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Herpetology
The study of reptiles and amphibians.
morphology
not all shared traits useful to determining phylogeny bc diff between homology and analogy
hybrid invariability
developmental problems in hybrid cause reduced survival
Ectothermic
Organisms that derive their energy from outside their bodies.
cons: ability to be warm may be sacrificed to stay wet, limited activity, heat loss by convection
pros: longer fasting, can inhabit food poor and variable enviros, most energy goes to other needs (growth and reproduction), greater capacity to be smaller, stable populations, can utilize small prey
behavioral thermoregulation: huddling, basking, can retain body temp by cutting blood flow to limbs allowing fluctuations in core temp that would kill mammals
Poikilothermy
An irregular body temperature that varies with the environment.
homeothermy
stable body temp
Amphibians
A class of ectothermic vertebrates that typically undergo metamorphosis and include frogs, salamanders, and caecilians.
Order Caudata
The order of amphibians known as salamanders.
Order Anura
The order of amphibians that includes frogs and toads.
Order Gymnophiona
The order of amphibians that includes caecilians, characterized by their snake-like appearance.
Cladistics
A method of classifying organisms based on common ancestry and evolutionary relationships.
assumes things change over time, organism is related to another by common organism, lineages bifurcate
Synapomorphy
A derived characteristic shared exclusively by evolutionary descendants and ancestor
Biological Species Concept
Defines a species as a group of interbreeding populations that are reproductively isolated from other such groups.
Amniotic Egg
An egg that has protective membranes and allows for reproduction on land.
Tetrapods
Four-limbed vertebrates that include amphibians, birds, reptiles, and mammals.
Nomenclature
A system of names used in a particular field or community.
Mitochondrial DNA
DNA found in the mitochondria used in genetic studies, particularly in species classification.
Morphological Species Concept
A concept that identifies species based on measurable physical traits.
Phylogenetic Tree
A diagram representing the evolutionary relationships among species.
tips: taxa under study (species or species groups)
branches: genetic divergence of taxa from its most recent ancestor
node: point where bifurcation happens
root: shows oldest common ancestor of all taxa on tree
phylogenetics
study of evolutionary history of species or grou; of species
polytomy
node where 3 branches, implies lack of clarity on order groups diverged
monophyletic
ancestor and all descendants
paraphyletic
ancestor and some descendants
polyphyletic
species w diff recent common ancestor
Ectothermy vs. Endothermy
Ectothermy is when an organism's body temperature is regulated by external factors, while endothermy is the regulation of body temperature through internal metabolic processes.
Cryptic Species
Species that are ecologically distinct but look similar and can hybridize.
Allopatric Speciation
The formation of new species through geographical separation from its ancestor
Parapatric Speciation
Speciation that occurs when populations are separated by environmental boundary (sharp transition)
reinforcement: selection against mating w other form (pre-zygotic)
Sympatric Speciation
The evolution of new species from a single ancestral species while inhabiting the same geographic region.
Tiktalik
An important transitional fossil linking fish and tetrapods discovered in Canada.
not true tetrapod just had well developed limbs but no attached girdles (attached to spine in true tetrapod, allows to push up and down, and gives greater locomotion)
Cutaneous Respiration
Breathing through the skin, common in amphibians.
Pedicellate Teeth
Teeth in amphibians composed of a basal pedicel and a distal crown.
Direct Development
A type of development in which the young resemble the adult form without a larval stage.
Paedomorphosis
The retention of juvenile traits in the adult form.
Tenremes
A group of mammals characterized by their long snouts and insectivorous diet.
Biodiversity
The variety of life in the world or in a particular habitat or ecosystem.
Amphibious
Adapted to live both on land and in water.
Fossil Gap
A discontinuity in the fossil record where few or no fossils exist from certain time periods.
