Hannah McCurdy-Adams  holding an adult blue racer. Photo: Ryan Wolfe

We’re here with the fourth and final blog in our series on the efforts involved with the blue racer conservation project.

Blue racers are one of the most endangered species of snakes in Canada, with only one population remaining and located on Pelee Island in Lake Erie. In previous blogs, we discussed some of the threats that blue racers face – including habitat loss and road mortality – and some of the work being done to help support the remaining population – like the population estimate surveys, habitat restoration and creation, and threat assessments.

Here we’ll focus on another key element in the recovery of blue racers in Canada: addressing unknowns regarding the genetics of the remaining population. Using DNA extracted from blue racer blood and tissue samples, researchers in the Lougheed Lab at Queen’s University are conducting genomic analyses to tackle a variety of knowledge gaps, including:

Inbreeding and Effective Population Size:

The blue racer census surveys discussed in previous blogs were carried out to provide an updated population estimate and will give us an idea of how many blue racers are a part of the Pelee Island population. However, there are some factors that may make a population function genetically as much smaller in terms of reduced diversity, with one example being inbreeding. The effective population size  uses genomic analyses to translate the population size estimated from our census surveys into theoretical population size taking into account the rate that genetic diversity is being lost.

Inbreeding, especially, is a concern in wildlife with small populations with limited or fragmented habitats and occurs when individuals that share many of the same genetic traits breed, resulting in offspring that have lower genetic diversity. This increases the likelihood that offspring will inherit potentially harmful traits that decrease fertility and survival. Over time, this can have population-level impacts and contribute to declines.

Through genomic analyses, the degree at which inbreeding is occurring can be quantified and will contribute to the estimated effective population size of blue racers on Pelee Island. The effective population size estimate will be an important factor in assessing whether the Pelee Island blue racer population may require ex-situ conservation support to increase genetic diversity in the future.

Genetic Distinction:

Since blue racers in Canada are now only found on Pelee Island, they are physically separated from individuals throughout the rest of their range, and as a result, genetic traits are unlikely to be exchanged between those populations through breeding. Over time, it’s possible that blue racers on Pelee Island have adaptive differences from populations on the mainland and may have become genetically distinct. By comparing DNA collected from blue racers on Pelee Island with those collected throughout the US, researchers will determine whether Canada’s blue racer population is genetically distinct, which will also help assess the potential future conservation needs of blue racers on the island. Down the line, if ex-situ conservation actions (such as headstarting for genetic rescue) are deemed necessary and appropriate, knowing what genetic traits are required for a snake to be successful within the habitat it is released in will be crucial.

Genomic analyses are currently ongoing in the lab, so keep an eye out for more information on the results and how they may impact blue racer conservation actions going forward!

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