FNR24150 Exam 1 Notes

Phylogeny of Amphibians

Oldest to most recent

1. Lissamphibia

2. Temnospondyli

3. %%Gymnophiona, Anura, Caudata (extant amphibians)%%

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Why land?

• unexploted %%food%% resources

  • aquatic habitat niches already occupied

• %%lack%% of large %%terrestrial predators%%

  • largely primitive plants & invertebrates

• %%low O2 in warm H2O%% (land O2 unlimited)

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Early Tetrapods

• Upper Devonian lobe-finned fish

  • %%pelvic and pectoral%% fins slowly transition to %%paired paddles%%

  • %%median fins%% still present

  • %%small ribcage%%

• Carboniferous labyrinthodont amphibian

  • %%paired paddles%% slowly turn into %%limbs%%

  • %%larger ribcage%% to account for %%organs%%

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More Phylogeny (indivudual spp. discussed further below)

• Era: Paleozoic, Period: Devonian

  • Ichthyostega, Tiktaalik

• Era: end of Paleozoic-beginning of Mesozoic, Period: end of Permian-beginning of Triassic

  • Triadobatrachus

• Era: end of Mesozoic-beginning of Cenozoic, Period: end of Cretaceous-beginning of Tertiary

  • Extant salamanders & frogs

• major evolutionary transitions in last %%350 years%%

• %%Amphibians%% were the %%dominant%% land animals for %%~75 million years%%

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Leposondyli

• very %%small%% yet very %%diverse%% early amphibians

  • similar to newts, eels, snakes, lizards, etc.

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Permian era

• %%droughty%% conditions

• %%reptile & early reptile spp.%% emerged and evolved

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Tiktaalik

• %%late Devonian%% ==(375 MYA)==

• discovered in %%Canada%% in %%2004%%

• predated %%Ichthyostega%% by %%5 million years%%

  • thought to be the oldest up til this point

• %%1-2m%% long

• most notable feature: %%front pair fins with wrist-like structure%%

• other features

  • ^^spiracles (primitive nostrils)^^

  • ^^lungs & gills^^

• %%1st%% tetrapod with %%proper neck%%

  • %%greater flexibility%% during short bouts on land

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Ichthyostega (“roof fish”)

• %%late Devonian%% ==(370 MYA)==

• discovered in %%Greenland%%

• 5 ft, 50 lbs

• fish & amphibian features

  • %%webbed feet%%

• could %%breathe air%% for %%short%% periods of time

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Eryops

• %%Permian (270 MYA)%%

• %%crocodile-like%% early amphibian

• %%aquatic%% & %%terrestrial%%

• had some structural %%features%% that would %%appear%% in %%later%% reptiles

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Diplocaulus (“double stalk”)

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• %%middle-late Permian (240-230 MYA)%%

• 3ft, 5-10 lbs

• %%wide V-shaped boomerang head%%

• possibly used to %%navigate strong currents%%

• facilitated rapid opening for %%suction-gape feeding%%

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Frog Evolution Trends

• several modifications for jumping

  • vertebral column %%short%% & %%inflexible%%

  • reduction in ^^presacral vertebrae^^

    • found within pelvis (cervical, thoracic, lumbar)

  • increase ^^rigidity^^, ^^absorption^^ of landing

  • transfer ^^energy^^ directly to ^^hind limbs^^

  • ^^enlarged^^ pelvic girdle, ^^strengthened^^ & ^^anchored^^ to vertebral column

  • ^^no ribs^^

  • ^^no tail as adult^^

  • overall body ^^truncated^^

  • hind limbs ^^elongated^^ for jumping

  • ^^muscles^^ modified for jumping

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Amphibamus (“equal legs”)

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• %%late Carboniferous (300 MYA)%%

• swamps in %%Europe%% & %%NA%%

• 6 inches, few ounces

• more %%salamander-like%% than frog-like

• %%33 presacral vertebrae%%

  • common characteristic of early amphibs (%%large amount%% of presacral vertebrae)

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Gerobatrachus (“frogmander”)

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• %%early Permian (290 MYA)%%

• found in %%Texas%% in %%2008%%

• why is it called “%%frogmander%%?”

  • ^^2 fused ankle bones^^

  • ^^backbone intermediate in length^^

  • decrease from 33 vertebrae in Amphibamus

  • ^^large tympanum (large, external ear on frogs)^^

  • ^^wide, frog-like skull^^

• likely %%transitional%%

  • ==240-275 MYA splitting frogs & salamanders==

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Triadobatrachus (“proto frog”)

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• %%early Triassic (250 MYA)%%

• found in %%Madagascar%%

• ==first fossil frog==

• characteristics

  • ^^short, stubby tails^^

  • ^^10 cm^^

  • ^^13-14 presacral vertebrae^^

  • ^^9 in modern frogs^^

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Viraella

• %%early Jurassic (~200 MYA)%%

• found in %%Argentina%%

• ==earliest “true” frog==

• may belong to %%Leiopelmatidae%% (modern family)

• %%classic%% frog-like head & large eyes

• legs modified for %%jumping%% (explored in next point)

