Herpetology Exam 1
Define taxon
(pl. taxa) is any group of organisms that is given a formal taxonomic name.
Define phylogenetic systems
- (cladistics) emphasized the importance of derived characters shared among taxa in recognizing monophyletic groups (clades) • Mostly using skeletal features or DNA • DNA is useful for present but skeletal is needed for past (fossils)
Amphibian Diversity Through Time
- Amphibians (SL) diversified rapidly in Carboniferous - Large loss of diversity in the Late Paleozoic - Rediversified in the Mesozoic and Cenozoic.
*The Australian Plate: Mixed Gondwanan and Laurasian Elements
- Australia, Antarctica, New Guinea, and New Zealand separated from Gondwana - NZ broke off 80-90 mya - Australia and Antarctica also formed a land bridge to South America (55-32 mya) - Australia has been geographically isolated for about 32 million years •Two units reflected in history •Ancient clades that are generally shared with Gondwana landmasses •Clades that entered Australia after connection with Asian plates in early Miocene
*Africa and Faunal Exchange with Southern Europe
- Biogeographic reconstructions of worldwide amphibian taxa suggest that Rancid frogs (1/3 extant frog diversity) originated in African tropics •All of Africa was tropical (~1 mya) •Arabian Peninsula was geographically part of Africa but collided with Eurasia about 19 mya •Mediterranean Sea was mostly dry for 600,000 yrs - direction connections between North Africa and southern Europe
Styles of evolution
- Divergent evolution- diverse descendants from a common ancestral species - Convergent evolution- similar characteristics in distantly related organisms - Parallel evolution- similar characteristics in closely related organisms.
*The Great American Biotic Interchange
- GABI: late Cenozoic paleozoogeographic biotic interchange event which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents. •The migration accelerated dramatically about 2.7 million years (Ma) ago during the Piacenzian age
*South America
- North and South America were separate by water gap from late cretaceous until Isthmus of Panama was completed •South America was isolated up until 35 mya •South America is home to a diverse assemblage of herps •Many lineages originated in South America and then dispersed worldwide
What are drawbacks to the phylogenetic tree?
- Qualitative rather than quantitative - Different phylogenetic hypotheses will be proposed
What are homologous structures?
- Similar structures inherited from a common ancestor The tetrapod forelimb is a good example of this.
What are analogous structures?
- Structures with similar function acquired as a result of convergent evolution - Flight has evolved several times, and each group has used a different method to take to the air
Describe why the history of amphibians is difficult to pinpoint
- Taxonomic questions are complicated by large gaps in the fossil record during which significant evolutionary radiation occurred. - Romer's gap (Lower Carboniferous) - Carroll's Gap (Permian-Jurassic)
What is the difference between phylogeny and taxonomy?
- Taxonomy is the field of biology that classifies living and extinct organisms according to a set of rules. - naming and classifying organisms - does not reveal anything about the shared evolutionary history of organisms - Phylogeny is the evolutionary history of a species or group of species - concerns evolutionary relationships of organisms - reveals the shared evolutionary history
Describe Diapsids and Synapsids
- Within Amniota there is a fundamental split between Diapsida (living snakes, lizards, and turtles) and Synapsida (Mammals + some extinct synapsids). - Anapsida is no longer considered a natural group. It is more likely a polyphyletic assemblage.
What is paraphyletic?
- a group that does not include all the descendants of a common ancestor - not considered to be a natural grouping
*Sky Islands
- evolve in isolation without gene flow from other mountain tops - ex) Quacitia Mts OK and AR- have Plethodon clades with little to no gene flow between them •Climate change may push suitable habitat for cool-adapted species to mountaintop into isolation or extinction
*Climate Change, Isolation, Refugia
- habitat change is the biggest factor that shapes where a population can live - climate change can fragment suitable habitat into separate refugia •Refugia: locations where species have persisted while becoming extinct elsewhere •Climate Change can be brief (geologic terms 10/100 thousand years)
Seychelles Islands
- india and the Seychelles rifted from Madagascar 87-60 mya - all islands were connected 10,000-16,000 years ago •Tiny area of islands harbors endemic lineages that are more than 65 mya •Sinks, geckos, caecilians, frogs Preserve ancient phylogenetic diversity
*Phylogeography
- is an integrative discipline that aims to understand the geographic ordination of genotypes. Phylogeographic approaches have been used to enhance our understanding of both biogeography and landscape genetics across a variety of spatial and temporal scales. • Speciation: the splitting of single lineage into two lineages we recognize and distinct species
Island Biography Phenomenon
- island gigantism and dwarfism ex) rattlesnakes off Baha peninsula are larger than where they occurred before - Adaptive radiations on islands ex) different ecomorphs, anoles legs changes length after secluded on an island - Island paleoendemism, preserve genetic diversity ex) Islands preserve genetic diversity of relict lineages - tuatara and Bremuda skink (19.8 millon years old)
*Island Biogeography
- islands are particularly interesting to biogeographers bc isolation promotes phylogenetic and morphological diversity - continental Islands: geographic connection to land mass - connections emerge/submerge with sea level changes •Oceanic Islands: usually volcanic islands so no tie to mainland. Species arrive in very low numbers.
What is cladistics?
