Date of Award

Fall 12-1-2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Gregory Glotzbecker

Abstract

Due to anthropogenic pressures, freshwater ecosystems are being rapidly destroyed worldwide. Accordingly, human impacts have also resulted in the loss of native aquatic biodiversity. In particular, the introduction of non-native species to aquatic habitats is of great concern. Historically, the introductions of many non-native freshwater fishes are the result of commercial baitfish aquaculture, food industries, and private aquarium release. The red shiner (Cyprinella lutrensis) is a small stream fish that is endemic to the Central U.S., and its natural range is restricted to East of the Mississippi River. Since the 1950’s, red shiner have been commercially raised and transported across the globe as fishing bait and ornamental fish. During the early 1990’s populations of invasive red shiner were first observed in the Coosa River Basin, located in Northwest Georgia, USA. Originating from bait bucket releases, the invasive red shiner quickly established within the Upper Coosa River Basin (USA) and now hybridizes with at least one native species of Cyprinella, the blacktail shiner (C. venusta). Over the past thirty years, red x blacktail shiner hybrids have become increasingly abundant and demonstrate an unknown level of hybrid viability. To date, little is known about the relative fitness of red x blacktail shiner hybrids compared to their parental species. If hybrids exhibit equal or greater fitness compared to parental species, then this could result in regional extinctions of native Cyprinella species. To assess the relative fitness of hybrid shiner, we evaluated morphology and maximum swimming velocity for red, blacktail, and hybrid shiner. Our results suggest that hybrid shiner are intermediate to parental species in both swimming performance and body morphology. In conclusion, we propose that red shiner x blacktail shiner hybrids may have a competitive level of fitness when compared to parental species, and hybrid shiner are potentially more harmful to native Cyprinella than pure red shiner.

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