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Triadobatrachus vs. Viraella

• Vieraella more truncated overall

  • %%reduction%% %%in presacral vertebrae%%

  • %%enlarged & fused%% pelvic bones in %%Viraella%%

  • fused %%tibiofibula%% in %%Viraella%%

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Paleobatrachus (“ancient frog”)

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• %%Cretaceous--Tertiary (130-135 MYA)%%

• found in %%Europe%%

• %%completely aquatic%%

  • inhabited %%swamp basins%%

  • %%volcanic gases%% preserved soft %%tissue%%

• resembles present day %%Xenopus%%

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Amphibians vs. Reptiles

• amphibians

  • clawless

  • scaleless

  • moist skin (respiration)

  • unshelled eggs

• reptiles

  • limbs & muscles

  • increased brain size (cerebrum & cerebellum)

  • more effective jaw

  • skeletal structure improved

  • skin toughened with scales

  • reduced cutaneous respiration

  • well-developed lungs

  • consequence of scales

  • amniote egg

  • no longer relied on water for breeding

  • arose from anthracosaurs (later tetrapods)

Order Caudata (Salamanders)

• characteristics

  • %%smooth%% skin

  • %%long tails%%

  • long %%cylindrical%% bodies

  • most have %%2 pairs%% of very %%well developed limbs%%

  • some have %%nasolabial groove%%

  • little groove that runs from nose to lips

  • %%costal grooves%%

  • body folds found on their sides

  • %%carniverous & cannibalistic%%

  • secretive & nocturnal

  • %%greater diversity%% in ^^development, respiration, and reproduction^^ than any other vertebrate group

  • %%nearly all%% salamander larvae have external gills

  • reabsorbed later

  • Sirenidae keeps external gills (paedomorphic)

• habitat & distribution

  • common throughout U.S.

  • 70% of ~400 spp. of salamander found worldwide are located in Central & NA

  • mostly found in %%moist woodland%% habitats

  • ^^hardwood & coniferous forests, grasslands, lowland floodplains^^

  • highly dependent on ^^precipitation, temperature, & vegetation type^^

  • %%Four-toed Salamander%% requires %%sphagnum bogs%%

  • %%22 spp. & 2 hybrid forms%% of the %%unisexual complex group%% are found in IN

  • some spp (Wester Lesser Siren) spend summers in %%estivation%% by encapsulating themselves in a %%mucous-lined cocoon%%

  • some %%permanently aquatic%% ^^(ponds, lakes, & streams)^^

  • some %%terrestrial%% ^^(under logs, leaf litter, rocks)^^

• reproduction

  • %%ephemeral wetlands%%

  • breeding season: %%late winter--early spring%%

  • few breed in fall

  • courtship practices

  • ^^nudging^^

  • ^^tail & chin tapping^^

  • ^^tail fanning^^

  • majority of salamanders have %%internal fertilization%%

  • male salamanders deposit sperm packets (%%spermatophore%%) which the females pick up with their %%cloaca%%

  • %%eggs%% are fertilized as they %%travel through the oviduct%% and encounter %%spermatophore%%

  • majority of salamander spp. are %%oviparous%% (lay unshelled eggs)

  • ==all IN salamanders are oviparous==

  • some give birth to %%gilled larvae%% (%%larviparous%%)

  • others give birth to %%fully transformed young%% (%%pueriparity%%)

  • eggs prone to %%desiccation/drying out%%

  • must lay eggs either in %%moist soil%% or in %%water%%

  • most %%do not provide parental care%%

  • many %%do guard eggs%%

• diet

  • %%carnivorous%%; mostly ^^insects, spiders, & earthworms^^

  • occasional %%cannablism%%

Salamander Family Phylogeny

• %%10%% recognized families

  • %%60%% genera

  • %%400%% spp.

• %%Sirenidae%% <3 & %%Cryptobranchidae%% most %%primitive%%

• Polytomy

  • ^^Proteidae^^

  • ^^Amphiumidae^^

  • ^^Plethodontidae^^

  • ^^Rhyacotritonidae^^

  • ==ALL RELATED; UNKNOWN WHICH IS MORE DERIVED OR PRIMITIVE==

• Salamandridae, Dicamptodontidae, & Ambystomatidae

  • most %%derived%% (especially %%Ambystomatidae%%)

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Sirenidae (“Sirens”) <3

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• 100 million years old--oldest extand Salamander families

• 4 spp. & 2 genera

• characteristics

  • eel-like bodies & front limbs

  • has %%forelimbs%%; ==NO HIND LIMBS==

  • %%paedomorphic%%

  • retain larval characteristics as adults

  • %%external gills%%

  • lack ^^eyelids, premaxillary teeth, & hind limbs^^

  • nocturnal

• distribution

  • fully %%aquatic%%

  • heavily %%vegetated%%, %%slow%% moving water

  • ^^shallow water, swamps, ditches, ponds, etc.^^

  • found primarily in %%southeastern NA%% (not really common in IN)

