Data from: Phenotypic selection on an ornamental trait is not modulated by breeding density in a pied flycatcher population

Most studies of phenotypic selection in the wild have focused on
morphological and life-history traits and looked at abiotic (climatic)
variation as the main driver of selection. Consequently, our knowledge of
the effects of biotic environmental variation on phenotypic selection on
sexual traits is scarce. Population density can be considered a proxy for
the intensity of intra- and inter-sexual competition and could therefore
be a key factor influencing the covariation between individual fitness and
the expression of sexual traits. Here, we used an individual-based data
set from a population of pied flycatchers (Ficedula hypoleuca) monitored
over 24 years to analyse the effect of breeding density on phenotypic
selection on dorsal plumage colouration, a heritable and sexually selected
ornament in males of this species. Using the number of recruits as a
fitness proxy, our results show overall stabilizing selection on male
dorsal colouration, with intermediate phenotypes being favoured over
extremely dark and dull individuals. However, our results did not support
the hypothesis that breeding density mediates phenotypic selection on this
sexual trait. We discuss the possible role of other biotic factors
influencing selection on ornamental plumage.