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

    </p>

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%%

    </p>

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
  • </p>

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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^^

    </p>

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)%%

    </p>

    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. </li>

      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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