The Ecology and Evolution of Geographic Ranges

Using modern GIS methods we have creating extent of occurrence maps for each species from the literature as a basis for refinement using further field and museum locality records, population density and persistence information, along with the many probable future taxonomic species revisions. In addition to investigating various patterns and questions, dissemination of the geographic database is one of the main goals of this project. To this end, the database has been donated to the Global Mammal Assessment, and will be distributed along with the other GMA data in the near future. We also are working closely with Bat Conservation International in specifically maintaining the bat geographic range database, linking the information to regional experts through their website and encouraging gap filling by identifying key areas or species to inventory.

Biodiversity is distributed unequally across the globe, with at least 44% of vascular plants and 35% of vertebrates endemic to 25 biodiversity "hotspots". Human population size and growth are also concentrated in these areas and thus potential catastrophic events could occur if these areas are eliminated. Previosly we demonstrated that, for primates and carnivores, significantly more evolutionary history (343 million years) is endemic to the hotspots than expected under a random model of extinction (Sechrest et al. 2002). However, a comparison of an area’s fauna against a random selection of species may not be a true test of the worth of that area as a conservation tool in protecting PD. We are currently evaluating hotspots against comparable areas of the world’s surface, rather than against random species selections of the same size, as being a fairer test of their worth.

Preliminary analyses (1000 replicates) indicate that hotspot ecoregions protect more PD than similar-sized ecoregion networks in other places. This seems true for the whole phylogeny (p=0.001) and for threatened (IUCN-rated Vulnerable or above) branches only (p < 0.001). Protecting all hotspot species leaves 14.6% of the mammal tree at risk. With only 54 clades unprotected the majority of this history is terminal branches (i.e. species). This rises to 21% if only those species in parks are protected. This shortfall (300 species) can be rectified by protecting species currently without representation in a park.

Future work will assess whether hotspots are reservoirs of high speciation rates, hold significant amounts of character diversity, and indeed should be reevaluated in terms of which areas actually are biodiversity hotspots when identified from modern GIS mapping records.

Future areas of research will focus on:

• How do species differences in geographic range size relate to ecological, morphological, and life history traits? Comparative tests will also examine relationships between geographic ranges and measures of biodiversity such as species richness and rarity.
• How are contemporary geographic range sizes in mammals influenced by human disturbances, as indicated by human population and land usage?
• How are geographic areas with high mammalian diversity associated with global change predictions?

In essence, the motivation for the proposed research is the recognition that taxonomic differences in geographic ranges are key to understanding which factors influence the current health and survival of species.

Hotspots of latent extinction risk in nonmarine mammals. Hotspots are defined as the 10% of grid cells with the highest mean latent risk values.