Tag: Sean Stankowski

Characterizing Genetic Relationships Underlying Adaptive Flower Color Divergence in Mimulus aurantiacus

Presenter: Connor Benson

Mentors: Matt Streisfeld and Sean Stankowski, Biology

Poster: 4

Major: Biology

Understanding the genetic basis of adaptive traits lends insight into the mechanisms that generate biodiversity. Flower color has been implicated as an adaptive trait in numerous studies, and is thought to be a primary driver
of speciation in angiosperms due to selection by differential pollinator preference. Here I used molecular genetic techniques to examine the relationship between two regulatory genes involved in the production of red floral pigment, a trait thought to underlie the evolution of two new subspecies in Mimuls aurantiacus. I used genotype-phenotype comparisons in lab bred plants to characterize how MaMyb1, the less studied of these two genes, impacts the production of red floral pigment. I also utilized virus-induced gene silencing in an attempt to understand the functional role of MaMyb1 in producing red flowers. My results thus far suggest that MaMyb1 does not play a significant role in producing red flower pigment. This work aims to better our understanding of the genetic relationships underlying flower color divergence in an important model system for the study of speciation.

Genetic Architecture of Local Adaptation and Reproductive Isolation in Mimulus aurantiacus

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.