Species accumulating on Earth at slower rates than in the past: Study

WASHINGTON - A new study has revealed that species are still accumulating on Earth but at a slower rate than in the past.

Computational biologists at the University of Pennsylvania developed a novel computational approach to infer the dynamics of species diversification using the family trees of present-day species.

Using nine patterns of diversification as alternative models, they examined 289 phylogenies, or evolutionary trees, representing amphibians, arthropods, birds, mammals, mollusks and flowering plants.

The study demonstrated that diversity is generally not at equilibrium.

Nonetheless, speciation rates have typically decayed over time, suggesting that the diversification of species is somehow constrained, and that equilibrium may eventually be reached.

“What we see is diversification rates that are declining but not yet to zero,” said Joshua Plotkin, assistant professor in the Department of Biology in the School of Arts and Sciences at Penn.

“We are not yet in equilibrium. Either there is a limit to the total species number and we haven’t reached it yet, or there is no such limit. But the rates of diversification are typically falling; when we will hit zero is not yet obvious,” Plotkin said.

Even though the study did not deal with the current anthropogenic loss of biodiversity, researchers were surprised at how little extinction they actually saw in the evolutionary trees of species.

The study also shows how analyzing molecular phylogenies can shed light on patterns of speciation and extinction; future work may reconcile this approach with the fossil record.

The study was conducted by Hilhne Morlon and Plotkin of the Department of Biology in Penn’s School of Arts and Sciences and Matthew D. Potts of the University of California, Berkeley.

The study was published in the journal PLoS Biology. (ANI)