Rapid and unpredictable changes of the G‐matrix in a natural bird population over 25 years

• DOI: 10.1111/jeb.12044
• Publication Date: 2012-12-13T14:20:28Z
• Authors: M. Björklund; A. Husby; L. Gustafsson
• Keywords: Sweden; 0106 biological sciences; Time Factors; Models, Genetic; Genetic Drift; Genetic Variation; 01 natural sciences; Songbirds; Genetics, Population; Multivariate Analysis; Animals; Selection, Genetic

AbstractKnowledge 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.