Saturday, 24 March 2012

A salamander named Jeff

Jefferson's Salamanders are one of my favorite Ontario salamanders, for several reasons, the least of which is their "rare" factor as they can only be found in a small handful of locations in Ontario. The ROM's website says that they are found at 30 sites in the province. They are listed provincially as "Threatened" due to a number of reasons, including road mortality, loss of habitat, being at the northern extent of their range, and strangely enough, genetics.

Jefferson Salamander - Waterloo Region

The story behind the genetics of Jefferson Salamanders and a few other closely related species is a long and complicated one that still has unanswered questions. I'll try to summarize it as best and briefly as I can. In the past, a hybrid event occurred with this species as well as others, and unisexual female salamanders were the result. In this part of Ontario the unisexuals make up the majority of most populations in southern Ontario and contain the Blue-spotted Salamander alleles ("L", for Ambystoma laterale) and Jefferson Salamander alleles ("J", for A. jeffersonianum). Instead of having the usual 2 alleles, these unisexuals have 3 alleles (in other areas, up to 5 alleles have been noted). For instance, they could be LLJ, or LJJ. The offspring they produce are essentially clones of the mother. They don't reproduce parthenogenically - rather, they use the sperm from one of the parent species to stimulate egg development, though no genetic material is contributed. LLJ salamanders use the sperm from a male Blue-spotted Salamander to stimulate egg development, and LJJ salamanders use the sperm from a male Jefferson's Salamander. All of the unisexuals are female.

female "unisexual" salamander - April 7, 2010

Since all the unisexuals are female, any male salamander that is found is a pure diploid individual of the parent species. Females, however, are impossible to identify in the field - it can only be done definitively by looking at their genome in the lab.

In this southern Ontario population, there are male and female Jefferson Salamanders, male and female Blue-spotted Salamanders, female "LLJ" salamanders, and female "LJJ" salamanders as far as I am aware. What I would speculate is that the Jefferson Salamander males often fertilize these unisexual salamanders, leaving the female Jefferson Salamanders unable to reproduce that year. Over time, some populations only have the unisexuals, with one of the parent species (usually Jefferson Salamander) no longer present.

Jefferson (left) and Blue-spotted Salamanders

As you can see from the above photo, the Jefferson Salamander is a lighter gray colour with tiny blue flecks, is larger in size, has long limbs, a long tail, and a long snout. Blue-spotted Salamanders are generally darker with large blue spots, have short limbs, a shorter snout, shorter tail and are overall smaller. The unisexuals are intermediate but with a wide range of variation.

I have been fortunate to stumble across several sites over the years where I believe I have found pure Jefferson Salamanders. I think that they are more common than what they're given credit for, but at the same time I have only seen about 35 individuals in my life, compared to exactly 450 Blue-spotted and "unisexual" salamanders. Last night, while out herping with some close friends, Chris stumbled across a perfect example of a Jefferson Salamander. They're still holding on in my area!

male Jefferson Salamander - March 23, 2012

male Jefferson Salamander - March 23, 2012

male Jefferson Salamander - March 23, 2012

1 comment:

  1. What time would you see a Jefferson Salamander,
    and would they be near Guelph? Is rain required?
    Would the new culverts on the newly paved section of Maltby facilitate salamander movement?