Amphibians
Blue-spotted Salamander
Ambystoma laterale · also called blue-spotted salamander
A blue-spotted salamander is a small, dark, silver-flecked woodland salamander of the Great Lakes region, easy to miss for most of the year as it hides under logs and leaf litter. It is also part of one of the strangest reproductive systems in the animal kingdom: interbreeding with the Jefferson salamander produces all-female hybrid lineages that clone themselves while occasionally borrowing, or simply stealing the use of, genes from males of either parent species.
Overview
The blue-spotted salamander, Ambystoma laterale, is a small mole salamander of mature forest in the Great Lakes region and northeastern North America, marked with pale blue flecks over a dark body. It hunts worms, slugs, and insects at night on the forest floor and breeds in early spring in temporary, fish-free vernal pools, often while snow is still on the ground nearby.
An unusual hybrid complex
Interbreeding with the closely related Jefferson salamander produces unisexual, all-female hybrid lineages that reproduce through a genetic strategy called kleptogenesis — mating with a male of a parent species to trigger egg development, and sometimes incorporating an extra set of his chromosomes. This reproductive system, which has persisted for millions of years despite theory predicting all-female lineages should be short-lived, is found in almost no other vertebrate group.
Status
Least Concern overall, but tied tightly to the combination of mature forest and small, easily overlooked, fish-free vernal pools that are frequently drained or degraded without much notice — a vulnerability that has made some regional populations, and the associated unisexual lineages, a specific conservation focus.
Blue-spotted Salamander: common questions
What is unusual about how blue-spotted salamanders reproduce?
In parts of its range, the blue-spotted salamander interbreeds with the closely related Jefferson salamander to produce lineages of all-female hybrid salamanders that reproduce through a highly unusual system combining cloning with borrowed genetic material. These unisexual females typically need to mate with a male of a parent species to trigger their eggs into developing, and depending on the population, they either simply use the sperm to activate development without incorporating its genes, or they occasionally add an extra set of the male's chromosomes to their offspring, a strategy that has let all-female lineages persist for a very long evolutionary time despite the usual expectation that clonal reproduction leads to a quick decline.
How do you tell a blue-spotted salamander from other similar salamanders?
The clearest feature is the pattern of pale blue or silvery flecks scattered over an otherwise dark bluish-black to grey body, concentrated especially on the sides, legs, and tail, which is distinct from the larger, more scattered yellow spots of the related spotted salamander or the more marbled pattern of the marbled salamander. Blue-spotted salamanders are also generally smaller and more slender than several of their mole salamander relatives, and in areas where hybrid lineages occur, individual animals can show intermediate or blended features, which is part of why the group as a whole has been intensively studied by geneticists.
When and where can you see blue-spotted salamanders?
They are almost entirely nocturnal and spend most of the year hidden underground or beneath logs and leaf litter in mature forest, so the best chance of seeing one is during the short early spring breeding migration, often on the first mild, rainy nights after snowmelt, when adults move from their forest hiding places to nearby vernal pools and other temporary, fish-free wetlands to breed. Outside this brief window, finding one usually means carefully searching under logs, bark, and leaf litter in suitable forest, and even then the salamanders are easy to overlook given their small size and secretive habits.
Are blue-spotted salamanders endangered?
The species as a whole is assessed as Least Concern and remains fairly widespread across the Great Lakes region and nearby areas, but it depends on a specific combination of mature forest and small, temporary, fish-free breeding pools that is easily lost even when the surrounding landscape looks otherwise intact, since vernal pools are frequently drained, filled, or degraded without much notice. Because of this vulnerability, along with the added conservation interest in the unusual all-female hybrid lineages associated with the species, some regional populations receive specific legal protection or conservation attention even though the species overall is not classified as threatened.