[img_inline align=”right” src=”http://padnws01.mcmaster.ca/images/DEarn.jpg” caption=”David Earn”]Conservation corridors are commonly believed to help protect species which are endangered by habitat fragmentation. But this may not be true.

In a paper published in the Nov. 16 journal Science, McMaster University applied mathematics professor David Earn presents mathematical results that can help determine if conservation corridors are a benefit, or in fact a threat, to endangered species.

Conservation corridors are pathways that make it possible for individual members of a given species to move more easily between habitat patches which may have been fragmented by urban expansion, deforestation of farmland, or other developments. The theory is that if the population of a species in one habitat patch is on the brink of extinction, then a “rescue” is possible because individuals from another habitat patch can use the corridor to help to repopulate the area. Unfortunately, thecorridor can have the opposite effect, putting an entire species at risk rather than confining the problem to what would have otherwise been an isolated area.

Earn's analysis provides formulas that make it possible to predict the
success of conservation corridors and other policies that affect
movement patterns of endangered species. He says, “The mathematical
results give us a tool to estimate the effects of altering dispersal
patterns. The key point is synchrony. Corridors have the potential to
synchronize population fluctuations, and consequently to cause local
extinctions to happen at the same time everywhere. That would be great
if we were dealing with pest species, but disastrous for species we want to conserve.”

The paper published today was written in collaboration with Simon Levin of Princeton University and Pejman Rohani of Cambridge University. In general, Earn's research is concerned with the development and analysis of mathematical models of biological systems.

Since joining McMaster in October 1999, he has published two other papers in Science on patterns of epidemics. He recently received the Premier's Research Excellence Award.