Implications of existing local (mal)adaptations for ecological forecasting under environmental change

Standing genetic variation represents a genetic load on population fitness but can also support a rapid response to short-term environmental change, and the greatest potential source of such standing genetic variation typically exists among locally adapted populations living along an environmental gradient. Here we develop a spatially-explicitly simulation model to quantify the contribution of existing genetic variation arising from migration-mutation-selection-drift balance to time to extinction under environmental change. Simulations reveal that local adaptation across a species range associated with an underlying environmental gradient could extend time to extinction by nearly three–fold irrespective of the rate of environmental change. The potential for pre-adapted alleles to increase the rate of adaptation changes the relative importance of established extinction risk factors, in particular it reduced the importance of the breadth of environmental tolerance and it increased the rel...