By Jed Kim
The Pacific Legal Foundation petitioned the U.S. Department of Fish and Wildlife on Wednesday to delist the Coastal California gnatcatcher from protections under the Endangered Species Act.
The foundation — which represents property rights groups in the matter — said that research shows the bird to be genetically identical to populations of gnatcatchers found in Mexico.
"There really is no genetic or other meaningful basis to distinguish the gnatcatchers that reside in Southern California from the gnatcatchers that are plentiful throughout most of Baja California," said Damien Schiff, a principal attorney with Pacific Legal Foundation.
The Coastal California gnatcatcher has been considered to be a subspecies of gnatcatcher, whose differences make it a distinct and rare variation of the bird.
This is the second time in five years that the Pacific Legal Foundation has petitioned to delist the California gnatcatcher. It's also the second time that the foundation has cited research by Robert Zink, a biologist at the University of Minnesota.
A 2013 study by Zink that was published in the ornithology journal the Auk showed that the California birds are genetically the same as birds in Baja at eight loci within the two populations' genetic sequences. Zink said that the similarities show that it's incorrect to classify the Coastal California gnatcatcher as its own subspecies.
“There’s no major, or any, genetic divisions from the north end of the range to the south end of the range, and because of that, the subspecies of which the current listing is based is not valid,” Zink said.
Other scientists disagreed with Zink's characterization. Some pointed out that the portions he studied only make up a small portion of the entire genetic sequences.
"That doesn't mean they are not discretely different at other genetic loci yet to be sampled, especially those associated with plumage," said James Remsen, curator of birds at the Louisiana State University Museum of Natural Science."Since we can't sample those genes, we are left with plumage itself."
The California and Baja gnatcatchers look different, with variations in coloration. Scientists said those visual differences often are caused by genetic ones. However, those differences can be missed by genetics studies.
“Genes that are commonly used in genetics studies are ones that are known to mutate at some certain slow rate," said Phillip Unitt, curator for the Department of Birds and Mammals at the San Diego Natural History Museum. "Conditions in the environment are likely to have an effect on the external appearance through evolution much more quickly than the parts that are addressed in many genetics studies."
Zink said that differences in appearance can largely be caused by environmental factors.
“If you grew up in Southern California, or we took you and we cloned you and we grew you up in a third world country, at age 20, you would look different, and you would look different, because you grew up in a very different environment,” Zink said. Petition.