Cracking Coevolution: Consequences of Space and Genetic Architecture
Author: Victoria Caudill
Affiliation: University of Oregon
Keywords: Coevolution
Coevolution between two species can lead to variation in phenotypes across geography, sometimes creating areas where the phenotypes of species closely match and other areas where they do not match at all. However, it is not well-understood how the genetic basis of the traits underlying coevolution affect phenotypic and genotypic variation, especially across a geographical area. I investigate the genetic dynamics of coevolution of two species undergoing reciprocal adaptation across space and time, using both theory and simulations inspired by the newt-snake system. In this system, Taricha granulosa (rough-skinned newt) has developed tetrodotoxin that poisons predators. One of their predators, Thamnophis sirtalis (garter snake), has developed resistance to this toxin. I explore the effects that genetic architecture of the toxin and resistance traits has on the coevolutionary dynamics by manipulating the mutation rate and the effect size of mutations, demonstrating how different genetic architectures lead to different coevolutionary outcomes in a geographically explicit setting. The outcomes of these simulations reveal that a species with genetic architecture of intermediate polygenicity has higher phenotype and population size, suggesting that there might be an optimal combination of mutation rate and effect size in the coevolutionary arms race.