceans nearly worldwide (temperate and tropical, but not

arctic)

• Feed on plants or animals attached to the substrate

Dermochelyidae

Dermochelyidae

(Leatherback sea turtle)

• 1 genus, 1 species (Dermochelys coriacea)

• Morphology is very different from cheloniids and other turtles

• Carapace is composed of small osteoderms embedded in leathery

skin (hence name)

• Has reduced skeleton and very paedomorphic (juvenile) morphology

• Yet, is largest living turtle, up to 2–2.5 meters long

• 1 genus, 1 species (Dermochelys coriacea)

Emydidae

-terrapins/pond turtles

• 12 genera, 57 species

• Most species and genera in North America, but a few in Latin

America and Europe

• Includes full range of habitats from aquatic to terrestrial

• Includes full range of diets from carnivorous to herbivorous

Testudinidae

Testudinidae

(tortoises)

• 17 genera, 58 species

• Found nearly worldwide in tropical and warm-temperate areas

• Most diversity in Africa and Asia

• Terrestrial, many herbivorous or omnivorous

• Enlarged scales on front of forelimbs

Galapagos islands has 1 species with 15 recognized

subspecies (2 are extinct) on different islands

• 3 species of tortoises in United States (genus Gopherus)

Gopherus agassizi

(Desert tortoise)

Gopherus berlandieri

(Texas tortoise)

Gopherus polyphemus

(Florida Gopher tortoise)

Are giant tortoises

from the Galapagos

and Seychelles closely

related?

-A phylogeny from combined

molecular and morphological data

shows they are distant relatives!

-In each case having evolved from

tortoises on the closest continent

Fossils show that there were many

species of giant tortoises on almost

all major landmasses! Giantism has

evolved repeatedly in tortoises

-Most went extinct during the

Pleistocene ice age

-The giants today may have arrived

on the islands as giants rather than

following the “island gigantism” rule

Geoemydidae

Geoemydidae

(eastern pond turtles)

• 73 species, 19 genera

• Global tropical distribution

• Aquatic, semi-aquatic, terrestria

Platysternidae

Platysternidae

(big head turtle)

• 1 species (3

subspecies)

• Asia

• Can not retract head

into shell

• Mainly terrestrial

and can climb

• Not a good swimmer

Dermatemydidae

Dermatemydidae

(river turtle)

• 1 species, 1 genus

• Central America

• Herbivorous, aquatic, nocturnal

• Only leaves water to lay eggs

• eggs can survive under water

Sex Determinism

the biological system that determines the development of characteristics associated with dimorphic sexes. It is a negotiation between genetics, hormones, and environment that varies within and between species

TSD/GSD

• Most turtles, all crocodylians, all rhyncocephalians, and some squamates have temperature-dependent sex determination (TSD)

• GSD: genetic sex determination

-sex chromosomes

• Only narrow range of temperatures will produce both sexes

(roughly 2º C)

• The specific relationship between temperature and sex varies among species: there are 3 types of TSD

TSD patterns: 1A

pattern 1A:

Low temp., all males

Intermediate temp., both sexes

High temp., all females

found most in TURTLES

TSD Pattern 1B

low temp; all females

intermediate temp;both sexes

high temp; all males

-some lizards

TSD Pattern 2

(crocodylians, some turtles and lizards)

-low temp; all females

intermediate temp; all males

high temp;all females

What Drives evolution of TSD?

• Some suggested factors

– sexual dimorphism

– unequal survival rates

– different sex maturation ages

– inbreeding avoidance

– mating competition

– sex-specific variation in hatchling phenotypes

Charnov-Bull hypothesis

One hypothesis: there are consequences to developing at different temperatures which may be advantageous for one or both sexes (Charnov and Bull 1977)

-jacky dragons

What might the disadvantages of TSD be?

• In an endangered species of sea turtle (Loggerhead;

Caretta caretta) 94% of hatchlings over 3-year period

were female

• In painted turtles (Chrysemys picta), estimated that

increase in global temperature by 4º C would

eliminate all males

Do you think global warming could lead to an

evolutionary shift in TSD patterns within turtle

species to allow them to survive?

• Disadvantage for turtles; can live a long time, but also take a long time to mature

• Fewer generations per unit time than most other

organisms, will adapt more slowly

• Important factor is amount of change for given

number of generations

• Fewer generations for same amount of time

means that turtles adapt relatively slowly

Authors argue that global

warming will produce all-

________ populations

female

What climate do TSD species generally occur

warmer climates with minimal exposure to fluctuating climates

parthenogenesis

asexual reproduction where an embryo develops from an egg without fertilization.

• Even though there are many parthenogenetic species, most of these lineages do not seem to last very long – some are thought to be only a few thousand years old

Parthenogenesis is common in squamates

All-female whiptails

• About 1/3 of ~45 Aspidocelis species are all-female parthenogenetic species, including several species in the U.S

• All-female species typically diploid (produce unreduced, 2N eggs)

• In some cases, diploid parthenogen will mate with bisexual species and form a new, triploid, parthenogenetic species!

