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Should We Just Call Dog Breeds a Different Species?
Jamie found an amusing bit this morning on Scientific American where the author proposes that dog breeds are different species. Now some of you might recoil when you hear this suggestion, but if you read the article to see why he makes this suggestion I suspect you'll crack a smile and appreciate the elegance of the solution.
You know what's funny? Dogs know dogs. They can be big, small, tall, round, thin, with or without tails, brown, red, white, spotted, yellow, shaggy, short haired, long legged, squat, etc, etc, etc. There is a massive amount of variation on display within the dog family.
But despite it all, dogs know dogs. Upon seeing another, they'll wag their tails or bark for a rotweiller the same as they would for a terrier. They'll all roam about in their little packs, somehow instinctively knowing they they naturally should.
And yet, if I have a man with different skin colour, or even simply different clothing, other men will consider his life worth less than even the smallest dog.
Makes you think.
May the Maths Be with you!
1) Creationists claim the science doesn't provide thorough enough proof of evolution
2) Evolutionary biologists should fudge their results to re-define something as being proof
3) ???
4) Profit
Something makes me think this scheme would just give creationists a big stick labelled "evolutionists fudge their results; it's all a load of cobblers" to beat the biologists with.
Just remember if you argue that dog breeds are different species, especially the case of the mastiff and chihuahua, or the teacup yorkie and newfoundland, these different species are verifiably the result of intelligent design. Selection was involved, but not natural selection.
Biologists already define a separate species as when two individuals cannot mate, be it due to genetics or mechanical or behavioural difficulties. The problem with dog breeds is that a Chihuahua can mate with a terrier, and a terrier can mate with a gun dog, and a gun dog can mate with the largest of dogs. Where would the author draw the line between species? There are a lot of cases like this in nature, and it is basically an arbitrary decision as to whether speciation has occurred. The whole premise of this article is essentially flawed, as it suggests that biologists have not already thought about these difficulties, when in fact this is basic pre-university biology.
I just knew this article would include some comparison of Chihuahuas to some breed of large dog (in this case, Mastiffs). So I'm going to go ahead and make a similar comparison of a 600-pound caucasian female to a 110-pound asian male. The male may have just as much trouble with the process as does the Chihuahua, but we'll still call the result be a human. Similarly, we'll call the spawn of a Chihuahua and a Mastiff a dog. Because it looks like a dog and it barks.
Whenever someone tells me they have a dog, I ask them what make it is. Try it, the reaction is brilliant.
Summation 2
It Makes sense, there just defending their spices! So Barking is just Alien language, they're communicating their plans for world Domination with each other!
The spice must flow?
Oh god, that woman is John Romero!
sounds rather spotty ...
Back in the 1800s there was this idea that all living things could be grouped into a neat, consistent classification system. As it turns out, reality isn't tidily organized like a giant clock.
Canis lupis is just a remarkably diverse species. Calling chihuahuas and wolves a different species is like calling Gary Coleman and Bao Xishun a different species. That is, completely ridiculous.
Arguing over where the line is between species is pretty dumb anyway. Nature is not divided into nice neat categories like that.
Give me Classic Slashdot or give me death!
When we observe Ring Species we are clearly catching mother nature red-handed in the act of speciation.
http://en.wikipedia.org/wiki/Ring_species
These things are freaky:
A--B--C--D--E--F--G--A
Members of a ring species can interbreed with their immediate neighbors, but not with distant neighbors halfway around the ring. (So in my diagrom, A can interbreed with B and G, but not C, D, E, or F. Sometimes the ring develops a break, and becomes a line:
A--B--C--D--E--F--G
Then to have a speciation event, all you need is another break in the line:
A--B--C
E--F--G
There are ring species comprised of small creatures who only live in a small range of elevation around the side of a mountain, so their habitat literally looks like a small ring. Two well timed avalanches could be enough.
Definite proof that cats are better than dogs.
How many cats lead blind people?
How many cats rescue injured people?
Perhaps serious scientists should stick with doing science, rather than refuting creationists and others with ideological agendas to push. Cause when you feed the trolls, the word gets around and you draw larger and larger numbers to be fed. Or in other words, one gets the impression that the refuters have an agenda of their own to push. Like the fine article, when one gets around to reading it, leaves behind.
