Low genetic variance in the duration of the incubation period in a collared flycatcher (Ficedula albicollis) population

The avian incubation period is associated with high energetic costs and mortality risks suggesting that there should be strong selection to reduce the duration to the minimum required for normal offspring development. Although there is much variation in the duration of the incubation period across species, there is also variation within species. Estimating to what extent this variation is genetically determined is needed if we want to predict the evolutionary potential of this trait. Here we use a long-term study of collared flycatchers to examine the genetic basis of variation in incubation duration. We demonstrate limited genetic variance as reflected in the low and non-significant additive genetic variance with a corresponding heritability of 0.04 and coefficient of additive genetic variance of 2.16. Any selection acting on incubation duration will therefore be inefficient. To our knowledge this is the first time heritability of incubation duration has been estimated in a natural bir...