Species distribution modeling

Integrating genetic and ecological approaches in the study of mechanisms driving geographic distributions of organisms is becoming more common (e.g., Graham et al., 2004b; Hugall et al., 2002; Johnson and Cicero, 2002; Lapointe and Rissler, 2005). The use of point-locality data and climate data in environmental niche modeling (Argaez et al., 2005) is proving to be a powerful approach to understanding how abiotic factors (e.g., temperature, precipitation, and seasonality) impact the geographic limits of lineages and species (Graham et al., 2004a; Wiens and Graham, 2005a). Results from correlative ecological niche modeling have provided insight into a variety of questions relevant to conservation and evolutionary biology. One area where niche modeling has not been used extensively is phylogeography (but see Hugall et al., 2002), although there is potential for niche modeling to provide insight into the abiotic factors affecting the geographic limits of genetic lineages and to shed light on whether speciation or genetic variation is associated with divergence in the ecological niche (Graham et al., 2004a; Kidd and Ritchie, 2006). Perhaps more importantly, combining niche modeling and genetic analyses can provide some insight into the role of ecological divergence in speciation, regardless of the particular geographic mode of speciation (i.e., parapatric, sympatric, allopatric).

Additionally, an understanding of the mechanisms driving divergence could help in species delimitation. By combining information on geographic distributions, ecological niche models based on environmental data, and genetic information from multiple loci, researchers can make strong inferences when diagnosing species (Wiens and Graham, 2005b). For example, two genetically unresolved lineages, with unique ecological niches, that are geographically distributed either parapatrically or allopatrically warrant further study to determine if the intervening region at the contact zone contains suitable habitat. If there is no suitable habitat in the contact zone, then gene flow between the lineages may be impeded, and this would support the conclusion that the two lineages are distinct, even with limited genetic divergence. However, if those two lineages had similar ecological niches with no biogeographic barrier separating their distributions and high-quality habitat for one or both at the contact zone, then it is less likely that the two lineages are distinct with no gene flow. However, the extent of gene flow in such a contact zone is still dependent on the level of reproductive isolation among lineages, information that is often difficult to obtain. Therefore, an understanding of geographic distributions, environmental niche dimensions, and genetic patterns is anticipated to assist in species delimitation.


Selected References

Argaez, J.A., Christen, J.A., Nakamura, M., Soberon, J., 2005. Prediction of potential areas of species distributions based on presence-only data. Environ Ecol Stat 12, 27-44.

Graham, C.H., Ferrier, S., Huettman, F., Moritz, C., Peterson, A.T., 2004a. New developments in museum-based informatics and applications in biodiversity analysis. Trends in Ecology & Evolution 19, 497-503.

Graham, C.H., Ron, S.R., Santos, J.C., Schneider, C.J., Moritz, C., 2004b. Integrating phylogenetics and environmental niche models to explore speciation mechanisms in dendrobatid frogs. Evolution 58, 1781-1793.

Hugall, A., Moritz, C., Moussalli, A., Stanisic, J., 2002. Reconciling paleodistribution models and comparative phylogeography in the Wet Tropics rainforest land snail Gnarosophia bellendenkerensis (Brazier 1875). PNAS 99, 6112-6117.

Johnson, N.K., Cicero, C., 2002. The role of ecologic diversification in sibling speciation of Empidonax flycatchers (Tyrannidae): multigene evidence from mtDNA. Molecular Ecology 11, 2065-2081.

Kidd, D.M., Ritchie, M.G., 2006. Phylogeographic information systems: putting the geography into phylogeography. Journal of Biogeography 33, 1851-1865.

Lapointe, F.J., Rissler, L.J., 2005. Notes and comments - Congruence, consensus, and the comparative phylogeography of codistributed species in California. American Naturalist 166, 290-299.

Wiens, J.J., Graham, C.H., 2005a. Niche conservatism: Integrating evolution, ecology, and conservation biology. Annual Review of Ecology Evolution and Systematics 36, 519-539.

Wiens, J.J., Graham, C.H., 2005b. NICHE CONSERVATISM: Integrating Evolution, Ecology, and Conservation Biology. Annual Review of Ecology, Evolution, and Systematics 36, 519-539.