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Author Topic:   Two species of crow evolving ...
RAZD
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Message 1 of 11 (850359)
04-06-2019 3:56 PM


quote:
Two Species of Crow Are Evolving Before Our Eyes in Europe
MICHELLE STARR
29 MAR 2019

Two European crows that look quite different from each other are actually diverging from a single species, right before our eyes. In Western Europe, it's the inky-black carrion crow (Corvus corone). In the east, the grey hooded crow (C. cornix).

They overlap in a very narrow zone running along the River Elbe in Germany, where they sometimes mate with each other to produce fertile hybrids - a strange result, since many species hybrids are infertile.

Now, genomic analysis has revealed that C. corone and C. cornix are actually almost indistinguishable from a genetic standpoint. The only significant genetic difference between them can be found in the gene responsible for colouration.

"Defining speciation as the buildup of reproductive isolation, carrion crows and hooded crows are in the process of speciation," said evolutionary biologist Jochen Wolf of Ludwig-Maximilians-Universität in Munich.

Exactly what was keeping the two populations apart was unclear - so Wolf and his colleagues performed genetic analyses of around 400 birds. These were selected from within the hybrid zone, as well as the zones on either side, where the species' territories don't overlap.

"Only two major effect genes which together encode the feather colour differ sharply on either side of the hybrid zone - the gray alleles are not found to the west of the zone and the black allele is absent in the eastern region," Wolf said.

"That's a very strong indication that there is rigorous selection on the basis of colour."

This suggests the crows are choosing mates based on colour. Birds of a feather literally, in this instance, flock together - carrion crows prefer black mates and hooded crows prefer grey ones.


Sexual selection.

Enjoy


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Message 2 of 11 (850361)
04-06-2019 5:43 PM


Thread Copied from Proposed New Topics Forum
Thread copied here from the Two species of crow evolving ... thread in the Proposed New Topics forum.
    
Tanypteryx
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Message 3 of 11 (850368)
04-06-2019 6:33 PM
Reply to: Message 1 by RAZD
04-06-2019 3:56 PM


An interesting article RAZD.

I didn't come to appreciate sexual selection as a mechanism of evolution separate from natural selection until I read The Evolution of Beauty: How Darwin's Forgotten Theory of Mate Choice Shapes the Animal World—And Us by Richard O. Prum.

From Goodreads:

quote:
A major reimagining of how evolutionary forces work, revealing how mating preferences--what Darwin termed "the taste for the beautiful"--create the extraordinary range of ornament in the animal world.

quote:
In the great halls of science, dogma holds that Darwin's theory of natural selection explains every branch on the tree of life: which species thrive, which wither away to extinction, and what features each evolves. But can adaptation by natural selection really account for everything we see in nature?
Yale University ornithologist Richard Prum--reviving Darwin's own views--thinks not. Deep in tropical jungles around the world are birds with a dizzying array of appearances and mating displays: Club-winged Manakins who sing with their wings, Great Argus Pheasants who dazzle prospective mates with a four-foot-wide cone of feathers covered in golden 3D spheres, Red-capped Manakins who moonwalk. In thirty years of fieldwork, Prum has seen numerous display traits that seem disconnected from, if not outright contrary to, selection for individual survival. To explain this, he dusts off Darwin's long-neglected theory of sexual selection in which the act of choosing a mate for purely aesthetic reasons--for the mere pleasure of it--is an independent engine of evolutionary change.
Mate choice can drive ornamental traits from the constraints of adaptive evolution, allowing them to grow ever more elaborate. It also sets the stakes for sexual conflict, in which the sexual autonomy of the female evolves in response to male sexual control. Most crucially, this framework provides important insights into the evolution of human sexuality, particularly the ways in which female preferences have changed male bodies, and even maleness itself, through evolutionary time.
The Evolution of Beauty presents a unique scientific vision for how nature's splendor contributes to a more complete understanding of evolution and of ourselves.

What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


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Faith
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Message 4 of 11 (850369)
04-06-2019 6:38 PM
Reply to: Message 1 by RAZD
04-06-2019 3:56 PM


The usual mountain out of a molehill or evolution out of mere variation. Yes sexual selection. Microevolution. Separate populations defined by feather color. Microevolution. To call it speciation is to indulge in the usual self deception that keeps the ToE fantasy alive.
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Percy
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Message 5 of 11 (850374)
04-06-2019 8:03 PM
Reply to: Message 3 by Tanypteryx
04-06-2019 6:33 PM


Sexual selection is completely natural, so couldn't it be just one type of natural selection? There could be natural selection by food source, by terrain, by weather variations, by sexual cues, etc.

--Percy


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Tanypteryx
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From: Oregon, USA
Joined: 08-27-2006
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Message 6 of 11 (850375)
04-06-2019 9:02 PM
Reply to: Message 5 by Percy
04-06-2019 8:03 PM


Sexual selection is completely natural, so couldn't it be just one type of natural selection?

That is what I thought also.

There could be natural selection by food source, by terrain, by weather variations, by sexual cues, etc.

Natural selection has a positive feedback loop that means increased frequency of certain alleles in a population and there may be a negative feedback loop decreases the frequency of others. We think of this as fit and less fit, when considering competition within a species or population, but it also can impact competition between species and whether one thrives and another goes extinct.