• reproduction

  • breeding season: %%early spring%%

  • %%200-700%% eggs deposited to base of %%aquatic vegetation%%

  • may have %%external fertilization%%

• %%special concern%%; may eventually become %%endangered%% :(

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Cryptobranchidae (“giant salamanders”)

• %%3%% spp. & %%2%% genera

  • ^^Eastern Hellbender^^ (%%smallest%%)

  • found only in northeastern USA

  • ^^Japanese Giant Salamander^^

  • ^^Chinese Giant Salamander^^ (%%largest%%)

  • 1.5m & ~100 lbs

• characteristics

  • %%paedomorphic%%

  • %%flattened%% body & head

  • %%skin folds%% for respiration

• distribution

  • %%fully aquatic%%

  • cold, fast moving streams

  • %%cool%% %%shallow%% areas where %%rocks not embedded in substrate%%

  • essentially nocturnal

• diet

  • %%primary: crawfish%%

  • fish, aquatic insects

• reproduction

  • %%external fertilization%%

  • %%multiple females%% may lay eggs in %%one male’s%% nest (which are defended)

  • male fertilizes eggs; %%chases away female%%

  • eggs hatch in %%~55-75 days%%

  • young remain in %%larval stage%% for %%2 years%%

  • %%juveniles%% require an additional %%3-4 years%% to reach %%sexual maturity%%

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Proteidae (“mudpuppies”)

• %%6%% spp. & %%2%% genera

• characteristics

  • similar to %%sirens%%, but have %%hind limbs%%

  • large, bushy external gills (%%paedomorphic%%)

  • %%caudal fins%%

  • %%4 toes%%

• diet

  • insects & fish

• distribution

  • %%fully aquatic%%

  • ^^lakes, ponds, rivers, & streams^^

  • rarely seen in depths less than 1 meter

  • commonly found %%20 meters below surface%%

  • found in %%central & eastern USA, southern Europe%%

• reproduction

  • ==internal fertilization==

  • males & females guard eggs

• why “mudpuppy?”

  • stems from the %%erroneous%% belief that members of this family smit %%barking sounds when disturbed%%

• %%special concern%%; may become %%endangered%%

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Ambystomatidae (“mole salamanders”)

• %%30%% spp.

• characteristics

  • stout bodies

  • thick, robust limbs

  • thick tails

  • short, blunt head

  • functional %%lungs%%

• reproduction

  • breeding season: %%spring%%

  1. males & females %%migrate%% in the hundreds to %%ephemeral ponds%%

  2. lay %%eggs%% in %%water%%

  3. stay in %%aquatic salamander larvae%% form for %%4-6 months%%

  4. %%metamorphose (indirect development)%%

  5. %%leave%% aquatic environment

  6. spend life on %%land%%

• why “mole salamanders?”

  • comes from their habit of %%staying underground & in burrows of other creatures%% except when breeding

• \

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Plethodontidae (“lungless salamanders”)

• %%2/3 of all salamander spp%%. belong here

• characteristics

  • primarily %%breathe%% through %%moist skin%%

  • %%thin, elongated%% bodies

  • prominent %%coastal grooves%%

  • ONLY family with ==nasolabial groove==

  • %%autotomize tail when attacked%%

• distribution

  • diverse habitats

  • fully/semi/not aquatic

• reproduction

  • %%internal fertilization%%

  • eggs hatch into mini adults ==(direct development)==

• diet

  • typically feed %%at night%%

  • ^^insects, millipedes, worms, spiders, snails, & mites^^

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Salamandridae (“newts”)

• characteristics

  • thick, %%granular%% skin

  • granules due to %%numerous toxic glands%%

  • %%aposematic%%

    • %%bright coloration%% usually to deter predators

  • unken reflex

  • %%posturing%% areas laden with %%high toxicity%%

  • tetrodotoxin

    • %%neurotoxin%% used for chemical defense

• distribution

  • live in %%forests%%

• reproduction

  1. lay %%eggs%% in %%water%%

  2. eggs --> %%gilled larvae%%

  3. partial transformation into %%red efts%% (2-3 years)

     1. really %%bright%% skin

     2. %%only terrestrial stage of newt%%

     3. %%only%% found in this %%family%%

  4. reach sexual maturity and %%spend life in water%%

• distribution

  • found in eastern & western NA, Europe, Africa, & Asia

• diet

  • eat invertebrates, amphibian, & fish eggs

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Anuran Diversity (Anura = “without tail”)

• currently 45 recognized families

• ~5,500 spp.

