30 October 2015

"Coywolf" - a new species?

As reported in The Economist:
Like some people who might rather not admit it, wolves faced with a scarcity of potential sexual partners are not beneath lowering their standards. It was desperation of this sort, biologists reckon, that led dwindling wolf populations in southern Ontario to begin, a century or two ago, breeding widely with dogs and coyotes. The clearance of forests for farming, together with the deliberate persecution which wolves often suffer at the hand of man, had made life tough for the species. That same forest clearance, though, both permitted coyotes to spread from their prairie homeland into areas hitherto exclusively lupine, and brought the dogs that accompanied the farmers into the mix.

Interbreeding between animal species usually leads to offspring less vigorous than either parent—if they survive at all. But the combination of wolf, coyote and dog DNA that resulted from this reproductive necessity generated an exception. The consequence has been booming numbers of an extraordinarily fit new animal spreading through the eastern part of North America. Some call this creature the eastern coyote. Others, though, have dubbed it the “coywolf”. Whatever name it goes by, Roland Kays of North Carolina State University, in Raleigh, reckons it now numbers in the millions...

He worked out that, though coyote DNA dominates, a tenth of the average coywolf’s genetic material is dog and a quarter is wolf... At 25kg or more, many coywolves have twice the heft of purebred coyotes. With larger jaws, more muscle and faster legs, individual coywolves can take down small deer...

The animal’s range has encompassed America’s entire north-east, urban areas included, for at least a decade, and is continuing to expand in the south-east following coywolves’ arrival there half a century ago... coywolves are now living even in large cities, like Boston, Washington and New York. According to Chris Nagy of the Gotham Coyote Project, which studies them in New York, the Big Apple already has about 20, and numbers are rising...

Some speculate that this adaptability to city life is because coywolves’ dog DNA has made them more tolerant of people and noise, perhaps counteracting the genetic material from wolves—an animal that dislikes humans. And interbreeding may have helped coywolves urbanise in another way, too, by broadening the animals’ diet.... Coywolves eat pumpkins, watermelons and other garden produce, as well as discarded food...

Whether the coywolf actually has evolved into a distinct species is debated...
More at the link, and a discussion thread at Reddit.  Quite interesting.


  1. Of course the dog and the wolf cannot form a new species since they are already considered a single species.

    The question of where a species begins and ends (such as here with the closely related canids) is really an academic game of taxonomy not really borne out in nature. Things are fuzzy and "close enough" species often have DNA represented in another species. We see this in the human genome where Neanderthal and other hominid DNA is present.

    I would wager that "coywolves" existed well before the Colombian Exchange.

    An interesting demonstration of the mostly artificial notion of "species" is the existence of ring species.

    And I just noticed that wikipedia now has an article on exactly this issue under species problem.

    1. What I've learned as a life scientist is that species are real, but what we call a species is just our best approximation of the actual thing. Just because nature doesn't fit into the perfectly square boxes doesn't mean no boxes are there at all.

    2. Interesting. I would like to better understand how you conceptualize species.

      I kind of think that the distinction we humans observe between species presently is mostly based on time and extinction. As a kind of thought experiment imagine an enormous world where there was room for all the extinct subspecies that connect cats and dogs back to a common ancestor (including the common ancestor itself) and some population of all those different animals still lived. In that world cats and dogs would be a kind of ring species. They couldn't breed with one another, but they could exchange genes with "subspecies" near them.

      It seems to me to be one continuous game played by nucleotides throughout time. When different populations separate they start to diverge. I cannot really meaningfully draw a line at any point and say "There. That is exactly the point where they cannot interbreed. Now they are different." The probability of successful interbreeding just starts to drop off in a weird non-predictable non-linear way.

      At some point the populations are different enough that the human brain's pattern matching system wants to put them into different categories and so it does. And that is right and good because there are other humans who have similarly evolved pattern matching brain circuits and they can collaborate and help organize and study the world using those circuits. I'm just not convinced that the categories exists outside the human brains.

  2. The underlaying colour of this descriptive writing, for me, is man's arrogance.
    Just because we can, we do.
    We rip out the natural habitat of every animal on the planet, destroy the environment, even go as far as to kill millions of our own.
    I rescue/steal pet rabbits that people have confined into shoebox sized cages and forgotten about, so I am not a type to rock the world with my actions, but if a modern day hero (in the real sense of the word) were to rise, politically, on a ticket of hamstringing humankind in it's compulsive need to dominate/ruin the entire world and ALL it's inhabitants, I would vote for that person.
    If they were to rise to power and be able to decimate the human population, and then decimate the remaining people, which would be for the greater good of the planet, then I would be a happy chappy.
    Where does everybody think we are heading ?
    Is everybody just focussed on the next tv, mobile phone, holiday or sexual partner ?
    Anyone have long vision ?

    1. I am deeply happy that such a mass murderer has not risen to power. And I assure you that if one did I would take up arms against him or her.

      Where do I think we are headed? Well based on evidence we are headed for stage four of the demographic transition. Have you looked at the population statistics?

      I think we have made tremendous strides in being able to pull nitrogen from the very air to fertilize fields and feed so many people. I think we have already made tremendous strides in the west in balancing our needs with those of the environment. As usual the past was awful. Rivers no longer burn and we no longer sufocate thousands in smog.

      There is much work to be done, but there is also reason for optimism. Spreading your hopelessness is counterproductive as it makes people think they might as well go distract themselves (with TV, phones, etc) instead of doing something.

    2. I would definitely not go as far as William Rocket, but there really are way too many people in the world. Where's Malthus when you need him?

  3. From what I understand, most people who work on these types of problems treat "coywolves" as simply hybrids, not hybrid species or new species. There needs to be a good amount of genetic isolation for a good amount of time (that vagueness was on purpose) from other related lineages. The hybrids I know of that are called hybrid species and widely accepted as such are parthenogenic and unable to breed with either of their parent races.
    As far as the phenotypic differences go, there's an additional factor likely at play here: where wolves aren't, coyotes are bigger and stronger. You see that in the Pleistocene where and when their ranges don't overlap. Then once wolves moved in, the coyotes get smaller, leaner, and started preying on smaller animals.


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