- method to classify organisms into groups (clades) by recognizing shared derived characters - In cladistics, we find the most reasonable tree that defines the phylogeny of organisms. - most reasonable tree = minimum character states present to define a tree
*Laurasian and Gondwanan origins of herps
- most modern reptile groups originated in Gondwana (with exceptions of lacertid lizards & emydid turtles) •Salamanders great example- all salamander families (except hynobiids) are present in NA - strongly suggests modern lineages originated on this continent
*Madagascar: Ancient Continental Fragment
- nearly all herp species are endemic (resticted to that region) - major radiation of species after land masses split (160 mya) •High species diversity but from only a few major lineages •Little dispersal to Madagascar since land masses separated
*Pangea and the mesozoic origin of modern herps
- terrestrial vertebrates 1st appeared in the late Devonian (360mya) - early Triassic 1st occurrence of species belonging to all three extant amphibian clades on Pangaea (230mya) • Pangaean origin of modern reptiles is also supported by fossils and molecular clock analysis •molecular clock: DNA and protein sequences evolve at a rate that is relatively constant over time and among different organisms.
*What is biogeography?
- uses information about natural history, phylogeny, geology, and climate to interpret the past and present distributions of taxa Data used in biogeographic analysis: 1. ecological info about the organisms distributions, habitat preferences 2. earth's history: past continental movements, origins of landscape features, climate 3. Phylogenies of organisms and estimated times of divergence in the past
What are Mesozoic lissamphibians and when did they appear?
-Clade containing modern frogs, salamanders, and caecilians -First definite lissamphibians appear in the Triassic. -All extant clades represented by Jurassic
Describe early tetrapds
-Numerous early tetrapods are known from the Devonian. -The relationship between these taxa and later amphibians is obscured by a lack of fossil evidence
Describe the late Paleozoic Peak in relation to amphibians
-Peak amphibian diversity was achieved in the Late Carboniferous/Early Permian -Diverse ecology -Two major clades -Temnospondyls (Eryops) -Lepospondyls (Diplocaulus) -Phylogeny can be uncertain despite a well sampled fossil record -Body sizes ranging from centimeters to several meters -Loss of diversity as global climate changed in the Permian
General trends in anuran evolution
-Reduction of trunk length -Rotation and lengthening of illium -Increased leg length
What is Romer's Gap?
-Romer's gap represents a break in the fossil record extending from the Late Devonian to the Mississippian (360-345 MA) -Lack of vertebrate fossils in this gap obscures the origin and relationships of later taxa. -Recent discoveries in Nova Scotia and Scotland are beginning to untangle the missing pieces of Romer's gap
*Methods of dispersal
1. Transoceanic dispersal: originated one continent and disperse to another via ocean - tortoise example: 2004, female walked ashore in Tanzania (750 km/ 7 weeks, terrible condition) - Iguana example: hurricane 1995, on veg mat 300km 2. Transcontinental dispersal: land bridge allowed exchange of organisms between continents 3. Human- mediated dispersal: intentional via et trade or for food or as stowaways on cargo ships - 5 species of herps make IUCNs list of "100 worst incvasive species" ex) Red-eared slider, American bull frog, cane toad were introduced intentionally ex) brown tree snake accidentaly introduced in Guam, decimated bird and lizard populations *ex) Coqui frog accidently transported to Hawaii - no bio impact (no amphibians in HI) but sound of calls lowers property value
*Two mechanisms for geoggraphic distribution of organisms
1. dispersal: movement to new location via walking, swimming, flying, drifting, or transportation 2. vicariance: new barrier fragments a continuous geographic distribution of organisms into two or more separate populations.
THREE EXTANT LISSAMPHBIANS LINEAGES = AMPHIBIANS list definitive traits
1.Nearly all amphibians have complex life histories - metamorphosis from an aquatic larvae to a terrestrial adult (all are fundamentally tied to water) 2.Permeable skin that acts as a respiratory organ (in addition to lungs) - can only happen when moist
Phylogeny Definition
= the science of evolutionary relationship between organisms • Often displayed in form of branching diagram • Cladograms or phylogenetic trees
What is a phylogenetic tree?
A branching diagram that shows evolutionary relationships among taxa
When were the first amniotes?
Amniotic eggs are first observed at 300 Ma, associated with the "reptiles" Hylonomus and Paleothyris. Both are small (~24cm) superficially lizard-like animals found in hollow tree stumps The synapsid (mammal-line amniote) Archaeothyris is also first recognized in the Late Carboniferous
parthenogenesis
Asexual reproduction in which females produce offspring from unfertilized eggs.
BOINDEA
Boas (Boinae), Pythons (Pythoninae) and Sand Boas (Erycinae) Content and distribution: • 25 genera, 98 species. Worldwide, except eastern and central U.S., most of Canada, most of Europe, and East Asia. • Morphology: Boids include some of the world's largest snakes, reaching up to 10 meters in length. The green anaconda (Eunectes murinus) is perhaps the heaviest bodied, while the reticulated python (Python reticulates) is the longest. Boids have kinetic skulls, are not venomous. They have remnants of hind limbs, vestigial pelvic girdles, and two lungs (although one is reduced). Many boids have labial pits that can detect infrared radiation. • Life history: constrictors and primarily ambush hunters. Habitats range from rain forest to mountain cloud forest to desert. All pythons are oviparous, whereas all boas and most sand boas are viviparous. Many pythons construct nests in which to lay their eggs and remain with their eggs until they hatch. Some female pythons coil around their eggs and shiver to generate heat for incubation. Some boids can eat very large prey. • Miscellaneous facts: Boids were much more widely distributed and diverse before the colubroids evolved during the Miocene (~20 mya). Today, boids are most diverse in places where there are no vipers, such as the Caribbean Islands and Australia.
