The Company of Wolves by Peter Steinhart

Author:Peter Steinhart [Steinhart, Peter]
Language: eng
Format: epub, mobi
ISBN: 978-0-307-79848-0
Publisher: Knopf Doubleday Publishing Group
Published: 2011-06-14T16:00:00+00:00

Things seemed to be going well. But in January 1989, at a meeting in Atlanta of the red-wolf recovery team, David Mech raised the old question of hybridization. Says Phillips, the people at the meeting were looking at the recovery plan’s goal of having 320 red wolves in captivity when Mech said he thought that number was too large and the cost too great for an animal that might not really be unique. Feeling there were still questions about its legitimacy as a species, he urged Ron Nowak and Barbara Lawrence to review the literature. If there were still disparate opinions about the identity of the red wolf, he believed the recovery team should resort to the new genetic analyses being conducted at the University of California at Los Angeles by Dr. Robert Wayne.

Wayne had collected blood and tissues from 276 gray wolves and 240 coyotes, sampling animals over the entire range of both species. He extracted from these samples bits of mitochondrial DNA. Mitochondrial DNA is a circular loop of DNA found outside the nucleus of a cell. Since it is outside the nucleus, it is inherited only along maternal lines. Unlike the DNA inside the nucleus, mitochondrial DNA is not responsible for physical characteristics like size or blood type or resistance to disease that determine a wolf’s fitness, so changes in it don’t increase or reduce an individual’s ability to reproduce. Because natural selection does not act upon them, mitochondrial DNA sequences evolve at rates five to ten times faster than the sequences in the DNA of a cell’s nucleus. So there is more variety in the mitochondrial DNA than in the nuclear DNA of any given species. That variety makes it useful for estimating how closely related individuals may be.

Wayne cut the mitochondrial DNA into small strips with restriction enzymes, which snip DNA strands between precise sequences of the four kinds of nucleotide—adenine, guanine, cytosine, and thymine—that make up DNA. He then looked at the sequence of nucleotides on the fragments. Theoretically, gray wolves would have one set of patterns and coyotes another.

The panel identified thirteen gray-wolf and twenty-four coyote genotypes, or patterns of DNA fragments. Coyotes had three times the genetic variety in their mitochondrial DNA, a finding that was consistent with the archaeological evidence that, as a species, the coyote is roughly three times as old as the wolf. But four of the wolf genotypes were found to be identical with coyote genotypes, and three other wolf genotypes were remarkably similar to coyote genotypes. Wayne concluded there had been at least six instances of hybridization, and that the genes from these matings had been widely disseminated among wolves in the Great Lakes region. He found coyote-wolf hybrids only in northern Minnesota, southern Ontario, and Quebec and on Isle Royale, but no coyote genotypes in wolves north of the present limits of coyote range. He found that coyote genotypes among wolves grew more likely as one moved east, that half the Minnesota wolves had coyote-derived genotypes, and that all the Quebec wolves sampled had them.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.