How hard would it be to selectively breed a new species?

Factual Questions
21

I would say that something with the morphological differences of a bulldog, for example, if it occurred in the wild, traditionally would have routinely been classified as a different genus from wolves. After all, Cape Hunting Dogs (Lycaon) and Dholes (Cuon) are classified as different genera from wolves, even though they resemble wolves far more than a bulldog (or many other breeds) do. (However, I don’t think the difference amounts to a familial one.)

Once you start talking about genetics you are getting into different territory. Many of the genetic differences between different forms are not due to selection, but are due to accumulation of random differences over time. These differences develop over thousands to millions of years, so there is no way you could create them in a short time without genetic engineering (that is, direct tinkering with the genome).

But you are confusing morphological and genetic similarity. Big changes in morphology can result from small genetic changes, while conversely, species can be very different genetically but very similar morphologically.

Years ago taxonomists had to rely purely on morphology, since genetic data was not available. New genetic data has in many cases caused a shift in taxonomy. Many species that were formerly classified in different genera on morphological grounds have now been merged in the same genus because they are not that different genetically.

One good example of this sort of thing is humans and chimps. Although quite distinct morphologically, humans and chimps are sufficiently alike genetically that there would be grounds for including them in the same genus. A Martian taxonomist might well do so. (And this is actually what Linneaus did, calling chimps Homo troglodytes).

As Gorsnak suggests, true family-level differences involve fairly radical morphological differences, and these could probably not be selected for in a coordinated way over a short period of time. Family-level genetic differences take tens of millions of years of evolution to accumulate.

However, I would point out that humans and chimps have traditionally been classified as different families on morphological grounds, even though genetically they could be in the same genus. It might be possible to select for a small number of regulatory genes that produced similar levels of morphological divergence in other animals.

22

If we want a small dog that can survive in the wild, how about we consider some sort of terrier rather than chihuahuas? Given a thriving rodent population (something that’s not exactly hard to come by), I can easily see a feral pack of Jack Russels, say, getting by on their own. But they’re still not too likely to breed with wolves (or hunt with them as a pack, or otherwise associate with them any more than with any other animal).

Neofio, I think that dogs are the furthest we’ve ever actually gone with selectively breeding for different forms (even with good old Drosophila, I don’t think we’ve managed to vary the adult size by a factor of 50). So if you want an empirical answer to how much we can change the animals we breed, dogs are the best we can do. And remember, we’ve been breeding dogs for longer than we have any other animal. With longer timespans, it’s quite reasonable to presume we could bring about more drastic changes, but we haven’t yet had any longer timespans, so we can’t yet prove absolutely that we can do it. If you’re willing to wait millions or billions of years, then sure, we could (if we last that long) breed things into any conceivable form at all.

23

If the object is to show a creationist that a new species can arise from an existing form it would be futile. The creationist could legitimately argue that an intelligent designer is involved in the process.

24

Isn’t a mule a different species? They have a different amount of chromosomes than either of their parents, which also differ from each other. I know they can’t procreate because of their odd number of chromosomes, but we are able to selectively create them when we want.

25

A mule would be considered a hybrid, not a new species. Sterile animals don’t get to belong to a species.

26

Nor do even fertile hybrids. A mule would be classified as Equus caballus x Equus asinus. A fertile wolf-coyote hybrid would be Canis lupus x Canis latrans. (Botanists, having to deal with hybrids more often, may give a species name to hybrids, but it is preceded by an “x” and does not indicate a true species.)

It is important to realize that not all organisms can be classified as a particular species. Also, the Biological Species Concept cannot be applied in a wide range of circumstances. In some cases, other species concepts must be applied; or else, as in the case of domestic organisms, certain conventions have been established for dealing with them.

27

Somewhere along the posts here time was put forth as a factor in our equation of creating a new species. In Nature not long ago a paper on cane toads in Australia was published, noting signifficant differences in leg morphology in the cane toad
(www.nature.com/nature/journal/v439/n7078/full/439803a.html). Still not a new species, but it kind of goes to show that even in nature rapid changes within populations do occur.

Another example of “rapid” speciation would be to look to the north. Its not that long ago we just could start shaking the ice away from our porch when the last ice age ended 10 000 to 15 000 years ago. Two examples come to mind, one is reindeer, which as a species is named Rangifer tarandus, but which is also described with seven different subspecies ranging across the polar areas. Another example would be the Herring Gull (Larus argentatus) with several subspecies ranging all around the polar circle. I guess some of the reindeer subspecies might be older than the last ice age, but the subspecies found at Svalbard, Rangifer tarandus platyrhyncus, is thought to have come up there some time when it was possible to walk over there, and it has only been isolated after the ice retreated.

But, Im not coming any further than subspecies, and its a different species we’re after isnt it? So many words for nothing…

28

Aren’t all the great apes (and humans) classified in the same family, Hominidae, now?

And wasn’t the previous calissification, placing us in a different family, based on behavioral traits more than morphological traits?

29

There’s no real “official” higher level classification (or for that matter, at the species level either). But yes, a modern cladistic classification would put the Great Apes and humans in a single family, Hominidae (rather than having a separate family Pongidae for chimps, the gorilla, and the orang). However, it would be just as cladistic to have four separate families for humans, chimps, the gorilla, and the orang.

Not that I am aware. It may have been more species-chauvinism than anything else. However, humans do have distinctive morphological traits, including bipedalism, reduced dentition, and a hypertrophied brain, that could merit separation as a family under traditional, non-cladistic classificatory schemes. (By the same token, birds were distinguished from “reptiles” under earlier non-cladistic systems.)