Pollen Viability as an Isolating Barrier in a Closely-Related Group of Monkeyflowers (Mimulus)

Authors: Clara Zook, Irene Martinez, James Sobel

Field of Study: Science, Technology, Engineering, and/or Math

Program Affiliation: Sobel Lab

Faculty Mentors: James Sobel

Easel: 28

Timeslot: Afternoon

Abstract: Speciation occurs through the accumulation of reproductive isolation. Sterility is one type of intrinsic postzygotic barrier affecting hybrid offspring through negative epistatic interactions or chromosomal rearrangements. This directly impacts the production of viable pollen, hindering successful reproduction. This study used section Diplacus from the widely diverse genus Mimulus to investigate how sterility in angiosperms evolves in hybrids. It performed pairwise, reciprocal intra- and intertaxon crosses and allowed seeds to germinate and grow into adulthood. Newly opened flowers were then used to stain pollen grains using an aniline blue solution to quantify viable pollen. It was observed that within each generation of interspecific crosses, pollen viability decreased in comparison to the parent species. With this crossing design and QTL mapping, it is possible to explore the mechanisms impacting pollen sterility and how they contribute to speciation.