Rapid Divergence of Genetic Variance‐Covariance Matrix within a Natural Population

The matrix of genetic variances and covariances (Gmatrix) represents the genetic architecture of multiple traits sharing developmental and genetic processes and is central for predicting phenotypic evolution. These predictions require that theGmatrix be stable. Yet the timescale and conditions promotingGmatrix stability in natural populations remain unclear. We studied stability of theGmatrix in a 20‐year evolution field experiment, where a population of the cosmopolitan parthenogenetic soil nematodeAcrobeloides nanuswas subjected to drift and divergent selection (benign and stress environments). Selection regime did not influence the level of absolute genetic constraints: under both regimes, two genetic dimensions for three life‐history traits were identified. A substantial response to selection in principal components structure and in general matrix pattern was indicated by three statistical methods.Gstructure was also influenced by drift, with higher divergence under benign conditions. These results show that theGmatrix might evolve rapidly in natural populations. The observed high dynamics ofGstructure probably represents the general feature of asexual species and limits the predictive power ofGin phenotypic evolution analyses.