Conservation genomic assessment of two imperiled freshwater fishes, Leon Springs Pupfish (Cyprinodon Bovinus) and Pecos Gambusia (Gambusia Nobilis)

Freshwater fishes are increasingly recognized as one of the most imperiled groups of vertebrates, with a growing body of research highlighting the significant threat posed to their biodiversity by human activities. Anthropogenic actions, such as habitat modification and destruction, pollution, overexploitation, and the introduction of invasive species, have led to a decline in the number of freshwater fish species worldwide. Addressing this imminent crisis requires comprehensive conservation efforts, stricter regulatory frameworks, habitat restoration, and heightened public awareness. This project aimed to provide data important for the conservation of two imperiled desert freshwater fishes, Cyprinodon bovinus and Gambusia nobilis, both of which are federally listed as endangered and have undergone range contractions throughout the western United States due to anthropogenic activity. Using genomic techniques, I assessed patterns of genetic diversity within and between populations of both species and screened for evidence of hybridization with introduced congeners. No evidence of contemporary hybridization was found between C. bovinus and C. variegatus, but admixture was detected among G. nobilis and its respective invasive congeners (G. geiseri and G. affinis). Fine-scale population structure was evident for both species of interest and estimates of effective population sizes were low for both species. The results of the study will help update conservation management plans to help mitigate the threat of extinction for both species.