June 3, 2009

Consequences of coextinctions are studied

U.S. scientists are warning of the possible consequences of coextinctions -- the loss of a species as well as the parasites or mutualists that depend on it.

North Carolina State University biologist Rob Dunn and colleagues said mathematical models suggest coextinctions are very common, yet there have been few reported cases of coextinction in scientific literature.

Since the diversity of parasitic or affiliated species -- which may include viruses, ticks, lice and bacteria "¦ but also so-called mutualists such as the crops pollinated by honey bees or the bees themselves -- is several orders of magnitude greater than that of their hosts, the numbers of coextinctions are also expected to be far greater than the number of extinctions of host species, he said.

We have long talked about the negative consequences of the endangerment of the species we love, he said, but getting left with their parasites is a consequence no one bargained for.

Additionally, Dunn said there is a potentially very dangerous consequence of coextinction.

There is a distinct possibility that declines in host species could drive parasite species to switch onto alternative hosts, which in turn could escalate the rate of emerging pathogens and parasites both for humans and our domesticated animals and plants.

The study appears in the Proceedings of the Royal Society B.