Genetic Monitoring of Wild and Captive Populations of Barrens Topminnow (Fundulus julisia)

Carla Hurt^1,*, Bernard Kuhajda², Lydia Burton^1,3, and Bennett Agee¹

¹Department of Biology, Tennessee Technological University, Cookeville TN 38505. ²Tennessee Aquarium Conservation Institute, Chattanooga, TN 37405. ³The Department of Applied Environmental Science, California State University, Monterey Bay, CA 93955. *Corresponding author.

Southeastern Naturalist, Volume 24, Special Issue 13 (2025): 1–16

First published early online: 12 June 2025

Abstract
Over the past 30 years, captive propagation and reintroduction efforts have been undertaken to mitigate the decline of the federally endangered Fundulus julisia (Barrens Topminnow [BTM]) throughout the Barrens Plateau region of Middle Tennessee. However, concerns remain about the loss of genetic diversity and adaptive potential in captivity, especially as reintroductions of captive-reared fish have had mixed success. This study analyzed genome-wide SNP genotypes in captive and wild BTM populations to assess patterns of genetic variation in captive populations relative to their wild counterparts. Estimates of heterozygosity and pairwise population distances indicated significant genetic drift and reduced genetic diversity when compared with source populations. Notably, a newly discovered natural population of BTM in the upper Collins River was found to be genetically distinct, warranting its classification as a separate evolutionarily significant unit. These findings can provide insights into the management of the BTM captive-breeding program and underscore the need for protection of the upper Collins River population.

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