Characterization of Novel Nematodes

Kaeli Evins ’23

Student: Kaeli Evins ’23
Research Mentor: Danielle Hamill (OWU Department of Biological Sciences)

Nematodes, or tiny roundworms, are one of the most abundant animals on Earth and have been used for understanding biological processes, human diseases, and more. This summer I am working to characterize a new species of nematode. My research involves a marked mating approach to determine if males of one species can fertilize and produce viable offspring when mated with the possible new species. The purpose of my research is to establish how our type of worm differs from its more widely studied relative, C. elegans, leading to a better understanding of these animals, how they live, and what biological processes they undergo.

Nematodes are a very diverse group of animals. Caenorhabditis elegans is the most intensely studied species of nematode. However, it is one of many nematode species, others of which may still be unidentified. Our research focuses on the characterization of a potential new species of nematodes that were found in Ohio and Florida. We expect that identifying and characterizing other species of nematodes will lead to a better understanding not only of these animals but of conserved biological processes as well.

This summer we focused on two types of worms. The first type, based on partial DNA sequences, we have identified as Oscheius myriophila. The second type, and our potential new species, was also partially sequenced and found to differ at the DNA sequence level from O. myriophila by approximately 1.6%. We believe this level of difference is significant and points to the worms being different species. However, to describe a new species, it’s important to consider other parameters as well including morphology, development, and reproductive isolation. This summer we focused primarily on the latter. Specifically we set up reciprocal crosses between O. myriophylla and the potential new species. Using a marked mating approach, we stained sperm in one type of worm and set up matings with hermaphrodites of the other type. Our results showed that the two types of worms could copulate, and the labeled sperm from the male could be observed inside of the uterus and in the spermatheca of the hermaphrodite it mated with. However, in spite of being in the right place at the right time, the heterotypic sperm appeared unable to fertilize the eggs; we did not detect out-crossed progeny. This result supports the hypothesis that our second type of worm is a new species, distinct from O. myriophila. This work is important not only for the sake of describing a new species, but also for the understanding of nematodes more generally.