What is Gymnophiona (amphibian)?
Caecilians (200 species) • Are elongated, legless, burrowing and aquatic • Found in tropics around the world • Little is known about their natural history
What are the 3 lineages of amphibians?
Caudata, Anurans, & Gymnophiona
SCOLECOPHIDIA: BLINDSNAKES AND THREADSNAKES
Content and distribution: • 30 genera, ~400 species. Distributed in SW U.S., Mexico, Central and South America, Africa, and SW Asia. Morphology • The Scolecophidia includes some of the smallest snakes; species range in length from 10-46 cm. Unlike other clades of snakes, the mandibles attach anteriorly, so their skulls are relatively akinetic and robust. They have undifferentiated ventral scales, which may help them bore through the substrate as they burrow. Eyes are very small or absent. Some have vestigial hind limbs. Life history: • All are fossorial and most inhabit moist tropical forests, eating ant and termite eggs and larvae. Most are oviparous. Miscellaneous facts: • As the most basal clade of the Serpentes, they give us a clue as to what snakes evolved from. It is thought that snakes originated as small fossorial animals and later "resurfaced" and radiated into the diversity we see today.
VIPERIDAE: VIPERS, ADDERS AND PITVIPERS
Content and distribution: • 34 genera, 320 species. Worldwide, except Australia. Morphology: • All are venomous. These snakes have a solenoglyphous dentition, or long, hollow fangs on a reduced, moveable maxilla. When the mouth is closed, the fangs are folded flat and posteriorly. When the mouth is opened to strike, the maxilla pivots and the fangs extend downward. • Viperids administer a primarily hemotoxic and cytotoxic venom. some species have developed neurotoxic venom as well. • They have extremely kinetic skulls • some can ingest prey weighing 1.5 times as much as the snake. • Most are heavy-bodied, but a few are arboreal and slender. Pitvipers have two highly-developed facial pits to detect infrared radiation. • Most pit vipers have a tail spine that produces a buzzing sound when vibrated against vegetation. In one group of pitvipers, the rattlesnakes, this has developed into an actual rattle Life history • Most viperids use a combination of ambush and active foraging. They often utilize cryptic coloration to avoid detection. • Most are viviparous, including all rattlesnakes. Parental care is common in this family; females remain with their young until at least their first shed.
COLUBRIDAE: COLUBRIDS
Content and distribution: • About 320 genera, with over 1800 species. Distributed worldwide. Morphology: • This is a very diverse group of snakes and there are no morphological synapomorphies, since the group is likely para or polyphyletic. About 1/3 of colubrids are venomous, rear-fanged snakes. Venom runs down the outside of slightly enlarged teeth near the rear of the mouth. Other morphological characteristics are highly variable. Life history: • Also highly variable. Most are oviparous. However, garter snakes (Thamnophis) are ovoviviparous. Many colubrid females only reproduce every two or three years. Most New World colubrids are active foragers. • Colubridae is a "trash can" taxon and is likely not monophyletic - it includes about 70% of all extant snake species.
Convergent Evolution
Distantly related taxa assume similar forms due to similar ecological niches
List the taxonomic hierarchy
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
When did Crocodilians first appear?
Eusuchia (true crocodiles) first appear in the late Cretaceous. They further diversified in the Tertiary after surviving the K-PG extinction event. All extant crocodilians are semiaquatic, although terrestrial forms persisted into the Eocene
Parallel Evolution
Independent origin of similar features in related organisms due to similar ecology
When do squamata appear (snakes and lizards)
Squamates first appear in the Middle Jurassic, with clearly recognizable modern clades appearing in the tertiary.
*When did turtles appear?
The origin of turtles (Testudines) has been widely debated. Their extremely unique morphology has led to difficulties identifying members of the stem group. Proganochelys appears in the Late Triassic and is definitely a turtle. Eunotosaurus (Late Permian) is believed to be a stem turtle and shows diapsid affinities. This supports recent molecular analyses which place turtles sister to archosaurs
Wallace's Line
The zoogeographical boundary proposed by Alfred Russel Wallace that separates the marsupial fauna of Australia and New Guinea from the non-marsupial fauna of Indonesia - idea that there must be movement in tectonic plates - One of the most famous biogeographic patterns on our planet. Name after Alfred Russel Wallace. He observed despite geographic proximity of island of Bali and Lombok two islands have very different fauna. Same in Borneo and Sulawesi. Explanation for this phenomenon is that present day island were much farther apart in geographical history before tectonic activity brought them together.