• %%constantly changing%% taxonomy

  • spp. discoveries

  • genetic technologies

• ==FROGS ARE LEAPERS; TOADS ARE HOPPERS==

• found on all continents %%except Antarctica%%

• reproduction

  • %%metamorphose%% (indirect development)

  • only %%4 spp.%% have tails as adults

  • usually %%external fertilization%%

• diet

  • tadpole: herbivorous

  • adults: carnivorous

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Scaphiopodidae (“Nearctic Spadefoot Toads”)

• characteristics

  • %%circular/sickle-shaped%% hardened keratinous structure on %%hindfoot%%, forming a %%spade%%

  • %%transitional%% spp.; somewhat %%warty and smooth%%

  • vertical pupils

  • %%don’t%% have prominent %%paratid glands%%

  • glands that secrete %%toxic substance%%

• distribution

  • found on tropical forest floors

  • NA, Europe, Asia, Africa

• reproduction

  • breed in %%temporary ponds%%; %%highly accelerated development%%

• diet

  • eat many insects

• special concern

Hylidae (“Treefrogs”)

• 800 spp. & 45 genera

• characteristics

  • %%smooth & somewhat warty%%

  • mostly well %%camouflaged%% (has %%flash colors%% though)

  • can have %%large or small toepad%%s depending on habitat

• distribution

  • most boreal, some aquatic or fossorial

  • NA, SA, Europe, Asia, Australia

• reproduction

  • all return to water to breed

  • %%external fertilization%%

• diet

  • carnivorous insectivores

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Bufonidae (“Toads”)

• ~500 spp.

• characteristics

  • %%thick, granular, warty%% skin

  • %%Bidder’s organ%%

  • vestigal ovary on larval testes

  • %%prominent parotid gland%% that secretes toxic substance

  • %%diurnal%% during %%spring & fall%%; mostly active at night in hot & humid weather

• distribution

  • most are terrestrial or fossorial

• reproduction

  • all return to water to breed

  • external fertilization

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Ranidae (“True frogs”)

• ~300 spp.

• characteristics

  • %%slim-waisted%% with long legs, %%smooth%% skin, & %%prominent tympanums%%

  • %%dorsal lateral skin folds%% on back or around tympanum

  • extensive hind feet %%webbing%%

  • aquatic & nocturnal

  • some fossorial, arboreal, or terrestrial

• reproduction

  1. eggs deposited in shallow pond or creek

  2. tadpoles

  3. froglets

  4. frogs

• diet

  • tadpoles: herbivorous

  • juveniles & adults: insectivorous

  • some can eat other frogs, turtles, small mammals/birds, etc.

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Phylogeny of Reptiles

• diverged from amphibians in %%Carboniferous%% era, %%Permian%% period (%%arid%% transition)

• %%better fossil record%%

• focus on

  • ^^synapsids (archosaurians)^^

  • ^^diapsids (archosaurians, lepidosaurs)^^

  • ^^anapsids^^

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Synapsids (“archosaurians”)

• %%branched early%% on from %%amphibian%% line

• completely %%terrestrial%%

• %%shelled & amniotic egg%%

• modern day %%mammal%%

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Diapsids (“archosaurians, lepidosaurs”)

• archosaurs

  • gave rise to modern %%birds & crocodilians%%

  • largely responsible for %%dinos%%

• lepidosaurs

  • modern %%snakes & lizards%% (Jurassic)

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Anapsids (“turtles”)

• Triassic

  • basic body plan %%(stayed the same for millions of years)%%

  • %%Odontochelys%%

  • late Triassic %%(220 MYA)%%

  • discovered in %%2008%%, predates %%Proganochelys by 10M years%%

  • %%“toothed shell”%%

  • found in %%E. Asia%%, shallow marine waters near shore

  • %%Proganochelys%%

  • late Triassic %%(210 MYA)%%

  • most well-known

  • %%“early turtle”%%

  • 3ft, 75 lbs

  • possess %%few teeth%%

    • %%modern turtles lack teeth entirely%%

• Jurassic

  • %%Eileanchelys%%

  • late Jurassic %%(165-160 MYA)%%

  • found in W. Europe %%(Scotland)%%

  • earliest %%pond%% turtle

  • discovered in %%2008%%

• Cretaceous

  • %%Archelon (marine turtles <3)%%

  • late Cretaceous %%(75-65 MYA)%%

  • found in oceans of NA

  • %%“Ruling Turtle”%%; 12 ft, 2 tons

  • large, %%flipper-like%% arms & legs

  • closest living relative: %%leatherback%%

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Early Reptiles: Amniotes

• Casineria: Early Carbnoiferous %%(340 MYA)%%

  • %%salamander-like%% early tetrapod

  • %%5 digits with claws%%

  • %%1st amniote%%

• amniotes

  • eggs survive %%out of water%%

  • disperse onto %%drier land%%

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1st Lizards, Hylonomus

• Carboniferous %%(315 MYA)%%

• discovered in %%Canada%%

• characteristics

  • %%earliest known reptile%%

  • among %%first amniotes%%, anapsid

  • small, lizard-like %%(8-12 in)%%

  • fossil with %%distinct toe & scales%%

  • numerous sharp teeth %%(insectivores)%%

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==Mesozoic (“Age of Reptiles”)==

• explosive radiation of reptiles

  • most %%numerous%% & %%largest%%

• dominant %%terrestrial%% & %%aerial%% animals

  • formidable %%marine%% predators

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Archosauromorphs

• ==“Ruling Reptiles” of Mesozoic==

  • early %%diapsid%% amniotes

• ancestral to ^^crocodilians, birds, & turtles^^

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Crocodilians

• surviving archosaurs

• early ancestors %%(Jurassic-mid Cretaceous)%%

• %%Stomato%%suchus

  • ~36 ft

  • swamps, N. Africa

• %%Sarco%%suchus

  • “flesh crocodile”

