Time for rescue: genetic conservation of imperiled fishes: Arkansas River Shiner (Notropis girardi), Peppered Chub (Macrhybopsis tetranema) and Plains Minnow (Hybognathus placitus).

Authors: Megan Osborne, Joanna Hatt, Stephen Davenport, Eliza Gilbert, Thomas Turner

Year: 2019

Abstract

The prairie rivers of the Great Plains have been altered significantly over the past century and these changes have disproportionately impacted the pelagic broadcast spawning guild of minnows. We used genetic monitoring time series data from microsatellites and mtDNA for Arkansas River Shiner, Notropis girardi, (2009-2019), Peppered Chub, Macrhybopsis tetranema, (2015-2018) and Plains Minnow, Hybognathus placitus, (2013-2015) to evaluate genetic status and trajectory of genetic change in these taxa. Genetic data was considered with reference to stream flow data and metrics of species density. Results indicate that the Canadian River harbors genetically diverse populations of these species despite losses of populations elsewhere. Metrics of genetic diversity were also stable across the time series for all taxa. Despite clear differences in contemporary abundance, all species have high values of haplotype diversity, consistently low values of nucleotide diversity and an excess of rare haplotypes. These results are indicative of populations that have experienced bottlenecks in the past but that have subsequently expanded rapidly. Despite all taxa having considerable standing stocks of genetic diversity, their persistence is not guaranteed. Populations that experience large fluctuations in abundance and have a narrow geographical distribution, face higher extinction risks than larger and more broadly distributed species. The presence of genetically diverse populations of all species in the Canadian River does however present an opportunity to establish captive populations using the Canadian River as a source. Captive populations of Peppered Chub and Arkansas River Shiner could serve as both an insurance policy for these taxa when drought conditions return to the southwest, and as a source of individuals for future reintroduction efforts.