Gregory F. Grether: UCLA Department of Ecology and Evolutionary Biology

Normal development depends on specific environmental inputs. Consequently, when a species encounters novel environmental conditions, some traits may develop abnormally. Changes in the environment can occur, for example, because of climate change or habitat degradation. Like genetic mutations, most environmental perturbations of development are detrimental, and thus natural selection would usually be expected to favor genetic changes that gradually restore the ancestral form of the trait in the new environment. I recently coined the term “genetic compensation” to describe this form of adaptive evolution. When genetic compensation occurs along a spatial environmental gradient, it partially or completely masks the effects of the gradient on trait development. This means that populations of a species that look the same in the wild may develop quite differently if placed in a common environment. In addition, genetic compensation may lead to a cryptic form of reproductive isolation between populations, explain some puzzling cases in which heritable traits exposed to strong directional selection fail to show the expected evolutionary response, and complicate efforts to monitor populations for signs of environmental deterioration. In this talk, I will explain how genetic compensation differs from related phenomena, such as genetic assimilation and canalization, and review putative examples to illustrate the above points.