In a way, you can see this happening with humans. Before anyone jumps on my comment, I am not about to say that people of different races are different species. Anyways, in cities with many races, you will see that the majority of people will date within their own race despite having no geographic or genetic boundary keeping them from dating another race. Instead, it is a matter of sexual selection because they choose to be with their own race rather than another race. Theoretically, if this preference to date within one's own race continues, different species where people are not capable of producing offspring or can only create sterile offspring could happen.
It is possible that other animals have a similar thing happen. Perhaps some animals are attracted to different traits despite being of the same species. As an example, perhaps with the bird of paradise, some females focus more on the dance while others focus more on the color of the male. This preference to focus on the dance or the color could be a matter of nurture, not nature. Therefore, the focus on either the dance or the color becomes passed down and speciation can occur between the good dancers and the birds with good colors.
Actually, there are two effects in play in cases of geographic isolation.
The first is, as you mentioned, the new hardships or abundances. But the second is the lack of gene flow between the two groups. Sufficient genetic exchange between two groups prevents speciation, even in wildly different environments. Insufficient genetic exchange between neighboring groups causes speciation even without differing hardships and abundances (as founder's effect becomes amplified over time).
I think one of the points is you don't need geographical separation to create new species, not to have beneficial mutations. Standard models of evolution (or simplified) would state that a positive mutation would spread through a homogeneous population without barriers and eventually all of the population would posses it. Either because it was passed down through generations, or because the ones WITH the mutation outbread the ones without, so in a few generations the new special reds would have supplanted the blues.
This study is staying that in thousands of generations, you have blues and reds and they cant breed with each other and produce offspring (or maybe the offspring is sterile).
Geographic isolation is not the definition of natural selection. Natural selection is when that little mutation that turns you from red to green also means you lay slightly more eggs than the reds, or have a slightly longer tongue for catching ants, or you're slightly harder for bats to detect, or whatever.
Geographic isolation just gives a population the opportunity to experience hardships or abundance distinct from their brothers and sisters.
@rek: I think what this articles is basically saying though is that if you took 2 groups of 10 people of similar descent and appearance and kept them in similar places but seperate, in 2000 generations neither group will look like the other.
This difference is partially due to the fact that over 2000 generations both groups are very unlikely to make the same choices when it comes to mating.
@KryptonZero: I know what they're saying (geographic isolation isn't necessary for speciation) — that's been known for years, but it's presented here as if geographic isolation was the only known cause of speciation, or a huge part of it. It's not. I don't think it ever was thought to be. Mutation is the foothold natural selection uses to churn out new species.
I can see how a mutation that neither helps nor hinders an organism would get passed along. But if it becomes a dominant trait and that population becomes different enough that it can no longer breed with the original stock isn't that sexual selection coming into play?
I mean the new population must have had something going on where the new trait spread enough to become another species.
What am I not getting here?
@Evil Tortie's Mom: R.O.A.C.H.: I don't know about their models, but I'm pretty sure that all the models I've seen are an example of natural and sexual selection to the point of being a different species.
@Grey_Area: You're getting it. The headline is misleading in so far as it...is inflammatory reporting of one study. What is this, the New York Post? Daily News? Bugle?
@Grey_Area: So, I can't read the actual article because . . . well . . because I don’t feel like logging on to my university account to access Nature for free.
But from the abstract it looks like they didn’t include environmental selection in the model.
I think where they’re going with this is that environmental/geographical selection might not be necessary for evolution, but that doesn’t mean it doesn’t play a role. The evolution of most new species probably occurs due to environmental/geographical selection (as well as other factors ie. genetic drift, bottle necking etc) but there are exceptions to the rule (such as the species mentioned at the end of the abstract) which could have evolved by the process demonstrated in the model.
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Edited by RandomFrequentFlierDent at 07/17/09 4:00 PM
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@Grey_Area: A question mark at the end of this headline would help. People would still click for page views, but it would be more accurate and less... what's the word... Murdoch-ian.
@mordicai: Really sorry about that. My bad. I have rewritten the headline and a few sentences to make it much more clear what they actually discovered.
