Blevins, L. J. | bioRxiv Science

bioRxiv2026

A Male Expressed Copulatory Plug Increases Female Fertility in Caenorhabditis Nematodes

The genomes of self-fertilizing hermaphrodites offer a unique opportunity to probe why some genes with sex-specific functions are lost while others are maintained. In the androdiecious species, Caenorhabditis elegans, the presence of mate plugging is polymorphic across genetic backgrounds. The production of a mating plug is controlled by a single gene, plg-1, which has male-specific expression. Given that males are present less than 1% of the time, this gene is likely lost through relaxed selection or purifying selection, especially if mate plugging is maintained through intrasexual selection in males as is often hypothesized. We capitalized on a diverse panel of almost 2,000 C. elegans natural strains to show that plg-1 is maintained in at least 61% of genetic backgrounds, despite the androdiecious mating system. Genetic diversity estimates suggest that the loss of plg-1 is correlated with species globalization. We show that hermaphrodite total fecundity is not correlated with plg-1 genotype, indicating that this gene is not being maintained through linkage to a hermaphrodite beneficial gene. We then demonstrate in both C. elegans and the obligate outcrossing species, C. remanei, that the presence of a mating plug does not assure paternity by preventing subsequent males from mating. Instead, females with a mating plug have an extended peak reproductive window and higher fecundity than females without a mating plug. Together, these results indicate that mate plugging is female beneficial. We suggest that this benefit is derived from mating plugs acting as a vulval cover that can inhibit sperm loss during egg laying, thus reducing sperm limitation. Our work indicates that mate plugging may not always invoke male competition and can instead represent reproductive cooperation. More broadly, it demonstrates that male-specific gene expression does not equate to male-specific function, especially in the context of reproductive interactions.

evolutionary biology↗

bioRxiv2023

Spatial and temporal variation in abundance of introduced African fig fly (Zaprionus indianus) (Diptera: Drosophilidae) in the eastern United States

The African fig fly, Zaprionus indianus (Gupta), has spread globally from its native range in tropical Africa, becoming an invasive crop pest in select areas such as Brazil. Z. indianus was first reported in the United States in 2005 and has since been documented as far north as Canada. As a tropical species, Z. indianus is expected to have low cold tolerance, likely limiting its ability to persist at northern latitudes. In North America, the geographic regions where Z. indianus can thrive and seasonal fluctuations in its abundance are not well understood. The purpose of this study was to characterize the temporal and spatial variation in Z. indianus abundance to better understand its invasion of the eastern United States. We sampled drosophilid communities over the growing season at two orchards in Virginia from 2020-2022 and several locations along the East Coast during the fall of 2022. Virginia abundance curves showed similar seasonal dynamics across years with individuals first detected around July and becoming absent around December. Massachusetts was the northernmost population and no Z. indianus were detected in Maine. Variation in Z. indianus relative abundance was high between nearby orchards and across different fruits within orchards but was not correlated with latitude. Fitness of wild-caught females decreased later in the season and at higher latitudes. The patterns of Z. indianus abundance shown here demonstrate an apparent susceptibility to cold and highlight a need for systematic sampling to accurately characterize the range and spread of Z. indianus.

ecology↗