Study: Starch Digestion Adaptation in Dogs

[Romy]

Originally Posted by Raegan

You can never outgrow your ancestry. Everything thing your ancestors were, you still are. So yes, you are an ape (and apes are monkeys). All squares are rectangles, but not all rectangles are squares.

Not really though, because at some point it just isn't remotely the same. For example, we human mammals aren't in any way prokaryotes.

Originally Posted by Raegan

In addition, there are multiple accounts of wolves acting like dogs, and dogs acting like wolves.

(Warning, some of those links have graphic descriptions of hunting)

Those are interesting links, though I wonder how much has to do with the two lines intermixing through the years vs. one giving rise to the other.

The gene for solid black in all wild wolves was introduced in a cross breeding between wolves and dogs that took place 12,000 - 121,000 years ago. It's a rather widespread coloration, which makes me wonder what other traits might have been introduced and potentially lay dormant until some human comes along and tests it.

ETA: To go back to the outgrowing your ancestry thing, it would be more accurate to say dogs are canids then, if humans are apes. We don't say humans are chimpanzees, because they aren't. Just the same, dogs are not wolves. They're both canids with a common ancestor.

[Raegan]

Originally Posted by Romy

Those are interesting links, though I wonder how much has to do with the two lines intermixing through the years vs. one giving rise to the other.

But that's exactly the point. Dogs and wolves interbreed freely and easily. Because they are the same species.

At best, the argument for their seperation is behavioral and cultural - it's artificial. It's because humans keep dogs in fences and kill wolves. In places where those things don't happen, dogs and wolves intermate regularly.

[Romy]

Originally Posted by Raegan

But that's exactly the point. Dogs and wolves interbreed freely and easily. Because they are the same species.

At best, the argument for their seperation is behavioral and cultural - it's artificial. It's because humans keep dogs in fences and kill wolves. In places where those things don't happen, dogs and wolves intermate regularly.

Actually, in places where those things don't happen wolves eat dogs (see Alaska). Coyotes and wolves have interbred occasionally as well, but it's not a normal occurrence despite them cohabiting the same land because coyotes are a food source for wolves.

[sillysally]

Horses, donkeys, and zebras can and do interbreed as well...

[Shai]

Originally Posted by sillysally

Horses, donkeys, and zebras can and do interbreed as well...

To be fair, however, their offspring is generally sterile.

[Romy]

Elaphe gutatta (corn snake) can hybridize with many species of king snake and produce fertile offspring. They aren't even classified in the same genus. They do not cross ever in the wild because king snakes eat other snakes. Even in captivity you have to bait and switch, with two king snakes together and then yank out the female and stick a corn snake in her place at the last second, and then you have to remove her as soon as the deed is done or the male will eat her after the fact.

Corn


California King


Here's an F2 hybrid, produced by breeding sibling F1 corn snake/california king snakes.


Servals and house cats produce fertile offspring, and I'm pretty dang sure that housecats are not servals. Both felids yes, but they're not the same species nor are house cats derived from servals.


Pretty much every species of cattle is fertile with each other. American bison, Asian yaks, European cattle, etc. all readily hybridize and produce fertile offspring.
Beefalo


Yakalo had some problems, only females were fertile.



Sulimov dogs were made from crossing golden jackals and dogs. The jackals had to be raised exclusively with dogs so that they would mate. Jackal DNA has never been found in domestic dog DNA except for possibly in Africaans and Azawakhs. I've read that it has been found in them, but haven't actually seen a published paper saying so. If anybody knows of one, I'd love to see it.

Grizzly bears and polar bears readily hybridize, in captivity and the wild. In captivity it was found that both genders of F1 hybrids were fertile with their parent species and with each other.


Servals X Caracals produce fertile hybrids.

Tigers x Lions produce ligers. I know for sure at least the females are fertile because I met a pair of Ti-ligons, which were F2 from breeding a liger to a tiger.

Bobcats and Canadian lynx freely hybridize in the wild and produce fertile offspring as well.

[sillysally]

Different species of parrots can interbreed depending on how closely relates the species are, and often produce fertile offspring. It generally doesn't happen in the wild but it's not uncommon for breeders to do it.

http://zoologica.wordpress.com/2009/...ybrid-parrots/

[sciatrix]

I'm just delurking here because evolutionary biology is my field and there are a couple of misconceptions that are bugging me a bit.

Basically, the definition of a species has to do with barriers to gene flow. Postzygotic isolation--that is, never being able to produce offspring together--is the gold standard, yeah, but there are also good biological species that can theoretically create offspring in really unusual conditions--like captivity!--but never or almost never do in the wild. Your king snake idea is an awesome example of this! No genes are being passed back and forth in the wild because king snakes generally eat corn snakes instead of mating with them, so you have reproductive isolation as a consequence of behavioral traits. So they're still good species even though you can, with careful finagling, get a fertile F1 hybrid, because in the wild they never reproduce together and gene flow between corn and king snakes is nonexistent.

Speciation is also a process, not an all/nothing boundary--there are honestly almost none of those in biology. You start with two populations of the same species, with no barriers to gene flow, and you end with two species where no genes can flow back and forth, but there are some intermediate steps along the way. Behavioral isolation like the king snake example and other forms of isolation that happen before mating can take place usually happen first, which is why we have so many examples of good species that can produce occasional hybrids under unusual conditions, like captivity.