Define monophyletic taxon
a monophyletic taxon is one that includes a group of organisms descended from a single ancestor
define paraphyletic taxon
a paraphyletic taxon as one that includes the most recent common ancestor, but not all of its descendants
Define polyphyletic taxon
a polyphyletic taxon is composed of unrelated organisms descended from more than one ancestor
Divergent evolution
evolution of one or more closely related species into different species; resulting from adaptations to different environmental conditions
Vicariance
lineages are split when barriers to gene flow arise = unique fauna on both sides of the divide over time
Taxonomy Definition
the science of categorizing or classifying living organisms
What are the 4 lineages of reptiles?
turtles, crocodilians, tuatara, and squamates
CAECILIANS: Indotyphlidae (Indo-African Caecilians)
• 10-20cm total length • Almost all have primary (encircles body) and secondary (partially encircles body) annuli
CAECILIANS: Siphonopidae
• 11 to 50 cm SVL • Found in Southern America • Typical borrowing behavior
CAECILIANS: Dermophiidae (Neotropical and Tropical African Caecilians)
• 20-60cm SVL • Thrive in disturbed landscapes due to increase in prey (earthworms)
CRYPTODIRA: Trionychidae (Softshell turtles)
• 25cm - 1m carapace length, shell is covered with leathery skin, fleshy proboscis (snorkel), limbs are webbed, fully aquatic, sexually dimorphic (f>m) • Great swimmers but spend most time buried in substrate • North America (SE, Midwest), Africa, Asia • Speckled softshell turtle (China) -largest living freshwater turtle (99cm), critically endangered.
SALAMANDRIODEA FAMILIES: Dicamptodontidae (giant salamanders)
• 34cm (just over foot long!) • Damp coniferous forest of PWN
CAECILIANS: Herpelidae (fish caecilians)
• 35 cm or less • Found in Africa• Mate in soil • Takes 2 years to mature into Adults
CAECILIANS: Icthyophiidae (fish caecilians)
• 50 cm SVL • Found in South Asia • Females attend clutches - rotate eggs, secrete to prevent degradation
ANGUIMORPHA
• 6 families of morphologically diverse lizards (supported by molecular DNA) • Varanidea (Monitors) • Largest lizard on earth (Komodo monitor, Varanus komodoenis), 3m SVL • Helodermatiidea • Only venomous lizards (Heloderma; Gila monster) -venom in lower jaw, blunt tails for fat storage, USA & Mexico • Lanthanotidea (earless monitors) only found in Borneo, semi aquatic • Shinisauridae (Chinese crocodile lizard) only found in China, semi aquatic
ANURA FAMILIES: Ranidea (true frog)
• 600 species in family • Widest distribution of frog families -found all over the world (except Antarctica) • Highly aquatic, powerful hindlimbs, extensive toe webbing
ANURA FAMILIES: Hylidae (American and Australian tree frogs)
• 724 species • Large range - NA, SA, Europe, Asia, Australia, Africa • Most lay eggs in water but some will in vegetation above
ANURA FAMILIES: Craugastoridae (fleshbelly frogs)
• 850 ssp (although taxonomy still not settled) • Direct development (no free-living tad pole stage) • Mostly in central and south America
What is a clade?
• A clade is a group consisting of a common ancestor and all its descendants • Clades must be monophyletic (descended from a common evolutionary ancestor)
SYSTEMATICS AND PHYLOGENY:SQUAMATA - SERPENTES
• A monophyletic group that is nested within the lizards • 15 major clades, 420 genera and >3,000 species (Colubroidea most diverse clade) • Snakes are found worldwide except at very high latitudes, and range in elevation from sea level to over 4,900 m • Five major clades are found in North America, north of Mexico
CHARACTERISTICS OF REPTILES: SCALES
• All retain scales (thickened and folded layers of epidermal and dermal tissue). • Osteoderms: thin slivers of bones deposited in dermal layer • Scutes: differ from other reptile groups - coordinated with development of underlying bone.
GENERALIZED LIFE HISTORY: SERPENTES
• All snakes are carnivorous • Some are generalists whereas others may specialize on lizards, toads, snails, eggs, or some other prey • Most snakes are not territorial • Some den communally during the winter • Combat between males over mates occurs in some snakes • Most snakes are oviparous, but ovoviviparity has independently evolved at least 30 times, often in species that live in colder environments • Parental care, usually in the form of egg guarding, has been documented in a few species
ALLIGATORIDAE
• Alligators and Caimens, 4 genera, 8 species • Restricted to Central and South America -except Alligator mississippiensis (USA & Mexico) • Couple exceptions but mostly inhabit rivers, lakes, lagoons (fresh water) • Teeth in lower jaw fit into pits in upper jaw - can't be seen when mouth is closed • Size >6m to 1.5 m total length
What is a crocodilian (reptile)?
