Speaker
Description
Drastically changing environments can cause the extinction of populations. Adaptation to the new conditions that prevents extinction is called evolutionary rescue. The question is: How does evolution save species?
New selection pressures can cause rapid evolutionary change. This has, for example, been observed in the Pacific field cricket Teleogryllus oceanicus on Hawai’i, which is under harsh predation pressure from the parasitoid fly Ormia ochracea. The fly locates the male crickets by their mating calls and deposits its larvae on the cricket which gets eventually killed. Within less than 20 generations, a sex-linked mutation causing an alteration to the wing structure became dominant on most islands. Males with this mutation are mute and thus safe from the fly. Yet, mute males cannot attract females from afar. They therefore keep close to the remaining calling males.
Motivated by this system, I develop mathematical models for evolutionary rescue in host-parasite systems, focusing on the consequences of frequency-dependent fitness of the rescue mutation for the dynamics and outcome of adaptation. I further aim to determine how the type of mutation (sex-linked vs. autosomal) influences the spread and persistence of the mutation. I hope that my models will allow us to gain insights into the dynamics of rescue (or extinction) under biotic stress.
