Wild Pairings: The Pitfalls and Promises of Hybridization
The many faces of mixed canids in the Northeast. (Courtesy of Maine Wolf Coalition)
This post is the third in a series on scientific and public policy issues related to carnivore protection and recovery in the Northeastern United States. Read the others here: Part One and Part Two.
Anyone who jokes that someone is a Neanderthal shouldn’t be surprised by scientific evidence that most people carry critical genetic traits from those extinct humans. Yet the debate over how to classify modern humans and Neanderthals in relation to each other rages on—just as it does for a growing number of wild animals that swap genetics through interbreeding.
For eons, the planet’s creatures (including humans) have made hard choices when conditions around them change. Many stay in the places they’ve always known and try to adapt, sometimes in remarkable ways like shifting breeding times and even body size and shape. Others are driven by wanderlust and strike out in search of new mates and territories. When that happens, previously separate populations converge, leading to new pairings and genetically mixed animals. As recently discussed in Rewilding Earth, this has occurred between wolves and coyotes throughout history and is evident today in wild canids in the Northeast.
Climate change is now a key reason why wildlife are moving far and wide and encountering each other. For example, lynx are uniquely adapted to snowy landscapes, but warming winters threaten lynx habitat, while a related feline, bobcat, has expanded its range—resulting in mixed offspring. Polar bears move, hunt, and rest on sea ice, which is declining in a warming Arctic, while some grizzly bears are moving northward—leading to reports of “pizzlies” or “grolars,” which genetic studies have shown are real but still rare.
The emergence of new creatures on the landscape is certainly fascinating, but it isn’t always something to celebrate. New pairings often reflect the will to survive in hard times, when habitats have changed and traditional mates are scarce. Some cross-species encounters can produce fertile offspring, but others cannot. Some offspring will inherit traits to thrive in new conditions, but others won’t.
Hybridization can also diminish unique genetic lineages and species. For example, “sparred owls” have emerged in the Pacific Northwest where barred owls have moved into the diminished forest habitat of the declining spotted owl. Sterilizing coyotes to prevent interbreeding has been one of the strategies used to advance the recovery of the rare, endangered red wolf.
At the same time, the forces of evolution and planetary change make hybridization inevitable—as evidenced by emerging new species from trees to fish to birds to butterflies. Given this, many scientists are calling for expanded study of the role of hybridization in perpetuating genetic material in the wild and as a conservation tool to support the survival of diverse species.
Alongside such complex scientific questions are thorny policy ones. Current laws and regulations are designed around known, distinct species. Currently, the U.S. Endangered Species Act (ESA)—the nation’s bedrock, essential, and effective tool for protecting wildlife and biodiversity—doesn’t address hybrid species closely tied to endangered and threatened ones. State hunting rules and management practices safeguard some species but promote the unfettered killing of others—even if the two groups look and behave similarly.
Going forward, federal and state species protections must be retained and strengthened, both for the sake of individual animals and wild nature as a whole. It will also be necessary to broaden conservation policy to include protections for naturally mixed species integral to ecological functions, such as predator-prey balance and controlling disease. This will require a more flexible “web of life” policy approach that reflects the transfer of genes in nature across species—complementing the traditional “tree of life” evolutionary concept that classifies “branches” of species connected through singular ancestors.
In a relatively short span of time, humans have made the planet very hot, crowded, and developed. Wild creatures able to cope with these harsh realities deserve understanding and protection—particularly because they may end up holding a key to ensuring that nature remains diverse, vibrant, and wild for eons to come.
A sketch of the web of life concept, showing gene transfer between similar species. (Courtesy of Bridgett vonHoldt)
Nadia Steinzor is an environmental consultant with 25 years of experience in policy analysis, research, writing, and communications. She has developed and managed projects to investigate the oil and gas industry’s impact on the climate and communities, secure governmental protections for air, water, land, and wildlife, and engage the public in advocacy efforts. Nadia works with the Rewilding Institute to ensure that wolves and other carnivores thrive and roam in the Northeast and beyond. Nadia holds an M.S. in environmental policy from the Bard College Center for Environmental Policy.