• Alligators and Crocodiles (25 species) • Mostly large, semi aquatic predators and classified as threatened or endangered in IUCN Red List • Includes largest living reptiles - Australian saltwater crocodile and Indian gharial
TURTLE MORPHOLOGY
• Among longest-lived vertebrate (150 yrs) • Absences of teeth - keratinous beak • Unique in pelvic and pectoral girdle are under vertebrate • Vertebrate are completely fused into shell • Turtle Shells have 2 parts • Carapace - dorsal • Plastron - ventral • Shell is covered by scutes - not aligned with underlying bone
SALAMANDRIODEA FAMILIES: Proteidae (olms and mud puppies)
• Aquatic and paedomorphic (large external gills) • lack maxillary bone • North America / Europe
ANURA FAMILIES: Scaphiopodidea (North American Spadefoot Toads)
• Burrow and come out during heavy rain • Can have rapid development times (8 days) • Hindfeet have well-developed keratinous spadelike metatarsal
CRYPTODIRA: Cheloniidae (Sea Turtles)
• Can't retract into shells • Completely marine only coming to shore to lay eggs, nest at night and are faithful to particular nesting areas • Traverse widely through temperate and tropical seas • Green sea turtles get their pigment from their diet (cartilage and fat a greenish color) • Warmer temps = females
History of herpetology (Carolus Linnaeus viewpoint)
• Carl von Linne aka Carolus Linnaeus called both groups " foul and loathsome" & "their Creator has not exerted his powers to make many of them" • Sadly mistaken on both accounts
LEPIDOSAURIA:SQUAMATA
• Caudal autotomy - tail breakage as a defensive mechanism • Tail will remain moving for 30 mins • Fracture plates with vertebrate, regenerated tail is made from cartilage rather than bone, usually can tell by size and color • Limb reduction • Repeated independent evolution of limb reduction • Reduced hindlimbs (Australian skinks) • Complete limb lessness evolved 25 separate times
SYSTEMATICS AND PHYLOGENY: SALAMANDERS where do they occur
• Caudata (cauda = tail ) • 10 families, 66 genera, 665 extant species • 40% occur in Central and South America • Found on every continent expect Australia • Most Phylogenetically diverse in North America
SYSTEMATICS AND PHYLOGENY ANURA: FROGS
• Comprise vast majority of amphibian diversity (88%) • Frog systematics is by far most active field • 2004-2015 30 families to 52
CROCODYLIDAE
• Crocodiles - 3 genera, 15 species • Fourth tooth is visible when mouth is closed • Go through 4,000 teeth in 1 lifetime (80 teeth x50) • Can get up to 7m in length, 2,000 lbs • Long-lived 35-75 yrs • Strongest bite of any animal in the world (5,000 lbspressure) • Widest distribution (India to Australia), largest reptile in the world, and reputation of eating humans comes from Crocodylus porosus (saltwater crocodile)
Describe amphibian skin
• Cutaneous mucus glands: • Secrete mucoproteins limit water loss and promote gas exchange • Breeding glands (nuptial pads) - arise from increased levels of androgen hormones • Granular glands: produce defensive secretions • Ex. Parotiod glands (dorsal warts) on bufonid toads
GEKKOTA CLADE
• Diverse clade (+1500 species) (25% of lizards) • Species range from 24 cm to 15-18 mm SVL (rivals dwarf chemeleons for smallest amniotes in the world) • Toe pads to cling to surfaces - most but not all. • Most are nocturnal • Vocal communication is rare in squatmates but geckos make clips/churps • Mostly oviparous (1 or 2 eggs per clutch) • Parthenogenesis occurs in some species • Defensive mechanisms are well developed • Tails are highly autotomic • Shed large patches of skin when grabbed (splitting zone within the dermis)
What is a reptile?
• Dry scaly skin, typically lay soft-shelled eggs on land, & three chambered heart (except crocodilians) • Birds are closely related to crocodilians so complete list would include them - they are so different they are normally excluded from herpetology • "reptiles" henceforth will refer to all extant reptiles besides birds
What are some shared characteristics of amphibians and reptiles?
• Ecothermy - rely primarily on environmental sources for heat for thermoregulation • Daily food requirement is 1/10 -1/7 that of bird or mammal of same size • To generate heat takes a massive amount of energy • Herps can focus new energy in secondary production (growth & reproduction) (50% vs 2%) • Exploit ecological niche on prey too small for birds and mammals • Cycle more biomass through ecosystem
AMPHISBAENIA
• Elongate and completely limbless (exception of Bipesand Blanus) • All species burrow - many resemble earth worms • Most species are < 15 cm long • Burrowing is achieved with an accordion-like motion -move easily forward or backward • Carnivorous - forage in ant galleries or prey on beetle larvae
SALAMANDRIODEA: Amphiumidae (congo eels)
• Elongate, paedomorphic, lack eyelids • up to 116 cm (46 in) long • Retained both pair of limbs • Slow moving rivers & swamps in SE USA
CRYPTODIRA: Emydidae (Pond and Box Turtles)
• Emydidae (Pond and Box Turtles) • Largest and most diverse family of turtles • 12cm-60cm, plastrons are hinged, the upper shell (carapace) of most emydids is the shape of a low arch, • Food habits range from strictly carnivorous to strictly herbivorous. • Clutch size can range from 2-50eggs • High relative abundance makes them well studied • Common in pet trade - red eared slider
Anuran life history
• External fertilization - mating posture called amplexus • 10% of anurans exhibit some form of parental care • many species are highly territorial, defending nests, oviposition sites, • Most are nocturnal • In the winter, many temperate anurans enter a state of torpor to avoid freezing; in arid regions, frogs may bury themselves underground, or minimize the cutaneous respiration
How does the future look for herps?
