The topminnow species Fundulus notatus and F. olivaceus have broadly overlapping geographic distributions that extend throughout much of the central and southern United States. In the northern portion of their respective ranges, in Missouri, the regional distributions of the two species coincide largely with recognized ecoregions. In the unglaciated southern half of Missouri, F. olivaceus is distributed throughout Ozark upland habitats while F. notatus is abundant in marginal large river and prairie habitats along the Ozark borders. An exception to this partitioning is the historical report of abundant F. notatus in the Bourbeuse and upper Meramec River drainages within the Ozark uplands ecoregion. We conducted an extensive survey of the Bourbeuse and Dry Fork Meramec Rivers to determine topminnow species composition in these systems. Our surveys found abundant F. olivaceus populations throughout these drainages and failed to uncover any F. notatus individuals. A review of museum accessions from the 1940s and 1960s confirms the historical presence of F. notatus in these river drainages, suggesting that a significant shift in topminnow species abundance has occurred in the past half century.


Biological Sciences


Funding for this project was provided by NSF grant DEB-1556778.

Keywords and Phrases

Ecoregion; Species Abundance; Hybridization; Species Replacement

Geographic Coverage

Central Missouri

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

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Creative Commons Licensing

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Publication Date

May 2020