Meeting Abstract
The relationship between population diversity and the severity of disease dynamics is a highly debated but poorly resolved theme in infectious disease ecology. Increased genetic diversity within a host population may reduce the severity of epidemics because diverse populations may harbor more resistant or resilient individuals. However, genetic diversity per se may not alone alter population-level effects of disease, as host behavioral phenotypes play an integral role in disease defenses and genetically diverse populations are not always phenotypically diverse. We identified genotypes of the fly Drosophila melanogaster that did not differ in susceptibility to the generalist entomopathogenic fungus Metarhizium robertsii but varied in a suite of behavioral traits that alter infection risk. We then produced populations that contained one of five different genotypes, mixtures of three genotypes that exhibited similar behavioral phenotypes, or mixtures of three phenotypically diverse genotypes. Populations were exposed to a 24hr pathogen pulse, and then allowed to interact naturally on pathogen-free food patches for 20 days where we measured mortality daily compared to pathogen-free controls. We found that mixed-genotype populations experienced greater mortality compared to monotypic populations only when made up of phenotypically diverse individuals. That is, genetic diversity alone did not alter disease dynamics, but phenotypically diverse populations died more rapidly, potentially because the presence of diverse behavioral phenotypes may increase the number of ways in which individuals can become infected and transmit infectious agents to conspecifics.
