As we place the finishing touches on our final report, I wanted briefly (I can never be as brief as I should) share some of our major findings and conclusions. We started this project back in October 2011 with the postdoc hire of Dr. John Robinson and over much of 2012 John synthesized genetic datasets and worked with the USFWS Regional GIS Center.
One has to remember that this was a pilot project; simply an effort to explore if there were even enough databases to produce reliable results. I have been continually amazed by the effort John has put in the project and the support provided by Jason Duke (GIS)– they can make any map look cool!
For those not aware the major goal of our study was to performed gap analysis in an effort to assess the representation of evolutionary hotspots in protected lands across the SALCC, where 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. John’s survey of the primary literature produced 16 terrestrial and 14 aquatic genetic datasets for estimation of genetic divergence and diversity (this was more than double the expected value).
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 identified numerous evolutionary hotspots for both terrestrial and aquatic taxa (see figure below for example), many of which were afforded some current protection. For instance, 14% of the cells identified as hotspots of aquatic diversity were found in currently protected areas.
Given the sparse sampling of populations in many of the datasets included in our metaanalysis (remember it was a pilot project) and the relatively low count surfaces for many of our peripherally identified hotspots, our results must be interpreted with caution as future collection efforts could lead to significant changes in the patterns documented here and subsequently the degree of protection afforded to hotspots.
Despite these caveats, there were two hotspots identified by our cross-species analysis showing low surface variance and high taxonomic representation (i.e., represented by > four species). These areas, which may be of general biological interest and warrant further study, were as follows: an area encompassing the panhandle of Florida and southern Georgia near the Apalachicola National Forest and a large portion of the coastal regions of North and South Carolina (see figure).
I will focus the remainder of my time on the large area of conservation interest we identified in southern Georgia and northern Florida. The area encompassing much of the Florida panhandle is recognized as a major suture zone (contact zone) for terrestrial and aquatic species. We expect that a geographic area such as a suture zone would display varying levels of genetic divergence (due to species specific isolating mechanisms or lack thereof) and greater than average levels of genetic diversity (due to hybridization and backcrossing) depending on the degree of isolation between species and populations and the level of secondary contact in and around a suture zone. Our terrestrial multispecies data fit this pattern, as the area included terrestrial hotspots of genetic divergence, diversity , and variance in genetic diversity. The area was also an aquatic hotspot of genetic diversity. The congruence of our observed data to that of expected is testament that the multi-species genetic landscape approach may be a valid tool for identifying general areas of high evolutionary potential for conservation design and delivery.
Overall, our results are encouraging and show the promise of genetic datasets for identifying patterns across species. We hope this work stimulates discussion and future genetic monitoring and assessment in the SALCC, with a particular focus on species that are widespread and common (see the Gambusia dataset of Hernandez-Martich and Smith or the studies of Pleurocera from Dillon and colleagues). This focus would allow for adequate population-level sampling across the large geographic area considered here.
PS please feel free to call or email with questions before or after the final report submission.