Jefferson Salamander

Taxobox
name = Jefferson Salamander
status = VU | status_system = IUCN3.1
trend = stable
regnum = Animalia
divisio = Chordata
classis = Lissamphibia
ordo = Caudata
familia = Ambystomatidae
genus = "Ambystoma"
species = "A. jeffersonianum"
binomial = "Ambystoma jeffersonianum"
binomial_authority = Green, 1827

The Jefferson Salamander ("Ambystoma jeffersonianum") is a mole salamander native to the north-eastern United States, southern and central Ontario, and south-western Quebec. It was named for Jefferson College in Pennsylvania, which in turn was named for Thomas Jefferson.

It is typically dark gray, brown, or black on its dorsal surface, but a lighter shade on its anterior. Some individuals may also have silver or blue specks on their sides; the area around the vent is usually gray. These salamanders are slender, with a wide nose and distinctive long toes, and range in size from 11 to 18 cm.

Like other mole salamanders, the Jefferson Salamander are burrowers; they have well developed lungs suited for this purpose. Nocturnal by nature, they can be spotted by day during the mating season. Breeding occurs in early spring, after the snow in the area has melted.

Habitat

The secretive adults tend to hide under stones or logs, or in leaf litter and other underbrush in deciduous forests during damp conditions. They are usually not found in conifer forests, likely due to the dryness and prickliness of some pine and spruce needles, which may injure amphibians with their thin skins. They are found burrowed underground for most of the year during dry or freezing conditions. They must get below the frost line (about 18 inches) in order to survive winter conditions in northern latitudes. They often burrow in rich sandy soils found in upland deciduous forests or sometimes in older growth damp hemlock forests.

Migration to their breeding area is quick, since breeding sites are usually close to the over-wintering burrows. The breeding sites they choose are fishless ponds and vernal pools, filled with spring snow meltwater in northern latitudes. Some breeding ponds may be hundreds of yards (meters) away from their forest home in fragmented landscapes.

Jefferson salamanders are one of the first amphibians to emerge in springtime at the northern edge of their range in southern Ontario, Canada where they are seen 'snowshoeing' across the still frozen understory of the forest to reach partially melted breeding ponds. Males migrate first with females following shortly thereafter. Since they exude a whitish liquid on their skin when handled and have small pores on their heads, there is thought that they may leave a scent trail during migration [http://links.jstor.org/sici?sici=0022-1511(199306)27%3A2%3C236%3ASHBATP%3E2.0.CO%3B2-M (Jaeger et al. 1993)] .

Reproduction

Eggs are laid in small agglomerations attached to submerged twigs or other natural support at the pond's edge. Clutches can contain between 5 to 60 eggs, averaging about 30. The age at which they first breed, and the frequency with which they breed are unknown; estimates are that females will first breed at 22 months, and males at 34 months. Eggs develop rapidly, and may hatch within 15 days. Larvae stay in the pond from two to four months, during which time they grow to between 3 and 8 times their hatching size.

A unique reproductive tactic for the Bluespotted-Jefferson Salamander Complex exists in nature. The Jefferson Salamander is now known not to breed in the lab with the Blue-spotted Salamander, which was previously thought to produce 'hybrids', the Silvery Salamander and Tremblay's Salamander, between this supposed mating of Jefferson salamander and Blue-spotted salamander. The Silvery salamander and Tremblay's salamander are now known through genetic testing to be polyploidy females (only 2% of males survive and they are sterile). These most often possess two of each chromosome from the Jefferson Salamander and one of each chromsome from the Blue-spotted Salamander, resulting in a LJJ genotype (also called a Tremblay's Salamander.) This genotype results when these polyploid females mate with a pure Jefferson salamander male, incorporating (often in warmer water conditions) the chromosome from the pure male Jefferson salamander into her egg, comprised of usually an LJ diploid chromosome set or LJJ triploid chromosome set to produce LJJ or LJJJ offspring, respectively. Often in cooler conditions, the LJ or LJJ female may mate with the Jefferson salamander male and only 'borrow' his spermatozoan to trigger genetic cloning of herself, not adding his chromosome (J) to her egg. The same polyploid reproductive strategy occurs for other mole salamander species. The presence of these polyploids makes it difficult to visually identify which species an individual may be, skewing population measures for both species.

Food

The larvae are carnivorous, typically consuming aquatic invertebrates. An insufficient food supply may result in cannibalistic behaviour. Adults are also carnivorous, eating a variety of small invertebrates.

References

* [http://links.jstor.org/sici?sici=0022-1511(199306)27%3A2%3C236%3ASHBATP%3E2.0.CO%3B2-M Robert G. Jaeger, Deborah Fortune, Gary Hill, Amy Palen, George Risher. Salamander Homing Behavior and Territorial Pheromones: Alternative Hypotheses. Journal of Herpetology, Vol. 27, No. 2 (Jun., 1993), pp. 236-239]
*IUCN2006|assessors=Hammerson|year=2004|id=59059|title=Ambystoma jeffersonianum|downloaded=12 May 2006 Database entry includes a range map and a brief justification of why this species is of least concern.
* [http://www.iucnredlist.org/search/rangemap.php?species=59059 IUCN Range
]
* [http://www.speciesatrisk.gc.ca/search/speciesDetails_e.cfm?SpeciesID=642 Environment Canada - Species at Risk: Jefferson Salamander]
* [http://collections.ic.gc.ca/amphibians/taxa/species/ambystoma_jeffersonianum.html Amphibians of Canada: Jefferson salamander]
* [http://www.npwrc.usgs.gov/narcam/idguide/ambyjeff.htm US Geological Survey - Northern Prairie Wildlife Research Center: Jefferson Salamander]
* [http://www.ohiohistorycentral.org/entry.php?rec=1032 Ohio History Central: Jefferson Salamander]
* [http://ebeltz.net/herps/biogappx.html#Jefferson Names of the Reptiles and Amphibians of North America]
* [http://www.uoguelph.ca/ib/faculty/faculty_bogart.shtml#publications Genetics of Jefferson Salamander References]