I suppose you could build some sort of multi-feline interferometer, and interpret the varying frequency of their mewing according to their individual proximity to objects.
Assuming you're reasonably confident not to be bumping into the ceiling or falling down holes, "how many cats can lead blind people" would be 3. 2 would lead to blind spots, 4 or more would provide redundant overlap.
How much longer before a chihuahua can't breed with *any* other dog currently listed as the same species? Won't it happen eventually?
Domestic turkeys can't breed without human intervention - but they CAN breed with the help of humans, same as chihuahuas can (and have) been bred with large dogs when given a "helping hand" or "a leg up".
There's no such thing as a "pure-bred dog" - every single so-called "pure breed" is a mutt. The kennel clubs perpetuate the myth of "pure blood lines" because there's $$$ and ego in doing so. It's not like you can't get a phony "pure-bred" registration for a dog - as an experiment, people even registered CATS as "pure-bred dogs." Time magazine published an expose on this a couple of decades ago - your "breeding papers" would be better used to toilet-train the puppy than as any sort of guarantee of anything. And no, nothing has changed in the intervening years ... it's still a crock of horse manure that promotes cruelty to animals, puppy mills, reinforcement of bad genes, etc.
The point of the article is that for purely mechanical reasons big dogs can't interbreed with small dogs. From the definition of species - i.e. able to interbreed and produce fertile offspring they are a different species.
But the sperm from one could fertilize the eggs of another. The fact that the mechanics don't work out is like claiming that neutering your pet makes it a new species.
Of course this guy is just poking fun at creationists, but mislabelling dogs as species would really help. For that matter it wouldn't help if they really were separate species.
1) Dog breeds may be a recent thing but nobody say them evolve either - it happended over a time longer than a human lifetime. If you're of a mind to deny these things then "I didn't see it with my own eyes" argument applies just as well here. Maybe God created Chihuahas and Great Danes. I slighty smarter creationist might complain that the selection pressure on most breeds was artificial.
2) Much more to the point, there are genuine species all around us at every conceivable stage of speciation. Heading towards branching, during branching, immediately after branching, long after branching, etc.
The best answer to a creationist who says "if it's true, why don't we see it?" is to ask "what is it you'd expect to see that isn't in fact all around you right now?!!". Anyone expecting to see Tigers bifuracte into furbys and unicorns in their own lifetime isn't worth trying to argue with, but anyone who realizes the timescale of evolution should realize that's not the case. The length of a human lifetime is so ridiculously short compared to the evolutionary timescales that we're essentially looking at snapshot of a movie.
Think of it this way: earth is 4.5 x 10^9 years old. If you had a feature length 2 hr movie of the whole of earth's history shot at 60 frames per second, then the movie would have 432,000 frames, and each frame would still encompass over 10,000 years of history! (4.5 billion / 432,000). And yet these creationists are expecting to see a whole movie playing in their 100 year lifetime...
So, realizing that our brief lifetime has doomed us to only be observing a snapshot of anything happening on an evolutionary timescale, the real question isn't why arn't we seeing it happen (trivial answer: your lifetime is too short, but rather if this is the movie of evolution we're caught in a still frame of, then what would you expect to see in this still frame? The answer of course is that you'd expect to see species caught at every stage of branching/speciation, which is exactly what we do see.
1) Species accumulating genetic change, living in subpolulations, apparently heading for branching: too many to list, but including things like forest/plains elephants, dogs(!), humans (assuming the races don't in the future start interbreeding indiscriminately). Even things like lions/tigers can still interbreed so (whatever arbitrary labels you want to slap on them) are really pre-branch rather than post-branch, even if we understand the amount of interbreeding in the wild to be close to zero (although it does occur).
2) Species that are essentially at the point of branching right now. A classic example might be horses/donkeys, which can still kind of interbreed, but not quite (their offspring, a mule, is sterile). Given that branching is more of a process than event (it's something that happens to populations, not individuals) there are many more less spectacular examples - I'd probably include some of those (technically) pre-brancing examples in this class.
3) Species that are post-branch (can no longer interbreed, but are still genetically very close) : any species withing the same biological genus, familiy, etc. One's that branched more long ago are more genetically different corresponding to biological order, class, etc. For a specific example, how about oursellves and chimps still with 98% shared DNA and only a few million years after having branched from a common ancestor.
