Genetic structure of the Silver Chub indicates distinctiveness of Lake Erie population

Abstract

ObjectiveSilver Chub Macrhybopsis storeriana is a small riverine minnow endemic to North American fresh waters. Its range extends from the southern USA to southcentral Canada; the latter includes a rare lacustrine population in Lake Erie. Anthropogenic activities pose an immediate threat to several Silver Chub populations, currently categorized from special concern to threatened at the state level in the USA and federally and provincially not‐at‐risk to endangered in Canada. Several studies have examined the anthropogenic causes for the decline of Silver Chub populations, but conservation efforts have been hindered by the lack of knowledge of the population genetics of this species.MethodsHere, we provide an assessment of the genetic diversity of Silver Chub populations across the USA and Canada using a fast‐evolving mitochondrial gene, with particular focus on the Lake Erie population.ResultWe found the Lake Erie population to be divergent from all other populations, with nearly all the haplotypes sampled there being private.ConclusionOur study provides genetic evidence that the Silver Chub population in Lake Erie could be considered a separate conservation unit.

Why are larger fish farther upstream? Testing multiple hypotheses using Silver Chub in two Midwestern United States riverscapes

“…One possibility is that Silver Chub use Kaw Reservoir either as refuge or perhaps during early portions of their life history, but surveys of the reservoir (e.g., using trawls; Kinney 1954) are needed to test this. Analysis of spawning locations within Lake Erie suggests that spawning might take place within rivers or river mouths (McKenna et al 2023), but the population of Silver Chub in Lake Erie may be quite different from other populations (Elbassiouny et al 2023). Other fishes are known to exhibit local adaptations in their spawning modes and egg characteristics (e.g., Striped Bass Morone saxatilis; Bergey et al 2003) and the same may be true for Silver Chub.…”

Assessing potential spawning locations of Silver Chub in Lake Erie

“…The 14,000‐ to 11,000‐year separation of Silver Chub in Lake Erie from the riverine progenitor (Mandrak and Crossman 1992) has resulted in their becoming genetically distinct from populations in the Assiniboine, Mississippi, Missouri, Ohio, and Wabash rivers (Elbassiouny et al. 2023 this issue). It is possible the novel evolutionary pressures of the lake environment that resulted in genetic differentiation also drove an evolution of spawning mode.…”

“…1994; Mandrak and Crossman 1992; also see Elbassiouny et al. 2023, this special section). Silver Chub was abundant in Lake Erie from the late 1800s (McCormick 1892) through the mid‐1950s.…”

“…Although primarily riverine, a Silver Chub population persists in Lake Erie. The dispersal pathway of Silver Chub into Lake Erie has not been rigorously investigated, but one possible pathway was when the outlet of glacial Lake Maumee flowed through what is now the Wabash River to the Mississippi River following the last glacial period (Dryer 1919;Lewis et al 1994;Mandrak and Crossman 1992; also see Elbassiouny et al 2023, this special section). Silver Chub was abundant in Lake Erie from the late 1800s (McCormick 1892) through the mid-1950s.…”

Avoiding a macabre future for Macrhybopsis—A special section on improving management and conservation of chubs

“…McKenna (2023, this special section) presents a spatially explicit model for Silver Chub habitat in Lake Erie to inform management decisions, while McKenna et al (2023) define the spatial distribution of spawning habitats for Silver Chub in Lake Erie. Elbassiouny et al (2023, this special section) address the potential for cryptic species within the broadly distributed Silver Chub, suggesting that the Lake Erie population represents a unique conservation unit. Together, these papers will inform Canadian efforts related to the recovery of Silver Chub under the Species at Risk Act.…”