Watershed Jumpers: Unraveling Complex Patterns of Fish Faunal Exchange in North Georgia

The southeastern United States is a aquatic biodiversity hotspot; however, many fishes endemic to the region are imperiled. Additionally, there is a lack of basic ecological and distributional data that can be leveraged for conservation. In extreme cases, we remain uncertain as to what drainages represent the native versus introduced ranges of fishes. Such scenarios create ambiguity surrounding which populations should be protected to conserve native biodiversity. Our study focuses on the Bandfin Shiner (Coccotis zonistius), a fish native throughout the Chattahoochee River system, but occurs in several adjacent systems where its nativity is unknown. Our objectives are 1) quantify patterns of shared ancestry with phylogenomic and population genomic analyses, and 2) estimate divergence times to understand faunal exchanges. We sampled populations within the Chattahoochee, Etowah, Coosawattee, Tallapoosa, Yellow, North Oconee, and Savannah river systems and plan to sample a reported population in the Toccoa River. After extracting DNA from tissue samples, we will perform 3RAD sequencing and the STACKS pipeline to filter SNPs for analyses. We will develop an analytical workflow in R that will characterize phylogenomic patterns of relatedness and signals of population structure. We will create demographic models that estimate divergence times, providing orders of magnitude that could range from millions of years ago to recent decades. Data from this project will provide foundational understanding of fish faunal exchanges in the region. Our results will guide the conservation of biodiversity by highlighting native fish populations while isolating potentially invasive introduced populations.