Scientists Rework Darwin's Species Diversity Theory

Scientists from Louisiana State University (LSU) are reworking famous English scientist Charles Darwin's species diversity theory, changing the way we think about evolution and speciation in the animal kingdom, new research describes.

To explain speciation, the research team refers to Darwin's famous finches, a group of related birds found only on the Galápagos Islands. His theory indicates that the variation in beak size and behavior specially evolved to their habitat, an example of speciation.

It has long been thought that dramatic changes in landscape, like the formation of the Andes Mountain range or the Amazon River, were the main drivers of species diversity. But now LSU researchers suggest that time and a species' ability to move actually play a bigger role - Darwin's theory 2.0. In fact, speciation occurred much later than some of these dramatic geographical changes.

"The extraordinary diversity of birds in South America is usually attributed to big changes in the landscape over geological time, but our study suggests that prolonged periods of landscape stability are more important," lead author Robb Brumfield said in a press release.

During the study, Brumfield and his colleagues examined the genealogy of 27 species of birds in the Neotropics, the most bio-diverse region on the planet. It extends from southern Mexico through Central America to southern Brazil, and includes the species-clad Amazon rainforest.

"By using detailed sampling of many bird lineages, we were able to get a clearer and larger picture of when and how species formed within those lineages," Brumfield explained.

This genetic data provided evidence of various incidents of species divergence. For example, over time they found between nine and 29 different of such occasions across the Andes Mountains alone. This shows that the formation of this famous geological landmark played an indirect part in species diversity, but wasn't its main driver.

Furthermore, Brumfield and his team realized that history and ecology affected speciation among these 27 bird species. It turns out that the longer a species stays in one place, the more time it has and the more likely it will disperse and diverge.

This has important implications for the conservation of habitat because if humans continue to develop crucial species environments, they will kill their opportunity to evolve and continue on.

The results and the new and improved theory are further described in the journal Nature.