• Why haven’t these species been more successful?

One hypothesis is that the asexuals tend to accumulate deleterious mutations (no recombination)

thermal biology def

thermal preferences and tolerances

the study of physiological and ecological consequences of body temperature and of the biophysical, morphological, and behavioral determinants of organism temperature.

body temperatures of different reptile and amphibian groups

• Most salamanders: ~15º C

• Frogs: low 20s

• Lizards: low 20s to low 40s (depending on group)

• Snakes: mid 20s

• Turtles: 20s to low 30s

Consequences of thermal biology for biogeography

Salamanders:• Most families of salamanders occur exclusively in temperate regions

• Many families occur on multiple continents, but only in temperate areas

• Can you think of salamander families that occur on multiple continents?

Cryptobranchidae- NA and Asia

Proteiidae- Europe and North America

body temp of temperate plethodontids vs tropical plethodontids

• Mean body temp. of temperate plethodontids = 13.5º C (n =28 species)

• Mean body temp. of tropical plethodontids = 14.2º C (n = 43 species)

niche conservatism does what to dispersal

limits dispersal of organisms between areas with different climates

patterns of biogeography in reptiles and amphibians determined by:

• Connections among continents (e.g., Gondwanaland)

• Niche conservatism (most dispersal is temperate-to-temperate

and tropical-to-tropical, not temperate-to-tropical or vice versa)

how does body mass effect thermoregulation

• Smaller mass, less thermal inertia, can achieve high body temperatures quickly, may come out when its not as hot

-most lizards have lower body temps while turtles have higher body temps

why do turtles bask

to thermoregulate, probably for cooler water temperatures

• Consequences of thermal biology: Diet

Herbivory generally evolves in clades with high body temperatures; some lizards, turtles

• Never in snakes, almost no amphibians

• Consequences of thermal biology: Activity patterns

• Species in high body temperature clades active by day

• Species in lower body temperatures generally active by night or cryptic

• Can’t get warm enough at night or cool enough by day

Homeotherm

“warm-blooded”): constant body temp

Poikilotherm

“cold-blooded”): body temp varies with environment

Heat Transfer- how does heat move

• Heat always moves from hotter to colder object

Conduction:

heat moves along a solid object (or two

solid objects in intimate contact) by transfer of

molecular energy from hotter to colder areas

Convection:

heat moves away from (or toward) a solid object by way of a current of air or liquid passing over the object

• Radiation

heat moves via infrared waves (even through a vacuum)

heliothermic

get heat from sun

Anurans tend to be nocturnal in ____ climates and diurnanal in ____ climates

nocturnal in hot and diurnal in cold

another word for hinernate

brumation= slowing of metabolic rate at colder temps

cryoprotectants in frogs

basically internal frog anti freeze

• Glycerol or glucose - intracellular

• Proteins – extracellular

active thermoregulator= ____ body temp variance

low

thermoconformer= ____ body temp variance

high

water balance terminology: Isotonic (isosmotic)

• Isotonic (isosmotic): same concentration

water balance terminology: Hypotonic

• Hypotonic (hyposmotic):

less concentrated

water balance terminology:• Hypertonic (hyperosmotic)

• Hypertonic (hyperosmotic):

more concentrated

Osmosis

the passage of a liquid through a membrane from a less concentrated solution to a more concentrated one

Osmotic Characteristics:Marine

Marine: body fluids < conc than seawater

– Water tries to leave (the ocean sucks!)

– Urinate little & reduced glomeruli, secrete salt

Osmotic Characteristics: Freshwater

Freshwater: body fluids > conc than water

– Water tries to enter

– Lots of filtration & many glomeruli, salt absorption

Osmotic Characteristics:Terrestrial

Desiccating

– Water tries to leave

– Reduced filtration & few, reduced glomeruli

– Dry urine production, sometimes salt secretion

xeric amphibians

amphibians in dry habitats

• No special difference in kidney between mesic

and xeric amphibians

• Dermis of xeric amphibians is slightly different

– G-layer is more pronounced

• Xeric frogs can dry out more before desiccation

(and death)

• Seek refuge underground

– Some secrete “cocoons”

• multiple layers of unsloughed dead skin

• Nocturnal activity

reptile kidney

• Low filtration rate

• Reduced size & number of glomeruli

• Aquatic spp. excrete NH 3 and urea

• Terrestrial spp. excrete pasty uric acid

• Active secretion of uric acid into tubule

– Precipitates into cloaca, so H 2O not drawn in

• Salts (& passively H 2 O) removed from cloacal

bladder; box turtles urinate when picked up

Bergmann’s Rule (1847):

In colder climates, bigger animals have an advantage because their bodies have less surface area compared to their volume.

