Heritability of the timing of autumn migration in a natural bird population

In recent decades, global temperature has increased at an unprecedented rat e. This has been causing rapid environmental shifts that have altered the s elective regimes determining the annual organization of birds. In order to assess the potential for adaptive evolution in the timing of autumn migrati on, we estimated heritabilities of the onset of migratory activity in a sou thern German blackcap (Sylvia atricapilla) population, Heritabilities (h(2) =0.34-0.45) and coefficients of additive genetic variation (CVA=4.7-5.7) w ere significant and consistent when estimated by different methods, irrespe ctive of whether they were derived from birds hatched in the wild or bred i n captivity In an artificial selection experiment, we selected for later on set of migratory activity, simulating expected natural selection on this tr ait. We obtained a significant delay in the mean onset of migratory activit y by more than one week after two generations of selection. Realized herita bility (h(2) = 0.55) was in agreement with expected heritability in the coh ort that the selection lille was derived from. Our results suggest that evo lutionary changes in the timing of autumn migration may take place over a v ery short time period and will most probably be unconstrained by the lack o f additive genetic variation.