Population genomics of Misgurnus spp. introduced to the United States

Aquatic invasive species pose an increasing threat to the ecosystems and economies of the United States. While invasions of lakes and large rivers have received considerable research attention, the biology of nonindigenous stream fishes remains underreported. Pond loaches (genus Misgurnus ) are native to shallow wetlands and slow-flowing waters across much of East Asia, where they are widely cultured for food and the ornamental pet trade, but have established successfully in diverse North American waterways, ranging from agricultural ditches to spring-fed streams. This genus has been introduced to 22 U.S. states and established in 12, where it has been associated with ecological impacts including competition with native fishes and habitat disturbance. We conducted a population genomic analysis to characterize the genetic diversity and structure of introduced populations. Using DArTseq-derived SNP data, we tested for genetic homogeneity among Misgurnus loaches in the U.S. and inferred patterns of relatedness among introductions. Phylogenomic analyses revealed three monophyletic clades, indicating that U.S. introductions comprise multiple distinct lineages rather than a single source. These findings contribute to a broader understanding of the population genomics of this ecologically problematic genus, supporting efforts to protect the biodiversity of freshwater ecosystems in North America.