So the still frame we're living in sure fits the bill - we see everying around us that we'd expect to see if species are created by branching from each other. OTOH if the creationists are right, and species are created by God then the number of species that exist along every conceivable degree of genetic difference (as opposed to isolated individual creations) is rather embarassing!
Of course these discussions are endl
TFA is laughably naÃve. They should be a different species? Oh, if only species were so cut and dry. People talk about species as if we're talking about the same thing, but the `distance` between polar bears and brown bears - considered different species - isn't as great as that between Reindeer and Caribou - considered the same species.
The dirty little secret of biology - and I'm going to get kicked out of the biologist club for this - is that we've got no ****ing clue what a species is. Oh, sure, we go around naming them all the time, but we don't actually know what we're doing yet. One list counts up to 23 different way to recognize species (known as species concepts). Some of these are mutually exclusive! The author seems to like the Reproductive isolation species concept. But under that concept, the mallard on the east coast is a different species from the mallard on the west coast. But when does the mallard cease to be east and west? What about all those ducks in between? While there's no doubt that the east coast and west coast are functionally isolated, the point at which that ceases to be is very hazy.
What about montane species? I'm thinking of Dall sheep, in particular. Geneflow (interbreeding) between sheep of non-ajoining mountain ranges is incredibly low, effectively zero. But I don't know anyone who'd make the argument that they're separate species.
So then maybe the author wants to argue that they're separate morphotypes, and should be species on that account. What about isopods, where they have a greater diversity of form within species. Let's face it, every dog looks vaguely dog-ish. The same can't be said for some isopods, or species of insects!
The truth is what is, and isn't, a species is currently nebulous, fuzzy, and wishy-washy. It may be that species, as an idea, don't exist. That wouldn't surprise me.
Those are all good examples of the problems with most simple definitions of "species". It's fairly common for intro biology classes (or textbooks) to go into these problems. There are many examples of what are sometimes called a "range species", in which nearby populations can interbreed, but more widely separated populations can't. There are a lot of example along shore lines, for obvious reasons.
Dogs are often used as an example of a slightly different problem: nontransitivity of the "same species relation". Domestics dogs can interbred with both jackals and the common gray wolf and produce fertile offspring, so you might be tempted to classify them all as subspecies of a single species. But if you crossbreed jackals and wolves, the offspring are usually sterile, so they're different species.
The lion/tiger case is an interesting problem. If you google for their hybrids, you'll find that whether or not the offspring are fertile depends on the sex of the parents and the sex of the offspring. The genetics is impressively complex.
Actually, these cases are handled by biologists via a simple caveat: If two populations can be interbred, but in their natural environments they don't do so, they're considered different species. The interesting part of this to biologists is studying the mechanisms that keep the populations apart.
One well-known case is that most North American ducks can interbreed, and the offspring are generally fetrile. So they're really all one species? No, because, although most hybrids are seen in the wild, they are exceedingly rare. The main separation mechanism is female selection. The males tend to approach any female duck during the spring+summer mating season, because they can't tell the females apart much better than we can (except for a few extreme cases like wood ducks). The females reject most of them, but accept the advances of males with the right color markings. Thus, a female mallard really wants to mate with a guy with a yellow beak and green neck (and the right wing bar), and a male without those colors is just too ugly to consider.
The occasional hybrids in the wild are sorta difficult to study, though, and not much is known about how they happen. The most reasonable hypothesis ("guess") is that the female's color-specifying genes are somewhat defective, so she isn't very good at picking the right guy. But it's not easy to test such things, since you can't watch all the millions of wild ducks, and in your lab, they will mate (eventually).
One fun example of problems with overly-simple definitions of "species" was from a bio prof who wrote on the board something like "Two individuals are the same species if they can mate and produce offspring." He asked the class what was wrong with this definition. I looked around, saw a lot of puzzled faces, and when nobody spoke up, I said what I thought was the obvious answer: "By that definition, you and I are different species." He and I were both male, so of course we could mate, but we couldn't produce any offspring at all. He just grinned, and went on with the lecture about other ways the term is defined, and the problems with all the definitions. I think I got a few brownie points for being able to point out the obvious problem with a definition you see all the time.
But it's yet another example of why you have to be rather careful in how you phrase your definitions.
And another "of course" is that the creationist crowd tends to pick their own definitions of "species", using definitions whose problems support their views.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.