Mating patterns can have large effects on the outcome of natural selection. For instance, assortative mating, which occurs when similar individuals are more likely to mate with one another than they would under random mating, increases trait variance. Increased trait variance, in turn, increases the response to selection. This research will examine the effects assortative mating has on the evolution of resistance to virus infection in wild squash. Many factors affect the degree of assortative mating in natural plant populations, including flowering period, virus infection, pollinator preferences and variation in the daily sex ratio. Wild squash will be planted in an experimental garden and censused through the flowering period to determine if virus infection or virus-resistance (conferred by a transgene) affects flower production and sex ratio. Fluorescent dye will be used to track pollen movement by pollinators. These data will allow quantification of patterns of assortative mating in virus-infected and healthy plants. These empirical data will then be used in mathematical models to investigate how variation in mating patterns affects the evolution of resistance.
This research will further our understanding of the effects of assortative mating on trait evolution in natural plant populations, and will enhance our understanding of resistance evolution when disease epidemics are patchy in space and time. In addition, using transgenic/wild hybrid squash will allow us to better understand the ecological consequences of the escape of transgenes into wild populations, which is one of the risks associated with the use of transgenic crops. The research will provide research training for a PhD student and several undergraduates.
