First Place in Poster Category – Science

STUDENT: Sarah D. Sherpinskas

ADVISOR: Dr. Megan Van Etten

ABSTRACT:

Pollinators are a key component to maintaining biodiversity globally, but recent studies have raised concerns over declines in pollinator populations. Pollinator declines could affect selection pressures, leading to long terms changes in species. To completely measure selection, fitness gained through male and female function must both be measured. Male fitness is difficult and costly to estimate due to the need for genetic markers to track paternity. To circumvent the use of expensive genetic markers, we plan to use a dominant mutation, purple stems, to trace paternity. However, if other traits differ between the mutant and the normal plants, selection estimates could be affected. Therefore, we must first determine whether the purple stemmed mutants are similar in other traits to the normal plants. To investigate this, we compared percent germination, growth rate, leaf size, flower size and flower number of purple-stemmed Brassica rapa plants to normal plants that had previously been selected to have smaller and larger flower sizes that will be used in future experiments. We found that germination and growth rate was similar across plants, that the purple-stemmed plants’ leaf size was larger than the smaller flowered plants but similar to the larger flowered plants, that flower size was intermediate to the smaller and larger flowered plants, and that flower number was similar to the smaller flowered plants. These results show that there are some trait differences that could affect estimates of selection in future experiments, particularly the large leaf size and low flower number that could indicate a difference in resource acquisition or resource allocation to reproduction. To reduce the impact of these differences, the purple-stemmed plants should be crossed with the normal plants for multiple generations so that only the gene responsible for the purple-stem trait is different. Only then can the trait be used to accurately estimate male and female fitness to better understand the long-term impacts of pollinator declines.