Lab Quiz 2~Salamander Diversity Flashcards
How many families are within Caudata? (Salamanders)
How many species?
9 families, ~640 species
Where are Caudata usually found?
Essentially all in Northern Hemisphere (Laurasian), generally in cool, wet temperate regions, some Plethodontids extend to lower Central America and South America
- usually absent from oceanic islands
- 4 ‘familes’ restricted to New World, with only Hynobiidae endemic to Old World
What is the typical generalized body form of the Caudata?
What are some deviations seen from this and in what groups?
short body, with four functional limbs
~deviations include elongated body, with reduced limbs (Amphiuma, Siren, Pseudobranchus)
What is the body size range for Caudata?
30 mm (Thorius) to 1.5-1.8 m (Andrais)
Typically, what type of breeders are Caudata?
~most are terrestrial, but some are aquatic
~exhibit internal fertilization but no intromittent organ (via spermatophores instead)
What is a spermatophore?
~a sperm cap on a gelatinous base
~the male deposits this following a courtship ritual and the female pics it up with cloacal lips for internal fertilization.
How do the ‘basal’ salamanders reproduce? (Sirenidae & Cryptobranchoidea)
~external fertilization and no courtship behavior (Sirenid courtship unknown, but no cloacal glands or spermatotheca so looks like no internal fertilization)
~have aquatic eggs and larvae
What are the different reproductive modes found within the Caudata?
- Generalized pattern ~ aquatic eggs and larvae
- Terrestrial eggs, aquatic larvae
- Terrestrial eggs & larvae, non-feeding larvae
- Terrestrial eggs with direct development
- Eggs retained in oviducts (viviparous)
What are some characteristics of Caudata larvae?
~more like adults than are tadpoles of anurans (limbs appear early)
~all carnivorous (none herbivores like tadpoles)
~they have ecomorphs (like tadpoles); in ponds and slow moving water they have large bushy gills, prominent tail fins, and laterally compressed bodies; fast moving water they have smaller gills, less prominent fins, depressed bodies, and calloused toes for gripping the bottom
What is paedomorphism?
retention of larval characters; ex. larval teeth, bone patterns or structure, absence of eyelids, the lateral line system, or external gills.
Which Caudata usually have paedomorphic forms?
Sirenidae, Amphuimidae, Proteidae, and Cryptobranchidae all generally aquatic and are paedomorphic.
What is paedomorphism the result of in salamanders?
neotony~somatic development terminates early
~can be facultative (depends on environmental cues) or obligatory (cannot transform)
What is heterochrony?
Changes in developmental timing
What are the different ecomorphs seen in Caudata?
Terrestrial, Scansorial, Fossorial, Aquatic, Aquatic burrower, Aquatic bottom-walker, Troglobitic
What are Caudate synapormophies?
- Operculum fused to ear capsule leaving only free columella
- Quadratojugals absent
- Angular bone fused with prearticular
- Second ceratobranchials lost at metamorphosis
- Palate remodeled at metamorphosis
- Late appearance of maxillae in ontogeny
What is the stem-based name of the Caudates? How far do the fossils in this group date back?
Urodeles & date back to at least mid-Jurassic (~170 mya).~Karaurus sharovi
In mid Jurassic there were “standard” salamander neotonic forms, long-bodied, and small present, with most ecomorphs represented, probably all families present throughout Laurasia
What group is sister taxa to all remaining salamanders? What families does this group consist of?
Cryptobranchoidei, composed of 2 families; Cryptobranchidae and Hynobiidae
Cryptobranchidae
2 genera, 3 species
~Cryptobranchus in E. US, retains one pair of gill slits, males construct nest under rocks in streams
~ Andrais in E. Asia, can reach up to 2 m, males construct nests in tunnels in river bar
They are the largest salamanders
Have incomplete metamorphosis, lack eyelids, retain lateral line, body and head dorsoventrally compressed, aquatic bottom-walkers in cold mountain streams and skin heavily folded, external fertilization, feed on crayfish, worms, insects captured via unique suction mechanism.
Hynobiidae
7-10 genera, ~55 species
~Temperate & subarctic regions of N. Asia with disjunct populations in mountains of S. Asia
~relatively small (100-250mm), external fertilization, free swimming larvae that undergo complete metamorphosis, most are terrestrial (ecological equivalents of the North American ambystomatids)
Sirenidae
2 genera, 4 species
~Siren (can reach nearly 1 m) & Pseudobranchus (small)
~ S.E. US and extreme N.E. Mexico
~first fossil of sirenid from Cretaceous of Sudan (65-90mya), phylogenetic relationships unknown, either sister to all other salamanders or sister to proteins
~eel-like with tiny forelimbs & no hind limbs
~obligatorily neotonic; external gills present, skin histologically similar to larval skin, non-pedicellate teeth, lack eyelids, maxilla reduced or absent
~Aquatic burrowers in slow moving waters like swamps, lakes, and marshes.
~feed on crustaceans, insects, & worms via suction-feeding
~aestivation in dried mud by secreting a mucous cocoon
~probably external fertilization
Salamandroidea
Group that contains all species of salamanders except Cryptobranchoids and Sirenidae; includes 6 families;
Protieidae, Salamandridae, Ambystomatidae, Rhyacotritonidae, Amphiumidae, Plethodontidae.
~extreme amount of diversity, with Plethodontidae being most diverse
~All have internal fertilization via spermatophores
Proteidae
2 genera, 6 species
~Necturus (found in E. North America), inhibits lakes and streams
~Proteus (in Karst regions of NE Italy & E. coast of Adriatic Sea) (Proteus anguinus~troglobitic ecomorph that lives in limestone caves, blind, pigmentless, reduced number of digits)
~Highly aquatic and neotonic with external gills and caudal fins, also lack maxillae
Treptobranchia
Consist of Ambystomatidae & Salamandridae
Salamandridae
~15-22 genera, ~90 species
~has four distributional centers: E. North America (Notophthalmus), W. North America (Taricha), E. Asia, & Europe, N. Africa, W.Asia
~fossil record suggests salamandrids invaded NA across Beringia
~some terrestrial as adults, others aquatic
~deemed highly “derived”
~many with glandular skin that can produce tetrodotoxins, often with aposematic coloration and elaborate defensive displays
~courtship often highly elaborate and prolonged
~different reproductive modes, oviparous- eggs in water or viviparous-advanced larvae in water or fully developed young
~Consists of Notophthalmus & Taricha with complex life cycles