Data from: Rapid and unpredictable changes of the G-matrix in a natural bird population over 25 years

Knowledge of the genetic variances and covariances of traits (the
G-matrix) is fundamental for the understanding of evolutionary dynamics of
populations. Despite its essential importance in evolutionary studies,
empirical tests of the temporal stability of the G-matrix in natural
populations are few. We used a 25-year-long individual-based field study
on almost 7000 breeding attempts of the collared flycatcher (Ficedula
albicollis) to estimate the stability of the G-matrix over time. Using
animal models to estimate G for several time periods, we show that the
structure of the time-specific G-matrices changed significantly over time.
The temporal changes in the G-matrix were unpredictable, and the structure
at one time period was not indicative of the structure at the next time
period. Moreover, we show that the changes in the time-specific G-matrices
were not related to changes in mean trait values or due to genetic drift.
Selection, differences in acquisition/allocation patterns or
environment-dependent allelic effects are therefore likely explanations
for the patterns observed, probably in combination. Our result cautions
against assuming constancy of the G-matrix and indicates that even
short-term evolutionary predictions in natural populations can be very
challenging.