Prum lays out a really compelling argument with many, many examples where characters are selected, usually by females, that have no positive effect on fitness. These characters can be appearance, behaviors or calls and are often combinations of features.

I was quite surprised to have to revise my view on this topic.


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


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Faith
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Posts: 30962
From: Nevada, USA
Joined: 10-06-2001
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Message 7 of 11 (850377)
04-06-2019 10:55 PM
Reply to: Message 6 by Tanypteryx
04-06-2019 9:02 PM


Natural selection has a positive feedback loop that means increased frequency of certain alleles in a population and there may be a negative feedback loop decreases the frequency of others.

Of course. The black feathered population has more alleles for black feathers, and probably lots of homozygosity for black feathers at the feather loci too, while the grey population has more alleles for grey feathers and the same genetic situation. The black feathered population has correspondingly fewer alleles for grey feathers, which will eventually decrease to zero as reproductive isolation continues, and the grey population for black feathers. This ought to be elementary my dear Watson, but evo theory manages to complicate the simplest things.

And of course it makes sense to categorize sexual selection as a type of natural selection, just as I've argued that geographic isolation is a form of natural selection too, as it isolates some particular collection of alleles and breeds them together to produce a new phenotype, which is all any selective process does.

And again, all this is within microevolution, it's ridiculous to make the arbitrary fact that the two populations don't interbreed into "speciation." It's nothing but two variations that happen to separate, and may possibly have a genetic barrier to interbreeding although that is not necessary. If it does it could be because of the greater homozygosity of the characteristic feather color in each population and the more fixed loci each has the less ability to combine the two.

Edited by Faith, : No reason given.


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Tanypteryx
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Posts: 2063
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 8.6


(1)
Message 8 of 11 (850381)
04-07-2019 12:23 AM
Reply to: Message 7 by Faith
04-06-2019 10:55 PM


This ought to be elementary my dear Watson, but evo theory manages to complicate the simplest things.

Yep, facts and evidence are just so complicated.

And of course it makes sense to categorize sexual selection as a type of natural selection

And of course, you don't have a fucking clue what you are talking about.

And again, all this is within microevolution, it's ridiculous to make the arbitrary fact that the two populations don't interbreed into "speciation."

Oh ok, I'll send out an alert right away that a YEC is making up a new rule. You should expect action soon.

It's nothing but two variations that happen to separate, and may possibly have a genetic barrier to interbreeding although that is not necessary. If it does it could be because of the greater homozygosity of the characteristic feather color in each population and the more fixed loci each has the less ability to combine the two.

Right, so you're just winging it, so to speak?


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


This message is a reply to:
 Message 7 by Faith, posted 04-06-2019 10:55 PM Faith has not yet responded

    
PaulK
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Posts: 14819
Joined: 01-10-2003
Member Rating: 3.5


(1)
Message 9 of 11 (850383)
04-07-2019 1:38 AM
Reply to: Message 4 by Faith
04-06-2019 6:38 PM


quote:

The usual mountain out of a molehill or evolution out of mere variation. Yes sexual selection. Microevolution. Separate populations defined by feather color. Microevolution. To call it speciation is to indulge in the usual self deception that keeps the ToE fantasy alive.

There is a lot of arrogant bluster there but no reason why this should not be considered an example of speciation in progress.

In fact the reality of two closely related - but easily distinguished - populations occupying different geographical regions - despite the lack of geographical barriers is reason enough to suspect that something of the sort is happening. That has been known for some time (it is also true in Britain). Steve Jones discusses it in Almost Like a Whale (aka Darwin’s Ghost)

I suppose that I should add the point that these crows have been considered separate species for a long time. The only new stuff is the genetic analysis - which includes evidence of selection.

Edited by PaulK, : No reason given.


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RAZD
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From: the other end of the sidewalk
Joined: 03-14-2004
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(1)
Message 10 of 11 (850398)
04-07-2019 6:58 AM
Reply to: Message 3 by Tanypteryx
04-06-2019 6:33 PM


I didn't come to appreciate sexual selection as a mechanism of evolution separate from natural selection until I read The Evolution of Beauty: How Darwin's Forgotten Theory of Mate Choice Shapes the Animal World—And Us by Richard O. Prum.

My pet theory is that sex is what has lead to increased intelligence in humans via more and more complex mating displays/rituals/song and dance.

I also see sexual selection as a mechanism for creating stasis in a breeding population in a stable ecology.

Mate selection operates at every mating opportunity, and thus can operate at a faster rate than other forms of natural selection in causing or suppressing changes to the breeding population.

See Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution

Enjoy


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆Zen☯Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 3 by Tanypteryx, posted 04-06-2019 6:33 PM Tanypteryx has acknowledged this reply

  
Theodoric
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Posts: 6040
From: Northwest, WI, USA
Joined: 08-15-2005
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Message 11 of 11 (850465)
04-08-2019 4:21 PM
Reply to: Message 7 by Faith
04-06-2019 10:55 PM


I thought you ran away.

Facts don't lie or have an agenda. Facts are just facts

"God did it" is not an argument. It is an excuse for intellectual laziness.

If your viewpoint has merits and facts to back it up why would you have to lie?


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