Dogs and wolves, if allowed to live in proximity to each other, will still freely interbreed without human intervention. Therefore they are not good species. (For example, feral dogs and wolves interbreed very commonly in Italian garbage dumps, where both are known to live without much in the way of human intervention.) This is not true of, say, dogs and coyotes--yes, rare hybrids exist, but there are enough natural behavioral barriers that they stay very rare even though coyotes and dogs often do live in close proximity to each other.

With respect to animals in different genuses being able to produce offspring together, well, while species are a natural unit of biodiversity (sort of the way that days, months and years are a natural unit of time), taxonomic classifications above that like genuses, families, and orders actually aren't (sort of like weeks). We sometimes use them as a shorthand to help us conceptualize the evolutionary tree of the species we're talking about, but they're largely a holdover from an older, Linnean school of classifying life. Most biologists today think primarily in terms of species.

Does that help to clarify anything?

[Romy]

Originally Posted by sciatrix

I'm just delurking here because evolutionary biology is my field and there are a couple of misconceptions that are bugging me a bit.

Basically, the definition of a species has to do with barriers to gene flow. Postzygotic isolation--that is, never being able to produce offspring together--is the gold standard, yeah, but there are also good biological species that can theoretically create offspring in really unusual conditions--like captivity!--but never or almost never do in the wild. Your king snake idea is an awesome example of this! No genes are being passed back and forth in the wild because king snakes generally eat corn snakes instead of mating with them, so you have reproductive isolation as a consequence of behavioral traits. So they're still good species even though you can, with careful finagling, get a fertile F1 hybrid, because in the wild they never reproduce together and gene flow between corn and king snakes is nonexistent.

Speciation is also a process, not an all/nothing boundary--there are honestly almost none of those in biology. You start with two populations of the same species, with no barriers to gene flow, and you end with two species where no genes can flow back and forth, but there are some intermediate steps along the way. Behavioral isolation like the king snake example and other forms of isolation that happen before mating can take place usually happen first, which is why we have so many examples of good species that can produce occasional hybrids under unusual conditions, like captivity.

Dogs and wolves, if allowed to live in proximity to each other, will still freely interbreed without human intervention. Therefore they are not good species. (For example, feral dogs and wolves interbreed very commonly in Italian garbage dumps, where both are known to live without much in the way of human intervention.) This is not true of, say, dogs and coyotes--yes, rare hybrids exist, but there are enough natural behavioral barriers that they stay very rare even though coyotes and dogs often do live in close proximity to each other.

With respect to animals in different genuses being able to produce offspring together, well, while species are a natural unit of biodiversity (sort of the way that days, months and years are a natural unit of time), taxonomic classifications above that like genuses, families, and orders actually aren't (sort of like weeks). We sometimes use them as a shorthand to help us conceptualize the evolutionary tree of the species we're talking about, but they're largely a holdover from an older, Linnean school of classifying life. Most biologists today think primarily in terms of species.

Does that help to clarify anything?

It does, although I disagree that wolves and dogs hybridize freely in the wild when they do encounter each other without human intervention. Most wild wolves will happily eat a dog.

http://onlinelibrary.wiley.com/doi/1...425.x/abstract

Hybridization with free-ranging dogs is thought to threat the genetic integrity of wolves in Europe, although available mtDNA data evidenced only sporadic cases of crossbreeding.

http://link.springer.com/article/10....610646?LI=true

And actually coydogs aren't that uncommon. Coyotes eat dogs, but their more fluid social structure and close proximity to people allows for a lot of coyote/dog interaction. There's a coydog in the local coyote pack, a whole litter of them (feral) were collected on the Tohono o'Odham reservation and were turned into a rescue in Tucson, AZ when I was living there. There's even a member on this board who has one.

http://onlinelibrary.wiley.com/doi/1...nticated=false

The Canadian lynx X bobcat occur pretty frequently in the wild, enough that there are serious concerns about hybridization impeding the recovery of the wild lynx population.

Observation of an adult female hybrid with three kittens, as well as placental scars in the reproductive tract of a second animal, suggest that hybrids may be reproducing successfully. We recommend that careful measurement, recording and photographing of key characteristics as well as genetic analysis of suspected lynx-bobcat hybrids be priorities for natural resource agencies where hybridization between these species may occur.

http://www.nrri.umn.edu/lynx/information/hybrid.html

The spotted owl's greatest threat to recovery now is hybridization with the common barred owl. And that polar bear/grizzly hybrid I posted the picture of was of a wild animal. Several have also been shot by hunters but I don't want to post pics because they're kind of gory.

[Pops2]

Originally Posted by Red.Apricot

I don't think any of those are defects--the theory of evolution is pretty comfortably established even with the second law of thermodynamics. :]

There's a lot more to evolution than the addition or loss of a chromosome, too--that's really not even close to the most common way things change.

Do you have any links about the relatedness of dogs and coyotes? That's fascinating.

No actually the theory is not comfortably established within the second law of thermodynamics. According to the second law, a subsystem within a system can only experience negative entropy (movement from chaos to order or order to greater order) by the ENTROPY of ANOTHER SUBSYSTEM. Applied to evolution, one species (subsystem) can only evolve (negative entropy) by feeding off the devolution (entropy) of another species (subsystem). Evolution theory says that negative entropy in one subsystem causes negative entropy in another. That is absolutely contrary to the second law.
According to the theory a portion of a foundation species changes its DNA in response to external factors and becomes a new species. Medical science has shown unequivocally that adding or taking away a chromosome to/from a normal DNA sequence almost universally results in defects that are survival disadvantages.
That's something that stayed in my brain from an article about ten years ago. Current searches showed ranges from 98.8 to 99.07 %.