Phenotypic Complexity and Evolutionary Rescue: A Geometric Approach

In the face of rapidly changing environments, understanding how fragmented populations undergo evolutionary rescue is central. This study utilizes analytical methods and simulations within a two-deme metapopulation model built on Fisher's geometric model (FGM). We investigate how sudden environmental shifts affect two subpopulations, each adapting to different phenotypic optima. By applying analytical techniques, we determine the probability distribution of the distances between these optima, which helps us calculate the intersection volume in the phenotypic space. This method also evaluates the probability of mutations that can simultaneously ensure the survival of both subpopulations and identifies the scope of one-step rescue mutations.

The dimensionality of the phenotypic space is central in determining the probability of a concomitant rescue of both subpopulations: a higher dimensionality entails reduced values of the probability of evolutionary rescue.The study stresses the importance of migration rates, local adaptation, and genetic variety resulting from novel mutations. These findings are relevant for creating conservation strategies that strengthen populations' ability to adapt to drastic environmental shifts.