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Abstract: Two years ago, we began collecting wild Drosophila melanogaster from a variety of geographic locations around New Jersey and surrounding areas, with the intent to examine naturally occurring variation using both morphometric, physiological and behavioral measurements. Isofemale lines were created from these collections by using a single female fly as the progenitor of the line. In each case, three replicate populations were started using different females. The populations were then inbred using full-sib matings for at least ten generations prior to collecting phenotypic data. Currently, we have 128 individual isofemale lines derived from 50 collection sites.

During routine reproduction of the lines, pupae are counted at 10d post-mating, with the lines having 74 ± 44.7 pupae (CV=61%). Having such large differences in reproductive fitness, we assessed gamete production in both male and female gonads of mature flies. Ovariole counts ranged from 8–35 per ovary per female, while spermatid counts between low and high fitness lines was an order of magnitude. The relationship between gamete production and fitness was multidimensional and not due to any single factor — meaning the poor fitness could be due to either male or female gamete production, or gametic incompatibility. Given the nature of the lines, we were not entirely surprised to see multifaceted relationships arise.

At the Summer, 2023 GEP meetings, I had the opportunity to chat with Dr. Andy Arsham — who helped us develop a photography system to photo and measure morphometry among our lines. Preliminary data confirm our previous observations demonstrating that there was a three-fold difference in body size and that we had large differences in sexual dimorphism of size with many lines exhibiting no differences in sexual dimorphism of body size. We have also observed what appear to be differences in wing morphometry and even eye color.

A major thrust of the project is to obtain genomic data from the lines using the Oxford Nanopore technologies. Given that all our research is being executed by undergraduate students, we have had to develop biochemical and genetic workflows that can accommodate their class schedules. Focusing on a team-based approach, we now have specific workflows to extract poly-A-mRNA from gonads and gDNA from both live and frozen flies. We have been successful in sequencing both molecules using the MinION Mk1C (v.9.4.1 chemistry) and are in the process of upgrading to the new flow cells. Existing data are being analyzed in my senior-level Bioinformatics class.