1/17/2012 1 WFS 433/533 1/17/2012 Lecture roadmap General Characteristics of Caudates Caudate Evolution Caudate Ecology Major Caudate families General Characteristics Very similar body plan - Small head, elongate body, four limbs, and tail Do not hop; use lateral undulation Do not actively vocalize Attract mates via pheromones (mental gland) Elaborate mating rituals (tail straddling)
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General Characteristicsfwf.ag.utk.edu/mgray/wfs493/Lectures/Salamander...1/17/2012 3 Salamander Evolution Body size variation (miniaturization) - Terrestrial species (Plethodontids)
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1/17/2012
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WFS 433/5331/17/2012
Lecture roadmap
General Characteristics of Caudates
Caudate Evolution
Caudate Ecology
Major Caudate families
General Characteristics
Very similar body plan
- Small head, elongate body, four limbs, and tail
Do not hop; use lateral undulation
Do not actively vocalize
Attract mates via pheromones (mental gland)
Elaborate mating rituals (tail straddling)
1/17/2012
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Fossil record of LissamphibiaTriassic, Jurassic and Cretaceous Periods
1) Anurans 2) Salamanders
3) Caecilians
Paleobatrachus
Triadobatrachus massinoti Karuaus sharovi
•Late Cretaceous
•Origin: Gondwanaland (SA)•Origin: Kazakstan
•Late Jurassic
•Origin: Madagascar
•Early Triassic (100 mya)(170 mya)(230 mya)
Apodops pricei
Caudate PhylogenyMore
Derived
Less Derived
Salamander Evolution
Important themes in salamander evolution….
- Lunglessness
- Small body size
- Feeding strategies
Convergent evolution; exploitation of different habitats
- Tree-tops; prehensile tails (Bolitoglossines)
- Longer bodies; reduced limb length
- Webbed feet
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Salamander Evolution
Body size variation (miniaturization)
- Terrestrial species (Plethodontids)
- Niche exploitation
Lunglessness
Hydromantes supramontis
Lunglessness
- General characteristic of terrestrial species
Feeding strategies
- Hyoid structure evolution
- Direct link between lunglessness and tongue morphology
- Evolved numerous times independently
Caudate Distribution 10 families
Low diversity throughout new-world tropics; absent entirely from old-world tropics
Biology and ecology poorly understood
Adaptive radiations
Mostly Temperate Distribution
10 Families
General Ecology Inhabit moist environments
- Facilitate oxygen exchange
Four families fully aquatic
- Cryptobranchidae
- Amphiumidae
- Sirenidae
- Proteidae
Six families terrestrial (not fully)
- Plethodontidae
- Hynobiidae
- Ambystomatidae
- Dicamptodontidae
- Rhyacotritonidae
- Salamandridae
Necturus maculosus
Plethodon glutinosusEurycea lucifuga
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General Ecology
Internal or external fertilization- Most families (7) exhibit internal fertilization (derived characteristic)
- External fertilization (synapomorphic feature)( y p p )
Some families exhibit parental egg care- Increases egg hatching success- Decreases predation and disease- Greater demand on female
Eurycea bislineata
General Ecology
Terrestrial salamanders important prey item
Densities may range from 2,950 sal/ha – 10,000 sal/ha
E t t l d 1 2-Equates to one salamander every 1m2
Higher biomass than birds and mammals combined
Plethodon shermaniPlethodon cinereus
Plethodon yonahlossee
Questions to Consider
What are some advantages to evolving internal fertilization?
What are the advantages to evolving g glunglessness, small body sizes, and different feeding strategies?
What is the ecological importance of salamanders?
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Family Ambystomatidae (Mole Salamanders)
One genus; 31 total species
New world distribution (US and Mexican plateau)
Incomplete metamorphosis common ( d h i / t ) A t l di d A(paedomorphosis / neoteny); A. talpodieum and A.tigrinum