Hundreds of species concepts exist, and within these concepts there are great controversies. As long time readers know, I am very skeptical of the validity of the red and Eastern wolves as distinct species, and I am even more controversial in that I think that the recent genome-wide analysis on coyotes and wolves have made question whether coyotes really should be thought of as a distinct species from wolves. I certainly don’t think it is controversial that wolves and dogs are the same species, but I’ve been drawn into long, drawn-out discussions about this subject.
If we accept these genome comparison studies (one that looked at wolves and domestic dogs and one that looked at wild North American wolves and coyotes), all North American Canis species, wild and domestic, have diverged from common ancestor within the past 50,000 years. There has been significant gene flow between wolves and coyotes across North America, including Alaska and Yellowstone National Park, where the wolves are said never to breed with coyotes, and there is even more significant gene flow between wolves and domestic dogs in Eurasia.
These animals do not fit Ernst Mayr’s concept of species at all in which reproductive isolation is the most important feature. A species is a population of organisms that can reproduce and bring about fertile offspring. Wolves, dogs, and coyotes can do these things.
Mayr’s concept has been criticized quite a bit because there are things that do reproduce and produce fertile offspring, but it doesn’t happen very much. Further, these two species could have been distinct for a very long time, such as the Grevy’s and plains zebra, which split about a million years ago but still are capable of producing fertile offspring.
Further, we’ve since gone into a different way of classifying animals in which descent from common ancestry is more important than arbitrary lines based upon more subjective features. This newer way of classifying organisms is called cladistics, and it fits with a way of organizing life that is deeply appreciative of evolution.
I prefer this way, but it certainly leads to controversy. If I say that dogs are wolves, am I endorsing an entire ways of viewing them that aren’t science-based at all. The arguments for strict dominance training models are based upon poorly designed studies of wolves, and the arguments for feeding dogs raw meat and bones are also based upon an appeal to nature argument that dogs are wolves.
But I am not making those arguments at all. I am simply placing dogs within the proper clade to which they belong in the wild bush that we once called the tree of life. I think, more controversially, that coyotes should be given the same proper placement.
My arguments for this classification have to do with the fact that gene flow still exists among all three populations and their very recent common ancestry.
This classification has to be put into perspective. For example, Old World and North American red foxes split from a common ancestor some 400,000 years ago. A very good case can be made that red foxes are actually two species, just based upon that genome-wide analysis alone. There has been virtually no gene flow at all between the two red fox clades, except in Alaska, where some Old World foxes introgressed into the New World population there some 50,000 years ago.
There are also other species of large carnivora that ought to be recognized if we were paying a little more attention. The leopard of Java, commonly thought of as a insular dwarf of the common or spotted leopard, may have diverged from the rest of their species some 800,000 years ago. More recent estimates suggest that they split off about 600,000 years ago,
This leopard is not commonly thought of as a distinct species, but it is likely multitudes more distinct than wolves, coyotes, and dogs ever could be from each other. More study does need to be performed, of course, but it seems likely that the Javan leopard really is its own thing.
Perhaps the most compelling case for a hidden species in a large carnivoran that I’ve seen is the case of the Qinling panda. Currently, two subspecies of giant panda have been recognized in China. The more common type is black and white. It is the one commonly on loan to zoos in the West, and they are the pandas I saw as a boy at the Cincinnati Zoo.
But there is also a rarer form that is found only the Quinling mountains. It was always thought of as odd because it is brown and white, rather than black and white. Because it is such an isolated population it was long suggested that its brown and white coloration was the result of inbreeding, and that may still be the case.
In 2005, this brown and white panda was given its own subspecies, usually just called the Qinling panda.
Full genome comparison of both forms of panda have revealed that they are quite distinct from each other. The two forms split 300,000 years ago,
Full genome comparisons revealed that coyotes and wolves split only 50,000 years ago. The same analysis revealed a much, much deeper division in giant pandas. Genomes revealed that there is a panda that really should be its own species. Call it the Qinling panda or the brown panda.
But moving this animal to a full species would mean that we have a very endangered species. There are no more than 300 Qinling pandas in the world, and it could be quite difficult to protect them.
The coyote and red and Eastern wolf problems revealed in genome comparisons are also quite complex. The coyote is in no way endangered. It has vastly expanded its range since European settlement– pretty much all of North America but the High Arctic has coyotes now. The red and Eastern wolves have genes from now defunct wolf populations. Both of these wolves will continue to cross with coyotes, and the only way to keep them from becoming totally swamped with coyote blood is to keep coyotes out of their ranges, a nearly impossible task.
Meanwhile, Eastern coyotes with wolf ancestry are evolving larger bodies. They are refining pack-hunting behavior. They are evolving into a sort of larger, pack-hunting wolf on their own.
What this means for wolf taxonomy and wolf conservation is really a complex question, but I don’t think this question can be answered until we fully account for the problems caused by both the recent split of wolves from coyote and the continued gene flow between them.
It is a question that really cannot be answered unless we’re looking at the broader picture. They are nearly as distinct from each other as many other animals that we are conventionally classifying as a single species now.
Natural History 