Genomic evidence of past and future climate-linked loss in a migratory Arctic fish

Despite widespread biodiversity losses, an understanding of how most taxa
will respond to future climate change is lacking. Here we integrate
genomics and environmental modelling to assess climate change responses in
an ecologically and economically important Arctic species. Environmentally
associated genomic diversity and machine learning are used to identify
highly vulnerable populations of anadromous (migratory) Arctic charr, and
we reconstruct estimates of effective population size spanning the
twentieth century to identify past climate-associated declines. We uncover
past region-wide declines in effective population size that correspond to
decreases in temperature and community biomass in the Northwest Atlantic.
We find vulnerable populations near the southern range limit, indicating
northward shifts and a possible loss of commercially important
life-history variation in response to climate change. The genomic approach
used here to investigate climate change response identifies past and
future declines that impact species persistence, ecosystem stability and
food security in the Arctic.