This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Broadening Participation of Groups Under-represented in Biology. The fellowship supports a research and training plan for the Fellow that will increase the participation of groups underrepresented in biology. The focus of this study is a colorful tortoise beetle found in tropical rainforests, called Chelymorpha alternans. This beetle varies in color across its range and incorporates toxins produced by host plants into the outer exoskeleton as a defense mechanism against predators. By incorporating toxic compounds, these organisms become distasteful to predators, and by using bright and contrasting coloration they advertise that they are toxic, making it easier for predators to learn and remember to avoid them. Often variation in color or pattern signals individuals who differ in their level of toxicity. This research seeks to understand how individual differences in the ability to incorporate toxins from the plants contributes to survival in beetle larvae and predation as adults. Understanding how some individuals are better equipped to process toxins will provide insights into the ways that insects adapt to their environment and to agricultural pesticides. To broaden participation, motivated high school and undergraduate students in the Memphis area will be mentored in research and outreach partnerships between the University and the community will be facilitated.
In order to understand how intraspecific variation mediates the sequestration ability of plant secondary metabolites by larvae of the polymorphic tortoise beetle, C. alternans, an integrative study assessing differences in gene expression, larval and adult fitness and functional genomics will be performed. In aposematic organisms, variation in color pattern often indicates individuals with differing levels of toxic protection. To investigate the genotypic and phenotypic impacts on larval survival, individuals of different genotypes will be assessed for larval survival. Predator bioassays with the ant predator, Azteca chartifex, will be conducted to assess genotypic and phenotypic impacts on adult palatability. Individuals that are better at processing secondary metabolites from the plant are expected to have higher survival through larval development, and those that are better at incorporating these metabolites are expected to have increased toxicity and experience less predation as adults. A cuticular hydrocarbon study will be used to analyze chemical variation between genotypes and phenotypes. Additionally, to assess variation in larval sequestration ability, the expression patterns of genes related to sequestration metabolic pathways will be determined. Combining chemical ecology, genomics and behavior will facilitate deeper insights in cascading effects on larval survival, adult chemical profiles and overall levels of palatability. To broaden the impact of the work, students will be mentored in research and community outreach will be conducted.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