  • ~40 ft

  • %%“Super Croc”%%

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Lepidosauromorphs

• %%2nd%% major Diapsid lineage

  • ancestral to %%squamates%% ^^(lizards, snakes), tuataras^^

• first appeared %%late Permian%%

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Tuatara (Sphenodontia)

• living fossils; %%Triassic%%

  • extant; New Zealand

• descended from %%beak-headed reptiles (Rhinocephalia)%%

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Order Testudines (or Chelonia), Turtles

• %%shells%% helped them persist for %%200 MYS%%

• %%400 spp.%%

• distribution

  • aquatic, semi-aquatic, terrestrial

• reproduction

  • oviparous %%(all lay eggs)%%

• diet

  • %%most%% adults are %%omnivorous%%; some completely herbivorous/carnivorous

  • all turles %%lack teeth%%,

• distribution

  • %%tropic & temperate%%

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Testudines, Chelydridae (“snapping turtles”)

alligator snapping turtle (endangered)

common snapping turtle

• %%2%% genera; Macroclemys & Chelydra

  • each with %%1%% spp.

• characteristics

  • large, long tails

  • muscular legs

  • massive head

  • greatly %%reduced plastrons%%

  • nocturnal, %%fully aquatic%%

  • %%eggs on land%%

• distribution

  • NA, SA, SEA

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Testudines, Kinosternidae (“mud & musk turtles”)

eastern mud turtle (endangered)

• %%4%% genera, %%23%% spp.

• characteristics

  • <6 in

  • %%glands%% on side produce %%musky odor%%

  • domed carapace & plastron %%(hinged)%%

• distribution

  • %%semi-terrestrial%%

  • %%poor swimmers%%; walks along bottom of streams & ponds

  • prefer %%sandy%% or %%muddy%% dwellings

• reproduction

  • lay %%several%% small clutches %%throughout%% year (4-5/clutch)

  • ==all but one spp. in IN have TDS (temperature dependent sex)==

  • warm = male (depending on spp.)

• diet

  • %%omnivorous%%, but prefer ^^insects, tadpoles, & fish^^

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Testudines, Emydidae (“basking, marsh, & box turtles”)

ornate box turtle (endangered)

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• %%42%% spp.

• %%relatively long-lived%%

  • eastern box turtle can live up to %%80-100+ years%%

• distribution

  • aquatic, semi-aquatic, some terrestrial

• %%low reproductive rates%%

  • countered by %%longevity%%

• diet

  • adult: omnivorous; some herbivorous

  • juvenlie: carnivorous

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Testudines, Trionychidae (“soft-shelled turtles”)

eastern spiny softshell

• ==GENETIC SEX DETERMINATION; NOT TSD==

• characteristics

  • %%long, tubular nose%%

  • fully webbed feet (good swimmers)

• distribution

  • almost fully aquatic

  • %%pharyngeal respiration%%

    • special %%throat lining%% that %%absorbs O2 from water%%

• reproduction

  • females lay clutches %%along sand bars/gravel banks%%

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Ectothermy: Amphibians & Reptiles

• primary heat source %%external%%

• heat %%not always available%% (winter)

• more %%economical%% (behavioural changes to be warm)

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Endothermic: Birds & Mammals

• primary heat source %%internal%%

• better in %%cold environments%%

  • more range than ectothermy

• more %%expensive%%

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Thermal Interactions & Heat Exchange in Ectotherms

• heat exchange with environment occurs via

  • ^^radiation^^

  • ^^convection^^ (smaller = faster temp change)

  • ^^conduction^^ (smaller = faster temp change)

  • color also a factor %%(dark absorbs more heat)%%

  \

  

  activity temperature range: range of temps an ectotherm can operate

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Body Temp Trends

• %%max%% & %%min%% voluntary can be %%highly variable%%

• %%tropical mean%% temps is %%higher%% than %%temp%%

• %%snakes & lizards%% tend to have %%highest body temps%%

• warmest to coolest

  1. lizards

  2. snakes

  3. turtles

  4. frogs

  5. salamanders

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Temp Ranges & Tolerances

• Active Body Temperature %%(ATR)%% varies depending on

  • taxa

  • habitat

  • season

  • genetics

• for most, range is between %%27C -- 35C%%

  • %%few%% reptiles have ATRs %%<20C%%

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Regulation of Body Temps

• due largely to %%behavioural changes%% (change posture/position, etc.)

