PS 35-166 - Conservation Genetics of the Comal Springs Dryopid Beetle (Stygoparnus comalensis)

Background/Question/Methods

The federally endangered Comal Springs Dryopid Beetle (Stygoparnus comalensis) is a subterranean obligate long-toed water beetle with an unusual life history. S. comalensis is aquatic as an adult, but larvae are terrestrial, requiring air-filled voids within the Edwards Aquifer as habitat. Existing where aquifer levels meet subterranean terrestrial voids, the degree to which aquifer levels fluctuate has the potential to both facilitate and limit dispersal of these beetles, and consequently affect the exchanging of genes between populations. The objective of this research is to use a genotyping-by-sequencing approach to characterize patterns of population structure across the only three known S. comalensis sites and to quantify admixture or gene flow between populations, as well as to inform effective conservation management strategies. I collected and extracted DNA from 89 individuals and generated genotyping-by-sequencing data to analyze population structure using hierarchal Bayesian modeling and population genetics analyses.

Results/Conclusions

Using ENTROPY, I genotyped 89 individuals at 43,587 single nucleotide polymorphism (SNP) loci. I analyzed patterns in these data by implementing a Principal Components Analysis and a hierarchal Bayesian clustering algorithm, as well as quantifying genetic distance by calculating multi-locus F_ST. Results indicate that some gene flow exists between the Sessom Springs and Fern Bank Springs populations, suggesting the possibility of subterranean connectivity. However, there is no evidence of gene flow between the Comal Springs population and the Sessom Springs or Fern Bank Springs populations. The amount of differentiation observed between the Comal Springs population and the other two populations is so great that conservation management agencies need to manage these populations as distinct units. Future work will include stable isotope analysis for 13C and 15N to see if diet and trophic ecology of S. comalensis differ between sites.