203T Poster - Population Genetics
Thursday June 09, 9:15 PM - 10:00 PM

Authors:
Robin Hopkins ¹; Antonio Serrato-Capuchina ¹; Charlie Hale ²; Matthew Farnitano ³; Federico Roda ⁴

Affiliations:
1) Harvard University; 2) Cornell University; 3) University of Georgia; 4) National University of Colombia

Keywords:
Complex traits

Many plant species have evolved pollen-pistil recognition systems to optimize reproductive success. The two most important pistil recognition systems distinguish between self/non-self pollen and between pollen from same/different species, resulting in self-incompatibility and heterospecific incompatibility, respectively. It has long been hypothesized that these recognition systems are mechanistically linked, but little is known about the extent of their genetic overlap across different types of pollen-pistil interactions or whether this overlap constrains the evolution of pistil recognition. Here we untangle the complex genetic basis of variation in the strength of pollen-pistil incompatibility in the Texas wildflower, Phlox drummondii. Natural populations of P. drummondii exhibit extensive variation in both the strength of the self-incompatibility and the strength of the heterospecific-incompatibility with the closely related species P. cuspidata. Furthermore, there is a significant positive correlation between the strength of self-incompatibility and heterospecific-incompatibility across individuals. We use quantitative trait locus mapping and genome-wide association mapping to identify the genomic regions controlling variation in pollen-pistil incompatibilities. We identify the extent to which the two pollen rejection systems are share genetic mechanisms or co-vary due to parallel patterns of selection and demography. Additionally, we reveal if and how the S-locus, which contains the pollen and pistil genes necessary for self-pollen recognition, is involved in the quantitative variation in the strength of self- and heterospecific-incompatibility within P. drummondii. Our work sheds new light on the long-standing questions about the genetic mechanisms plants use to choose their mates. By exploring whether self and heterospecific incompatibilities share genetic mechanisms, we can additionally generate predictions for how the evolution of one incompatibility may affect the other.