Heritability and correlations among learning and inhibitory control traits in common pheasants (Phasianus colchicus). Heritability of cognitive traits in Phasianus colchicus

To understand the evolution of cognitive abilities, we need to understand both how selection acts upon them and their heritability. Recent work suggests that there are fitness consequences for free-living individuals with particular cognitive abilities. However, our current understanding of the heritability of these abilities is limited to a narrow range of traits and is restricted to domesticated species that have been subjected to artificial selection. We investigated genetic variance for, and correlations among four cognitive abilities: inhibitory control, visual and spatial discrimination, and spatial ability, measured on > 450 pheasants, Phasianus colchicus, over 4 generations. Pheasants were reared in captivity but bred from adults that lived in the wild and hence, were subject to selection on survival. Pheasant chicks are precocial and were reared without parents, enabling us to standardise environmental and parental care effects. We constructed a pedigree based on 15 microsatellite loci and implemented animal models (a type of mixed-effects model) to estimate heritability. We found moderate heritabilities for discrimination learning and inhibitory control ability but heritability for spatial ability was low. Principle components analysis revealed no leading factor to explain phenotypic correlations, suggesting a modular view of the structure of animal cognition, whereas, genetic correlations revealed a leading component that explained 69% of the variation. Our findings highlight that the expression of cognitive traits is greatly influenced by environmental factors which potentially masks the underlying genetic structure.