DARWINISTS VS EVOLUTION:

Spotted Owls Face Genetic Bottleneck (Emily Sohn, 6/25/09, Discovery News)

[T]he owl's numbers have been dropping by 3 to 4 percent each year. One reason is competition with the barred owl, whose range has been expanding. Habitat loss remains a problem, too. Funk and colleagues suspected that genetic bottlenecking might also add to the owl's woes.

For their study, the researchers scanned DNA from more than 350 northern spotted owls across the animal’s range. Then, they ran a bottleneck test, which looks for the loss of certain rare gene-forms, or alleles. When a population shrinks, chances rise that uncommon alleles will disappear.

Analyses, published in the journal Conservation Genetics, showed signs that populations of northern spotted owls had indeed shrunk, especially in the Cascade Mountains of Washington -- the same region where field studies have shown the sharpest population declines.

The loss of genetic diversity is an added blow to the loss of individual birds. Once they're gone, gene forms don't always come back.

"We knew from census data that there was a problem," Fleischer said. "We didn't know it was something that we would see in genetic variation at this stage."

One of the spotted owls greatest challenges is that since they aren't actually a species they just breed with the barred owls.

Posted by Orrin Judd at June 25, 2009 9:18 AM