• amphibians (terrestrial) handle regulation differently because of %%moist skin%%

  • %%low resistance to water loss%%

• Tb %%(body temp)%% largely tracks Te %%(environment temp)%%

  • couple of degrees %%cooler due to evaporation%%

• %%reptiles%% can be exposed to sun %%without excessive water loss (scales)%%

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Dormancy

• response to %%temp extremes & environmental cues%%

• can occur in %%3 different forms%%

  1. hibernation

  2. freeze tolerance

  3. estivation

• Scaphiopus: active 1 month/year in Arizona

• Thamnophis: active 4 months/year in Manitoba

• dormancy forms explained

  1. hibernation

     1. %%Tb%% largely allowed to track %%Te%%, except that %%metabolic activities slowed%% even more than “normal” for a given temp

     2. %%animals tend to move%% during hibernation (brumation)

     3. %%aquatic%% hibernators %%sink to bottom%%

  2. freezing tolerance

     1. %%ice%% crystals %%destroy%% cells & %%extracellular fluid freezes%% & %%dehydrates%% cells

     2. %%few%% spp. can do this (Pseudacris crucifer <3)

     3. use %%cryoprotectants (glycerol or glucose)%%; replace water in cells with antifreeze

  3. estivation

     1. animals inhabiting %%desert & semidesert%% environments

     2. %%physiology not well-known%%

     3. animals flee to %%deep burrows%% with %%high humidity & moist soils%% & %%reduce their metabolisms%%

     4. \

     eastern spadefoot, Scaphiopodidae

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Order Squamata (“Lizards”) [snakes will start later]

• %%8,000%% spp.; %%5,000%% are %%lizard spp.%%

• most %%abundant & diverse%% reptilian group that exists today

• lizards will %%autotomize%% (lose) tails as defense mechanism

• reproduction

  • extremely diverse, but all have %%internal fertilization%%

  • some %%oviparous%% (lay eggs outside of body)

  • some %%viviparous%% (live birth)

  • some %%ovoviparous%% (eggs hatched within body)

  • some have significant courtships (lizards)

  • lay %%flexible%% or %%hard%% eggs

  • %%little parental care%%

• diet

  • carnivorous

• distribution

  • occur in all %%tropical & temperate%% regions

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Phrynosomatidae (“spiny lizards”)

northern fence lizard (Sceloporus undulatus)

• %%125%% spp.

• %%many morphological differences%%

• distribution

  • Sceloporus: arboreal, terrestrial, rock-dwelling

• reproduction

  • most %%oviparous%%

  • some %%viviparous%%

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Anguidae (“glass or alligator lizards”) ==LEGLESS==

western glass lizard (Ophiosarus attenuatus)

• %%120%% spp.

• characteristics

  • has all characteristics of lizard %%(moveable eyelids, external ear)%%

  • long & have shiny scales underlined with %%bony plates (osteoderms)%%

  • %%autotomize%% their tails (which are %%~2/3--3/4 of whole body%%)

  • highly %%terrestrial%% & %%semi-fossorial%%

• reproduction

  • mostly %%oviparous%%

  • some %%ovoviviparous%%

  • few %%viviparous%%

• diet

  • carniverous

• distribution

  • NA, SA, Europe, Asia

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Teridae (“whiptails & racerunners”)

six-lined racerunner (Aspidoscelis sexlineatus)

• %%110%% spp

• characteristics

  • %%long, slender%% bodies with well-developed %%limbs%% & very long tail

  • often have %%yellow stripes%% on body

  • males have %%blue/green chest%% during %%breeding%%

• distribution

  • only found in NA & SA

  • terrestrial; %%sandy prairie%%

• reproduction

  • %%oviparous%%

  • some spp. are %%parthenogenic%%

  • populations are %%all female%%, so all eggs laid are %%unfertilized & clones of the mother%%

  • six-lined racerunner is ==NOT PARTHENOGENIC==

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Scincidae (“skinks”)

five-lined skink (Plestiodon fasciatus)

little brown skink (Scincella lateralis)

• %%largest of all lizard families (1200 spp.)%%

• characteristics

  • %%osteoderms%% give them stiff & shiny bodies

  • %%autotomize%% tails

• distribution

  • %%highly varied%%

  • ^^terrestrial, semi-fossorial, diurnal, etc.^^

  • everywhere except Antarctica

• reproduction

  • ^^oviparous, ovoviviparous, viviparous^^

• diet

  • insectivorous

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Order Squamata (“snakes”)

• %%3000%% spp.

• characteristics

  • %%immovable%% eyelids

  • legless

  • no external ears

  • %%Jacobson’s organ%% (tongue-flicking)

  • left lung either %%entirely absent or highly degenerate%%

• distribution

  • highly varied habitats ^^(terrestrial, arboreal, etc.)^^

• reproduction

  • mostly %%oviparous%%, but can be other two

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Viperidae (“vipers”)

eastern massasauga rattlesnake (Sistrunus catenatus catenatus)

timber rattlesnake (Crotalus horiddus horiddus)

• %%215%% spp.

• characteristics

  • long %%hinged fangs%% with a %%hemotoxin%% (swelling & hemorraging)

  • cobras have a %%neurotoxin%% (central nervous system)

  • %%broad%% heads & %%stocky%% bodies

  • %%Loreal pit organ senses heat%%

• habitat

  • terrestrial with wide variety of habitats

  • NA, SA, Europe, Africa, Asia

• reproduction

  • viviparous

• diet

  • carniverous

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Colubridae (“snakes”)

• was 2000, but now %%650%% spp.

