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Abstract Detail

The North American Coastal Plain: a Global Biodiversity Hotspot

Sorrie, Bruce [1], Weakley, Alan [2].

Fractal hotspots: another look at the biogeography of the Southeastern Coastal Plain.

In earlier (2001 and 2006) enumerations and analyses of vascular plant endemism in the Southeastern Coastal Plain, we compiled information on the native flora, determined which taxa were endemic to the region, subjectively analyzed the distributions of the endemics, and characterized 27 phytogeographic patterns that emerged from that analysis. Here we revise, update, and more quantitatively elaborate our earlier results, adding an analysis of the habitats of the endemics. Primary areas of endemism remain those centered in the Florida Panhandle, the Florida Peninsula, and the Carolinas, with additional secondary areas in the West Gulf Coastal Plain, the New Jersey Pine Barrens (and vicinity), and others. In each area, we see a fractal pattern of endemism, with one or more geographically small scale epicenters of endemism, around which are centered progressively broader endemics. As expected, narrow endemics are typically habitat specialists, but they occur in habitat types which are widely distributed across the ecoregion in recent times. This suggests that the high endemism of the Coastal Plain is not generated by strong edaphic factors and islands of habitat (such as physical islands, isolated mountain ranges, or areas of serpentine bedrock and soils) that are often cited as primary generators of endemism. In contrast, each area of endemism includes species from many and often extremely disparate habitat types (xeric longleaf pine, wet longleaf pine, seasonally-flooded depressions, coastal dunes, mesic bluffs, shrub bogs, glades, etc.) which are closely juxtaposed spatially. This biogeographic pattern of endemic hotspots with ecologically diverse endemics suggests a history of successive restriction of components of the flora to particular relictual hotspots, accompanied by isolation and speciation, and followed by re-expansion (to varying degrees) from them. This bellows or accordion generation of species has resulted in both the high number of endemics in the ecoregion as a whole, as well as exceptional richness of closely related taxa at finer spatial scales (such as 30 species of Rhynchospora in a homogeneous wet savanna in North Carolina). This pattern of combined relictual and active biodiversity generation, reflected in both coarse-scale and fine-scale richness, coupled with the prevailing effects of ecological processes such as fire that are pervasive across the Coastal Plain, may be root causes of the North American Coastal Plain biodiversity hotspot.

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1 - North Carolina Natural Heritage Program, NC, USA
2 - University of North Carolina at Chapel Hill, Biology, Cb 3280, University of North Carolina, Chapel Hill, NC, 27599-3280, USA

North American Coastal Plain

Presentation Type: Symposium or Colloquium Presentation
Session: SY08
Location: Elmwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 1:45 PM
Number: SY08002
Abstract ID:847
Candidate for Awards:None

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