Volume 79, Issue 4, 1 April 2025

While genetic correlations can concentrate additive genetic variance into trait combinations that do not align with selection, genetic correlations themselves may evolve during divergence. Populations of the mycophagous fly Drosophila subquinaria have diverged between regions that are either allopatric or sympatric with its close relative, Drosophila recens . We used replicate breeding designs to estimate additive genetic variances and covariances (G -matrices) for a suite of chemical signaling traits that have diverged between regions. Our results suggest that G has evolved in sympatry following colonization from the ancestral allopatric region and may not have substantially constrained divergence in this case.

Living in a predictable environment can optimize cellular processes in an organism which can include loss of nonessential gene functions. At the same time, growing in a predictable environment can allow organisms to accumulate standing genetic variation, some of which may not have any role in that environment, but can provide fitness benefits upon an environmental change. To test how these processes influence population fitness, we experimentally evolved yeast populations in a predictable environment in the laboratory for 1,000 generations. We then tested the fitness and evolutionary adaptation of the evolved populations in new environments. We observed physiological changes during adaptation and accumulation of genomic mutations, some of which led to loss of function.