• characteristics

  • can be 7in -- 12ft

• distribution

  • terrestrial & aquatic

• reproduction

  • oviparous

  • ovoviviparous

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Natricidae (“snakes”)

redbelly water snake (Nerodia erythrogaster)

Kirtland's snake (Clonephis kirtlandii)

• %%200%% spp.

• distribution

  • mostly tied to aquatic environments

• reproduction

  • viviparous

  • ovoviviparous

• diet

  • carnivorous

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Dipsadidae (“snakes”)

• %%700%% spp.

• characteristics

  • small-medium

  • from New World

• distribution

  • %%secretive%%; hides under cover

• reproduction

  • oviparous

• diet

  • diverse ^^(invertebrates, amphibians, etc.)^^

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Reproduction & Life Histories

• fertilization can happen %%inside/outside of female%%

• development can be %%direct/indirect%%

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Gametogenesis & Ovulation

• most amphibians, 2 sexes required

• reproductive %%timing%% has %%internal%% controls

  • ultimately coordinated by %%environment%% (temp & photoperiod change)

• Gametogensis

  • %%division & growth of gametes%% within %%ovaries & testes%% through %%hormonal activation%%

• Vitellogensis

  • %%accumulation of nutrients%% in cytoplasm of developing egg

  • rapid growth of oocytes (egg 10-100x size)

• Ovulation

  • occurs when %%follicular%% & %%ovarian walls%% rupture

  • releases ova into oviduct

  • as eggs pass through oviduct, %%protective membrane%% are deposited around them

    • %%number of layers is spp. specific%%

  • %%amphibian%% eggs are %%anamniotic%%

  • eggs expelled in %%gelatinous masses or strings%%

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Fertilization

• %%penetration of sperm & fusion of male & female pronuclei%%

• %%many%% sperm can reach the egg, but %%only one%% will penetrate it

  • %%salamanders%% have %%polyspermic fertilization%%

  • sperm heads %%(acrosomes)%% %%digest%% eggs membranes, making %%tiny hole%%

  • sperm pronuclei %%moves into ova cytoplasm; fusion%%

• 2 types

  1. external

     1. normal for %%Sirenidae & Cryptobranchidae, and most Anurans%%

  2. internal

     1. found in %%other salamander families%%

• external

  • %%simultaneous shedding of eggs & sperm into water%%

  • constrain where eggs are laid

  • %%frogs%%: males grasp female in amplexus so their %%cloacas align%%

  • %%salamanders%%: either amplexus or %%male follows female%% to deposit

  • %%inguinal amplexus%%

  • male has %%front legs%% around female’s %%upper waist%% (under arms)

  • %%cephalic amplexus%%

  • male’s %%hind legs%% wraps around %%female’s head%%

• internal

  • few frog spp. (Pacific NW), Salamandroidea salamanders, all caecilians

  • allows eggs to be laid in %%spot & time of choice%%

  • %%frogs%%: %%hemipenis%% delivers sperm to %%female cloaca%%

  • %%salamander: spermatophores%% deposited %%externally%%

  • proteinaceous pedicel capped by sperm packet

  • %%spermatheca%%

  • %%sperm storage%% in series of tubules on %%cloaca’s roof%%

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Reproduction without Fertilization

• asexual reproduction

  • %%without male%% contributions

  • %%100% female populations in some taxa%%

  • 2 types

  1. Hybridogenesis: progeny only %%transmits female chromosome; all female populations%%

  2. Gynogenesis: diploid/triploid egg only %%activated by sperm; no male chromosomes incorproated into embry%%

     1. only female offspring

     2. fathers from 5 specific spp.

        1. ^^Jefferson salamander, blue spotted salamander, tiger salamander, smallmouth salamander, streamside salamander^^

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Gynogenesis

• “unisexual” hybrid Ambystoma complex

• %%5 MYA%%

• ploidy # varies

• %%17 different combos%%

  • e.g. 2n, 3n, 4n, 5n (n = copies of genetic contribution)

  • if 4n with 4 blue spotted salamander & 1 Jefferson, will look more like blue spotted

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Parental Care

• any form of %%post-egg laying parental behaviour%% that increases %%offspring survival%% at some %%expense of parent%%

• most %%amphibs show no parental care%% aside from %%nest construction%%

• represented by a variety of behaviours

  1. nest, egg, or young attendance/guarding

  2. egg brooding

  3. egg, larval, or hatchling transport

  4. feeding of young

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Development

• Exotrophic

  • %%limited%% amount of %%yolk%%; allows females to lay %%more, but smaller eggs%% (quantity > quality)

  • larvae %%hatch quickly%%, but must %%feed themselves%%

• Metamorphosis

  • %%shift%% from %%embryonic & larval stage%% to mature %%terrestrial stage%%

  • initiated %%hormonally%%, but %%environment%% also plays a role ^^(crowding, predation, food availability, etc.)^^