• Extinction Rate of Amphibians is 200x greater than background extinction rate • Human activities impact herps more due to life history traits • Habitat loss, pollution, disease • Golden Toad - Costa Rica
GYMNOPHIONA LIFE HISTORY
• Fertilization in caecilians is internal and effected by a phallodeum • 50-80% oviparous (5-100 eggs), Females remain with eggs until hatching • Viviparity evolved independently (3 families) - developing young are nourished by secretions of cells • Fetal nutrition: • Dermaphagy (not found in any other tetrapod group): after hatch mother begins a modified sloughing process, skin becomes engorged with lipids, young consume skin in 7 mins and they cycle begins 64 hours later. •Oophagy developing embryos eat unfertilized eggs or other embryo
Caudata life history
• Fertilization is external in cryptobranchids, hynobiids, and sirenids and internal via spermatophores for all others • Deposit aquatic eggs that develop into larval stage - however there is direct development at the species level (300). • Paedomorphosis - never completely metamorphose but become reproductively mature while retaining a larval body form
PLEURODONTA
• Few morphological characteristic but molecular DNA supports the clade • Contains 12 families that are mostly restrained to North and South America •Phrynosomatidae (spiny and sand lizards) - make large portion of lizard fauna in SW USA • Dactyloidae (Anoles) - most widely studied lizard (1 genus but 390 species) -All over SE USA • Crotaphytidae (Collarded and Leopard Lizards) - colorful lizards of mesic/arid areas in North America • Iguanidae (Iguanas) - herbivores, size range from 14 - 70 SVL, 30 out of 39 species on a IUCN list BUT considered invasive species in FL
CAECILIANS: Scolecomorphidae (buried-eyed caecilians)
• Found in Africa • 20-45 cm SVL • Skull lacks eye orbits - vestigial eyes are attached to end of tentacles
CAECILIANS: Chikilidae
• Found in India • Discovered in 2012 - most recent family
CAECILIANS: Rhinatrematidae (Neotropical tailed caecilians)
• Found in South America • 33 cm SVL • Have true tail • Cryptic surface forms - zygokrotaphic skull • Oviparous with free-living larvae
Describe caudata morphology (salamanders)
• Four limbs, long tail, coastal grooves • aquatic larvae have true teeth on both upper and lower jaws, gill slits and external gills • The optic notch and middle ear are absent, as are several skull bones, including but not limited to the postorbital, post parietal, jugal, basioccipital, and ectopterygoid.
What is an Anura (Amphibian)?
• Frogs (6,483 species) largest group of amphibians • "Anura" is from two Greek words (an oura) meaning "without a tail" • Short bodies, no tails, 4 well developed limbs
GAVIALIDAE
• Gharial and False Gharial • 2 genera, 2 species • Long narrow snouts • Gavialis gangeticus, 6.5m, male will have a boss • Tomistoma schlegelii, 4m, doesn't have a boss • Most aquatic of all crocs - weak limbs on land • Found in fast moving rivers • Primary eat fish • Long-lived species (29 years) • Reach maturity at 10 yrs, clutch size 28-60 eggs, females do not carry hatchlings in mouth but do stay to protect them, males also stick around
What is an amphibian?
• Grouped as Lissamphibia - Greek liss means "smooth"- refers to amphibians scale-less skin • Their skin is what shapes aspects of their lives - • Skin is permeable to water & gases - limits terrestrial activities • Greek amphi means "double" or both & bios means "life" • Only terrestrial vertebrates with a complex life history • Metamorphosis into adult life stage
CROCODYLIA MORPHOLOGY
• Heavily armored form thick plates of osteoderms - s • Sheds 1 scale at a time • elongate body, long snout, powerful tail limbs, feet are webbed • Evolved a secondary palate which separates buccal cavity from respiratory passage - allows breathing to continue when mouth is underwater. • Aquatic to varying degrees • Eye has transparent membrane that closes underwater • Nostrils are dorsally located - can close by valves when diving • All these adaptations allow the to breath while holding prey underwater • Can also move fast on land (10mph), faster in water (22mph) • Oviparous - lay eggs in mounds or in ground • Temp sex dependent - high temps = males • Parents guard nest - may break them open to release hatchlings, carry them to water in mouth, stay with young for weeks or months (like other archosaurs) • Sensory organs on head - detect movement in the water • Extremely well developed sense of hearing and smell • Crocs do not chew - tear and gulp their food • Swallow rocks to help with digestion • Go a year without eating • Hunted almost to extinction for their skin • Now they are farmed commercially
ANURA FAMILIES: Microhylidae (narrow-mouthed frogs)
• High diverse ecosystems (arid - rainforest) • Very small (1.5 cm) length • Highly diverse in life history strategies • Can be arboreal, terrestrial, aquatic
CAECILIANS: Typholonectidae
• Highly aquatic • 20cm - 1m SVL • All are viviparous - give birth to live juveniles who shed their gills quickly
SCINCOMORPHA
• Includes most species-rich family (Scincidea -1,600 families) skinks and their close relatives • Body forms are extremely variable (robust limbs & short body vs elongate snakelike body) • have very long tapering tails with small legs and five toes • Cone shaped heads with large, symmetrical, and shield-like scales - makes it difficult for predators • Example: Cordylidea: gridled lizards - transversedcircles around the body and have very spiny tail
SALAMANDRIODEA FAMILIES : Salamandridae (salamanders and newts)
• Lack rib/costal grooves and have rough skin • Produce a toxin - usually bright colored • Eft stage - juvenile stage, terrestrial
CRYPTODIRA: Chelydridea (snapping turtles)
• Large headed, freshwater turtles with powerful jaws - 23 lbs • Carapace can reach 8-14 inches (20-36 cm) in length, and adults can weigh up to about 45 pounds (16 kg) • Plastron is reduced so they can't retract neck/limbs into shell • Not strong swimmer, move by walking on bottom of water body • Eat anything they can swallow • Nests are on land away from water• 15-50 eggs
CRYPTOBRANCHOIDEA: (hellbenders & giant salamanders)
• Largest extant salamanders • Cold streams - Asia & US • Undergo incomplete metamorphosis (one pair of gill slits & no eyelids)
What are squamates (reptile)?
