FNR24150 Exam 1 Notes

Phylogeny of Amphibians

Oldest to most recent

1. Lissamphibia
2. Temnospondyli
3. %%Gymnophiona, Anura, Caudata (extant amphibians)%%

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)

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%%

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%%

Leposondyli

• very %%small%% yet very %%diverse%% early amphibians
  • similar to newts, eels, snakes, lizards, etc.

Permian era

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

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

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

Eryops

• %%Permian (270 MYA)%%
• %%crocodile-like%% early amphibian
• %%aquatic%% & %%terrestrial%%
• had some structural %%features%% that would %%appear%% in %%later%% reptiles

Diplocaulus (“double stalk”)

• %%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%%

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

Amphibamus (“equal legs”)

• %%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)

Gerobatrachus (“frogmander”)

• %%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==

Triadobatrachus (“proto frog”)

• %%early Triassic (250 MYA)%%
• found in %%Madagascar%%
• ==first fossil frog==
• characteristics
  • ^^short, stubby tails^^
  • ^^10 cm^^
  • ^^13-14 presacral vertebrae^^
  • ^^9 in modern frogs^^

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)

Triadobatrachus vs. Viraella

• Vieraella more truncated overall
  • %%reduction%% %%in presacral vertebrae%%
  • %%enlarged & fused%% pelvic bones in %%Viraella%%
  • fused %%tibiofibula%% in %%Viraella%%

Paleobatrachus (“ancient frog”)

• %%Cretaceous--Tertiary (130-135 MYA)%%
• found in %%Europe%%
• %%completely aquatic%%
  • inhabited %%swamp basins%%
  • %%volcanic gases%% preserved soft %%tissue%%
• resembles present day %%Xenopus%%

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%%)

Sirenidae (“Sirens”) <3

• 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%% :(

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%%

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%%

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

• \

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^^

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

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

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

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

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.

Phylogeny of Reptiles

• diverged from amphibians in %%Carboniferous%% era, %%Permian%% period (%%arid%% transition)
• %%better fossil record%%
• focus on
  • ^^synapsids (archosaurians)^^
  • ^^diapsids (archosaurians, lepidosaurs)^^
  • ^^anapsids^^

Synapsids (“archosaurians”)

• %%branched early%% on from %%amphibian%% line
• completely %%terrestrial%%
• %%shelled & amniotic egg%%
• modern day %%mammal%%

Diapsids (“archosaurians, lepidosaurs”)

• archosaurs
  • gave rise to modern %%birds & crocodilians%%
  • largely responsible for %%dinos%%
• lepidosaurs
  • modern %%snakes & lizards%% (Jurassic)

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%%

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%%

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)%%

==Mesozoic (“Age of Reptiles”)==

• explosive radiation of reptiles
  • most %%numerous%% & %%largest%%
• dominant %%terrestrial%% & %%aerial%% animals
  • formidable %%marine%% predators

Archosauromorphs

• ==“Ruling Reptiles” of Mesozoic==
  • early %%diapsid%% amniotes
• ancestral to ^^crocodilians, birds, & turtles^^

Crocodilians

• surviving archosaurs
• early ancestors %%(Jurassic-mid Cretaceous)%%
• %%Stomato%%suchus
  • ~36 ft
  • swamps, N. Africa
• %%Sarco%%suchus
  • “flesh crocodile”
  • ~40 ft
  • %%“Super Croc”%%

Lepidosauromorphs

• %%2nd%% major Diapsid lineage
  • ancestral to %%squamates%% ^^(lizards, snakes), tuataras^^
• first appeared %%late Permian%%

Tuatara (Sphenodontia)

• living fossils; %%Triassic%%
  • extant; New Zealand
• descended from %%beak-headed reptiles (Rhinocephalia)%%

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%%

Testudines, Chelydridae (“snapping turtles”)

• %%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

Testudines, Kinosternidae (“mud & musk turtles”)

• %%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^^

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

• %%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

Testudines, Trionychidae (“soft-shelled turtles”)

• ==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%%

Ectothermy: Amphibians & Reptiles

• primary heat source %%external%%
• heat %%not always available%% (winter)
• more %%economical%% (behavioural changes to be warm)

Endothermic: Birds & Mammals

• primary heat source %%internal%%
• better in %%cold environments%%
  • more range than ectothermy
• more %%expensive%%

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)%%

  

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

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%%

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)%%

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

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

Phrynosomatidae (“spiny lizards”)

• %%125%% spp.
• %%many morphological differences%%
• distribution
  • Sceloporus: arboreal, terrestrial, rock-dwelling
• reproduction
  • most %%oviparous%%
  • some %%viviparous%%

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

• %%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

Teridae (“whiptails & racerunners”)

• %%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==

Scincidae (“skinks”)

• %%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

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

Viperidae (“vipers”)

• %%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

Colubridae (“snakes”)

• was 2000, but now %%650%% spp.
• characteristics
  • can be 7in -- 12ft
• distribution
  • terrestrial & aquatic
• reproduction
  • oviparous
  • ovoviviparous

Natricidae (“snakes”)

• %%200%% spp.
• distribution
  • mostly tied to aquatic environments
• reproduction
  • viviparous
  • ovoviviparous
• diet
  • carnivorous

Dipsadidae (“snakes”)

• %%700%% spp.
• characteristics
  • small-medium
  • from New World
• distribution
  • %%secretive%%; hides under cover
• reproduction
  • oviparous
• diet
  • diverse ^^(invertebrates, amphibians, etc.)^^

Reproduction & Life Histories

• fertilization can happen %%inside/outside of female%%
• development can be %%direct/indirect%%

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%%

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%%

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^^

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

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

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%%

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==

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

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%%

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%%

Gametogenesis & Ovulation

• Vitellogenesis very important in egg-laying vertebrates
  • accumulation of nutrients → yolk
• %%vitellogenin%% selectively absorbed by %%oocytes%% & enzymatically converted to %%yolk proteins%% %%(pinocytosis)%%

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

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%%

Reproduction without Fertilization (reptiles)

• Asexual

  • 1 type in reptiles

  1. parthenogenesis

     1. females reproduce without sperm
     2. inheritance is clonal

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%%

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

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%%

Age

• similar to amphibians ==(periodicity > age)==
  • conception → hatcling/birth
  • sexual maturity
  • reproductive senility
• %%reproductive periodicity%% very important
• %%longevity%% can be great for some reptiles

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