Evolution of thermal physiology alters the projected range of threespine stickleback under climate change

Species distribution models (SDMs) are widely used to predict range shifts
but could be unreliable under climate change scenarios because they do not
account for evolution. The thermal physiology of a species is a key
determinant of range and thus incorporating thermal trait evolution into
SDMs might be expected to alter projected ranges. We identified a genetic
basis for physiological and behavioural traits that evolve in response to
temperature change in natural populations of threespine stickleback
(Gasterosteus aculeatus). Using these data, we created geographic range
projections using a mechanistic niche envelope approach under two climate
change scenarios. Under both scenarios, trait data was either static (‘no
evolution’ model), allowed to evolve at observed evolutionary rates for
the trait (‘evolution’ model), or allowed to evolve at a rate of evolution
scaled in association with the variance that is explained by quantitative
trait loci (QTL; ‘scaled evolution’ models). We show that incorporating
these traits and their evolution substantially altered the projected
ranges for a widespread panmictic marine population, with over 7-fold
increases in area under climate change projections when traits are allowed
to evolve. Evolution-informed SDMs should improve the precision of
forecasting range dynamics under climate change, and aid in their
application to management and the protection of biodiversity.