Acoustic Communication
Behavioral trait in amphibians where sounds are used for mating and territory establishment.
is the gopher frog (Rana capito) characterized as a species of special concern
YES
what frog in florida is exception to rule of egg to tadpole to frog development?
greenhouse frog
what glands secrete poison in cane toads?
paratoid glands
how to tell the difference between a siren and an amphiuma?
sirens have 2 front limbs while amphiumas have 4
what does red eft stage refer to?
juvenile stage of an eastern newt
Eating a dozen salamanders from this most toxic family could make you very ill or kill you
Salamandridae
Very long ilia (1 of 3 paired bones that make up pelvic girdle, or hip bones, are characteristic of
Anura
The unisexual triploid Ambystoma usually reproduce by gynogenesis, which is:
Mating with diploid males but not incorporating their DNA into the offspring
Internal fertilization in salamanders usually occurs by means of a
spermatophore
The primary habitat of the first Devonian tetrapods is thought to have been
water
why are amphibians and reptiles grouped together?
ectothermic vertebrates
Ross Allen
everglades rat snake named after him
Bill Haas
miami serpentarium, pioneered venom milking and anti venom, controversially practiced self envenoming
Archie Carr National Wildlife Refuge
major sea turtle nesting site
Walter Auffenberg
monitor and iguana conservation
Lora Smith
technically outside of FL, gopher tortoise research methods
heart w 2 auricles, 2 ventricles, warm red blood
viviparous: mammals
oviparous: avians
heart w 1 auricle, 1 ventricle, cold red blood
lungs voluntary: amphibians
reptiles (lizards, frogs)
serpents (amphisbaenians, snakes)
nantes: everything not grouped above
external gills: fish
heart w 1 auricle, 0 ventricles, cold pus like blood
antennae: insect
tentacles: vermes from arthropod invertebrates
tetrapoda- four legs: birds, reptiles, amphibians
evolved ~400 mya, many traits not initially derived to live on land
punctuated equilibrium hypothesis
evolutionary development is marked by isolated episodes of rapid speciation between long periods of little/no change. once species appears in fossil record the population will become stable, showing little evolutionary change
loss of opercular bone between pectoral girdle and skull
allows for head movement independent of body, allows for better head movement in shallow water to try to capture prey without need to move entire body
zygapophyses
add stability during movement to axial skeletons, is one of 2 paired processes of vertebra that interlock it w adjacent vertebra, help guide movement of vertebral column and protect spinal cord
early tetrapodomorphs
lived in aquatic shallows w useful adaptations to potential life on land
-benefits of living in shallow:
-escape predation from large fish
-reduce predation of eggs
-exploit unfilled niches
-better thermoregulation
reasons to leave water
-Devonian: early plants, facilitated by fungi, colonized land and led to anoxia (lack of oxygen) and went up to land for more O2
-overland movement to escape drying enviros
-new habitats w few competitors
-juvenile dispersal
-search for safer location to lay eggs
-basking in sun increased thermoregulation
Tungsenia paradoxa
earliest known “finned stem-teirapod”, from lower devonian (409 mya) of china
Romer’s gap
fossil gap between early and modern tetrapods (~30 mil years), early tetrapods had 8 but modern have 5
Perderpes helps fill gap
operculum muscle
attachment to suprascapula, allows them to feel sound through legs
levator bulbi muscle
muscle in amphibian eye socket and pushes eyes downward to move food down throat and elevates eye
anthracosaurs
main adaptation: amniotic egg
anapsia: extinct
synapsid: early mammal like and mammal ancestors
diapsid: birds and modern reptiles
hemipenes define lepidosaurs (lizards and snakes)
archosaurs and testuoines have single copulatory organs, turtles are archosaur or just outside
amphibians
8715 species, 74 families
Anura (without tail)
7678 species, 54 families
frogs and toads
under clade Salienta
Caudata (having tail)
salamanders
Urodela (tail visible) is commonly used for crown group and Caudata is total group
816 species, 10 families
Gymnophiona (naked snake)/Apoda (without foot)
221 species, 10 families
Caecilians
frogs and salamanders split 250 mya, proto-frogs appear in early Triassic, 1st true frogs and salamanders in early Jurassic
Doleserpeton
temnospondyli
lower permian, oklahoma (250-270 MYA)
pedicellate teeth
Dissorophidae
ancestor to Lissamphibia (mid-Permian)
Gerobatrachus hottoni
Permian (290 MYA)
characteristics of both salamanders and frogs, creates arguments of monophyly
first true salamanders
Marmorerpeton: early neoteny, Karauridae (Karaurus sharovi)
extant family of salamanders in late Cretaceous
first Caecilians
Eocaecilia micropodia
still has feet
early Jurassic (190 MYA), US
Triadobatrachus massinoti
one of earliest lissamphibia
lower triassic
ancient frogs
Prosalirus bitis: from NA, suggests ancestors of Lissamphibia
Dicroglossidae: oldest extant frog family
is Lissamphibia monophyletic?