This helps them keep heat inside. So, as temperatures drop, animals tend to grow larger. This is all about how they manage to gain and lose heat, which is produced by their metabolism.

Body Size Evolution and Environment-• Surface Law (Schmidt-Nielsen 1984) –

Smaller organisms lose heat more quickly and also lose water faster through their skin because they have a higher surface area-to-volume ratio compared to larger, more robust organisms.

What functions do venom serve

digestion, defense, and prey acquision

Van Valen’s Red Queen Hypothesis

• Idea that reciprocally interacting organisms are coevolving to remain competitive

ex:daphnia and parasites; garter snake and newts

three steps of a snake bite

1. Diversification

2. Venom Variation

3. Antivenomics and clinical management

Salt Glands

• Marine turtles secrete salt from lacrimal glands

• Galapagos iguanas spew salt from nasal glands

thru nostrils

• Desert lizards secrete salt from nasal glands

(ring of salt around nares)

Xeric Reptiles- how do they conserve water

• Dry feces, uric acid, reabsorb cloacal water

– Lizard feces capped with dollop of dry, white uric acid

• Drink when available

– Gopher tortoises increase wt by 40% after rain drinking

– Wait at dug holes

• Microhabitat selection and behavior

– Nocturnal when too hot

– Avoid hot, dry wind

– Rain harvesting

Locomotion term:Saltatory

Jumping

Locomotion term:Cursorial

running

Locomotion term:Arboreal

climbing

Locomotion term: Saxicolous

rock-jumping

Locomotion term: Torrential

living in fast-flowing streams

Salamander locomotion

• Diagonal stepping in terrestrial species

– Must maintain center of balance

– Bend spine to support

– Bend gives longer stride

– Fast, wriggling lateral undulations à predator

avoidance

• Arboreal salamanders: How climb?

– Expanded digits

– Sticky secretions

– Some use suction cups

– E.g., Bolitoglossa

Aquatic salamanders: How swim?

– Laterally compressed tails

– Undulatory motion

Bolitoglossa altamazonica

be able to label frog skeleton:

Radioulna

Tarsals

Urostyle

Tibiofibula

• Arboreal and torrential anuran species Both have

• Have enlargened toe pads that they use for adhesion

• Some capillary adhesion, most force comes from mucous generated by specialized cells in the pads

Caecilian locomotion

– Burrowers with shovel-like snouts

– Strong, compact skulls

– Can go backwards or forwards

– Hydrostatic skeleton

Reptile locomotion

• Skeletons better developed for terrestrial

locomotion

• Crocodilians:

– Swing splayed out limbs under body like mammal

– Can even gallop, or run bipedally! Usually diagonal stepping

– In water, propelled by tail undulations

– Limbs at sides, used for stabilizing

lizard locomotion

• Walk with diagonal stepping

• Can run bipedally or quadrupedally

• Tail acts to counterbalance body, especially

when bipedal

• Bipedal faster than quadrupedal for most (but

not for collared lizards)

• Swimming:

– Water: undulations of tail and body

– Sand: undulations of tail and body

• Fringes on toes

• Shovel-like noses

lamellae

plate-like scales

how do arboreal lizards climb

• Gekkotan lizards:

– Toes have lamellae = plate-like scales

– Lamellae have hair-like setae (30-130 microns long)

– Setae branch to terminate with spatula-shaped

structures (0.2-0.5 microns wide)

– “Stick” to surface by van der Waals forces

Setae cling through intermolecular

forces

Angle of setae critical in forming and breaking bonds (watch how toes curl!

snake locomotion

Undulatory – wavelike

push off of 3 points of substrate

• Concertina – bunch up and push forward

• Rectilinear – no undulations, like a caterpillar

• Sidewinding – sections of the body alternately

lifted moved forward, and set down

side winding

– 2-3 separate tracks

– All forces directed vertically against substrate

– Good for unstable surfaces (e.g. sand)

in 2004 4 how many species of amphibians

5743

what percent of amphibians are declining

• 2468 species, or 43.2%, in decline

what percent of amphibians are increasing

28 species, or 0.5%, increasing

What percent of amphibians are stable

1552 species, or 27.2% stable

What percent of amphibians are unknown

• 1661 species, or 29.1% unknown

what percent are globally threatened

• One-third (32.5%) were globally threatened

(IUCN Red List of Vulnerable, Endangered, or

Critically Endangered)

how many total and probable extinctions of amphians since 1980

122 species

more than birds and mammals

causes of amphibian extinctions

• Habitat loss/degradation

• Global weather changes

• Global increase in UV-B

• Pathogens (e.g.,chytrid fungus, iridovirus)

• Chemical contaminants

• Exotic species

• Interactions

Why are amphibians so vulnerable?

• Biphasic lifestyle

• Thin, fragile, permeable skin

• Unshelled eggs exposed to soil, water,

and sunlight

• Fluctuate widely in population density

• Strongly philopatric (stay in one area)

• Metapopulation dynamics