Living on the edge: the evolution of spatial cognition in food-caching chickadees

There is a tremendous amount of intra- and inter-specific variation in animal cognitive abilities, and understanding the evolutionary mechanisms generating such variation is an important issue in evolutionary biology. Here we review our research on spatial cognition in food-caching chickadees, which use spatial cognitive abilities to recover previously made food caches to survive harsh winters. This work ranges from comparing multiple populations along environmental gradients to investigating the causes and consequences of individual variation in spatial learning and memory abilities, to describing the genetic basis of such variation. Our data show that (i) chickadees in harsher environments have better spatial cognitive abilities and a larger hippocampus with more hippocampal neurons, with differences between populations persisting in common garden experiments; (ii) chickadees tested in the wild show extensive individual variation in their learning and memory abilities; (iii) this variation is highly heritable and has a genetic basis; and (iv) this variation is associated with significant differences in survival, lifespan and reproductive success. Overall, our data provide strong evidence that spatial cognitive abilities in food-caching chickadees are shaped by natural selection, which generates differences among populations living across heterogeneous environmental conditions. This article is part of the Theo Murphy meeting issue ‘Selection shapes diverse animal minds’.