Maine Coyotes: How Many Wolf Genes?
By Wally Jakubas

The topic of wolf-coyote hybridization has received considerable attention the past 10 to 15 years because of its implications on wolf restoration in the Northeast; coyote size and behavior; and, the evolutionary history of canids in the Northeast and Great Lakes.

In 2004, IF&W in collaboration with Paul Wilson, Trent University, completed a coyote genetic study in which the DNA and body characteristics of over 100 Maine coyotes were analyzed to determine if coyotes had hybridized with wolves. This study determined that over 22% of Maine’s coyotes had genes that could be traced back to wolves.

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The study also raised some interesting questions regarding the genetic identification of wolves, when it was discovered that a 27-pound female coyote had one of the highest levels of wolf genes of any of the coyotes in the study. Most importantly, this research highlighted how difficult it would be for wolves to naturally recolonize Maine, without hybridizing extensively with coyotes.

This fall, Dr. Roland Kays, New York State Museum, and colleagues at the University of California, Los Angeles published a follow up genetic study in which they reanalyzed the biological samples from the same Maine coyotes used in IFW’s 2004 study. In total, they looked at the genetic make-up of over 686 coyotes and measured 196 coyote skulls from 10 states and 2 Canadian provinces. While Dr. Kays’ study did not try to duplicate the techniques used in IFW’s earlier study, the two studies share some similar findings. Their work clearly showed that Maine coyotes had hybridized with wolves in the recent past. A minimum of 1/3 of the coyotes from Maine had genes from a wolf ancestor. In addition, they found correlations between the presence of wolf-related genes in coyotes and certain skull characteristics. These particular skull characteristics were related to jaw musculature -- a feature that could improve the ability of coyotes to kill large prey.

This finding supports earlier speculation, that the introduction of wolf genes into the coyote population may have improved the ability of coyotes to prey on deer and improved their ability to survive in the northeast. Coyotes in the northeast also appear to be similar to wolves in the amount of difference between males and females in body size. This difference in body size between the sexes is not so apparent in western coyotes.

Lastly, Kays’ team speculated that the coyote population in the northeast was founded by only a few individuals crossing the St. Lawrence River. Ancestors of these founding coyotes likely crossed through Ontario and Quebec where wolves were prevalent, and where wolf / coyote hybridization occurred. This makes northeastern coyotes very different from coyotes in the Midwest or Mid-Atlantic states, who have a wide diversity of coyote ancestors and a lower proportion of wolf genes in their genetic makeup.

The results of this study illustrate one of the more uncommon ways a species can adapt to a new environment -- hybridization. In the case of the northeastern coyote, there is a certain irony in this adaptation. Wolves and their aggression towards coyotes kept coyotes out of the northeast until man extirpated the wolves; yet it is these same wolves, which hybridized with the founding coyotes, whose genes may now be helping coyotes to survive in the northeast today.

Coyotes still have not replaced all of the ecological functions of wolves in the northeast. However, hybridization with wolves may have passed on traits which make them better hunters and more capable of facing the challenges of living with humans. For wildlife professionals and the greater conservation community, this and other recent studies on wolf-coyote hybridization have brought up some challenging questions to deal with.

These include (1) should we be concerned about the genetic integrity of a population if it does not threaten the health of the ecosystem; (2) should we conserve evolutionary processes that result in hybridization or should we strive to preserve the genetic characteristics that a species had a hundred years ago; and (3) have we recovered a wolf population if their genetic make-up, today, is significantly different from when humans first caused the demise of their population?

Wally Jakubas is the Mammal Group Leader for the Maine Department of Inland Fisheries and Wildlife.

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