Create your own conference schedule! Click here for full instructions

Abstract Detail

Population Genetics/Genomics

Host-association determines population genomic structure of a parasitic plant through impacts on reproductive traits and pollination.

Trade-offs in parasite fitness between host species can select for phenotypes adapted to particular host species, thereby facilitating divergence between host species-associated populations. However, gene flow and, thus, the potential for adaptation to host species is also mediated by vectors. To understand the relative roles of these processes, I study the population genomic structure of a geographically-widespread parasitic plant species (desert mistletoe, Phoradendron californicum) with respect to interactions with both host species and “vectors” (i.e. seed dispersers and pollinators). I find that mistletoes on mesquite hosts (e.g. Prosopis velutina) represent a genetically-distinct population from those on other locally interspersed host species (e.g. Senegalia greggii, Parkinsonia spp.). Reproductive ecology, notably flowering time and pollinator community composition, differs between these host races, contributing to strong but asymmetric reproductive isolation between the host races. Consistent with reinforcement of isolating mechanisms, reproductive traits differ more between the host races in sympatry than in allopatry, despite correlations between trait values and environmental factors. Additionally, populations on mesquite experience opposing selection on first flowering date when living in sympatry and allopatry with the other host race, predicted to lead to increased host-associated divergence over time. Preliminary results indicate that, while mistletoes are strongly differentiated based on host species, this biotic effect interacts with geographic factors to determine population genomic structure at the range-wide scale. In total, these results provide unique insights into the relative contributions of biotic and abiotic factors to population structure, adaptation, and the potential for speciation in parasitic plants.

1 - Arizona State University, School of Life Sciences, 734 W. Alameda Drive, Tempe, AZ, 85282, United States

Keywords:
Parasitic Plants
spatial genetic structure
phenology
Seed dispersal
Pollination
mistletoe
Legumes
sonoran desert
gene flow
reproductive isolation
reinforcement
host specialisation
population differentiation.

Presentation Type: Oral Paper
Session: POPGEN1, Population Genetics/Genomics I
Location: Tucson H/Starr Pass
Date: Monday, July 29th, 2019
Time: 8:30 AM
Number: POPGEN1003
Abstract ID:454
Candidate for Awards:Margaret Menzel Award