• Lizards (6,175 species) and snakes (3,496 species) • Largest group of reptiles • Lizards: mostly diurnal, brightly colored, and use conspicuous visual displays in social behavior - important subjects for behavioral & ecological studies • Snakes: legless, elongated body
SISTER GROUP TO SALAMANDRIODEA: Sirenidae (sirens)
• Long, slender, eel-like • Reduced pelvic girdles and hindlimbs • Aquatic - lakes, marshes, and swamps • In southern US and Mexico • Some species are 6in others can be 3ft.
GYMNOPHIONA MORPHOLOGY
• Many morphological structures are reduced • No extant species had limbs or pectoral/pelvic girdles • Eyes are reduced (covered by a layer of skin or bone) • Tentacles - chemosensory organ • Burrow (headfirst) = skulls robust but small diameter • Stegokrotraphy (completely roofed bone) or zygokrotaphy (more kinetic)
Generalized morphology of snakes
• Most snakes completely lack limbs • Boidae, have vestigial hind limb remnants • elongate in body form and the left lung is reduced or absent in most species • 120 presacral vertebrae, and have paired musk glands in the tail • ventral scales on a snake correspond on a 1-to-1 basis to the precloacal vertebrae • have very kinetic skulls that allow them to swallow relatively large prey
SALAMANDRIODEA FAMILIES: Plethodontidae (lungless salamanders)
• Most species rich family (2/3 of all salamander species) • Lack lungs - only cutaneous respiration • Fast moving streams • Greatest diversity of morphological specializations • Most females are oviparous & brood eggs
ANURA FAMILIES: Ascaphidea (Tailed Frogs)
• Only found western US and Canada • Highly aquatic - cold streams • Intromittent organ resembling tail • Extension of cloaca
LEPIDOSAURIA:SQUAMATA
• Phylogentic analyses and DNA - snakes are derived from within lizards • General Anatomy: • Hemipenes: pair copulatory organs, hindwall near vent - Parthenogenesis: ability to produce offspring without mating • Two distinct patterns of tooth attachment • Acrodont: attached to jawbone, rarely replaced (tuatara) •Pleurodont: inner side of jawbone, replaced in staggered sequence. (breaded dragons)
GENERALIZED LIFE HISTORY - MORPHOLOGY: Serpentes
• Pupil shape: • diurnal species have round pupils • nocturnal species have vertical pupils • fossorial species have very reduced eyes • Sit-and-wait predators are usually heavy-bodied whereas active foragers are more slender. • Arboreal species are very elongate and may have prehensile tails • Blotched and ringed snakes are more likely to rely on crypsis to avoid predators, whereas unicolored and striped snakes are likely to try to flee
CRYPTODIRA: Dermochelyidae (Leatherback Sea Turtles)
• Relatively unchanged morphology since dinos • Largest extant turtle - carpace length 2-2.5m and mass of 700 kg • Shell is unique in that is composed of thousands of osteoderms embedded in leathery skin • Main feed on jelly fish • Large body allows it to inhabit colder temperatures -swim 10,000 miles in a year between nesting and foraging grounds • Dive deeper most marine mammals - 4,000 ft
SALAMANDRIODEA FAMILIES: Ambystomatidae (mole salamanders)
• Robust - adults 30 cm • North America • Many reproduce in vernal ponds- migrate
What is a Caudata (amphibian)
• Salamanders - 650 species • Have elongated trunks and tails • 4 legs (most species) • Costal grooves - facilitate water movement
SALAMANDRIODEA: Rhyacotritonidae (torrent salamanders)
• Single genus • Well shaded, cold streams in PNW • Squared-off glands posterior to vent
LEPIDOSAURIA: RHYNCHOCEPHALIA
• Sister taxon to Squamata • Mesozoic Rhynchocephalians included the same diversity in adaptations and behavior as seen in modern lizards • Now restricted to 1 lineage (Sphenodontidea) represented by 1 (Sphenodon punctatus) species in NZ • Largely unchanged in 190 millon years • Tuatara = "spines on back" in Maori • 30 cm SVL • Carnivorous (invertebrates, bird eggs and nestlings) • Found basking at edge or burrow during day but most nocturnal
CRYPTOBRANCHOIDEA: Hynobiidae (Asian salamanders)
• Small (10-25 cm) • Complete metamorphosis • Mountain streams
CRYPTODIRA: Kinosternidae (American Mud and Musk Turtles)
• Smallest turtles in North America (11-15cm). • All are carnivorous (snails, clams, insects) • Release fowl smelling musk • Bottom walkers rather than strong swimmers -usually found in aquatic areas with heavy vegetation • Males are larger than females, clutch size ~6 eggs • Most species are considered common
ACRODONTA
• Sometime called Old World iguana (Africa, Asia, Australia) •Chamaeleonidea • Ability to change color • Zygodactylous feet • Prehensile tail • Eyes can move independently • Tongues can be projected >body length distance to catch prey • Agamidea (Dragons and Relatives) • Scales are modified to from extensive crests, fills, or spines • Sexually dimorphic & intraspecific interactions
SYSTEMATICS AND PHYLOGENY GYMNOPHIONA: CAECILIANS
