Fitness of interspecific hybrids in the genus Cyprinella: An evaluation of swimming performance in stream fishes

As the result of anthropogenic disturbance, freshwater ecosystems are rapidly being destroyed worldwide. Accordingly, such impacts are also resulting in the loss of aquatic biodiversity. Specifically, the introduction of non-native aquatic species is becoming an increasing concern. Historically, many non-native freshwater fish introductions have been the result of commercial baitfish aquaculture and private aquarium release. Cyprinella lutrensis (the red shiner) is endemic to much of the central U.S., and its natural range does not extent east of the Mississippi River. Since the 1950’s, red shiner have been cultivated and transported across the globe as both bait and aquarium fish. During the early 1990’s, invasive red shiner populations were first observed in the Coosa River Basin, located in northwest Georgia, USA. Originating from bait bucket releases, invasive red shiner have quickly established in this area, and readily compete and hybridize with at least one native species of Cyprinella (Cyprinella venusta), the blacktail shiner. Over the past thirty years, red x blacktail shiner hybrids are becoming more abundant and demonstrate an uncertain level of viability. To date, little is known about the relative fitness of red x blacktail shiner hybrids compared to parental species. If hybrids exhibit a higher level of fitness compared to parental species, then this could result in regional extinctions of native stream fishes. To better understand the relative fitness of native blacktail shiner vs. hybrid shiner, we examined swimming performance as a widely accepted proxy. Blacktail, red, and hybrid shiner were collected in Northwest Georgia during the time frame of August 2020- March 2021. Individual swimming performance trials were then conducted in a recirculating flow chamber. During these trials, a suite of physiological and morphometric measurements were recorded. Here, we present an analysis of our preliminary data, investigating differences in fitness among native and hybrid shiner

Data from: Rapid movement and instability of an invasive hybrid swarm

Unstable hybrid swarms that arise following the introduction of non-native species can overwhelm native congeners, yet the stability of invasive hybrid swarms has not been well documented over time. Here we examine genetic variation and clinal stability across a recently formed hybrid swarm involving native blacktail shiner (Cyprinella venusta) and non-native red shiner (C. lutrensis) in the Upper Coosa River basin, which is widely considered to be a global hotspot of aquatic biodiversity. Examination of phenotypic, multilocus genotypic, and mitochondrial haplotype variability between 2005 and 2011 revealed that the proportion of hybrids has increased over time, with more than a third of all sampled individuals exhibiting admixture in the final year of sampling. Comparisons of clines over time indicated that the hybrid swarm has been rapidly progressing upstream, but at a declining and slower pace than rates estimated from historical collection records. Clinal comparisons also showed that the hybrid swarm has been expanding and contracting over time. Additionally, we documented the presence of red shiner and hybrids farther downstream than prior studies have detected, which suggests that congeners in the Coosa River basin, including all remaining populations of the threatened blue shiner (Cyprinella caerulea), are at greater risk than previously thought

THE APPLICATION OF MULTILOCUS GENOTYPING TO DETECT INVASIVE HYBRIDS IN THE GENUS CYPRINELLA**

Due to anthropogenic pressures, freshwater ecosystems are being rapidly destroyed worldwide. Human impacts also have 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, or private aquarium release. The Red Shiner (Cyprinella lutrensis) is a small stream fish endemic to the central USA, with its natural range largely restricted to West 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 of Northwest Georgia, USA. Originating from bait bucket releases, it quickly established within the Upper Coosa River Basin, and now hybridizes with at least one native Cyprinella, the Blacktail Shiner (C. venusta). Prior research suggests that hybrid shiners are intermediate to parental shiners in both swimming performance and morphology. Following previous studies that use swimming as a proxy for fitness, this may mean that hybrids have competitive levels of fitness when compared to parentals. Positive identification of hybrid shiners is critical to the conservation of native species in the Coosa, and previous work has largely relied on the use of morphological traits. To confirm the reliability of morphological traits used for hybrid identification, we collected twenty morphologically intermediate specimens identified by microsatellite genotyping. Seven previously developed nuclear loci will be used to detect the presence of genetic admixture from Red and Blacktail Shiner. PCR products will be scored with genotype analysis software. Individuals were then assigned to an admixture category according to the average assignment values to the first cluster which were developed by previous studies

Cyprinella hybrid zone data 2008_2011

Phenotypic, mtDNA haplotype, and multilocus genotype data for Cyprinella collected in 2008 and 2011