Research about Alabama, Florida, Georgia, North Carolina, South Carolina, Virginia

USGS2016

Mechanisms of aquatic species invasions across the South Atlantic Landscape Conservation Cooperative region

Invasive species are a global issue, and the southeastern United States is not immune to the problems they present. Therefore, various analyses using modeling and exploratory statistics were performed on the U.S. Geological Survey Nonindigenous Aquatic Species (NAS) Database with the primary objective of determining the most appropriate use of presence-only data as related to invasive species in the South Atlantic Landscape Conservation Cooperative (SALCC) region. A hierarchical model approach showed that a relatively small amount of high-quality data from planned surveys can be used to leverage the information in presence-only observations, having a broad spatial coverage and high biases of observer detection and in site selection. Because a variety of sampling protocols can be used in planned surveys, this approach to the analysis of presence-only data is widely applicable. An important part of the management of natural landscapes is the preservation of designated protected areas. When the hydrologic connection was considered in this analysis, the number of potential invaders that could spread to each protected area within the SALCC region was greatly increased, with a mean exceeding 30 species and the maximum reaching 57 species. Nearly all protected areas are hydrologically connected to at least 20 nonindigenous aquatic species. To examine possible factors which may contribute to nonindigenous aquatic species richness in the SALCC region, a set of exploratory statistics was employed. The best statistical model that included a combination of three anthropogenic variables (densities of housing, roads, and reservoirs) and two environmental variables (elevation range and longitude) explained approximately 62 percent of the variation in introduced species richness. Highest nonindigenous aquatic species richness occurred in the more upland, mountainous regions, where elevation range favored reservoirs and attracted urban centers. Lastly, patterns seen in a diffusion model may reflect less about the diffusion process of the organism and more about the opportunistic nature of the data collection process. These results of the model are considered exploratory in nature.

Alabama, Florida, Georgia, North Carolina, South C↗

USGS2014

Identification of evolutionary hotspots based on genetic data from multiple terrestrial and aquatic taxa and gap analysis of hotspots in protected lands encompassed by the South Atlantic Landscape Conservation Cooperative.

The southeastern United States is a recognized hotspot of biodiversity for a variety of aquatic taxa, including fish, amphibians, and mollusks. Unfortunately, the great diversity of the area is accompanied by a large proportion of species at risk of extinction . Gap analysis was employed to assess the representation of evolutionary hotspots in protected lands w h ere an evolutionary hotspot was defined as an area with high evolutionary potential and measured by atypical patterns of genetic divergence, genetic diversity, and to a lesser extent genetic similarity across multiple terrestrial or aquatic taxa. A survey of the primary literature produced 16 terrestrial and 14 aquatic genetic datasets for estimation of genetic divergence and diversity. Relative genetic diversity and divergence values for each terrestrial and aquatic dataset were used for interpolation of multispecies genetic surfaces and subsequent visualization using ArcGIS. The multispecies surfaces interpolated from relative divergences and diversity data identified numerous evolutionary hotspots for both terrestrial and aquatic taxa , many of which were afforded some current protection. For instance, 14% of the cells identified as hotspots of aquatic diversity were encompassed by currently protected areas. Additionally, 25% of the highest 1% of terrestrial diversity cells were afforded some level of protection. In contrast, areas of high and low divergence among species, and areas of high variance in diversity were poorly represented in the protected lands. Of particular interest were two areas that were consistently identified by several different measures as important from a conservation perspective. These included an area encompassing the panhandle of Florida and southern Georgia near the Apalachicola National Forest (displaying varying levels of genetic divergence and greater than average levels of genetic diversity) and a large portion of the coastal regions of North and South Carolina (displaying low genetic divergence and greater than average levels of genetic diversity) . Our results show the utility o f genetic data sets for identifying cross - species patterns of genetic diversity and divergence (i.e., evolutionary hotspots) in aquatic and terrestrial environments for use in conservation design and delivery across the southeastern United States.

Alabama, Florida, Georgia, North Carolina, South C↗