In our modern world, human advance and other causes destroy the natural world and many species. Many organizations, including the American government and the World Wildlife Fund, fund continued efforts in the fight to conserve species. Publicity on the conservation of species like the Giant Panda by the World Wildlife Fund gives a sense of the enormous amounts of money being spent on these efforts. Every year the national news tells of a new species of plant or animal falling under a certain level of population and earning the label “endangered species.” The preservation of these species requires proper habitat conservation. Proper habitat conservation requires an understanding of habitat use to predict the changes in species diversity (Ogden & Thorpe 2002). Current conservation measures usually focus on a single area of consistent habitat to save. This concentration on single habitat types is based on a misunderstanding that many ecologists have, that saving a patch of habitat is sufficient for species conservation. The research done by Ogden and Thorpe indicates that saving a gradient, an area of changing habitats, would be a better approach to conservation (Tautz 2003).

In a recent article by Ogden and Thorpe (2002), the authors detail evidence supporting this theory. Ogden and Thorpe researched how speciation (the creation of species) occurs among lizards in the rainforest. They chose the lizard Anolis roquet for this study because this species is known for its quick adaptation to climate and habitat. The lizards were collected from three different transects, on the island of Martinique in the South Caribbean. Transects are lines that cut across the island chosen for their specific characteristics. In the distant past, smaller volcanic islands merged to form the present day Martinique each island had its own group of Anolis roquet, giving two distinct lineages for the lizard on Martinique. This allowed the creation of the first transect with a constant habitat, yet two different lineages. The second transect, called the ‘habitat transect’, has a constant lineage and exhibits a change, or gradient, of habitat from rainforest to woodland. The third transect was a control group with constant lineage and habitat. Once the researchers had collected the lizards, they genetically mapped five adults from each region. Each of the five adults was also examined for sixteen morphological characteristics, like leg length and color, for further grouping. This data generated some interesting discoveries about Anolis roquet along the different transects.

From the data collected, Ogden and Thorpe were able to show that this species can adapt to its habitat without a change in genetic material available. Furthermore, along the ‘habitat transect’, where the lizard changed the most, no geographical separation occurred. The lizards moved freely through the geographical area, so this was not the cause of the gene pool being limited in any meaningful way. Allopatric speciation, where the smaller gene pool required for animals to change to a significant degree occurs through lineage and geographical separation has been long held to be scientific fact. In spite of this ‘fact’, there was no evidence of genetic changes based on lineage in any of the transects. (Ogden & Thorpe 2002) In fact, in the ‘habitat transect’ the researchers observed significant phenotypical differences between the lizards in each of the habitats at different elevations. (Ogden & Thorpe 2002) Phenotypical differences are characteristics that one can easily observe based on both genetics and environment. These findings suggest the possibility of sympatric speciation, where new species are created in a single population.

These results are part of one of many preliminary studies into the area of ecological speciation. It is also important to keep in mind that this research only represents one competing theory in a field with many different models for a single biological process. With the results of the study, “Indicating that habitat ecology is more important for gene flow than historical contingencies,” (Tautz 2003) will force a rethinking of speciation. Conservationists must modify their efforts to save endangered species by finding changing areas of habitat to preserve the broadest range of a species, rather than the old misconception of saving a small isolated patch of habitat.

References

Doebeli, M. & Dieckmann, U. (2003). Speciation along environmental gradients[Electronic Version]. Nature 421, 259-264 . http://dx.doi.org/10.1038/nature01274

Ogden, R. & Thorpe, R. S. (2002). Molecular evidence for ecological speciation in tropical habitats[Electronic Version]. Proc. Natl Acad. Sci. USA 99, 13612-13615. http://dx.doi.org/ 10.1073/pnas.212248499


Tautz, D. (2003). Evolutionary biology: Splitting in space[Electronic Version]. Nature, 421, 225-226. http://dx.doi.org/10.1038/421225b