NSF PRFB FY23: The role of hybridization on diet breadth evolution of a extreme dietary generalist

Comerford, Mattheau S, Boston MA

Investigators

Abstract

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2023, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment, and Phenotypes. The fellowship supports research and training of the fellow that will contribute to the area of Rules of Life in innovative ways. A guiding interaction known to contribute to Earth’s biodiversity is the relationship between insect herbivores and the plants they consume. The diet of an insect is limited by the interplay between their genetics, the plant’s defensive compounds, and the insect predators which hunt them. Speciation events often occur when one of these three factors changes. However, for this to happen, novel genes must arise. One source of genetic change is through hybridization (i.e., mating between closely related but genetically distinct organisms). This project assesses the influence of hybridization on insect herbivores’ diet. To do so, regions of high and low hybridization between two closely related caterpillars are evaluated. Here, lab and field experiments are conducted in collaboration with veterans from the community college system. Such collaborations provide sources of research experience not normally afforded to community college students. This effort will help to foster increased representation of veterans in STEM. This research explores an overlooked and potentially powerful window into diet-breadth evolution of insect herbivores via gene flow between organisms that are potentially undergoing contemporary speciation. The fall webworm (Hyphantria cunea) is an extreme generalist herbivore whose diet includes >600 hostplant species. The fall webworm has diverged into two genetically distinct biotypes with different diet-breadths. Despite sharing geographic overlap, the timing of their life histories has maintained reproductive isolation except for a zone of hybridization occurring along their northern range limits, where their developmental phenology is constrained by a shorter seasonal window. This project takes advantage of variation in reproductive isolation to test hybridization’s downstream influence on diet breadth by conducting 1) a survey and genome sequencing of populations in a north-south transect spanning different degrees of overlap in phenology, 2) lab-based herbivore performance assays to compare hybrid performance on the biotype’s intermediate host plants, and 3) field experiments in association with veterans to evaluate differences in predation of hybrids on alternative host-associations. By exploring the role of gene flow on diet-breadth evolution, this study will contribute to determining the maintenance of contemporary and future biodiversity. 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.