Presenter: Hanna McIntosh
Faculty Mentor: Matt Streisfeld, Sean Stankowski
Presentation Type: Poster 76
Primary Research Area: Science
Major: Environmental Science
Funding Source: UROP Mini-Grant, University of Oregon, $1000
A major goal of speciation research is to understand the genetic architecture of isolating barriers. Theoretical studies predict that isolating barriers are most effective if they have a simple genetic basis and are controlled by loci in
the same genomic regions. To test this hypothesis, we used Quantitative Trait Locus (QTL) mapping to determine the genetic architecture of floral trait divergence between red and yellow ecotypes of the monkeyflower Mimulus aurantiacus. These ecotypes are closely related, but partially isolated due to preferences of different pollinators for contrasting floral traits. We phenotyped an F2 mapping population (n=226) and used RADseq to generate a high- density genetic map to investigate two floral traits—color and size—thought to underlie preference. Using a multi- QTL model, we identified 2 QTLs for flower color and 3 QTLs for flower size. For size, the total phenotypic variation explained by the 3 QTLs was 36%, indicating that this trait is controlled by many genes of small effect. In contrast, a single QTL explained over 65% of variation in flower color. While recent studies have shown that multiple isolating traits are controlled by the same genomic region, we observed no QTL overlap for color and size. In addition to revealing the genetic basis of adaptation in M. aurantiacus, our results show that complex, simple, and genetically- independent traits can contribute to reproductive isolation early in speciation.