fossil gap and morphologically/ development male it hard to tell, some develop directly, gastroincubation, viviparous eggs
however, have shared derived traits like pedicellate teeth, green rods
class Amphibia
tetrapod vertebrates that pass through larval stage and undergo metamorphosis into terrestrial adults
some have <4 limbs
direct development-larvae develop in egg
paedomorphosis- do not metamorphose
paedomorphosis
adult retains juvenile traits
paedogenesis
when a juvenile reproduces
class Amphibia synapomorphies
amniotic egg (gelatinous capsules, embryo, yolk), no amnion (sac filled w amniotic fluid which protects embryo, chorion plays key role in blood and gas between mother and fetus, develops into fetal aspect of placenta, allantois- respiratory organ and excreta resevoir)
scales and claws absent
pipidae claws made of bone not keratin
10 pairs of cranial nerves
2 occipital condyles articulate w 1st cervical vertebra- Atlas (upward/downward but not side to side movement)
1 sacral vertebra (sacrum)- enlarges transverse (90 degrees) processes (diapophyses) articulate w pelvic girdle
teeth
homodont (structurally uniform)
polyphyodont (continually replaced)
pedicellate- divided into a basal pedicel and distal crown
3 chambered heart (2 atria, 1 ventricle)
2 types of multicellular glands
mucous
poison (granular)
cutaneous respiration
gilled larval stage, metamorphosis
internal (tadpoles), external ( axololts)
reduced number of cranial bones (no tabular, temporal, supraoccipital, basoccipital, jugal, postorbital)
amphibian papilla (papilla amphibiorum)- sensory region in inner ear for low frequency sounds
opercular bone in inner ear, connected by muscle to pectoral girdle, transmits low frequency vibrations from legs to amphibian papilla
tympanum, stapes transmit high frequencies
tympana lacking in salamanders, caecilians, and some frogs
green rods in retina (except caecilians), also have red rods, single cones, double cones, limited color vision
levator bulbi muscle- elevates eye
fat bodies associated anatomically, physiologically, and developmentally w gonads
unique chromosomes/DNA patters, reduced number of chromosomes, increase in nuclear DNA, high interspecific variability in genome size
amphibian skin
larvae: skin is 3-5 layers, is highly vascularized, and living
adults: 5-7 layers, dead keratinized layer, thicker skin less likely to be used for gas exchange
breeding + reproduction: may have nuptial pads to hang onto females, can direct pheromones towards females, may brood young in skin
amphibian respiration
gills (atleast as larvae)
lungs (the Hyobrachial apparatus)
skin: most CO2 loss, more prone to dessication, needs to be very vascularized
heterochromy in amphibians
alteration of development rates of body tissue
paedomorphic- as adult, retain juvenile traits, has same age to reach maturity
paedogenic (paedotypic)- accelerates reproductive tissues so it can reproduce while looking like juvenile
courtship in amphibians
anurans: very complex and often driven by audio communication
salamanders: very complex due to variability in internal vs external fertilization, involves highly derived chemical intra specific communication
caecilians: not much known due to their secretivity
amphibian reproduction
frogs: almost exclusively external fertilization
salamanders: 3 families w external fertilization, most internal, typically don’t have copulatory organ genetic transfer facilitated through spermatophore
caecilians: almost exclusively internal fertilization, have phallodeum (copulatory organ, part of cloaca) and specialized glands (male Mullerian glands) to facilitate sperm transfer
aquatic larvae or direct development
amphibian parental care
anurans: from no involvement to care until metamorphosis
salamanders: primarily not involved but some nest guard
caecilians: some have no involvement, but group typically invests a lot of resources
salamander synapomorphies
adults possess long, well developed tail