• Paedomorphosis

  • retention of %%juvenile characteristics as adults%%

  • two types

  1. progenesis: %%accelerated sexual maturity%% relative to %%stomatic growth%%

  2. neoteny: %%slowing of stomatic growth%% with %%onset%% to %%sexual maturity%%

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Growth

• %%addition%% of enw tissue %%in excess%% oif what was lost in damaged tissue

• two types

  1. embryonic

     1. increase when %%high quality food%% is in %%abundance%%

     2. influenced by temp (higher = faster development; not too extreme though)

  2. juvenile

     1. %%much slower%% because of unpredictable food & environment

• ==GROWTH IN AMPHIBIANS IS INDETERMINATE/NEVER-ENDING==

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Age

• intervals ==(periodicity & not age)== are important

  1. sexual maturity (4 months -- 7 years)

  2. Embryogenesis (can be %%truncated%% in %%Scaphiopodidae%%)

  3. larval period → metamorphosis

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Dynamics of Reptilian Reproduction

• multitude of %%patterns%% geared to the %%right environment%% for %%offspring%%

• %%all temperate%% spp. are %%cyclic%%

• %%tropical%% spp. %%cyclic%% or %%acyclic%%

• 2 patterns (temperate salamanders)

  • %%winter/spring%% mating & egg disposition (Ambystomatids)

  • %%late summer/fall%% mating & spring egg disposition (Plethodontids)

• mate attraction & selection

  • %%location%% usually %%not%% a problem

  • reproduction more %%efficient%% within %%home range%% (sometimes movement is necessary)

  • %%courtship%% is key

  • female-heavy investment in gametes = %%most fit mate%%

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Reproduction & Life Histories of Reptiles

• major difference in reptilian reproduction compared to amphibians

  • all have %%internal fertilization%%

  • %%direct%% development

  • %%amniotic egg%%

  • development can occur on %%much drier land%%

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Gametogenesis & Ovulation

• Vitellogenesis very important in egg-laying vertebrates

  • accumulation of nutrients → yolk

• %%vitellogenin%% selectively absorbed by %%oocytes%% & enzymatically converted to %%yolk proteins%% %%(pinocytosis)%%

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Cleidoic (shelled) egg

• %%prevents desiccation%% & contamination by %%environmental pathogens%%

• creates own %%aquatic environment%%

• by %%folding & curling%%, reptile embryo can be %%very long%%

• 3 extraembryonic membranes are formed (no need to know function)

  1. Allantois

  2. Chorion

  3. Amnion

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Fertilization & Copulation

• copulatory organs

  • turtle & crocodilians: a penis of %%spongy connective tissue%% erects & retracts via vascular pressure (similar to mammals)

  • tuataras don’t have copulatory organs

  • squamates: %%penis lost%% & later replaced by %%hemipenis%%

• sperm storage

  • %%delayed fertilization%% → females can %%mate with more than one%% male → %%multiple progeny%%

  • sperm storage tubules on %%upper-mid%% section of %%oviducts%%

  • mechanism for %%expelling sperm%% from these tubules is %%unknown%%

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Reproduction without Fertilization (reptiles)

• Asexual

  • 1 type in reptiles

  1. parthenogenesis

     1. females reproduce without sperm

     2. inheritance is clonal

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Parental Care

1. pre-depositional

   1. involves %%quantity & size of egg components%% (egg components = eggshell, protein, lipids, yolk [oviparous reptiles])

   2. hatchling turtles & crocodilians have %%50-70% more lipids than required%%

2. post-depositional

   1. selection of best sites

3. live-bearing

   1. 20% of all lizards & snakes

   2. ovoviviparous

      1. holds eggs %%much longer%% than %%oviparous%% spp.

      2. embryos can be supported %%entirely%% by %%egg yolk%%

      3. embryos can absorb %%some nutrients%% through %%oviducts%%

   3. viviparous

      1. %%placenta-like%% structure transfers %%nutrients to developing embryo%%

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Embryo Development

• %%direct%% development in %%all%% reptiles

• %%clutch & egg size%% msy be %%proportional to body size%%

  • larger female = larger eggs & clutch

• reptilians that develop from terrestrial egg

  • humidity (more important for leather eggs)

  • temperature (ATR)

• temperature-dependent sex determination %%(TSD)%%

  • %%widespread%% in reptiles

  • found in ^^all crocodilians, tuataras, & 11 spp. of turtles & squamates^^

  • %%average%% temp during %%2nd trimester%%

  • crocs & lizards: male at high temps

  • turtles: females at high temps

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Growth

• 2 growth pulses

  1. embryonic

     1. %%increases%% when %%yolk%% is available & %%decreases%% with %%lower Te%%

  2. juvenile

     1. %%much slower due to unpredictable food & environment%%

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Age

• similar to amphibians ==(periodicity > age)==

  • conception → hatcling/birth

  • sexual maturity

  • reproductive senility

• %%reproductive periodicity%% very important

• %%longevity%% can be great for some reptiles

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Dynamics of Reproduction

• mate attraction & selection

  • %%most fit male >>>%%

  • %%territory more important%% because of reduced need to breed

  • courtship:

  • %%visual%% signals are important, but also %%tactile%% & %%chemosensory%% receptors involved

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