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The Jefferson salamander (''Ambystoma jeffersonianum'') is a mole salamander native to the northeastern United States, southern and central Ontario, and southwestern Quebec. It was named after Jefferson College in Pennsylvania. 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 burrows; 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. ==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; females are estimated to 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 polyploid 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 chromosome from the Blue-spotted salamander, resulting in an 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, usually having 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「jefferson salamander」の詳細全文を読む スポンサード リンク
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