forelimbs always present and hind limbs typically present'
forelimbs and hindlimbs same size
no tympanum or middle ear cavities
many skeletal elements cartilaginous, skull, between vertebrae, pelvic and pectoral girdles
most have opisthocoelous vertebrae (anterior of centrum convex, posterior concave), some amphicoelous (both surfaces concave)
larval gills external and larvae possess 3 pairs of gills
pond type: large feathery gills, low O2, extensive respiratory surfaces (Ambystoma
stream type: reduced gills, live in cool water w high O2 content (Gyrinophilus)
mountain brook type: atrophied gills, rich O2, respiration primarily cutaneous (Desmognathus)
larvae possess true teeth
primarily in northern temperate zones
fertilization internal (derived lineages) or external (basal lineages), internal fertilization by female picking up spermatophore, no copulatory organ
aquatic or terrestrial (or both)
development direct or indirect (via larval stage)
paedomorphosis (interspecific, between species)/paedogenesis: when juvenile organism reproduces (intraspecific, within species)
hybridogenesis
maintenance of an interspecific hybrid lineage by having hybrids exclude the chromosome set of one parental species
Caecilian synapomorphies
no limbs or limb girdles present
burrowing mode of life, in most soil, some aquatic (with fins)
unusual sense organ: retractable tentacle, one on each side of head, present only in caecilians, outgrowth of brain emerges from eye socket or hole in skull between eye socket and nostril, olfactory in function, incorporates some eye structure
skull in compact solid structure compares to skulls of other amphibians which have many fenestrations- extensive fusion of cranial elements, presumably related to burrowing habits (do have lower and upper teeth)
eyes small to vestigial- no eyelids, eyes buried under skin or under bone
left lung often rudimentary, 2 species known to be lungless (Caecilita iwokramae and Atrectochoana eiselti)
body ringed with primary folds (annuli)- then secondary folds in some. makes segments, each associated w 1 vertebra
tiny dermal scales in folds, only scales found in amphibians (not in all groups)
no external ear openings, but can hear low frequency sounds transmitted through skull to inner ear
distributed worldwide in tropics (except Madagascar and Australia)
Caecilian reproduction
70% oviparous- female guards eggs
aquatic larvae or direct development
some young feed on mother’s skin or skin secretion
some families exhibit viviparity, development of embryo inside mother
phallodeum- copulatory organ, part of cloaca
male mullerian glands- enhance fluid transport of sperm
Caecilians
225 species, 10 families
viewed as poorly diversified, primitive group
families
Rhinatrematidae
3 genera, 14 species
northern SA
considered most basal family
Ichthyophiidae
2 genera, 58 species
SE asia, india, and sri lanka
Caeciliidae
2 genera, 51 species
central and SA
more specialized for burrowing
Typhlonectidae
5 genera, 14 species
tropical SA
specialized aquatic forms
tail absent
no secondary folds- no scales
both lungs well developed- diff from all other caecilians
Scolecomorphidae
2 genera, 6 species
Africa
tail absent
secondary folds and scales absent
Anuran key characteristics
reduced amount of vertebrae (5-9 presacral vertebrae)
limb specialization
long hind limbs and short front limbs
fused specialized bones include tibio-fibula, radio-ulna, urostyle which allows for force absorption when jumping
adults- no lower teeth, broad skull w few bones
larvae have internal gills, lack true teeth
highly variable life histories, tadpoles vs direct developers
external fertilization, inguinal, pectoral, cephalic
auditory communication incredibly important
Anuran tadpole body plan
type 1
jaws not specialized for feeding
separate brachial w 2 external openings
forelimbs develop posterior to brachial
type 2
simple modification of jaw
type 3
specialized jaw structure w keratin sheath
type 4
more specialized