Genetic Paths to Evolutionary Rescue and the Distribution of Fitness Effects Along Them

Matthew M Osmond (1) , Sarah P Otto (1) , Guillaume Martin (2)

1 UBC - University of British Columbia
2 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier

The past century has seen substantial theoretical and empirical progress on the genetic basis of adaptation. Over this same period a pressing need to prevent the evolution of drug resistance has uncovered much about the potential genetic basis of persistence in declining populations. However, we have little theory to predict and generalize how persistence-by sufficiently rapid adaptation-might be realized in this explicitly demographic scenario. Here we use Fisher's geometric model with absolute fitness to begin a line of theoretical inquiry into the genetic basis of evolutionary rescue, focusing here on asexual populations that adapt through de novo mutations. We show how the dominant genetic path to rescue switches from a single mutation to multiple as mutation rates and the severity of the environmental change increase. In multi-step rescue, intermediate genotypes that themselves go extinct provide a 'springboard' to rescue genotypes. Comparing to a scenario where persistence is assured, our approach allows us to quantify how a race between evolution and extinction leads to a genetic basis of adaptation that is composed of fewer loci of larger effect. We hope this work brings awareness to the impact of demography on the genetic basis of adaptation.

Mots clés: Antimicrobial drug resistance; Evolutionary escape; Fisher's geometric model; Genetic basis of adaptation

Domaines: Evolution [q-bio.PE]

Matthew M Osmond, Sarah P Otto, Guillaume Martin. Genetic Paths to Evolutionary Rescue and the Distribution of Fitness Effects Along Them. Genetics, In press, pp.genetics.302890.2019. ⟨10.1534/genetics.119.302890⟩. ⟨hal-02420679⟩