RAD‐tag and mitochondrial DNA sequencing reveal the genetic structure of a widespread and regionally imperiled freshwater mussel, Obovaria olivaria (Bivalvia: Unionidae)

Abstract

Obovaria olivaria is a species of freshwater mussel native to the Mississippi River and Laurentian Great Lakes‐St. Lawrence River drainages of North America. This mussel has experienced population declines across large parts of its distribution and is imperiled in many jurisdictions. Obovaria olivaria uses the similarly imperiled Acipenser fulvescens (Lake Sturgeon) as a host for its glochidia. We employed mitochondrial DNA sequencing and restriction site‐associated DNA sequencing (RAD‐seq) to assess patterns of genetic diversity and population structure of O. olivaria from 19 collection locations including the St. Lawrence River drainage, the Great Lakes drainage, the Upper Mississippi River drainage, the Ohioan River drainage, and the Mississippi Embayment. Heterozygosity was highest in Upper Mississippi and Great Lakes populations, followed by a reduction in diversity and relative effective population size in the St. Lawrence populations. Pairwise FST ranged from 0.00 to 0.20, and analyses of genetic structure revealed two major ancestral populations, one including all St. Lawrence River/Ottawa River sites and the other including remaining sites; however, significant admixture and isolation by river distance across the range were evident. The genetic diversity and structure of O. olivaria is consistent with the existing literature on Acipenser fulvescens and suggests that, although northern and southern O. olivaria populations are genetically distinct, genetic structure in O. olivaria is largely clinal rather than discrete across its range. Conservation and restoration efforts of O. olivaria should prioritize the maintenance and restoration of locations where O. olivaria remain, especially in northern rivers, and to ensure connectivity that will facilitate dispersal of Acipenser fulvescens and movement of encysted glochidia.

Mitochondrial sequence data reveal population structure within Pustulosa pustulosa

“…This is likely due to freshwater connectivity within the Mississippi basin and, we speculate, a post-glacial radiation into the Lake Erie basin. In contrast, other studies have found more population differentiation among freshwater mussels from the Mississippi basin and the Great Lakes; namely Obovaria olivaria ( Bucholz et al, 2022 ), Elliptio dilatata and Actinonaias ligamentina ( Elderkin et al, 2008 ), Amblema plicata ( Elderkin et al, 2007 ), and Cumberlandia monodonta ( Inoue et al, 2014 ). However, some key differences in these species compared to P. pustulosa include smaller ranges or sampling sites that do not extend into Texas, and much lower haplotype diversity, which limit direct comparisons.…”

Phylogeny and biogeography of Indochinese freshwater mussels in the genus Pilsbryoconcha Simpson, 1900 (Bivalvia: Unionidae) with descriptions of four new species

“…However, this biogeographic pattern contrasts with unionid mussels in the tribes Rectidentini and Contradentini (e.g., Hyriosis 4 , 6 , Ensidens 4 , 8 , Physunio 4 , and Lens 4 ), in which the Lower Mekong lineages are relatively close to those of the Chao Phraya Basin. These contradictory biogeographic patterns may reflect the difference in historical radiation in Indochina River systems among different unionid tribes, and thus inviting further comparative biogeographic studies of multiple unionid taxa with extensive sampling throughout the distribution range and modern genomic techniques (e.g., RADseq derived SNPs 64 , 65 ) to be conducted in the future.…”

Community‐wide correlations between species richness, abundance and population genomic diversity in a freshwater biodiversity hotspot

“…To characterize genetic diversity, we performed reduced‐representation genomic sequencing (Ali et al, 2016; Andrews et al, 2016) following the Best‐RAD protocol (Ali et al, 2016; Bucholz et al, 2022). DNA was normalized to 10 ng/μL/individual.…”