COS 194-5 - Demographic history and selection in the narwhal (Monodon monoceros) and bowhead whale (Balaena mysticetus), with implications for changing climates in the Arctic
Associate Professor University of Manitoba Winnipeg, Manitoba, Canada
Background/Question/Methods
The Arctic is warming up significantly faster than other parts of the world, making this region and its inhabitants especially vulnerable to climate change. Marine mammals specialized for Arctic environments have important roles in the ecosystem, as both predator and prey, and changes in their abundances and distribution may severely impact marine wildlife. Investigating demographic histories and signatures of selection can reveal patterns of genetic diversity and adaptation, which provide important background for predicting species performance to environmental changes and guiding conservation strategies. However, much of the genomic background remains unknown for many Arctic marine mammals. We used whole-genome data to examine demographic history and selection in two Arctic whales: the narwhal, Monodon monoceros, (n = 66) and bowhead whale, Balaena mysticetus, (n = 23).
Results/Conclusions
Narwhal effective population sizes gradually expanded following an initial decline. Bowhead whales exhibited a similar broad pattern with an initial decline, then increased to a stable effective population size for many generations followed by an additional increase in more contemporary years. Population structure in the narwhal revealed presence of local genetic attributes, specifically differentiating northern and southern sampling sites in the Canadian Arctic. In bowhead whales, however, population analyses suggest gene flow may be high across their wide-ranging distribution. To assess the degree of potential maladaptation to future climate scenarios, we identified candidate genomic regions associated with environmental gradients. Our results reveal historical patterns of effective population sizes in two key Arctic marine mammals. Together with contemporary population structure and assessments of future adaptations, we identified subgroups that may be at particular risk and assessed how they may perform to predicted climate change.