• Taxonomy is uncontroversial, strong support over multiple datasets • 10 families, 35 genera, 200 species • Little documentation on IUCN lists but likely facing same declines as other amphibians • Chytrid infection
CRYPTODIRA: Testudinidae (Tortoises)
• Terrestrial, high domed shell, limbs stout and heavily scaled for protection • Long-lived 80-150 years • Small clutch sizes 1-2 eggs • Herbivores or omnivores • Live in very arid environments or in wet rainforests • Species Gopherus construct burrows -spadelike front feet - species in FL and SW
VERTEBRATE PHYLOGENY
• The amniotic egg distinguishes reptiles from amphibians • No longer require water to reproduce - inhabit all of Earth's tropical, temperate, and alpine habitats. • Lepidosaur Clade = lizards, snakes, and tuatara • Sister taxon to Archosauria
LACERTOIDEA
• This clade is supported only by molecular DNA -morphological characteristics were lost early in evolution of amphisbaenian lineage • Name referring to the presence of tile-like (squarish or quadrangular, and sometimes raised) scales • Teiidae (Whiptails) -All over N & S America • Lacertidea (Wall Lizards) native to Afro-Eurasia. at least 300 species in 39 genera. They represent the dominant group of reptiles found in Europe. • Gymnophthalmidea (Microteiids) - evolution of limb lessness has evolved multiple times
CHARACTERISTICS OF REPTILES: SENSORY
• Touch • Scale organs: occur in different areas of body and have hair like structures • Able to detect vibrations through soil (rain or prey) • Hearing • Columella: single sound transmitting bone • Vision • Scleral ossicles: thin plates of bones around eyes • Ciliary muscles: change shape of lens when focusing • Pupils can be round, horizontal, vertical • Snakes can see more of light spectrum than humans • Pit Organs (Infrared detection) • Can detect temp differences 0.001C
What are Rynchocephalia (reptile)?
• Tuatara (1 species) found in NZ • Look like lizards but have distinct primitive skeletal features• 55,500 exist in wild on 32 islands off mainland NZ
What are testudines (reptiles)?
• Turtles (341 species) - shell that encompasses trunk • Shape of shell reflects habits and habitat
ANURA FAMILIES: Bufonidae (true toads and harlequin frogs)
• Unique by having a Bidder's organ • Teeth are completely absent from Bufonid skulls • Prominent cutaneous glands on posterodorsal portion of head (parotiod glands)
CAECILIANS: Caeciliidae (Common Caecilians)
• Very few natural history data • 1.5m (total length) • Skull covers eye sockets • Costa Rica to South American
What is herpetology?
• is the branch of zoology concerned with the study of amphibians and reptiles • The study of ectothermic tetrapods - cladistically birds are included in Reptilla but not traditionally • Based in Greek root - herpes "a creeping thing"
ANURA MORPHOLOGY
• nine or fewer presacral vertebrae (usually eight) • three or four posterior to the sacrum are fused into a rod called the urostyle • radius and ulna (forearm bones), and the tibia and fibula (shank bones), are fused to each other • ankle bones, are greatly elongate, providing an additional level in the legs of frogs, which they utilize in jumping • several skull bones are lacking in frogs, although their heads remain highly ossified • tongue is often large, and free posteriorly • Males of most species have vocal sacs • The tadpole stage of many anuran life histories is also unique to frogs, with several specializations such as internal gills and the absence of true teeth
Why study herpetology?
• the vast number of species it includes (7,300 amphibians; 10,000 reptiles) • played key roles in biological specialization in developmental biology, behavior, ecology, and medicine
*Methods of evolution
•Charles Darwin and Alfred Wallace •Evolution by Natural Selection •More organisms are born than can possibly survive to reproduce •Variation gives competitive advantages to some individuals •Individuals better suited to their environment live to pass on their traits
IGUANIA
•Iguanian lizards inhabit all continents, primarily diurnal, sit-and-wait predators •Two major subclades: -Acrodonta -Pleurodonta
How do we determine which group organisms belong to?
•Most groups were originally created based on similarities in appearance. Sometimes appearances can be deceiving though. •Phylogenetics is the grouping of organisms by apomorphic characters (morphological or genetic) •Shared characteristics reflect common ancestry
What are clades based on?
•Nodes •Branches •Apomorphies
What is a Phylocode?
•Phylocode is a system of taxonomy meant to more accurately reflect phylogeny. •Uses a series of unranked clades based on common ancestry instead of ranked Linnaean groups.
Describe parts of the amniotic egg
•Represents freedom from water bodies •Amniotic membrane •Allows oxygen to enter •While retaining water •Allantois •Holds embryo's waste •Chorion •Regulates exchange of O2 and CO2 •Most amniote eggs have harder covering than non-amniotic eggs •Difficult to recognize in the fossil record