Selection and drift influence genetic differentiation of insular Canada lynx (Lynx canadensis) on Newfoundland and Cape Breton Island

Abstract

Island populations have long been important for understanding the dynamics and mechanisms of evolution in natural systems. While genetic drift is often strong on islands due to founder events and population bottlenecks, the strength of selection can also be strong enough to counteract the effects of drift. Here, we used several analyses to identify the roles of genetic drift and selection on genetic differentiation and diversity of Canada lynx (Lynx canadensis) across eastern Canada, including the islands of Cape Breton and Newfoundland. Specifically, we assessed whether we could identify a genetic component to the observed morphological differentiation that has been reported across insular and mainland lynx. We used a dinucleotide repeat within the promoter region of a functional gene that has been linked to mammalian body size, insulin‐like growth factor‐1 (IGF‐1). We found high genetic differentiation at neutral molecular markers but convergence of allele frequencies at the IGF‐1 locus. Thus, we showed that while genetic drift has influenced the observed genetic structure of lynx at neutral molecular markers, natural selection has also played a role in the observed patterns of genetic diversity at the IGF‐1 locus of insular lynx.

Genome-wide sampling suggests island divergence accompanied by cryptic epigenetic plasticity in Canada lynx

“…).While our population divergence time estimates are scaled by mutation rate and generation time, all reasonable metrics support a historic colonization (> 1,000 years). Our analyses also indicated that Newfoundland underwent a demographic bottleneck after colonization, consistent with microsatellite data(16), and that genetic diversity remains low compared to mainland populations.Row et al (15) showed a minimal barrier effect of the Rocky Mountains to Canada lynx, which is also supported with our SNP data. Despite minimal range-wide nuclear divergence in lynx, it remains possible that distinct environmental variation might be driving unique patterns of functionally important differentiation at the range margins, including Alaska and Newfoundland.…”

“…Here, we assessed whether environmental variation, geographic distance, or insularity were determinants of DNA methylation structure in a free-ranging carnivore. Our study species, the Canada lynx (Lynx canadensis), is a mid-sized felid that is highly mobile and whose neutral genetic variation (i.e., microsatellites) exhibits low levels of genetic differentiation across the mainland, with divergent island populations (15,16). Although some hypotheses exist regarding the colonization of Newfoundland (15), no formal demographic analyses have been investigated using genome-wide markers.…”

Spatial and environmental influences on selection in a clock gene coding trinucleotide repeat in Canada lynx (Lynx canadensis)

“…1). The samples used in this study were a subset of those used in Koen et al, (2014), with the addition of western Canada lynx samples used by Prentice et al, (2017a), and Cape Breton Island lynx samples used by Prentice et al, (2017b).…”

Spatial and environmental influences on selection in a clock gene coding trinucleotide repeat in Canada lynx (Lynx canadensis)

“…Canada lynx samples used byPrentice, Bowman, Lalor et al (2017), and Cape Breton Island lynx samples used byPrentice, Bowman, Khidas et al (2017).…”

“…uals sampled within or east of Manitoba [N = 1,466], and "western lynx" including individuals sampled within or west of Alberta/Yukon [N = 423];Figure 1a), and repeated the analysis on each subset independently to reduce unexplained environmental variation in the data when analysed from a continental scale. We were specifically interested in the eastern lynx data set, where preliminary analyses showed indications of selection in peripheral and insular populations of lynx(Koen et al, 2015;Prentice, Bowman, Khidas et al, 2017).Further,Row et al (2014), reported a correlation between neutral genetic variability and a winter climate gradient in lynx across the Pacific-North American (PNO) and North Atlantic Oscillation (NAO) climatic systems in eastern Canada, and suggested restricted dispersal in lynx between Manitoba and Quebec supporting the potential for selection in this region.…”