Population genomics of the endangered freshwater mussel, Arcidens wheeleri (Unionoidea: Unionidae: Anodontini), in the Little River, Arkansas, USA.

This article focuses on the population genomics and conservation status of the federally endangered freshwater mussel Arcidens wheeleri in the Little River, Arkansas. Using genome-scale single-enzyme restriction-site-associated DNA sequencing (RADseq), the study found that A. wheeleri in the Little River constitutes a single genetic population exhibiting low observed heterozygosity, high inbreeding (FIS = 0.33), and a small effective population size (Ne ≈ 32), indicative of a recent genetic bottleneck and ongoing loss of genetic diversity. Demographic modeling supports a historical population expansion followed by a severe decline approximately 1,100 years ago, with current genetic data underscoring the species’ high risk of extirpation. The authors recommend immediate habitat protection and restoration, alongside further research on host fish identification and propagation protocols, as critical steps for the species’ recovery.