Data from: Environmental drivers of varying selective optima in a small passerine: a multivariate, multiepisodic approach

In changing environments, phenotypic traits are shaped by numerous agents
of selection. The optimal phenotypic value maximizing the fitness of an
individual thus varies through time and space with various environmental
covariates. Selection may differ between different life cycle stages and
act on correlated traits inducing changes in the distribution of several
traits simultaneously. Despite increasing interests in environmental
sensitivity of phenotypic selection, estimating varying selective optima
on various traits throughout the life cycle, while considering (a)biotic
factors as potential selective agents has remained challenging. Here, we
provide a statistical model to measure varying selective optima from
longitudinal data. We apply our approach to analyse environmental
sensitivity of phenotypic selection on egg-laying date and clutch size
throughout the life cycle of a white-throated dipper population. We show
the presence of a joint optimal phenotype that varies over the 35-yr
period, being dependent on altitude and temperature. We also find that
optimal laying date is density-dependent, with high population density
favoring earlier laying dates. By providing a flexible approach, widely
applicable to free-ranging populations for which long-term data on
individual phenotypes, fitness and environmental factors are available,
our study improves the understanding of phenotypic selection in varying
environments.