Baffling genetic barrier in some closely related species prevents interbreding

[shunyadragon]

Source: http://www.scientificamerican.com/article/baffling-genetic-barrier-prevents-similar-animals-from-interbreeding/?&WT.mc_id=SA_DD_20140822

. . . two species of birds — carrion crows, which predominate in western Germany, and the closely related hooded crows that prevail further to the east, in Sweden and Poland. The two groups can mate with each other, but they look very different — carrion crows are black, and hooded crows have black-and-gray bodies — and the birds strongly prefer mates of their own kind. For a long as anyone can remember, the two groups have remained distinct, save for a narrow band of habitat stretching from Denmark through eastern Germany to northern Italy where they sometimes intermingle.

The crows present a puzzling question to biologists, which gets to the heart of what it means to be a species: Given that hooded and carrion crows can mate and swap genes, how do the two groups maintain their individual identities? It’s as if you mixed red and yellow paint in a bucket but the two colors stubbornly refused to make orange.

In new research published in June in the journal Science, Wolf’s team has found that a surprisingly small chunk of DNA may hold the answer. A comparison of the carrion and hooded-crow genomes showed that the sequences are almost identical. Differences in just 82 DNA letters, out of a total of about 1.2 billion, appear to separate the two groups.

Almost all of them are clustered in a small part of one chromosome. “Maybe just a few genes make a species what they are,” said Chris Jiggins, a biologist at the University of Cambridge in England, who was not involved in the study. “Maybe the rest of genome can flow, so species are much more fluid than we imagined before.”

The findings are striking because they suggest that just a few genes can keep two populations apart. Something within that segment of DNA stops black crows from mating with gray ones and vice versa, creating a tenuous mating barrier that could represent one of the earliest steps in the formation of new species. “They look very different and prefer to mate with their own kind, and all of that must be controlled by these narrow regions,” Jiggins said.

Crows aren’t alone in their behavior. A deluge of genetic data in recent years suggests that interbreeding between species is more widespread than scientists ever imagined. “I think people will be surprised and the view of species will be challenged as more data comes along,” Jiggins said. “I think it will lead to a fundamental shift in how they view what a species is.”

© Copyright Original Source

[klaus54]

So, Jorge was right all along.

Capital "E" Evolution is pure evil metaphysics.

I shouda listened to him,

K54

[Roy]

I've heard of these before. IIRC they do interbreed, but the crossbreeds are weaker than either true breed. Thus there's selection pressure against interbreeding. What you've quoted suggests that being heterozygous for that DNA segment is bad news. Though if there's so little difference between the birds, I can't see how there can be much that would provide any breeding preference, so maybe there isn't any substantial barrier yet, it's just that the downside of doing so keeps the populations pure.

Roy

[tabibito]

The differences in colouration might play a part. Or maybe they don't like each others songs.

[phank]

One implication of this is, it could require amazingly small changes to trigger a speciation branching event. Something that causes slightly different coloration, pheromones, mating displays, etc.

[Teallaura]

Subscribing so I can reread this later. I don't get it yet.

[Darth Executor]

Source: http://www.scientificamerican.com/article/baffling-genetic-barrier-prevents-similar-animals-from-interbreeding/?&WT.mc_id=SA_DD_20140822

. . . two species of birds — carrion crows, which predominate in western Germany, and the closely related hooded crows that prevail further to the east, in Sweden and Poland. The two groups can mate with each other, but they look very different — carrion crows are black, and hooded crows have black-and-gray bodies — and the birds strongly prefer mates of their own kind. For a long as anyone can remember, the two groups have remained distinct, save for a narrow band of habitat stretching from Denmark through eastern Germany to northern Italy where they sometimes intermingle.

The crows present a puzzling question to biologists, which gets to the heart of what it means to be a species: Given that hooded and carrion crows can mate and swap genes, how do the two groups maintain their individual identities? It’s as if you mixed red and yellow paint in a bucket but the two colors stubbornly refused to make orange.

In new research published in June in the journal Science, Wolf’s team has found that a surprisingly small chunk of DNA may hold the answer. A comparison of the carrion and hooded-crow genomes showed that the sequences are almost identical. Differences in just 82 DNA letters, out of a total of about 1.2 billion, appear to separate the two groups.

Almost all of them are clustered in a small part of one chromosome. “Maybe just a few genes make a species what they are,” said Chris Jiggins, a biologist at the University of Cambridge in England, who was not involved in the study. “Maybe the rest of genome can flow, so species are much more fluid than we imagined before.”

The findings are striking because they suggest that just a few genes can keep two populations apart. Something within that segment of DNA stops black crows from mating with gray ones and vice versa, creating a tenuous mating barrier that could represent one of the earliest steps in the formation of new species. “They look very different and prefer to mate with their own kind, and all of that must be controlled by these narrow regions,” Jiggins said.

Crows aren’t alone in their behavior. A deluge of genetic data in recent years suggests that interbreeding between species is more widespread than scientists ever imagined. “I think people will be surprised and the view of species will be challenged as more data comes along,” Jiggins said. “I think it will lead to a fundamental shift in how they view what a species is.”

© Copyright Original Source

[shunyadragon]

Not totally new. I read something like this before concerning tropical birds, and the relationship between varieties, subspecies and closely related species, but was only observations in the wild and certain closely related groups did not appear to interbred.

[shunyadragon]

Found one of the references, but the text or published paper:

2012 J. Dylan Maddox, “Inbreeding avoidance, genetic neighborhoods, and gene flow in a tropical bird with limited dispersal" Florida Museum of Natural History.

Still looking . . .

[Duragizer]

So, Jorge was right all along.

Capital "E" Evolution is pure evil metaphysics.

I shouda listened to him,

K54

Why doesn't metaphysics ever come in amoral or morally ambiguous flavouring anymore?

[Jorge]

Why doesn't metaphysics ever come in amoral or morally ambiguous flavouring anymore?

"S" for "STOOPID"!!!

Yayyyyyyy !!!!!!! He's back !!!!!!!!!! Mr "S" himself !!!!!!!!! He was missed!

Jorge

[Teallaura]

Dur!

[Duragizer]

Yayyyyyyy !!!!!!! He's back !!!!!!!!!! Mr "S" himself !!!!!!!!! He was missed!

Jorge

Just remember: embracing the absurd is a means to an end, not the end itself.

[Truthseeker]

What might embracing the absurd lead to?

[jordanriver]

One implication of this is, it could require amazingly small changes to trigger a speciation branching event. Something that causes slightly different coloration, pheromones, mating displays, etc.

if that's all it takes, it seems to me rapid speciation is more common than was previously thought.