@Annalee Newitz: Looking back over the comments, the level of freak out is kind of hilarious (not that I can say much about it, having experience it myself)
I guess it's important to watch what you say about evolution around science-y people.
@Annalee Newitz: I think I basically used "natural selection" to mean environment, which you guys are right isn't correct. So I've said now that what the researchers are emphasizing is that a particular kind of environment isn't required for natural selection to take place. Sexual selection alone can drive evolution.
While this is certainly interesting, I'm surprised with the claims made here. This isn't exactly completely new knowledge, IIRC: I remember hearing/reading several years ago that if you study the DNA of Chimpanzees and compare it to that of Humans, you find that two random chimps are less closely related than two random humans, which makes sense since chimpanzees are older than humans, as a species. Even without any type of selection, natural, artificial, sexual, etc., genetic drift would happen, but the rate at which new species would arise would drastically drop, methinks. The random process of mutation coupled with the non-random process of selection is what makes evolution work so quickly and so effectively.
@The_Sporean_Bob: You can’t really say that the chimpanzee species' are older then the human species' since technically we split from a common ancestor 6 million years ago.
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Edited by RandomFrequentFlierDent at 07/17/09 3:20 PM
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@RandomFrequentFlierDent: But there are a hell of a lot more of us, so you'd think humans would have greater genetic drift. Or am I getting all these terms mixed up?
Damn you Annalee, making me think and stuff!
@Grey_Area: Well, genetic drift usually has more of an effect on smaller populations, so I think Bubbles and his crew would suffer from it more.
I haven't read the actual article yet (I'm going to go do that now) but from what I can tell the results are all based on mathematical modelling which isn’t always entirely translatable to the real world.
if you split up NATURAL selection and SEXUAL selection in terms of evolution, then i guess natural selection would be of no importance at all. the only thing that matters is who reproduces ... i guess "being dead" factors large in whether or not you can attract a mate.
@grime: well if you are that race in Voyager, you bread solely by the acquisition of dead bodies... and then you date Harry Kim. i'd love to see the Christian Sciences explain Harry Kim.
I mean, there is literally no reason for the peacock outside of sexual selection. You can't tell me that tail was actually good for anything but impressing the ladies.
@Belabras: I've recall reading that Darwin once wrote in a letter "the mere sight of a peacock makes me sick".
I do believe that being able to carry such a tail (and be alive while doing it) it's a living proof of the male's speed, strength or wits; thus, females find him attractive.
@ManchuCandidate: Is this really like entropy? A homogenous group splitting or self-organizing into different specialized subsets. Would you explain your reasoning, please?
@Grey_Area:
Only in reference to "disorder" in genetics and not energy. As creatures reproduce, we get variants due to the inherent messiness of DNA combining from the egg and sperm. These variants start off small but over time they increase due to breeding patterns till eventually it becomes a new species.
07/19/09
It is possible that other animals have a similar thing happen. Perhaps some animals are attracted to different traits despite being of the same species. As an example, perhaps with the bird of paradise, some females focus more on the dance while others focus more on the color of the male. This preference to focus on the dance or the color could be a matter of nurture, not nature. Therefore, the focus on either the dance or the color becomes passed down and speciation can occur between the good dancers and the birds with good colors.
07/17/09
The first is, as you mentioned, the new hardships or abundances. But the second is the lack of gene flow between the two groups. Sufficient genetic exchange between two groups prevents speciation, even in wildly different environments. Insufficient genetic exchange between neighboring groups causes speciation even without differing hardships and abundances (as founder's effect becomes amplified over time).
07/17/09
This study is staying that in thousands of generations, you have blues and reds and they cant breed with each other and produce offspring (or maybe the offspring is sterile).
07/17/09
07/18/09
Whaaaaaaat? Did you read the post or are you just having trouble understanding it?
This is not about disproving evolution
07/17/09
Geographic isolation just gives a population the opportunity to experience hardships or abundance distinct from their brothers and sisters.
07/18/09
This difference is partially due to the fact that over 2000 generations both groups are very unlikely to make the same choices when it comes to mating.
07/18/09
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07/17/09
god bless Atwood.
07/17/09
I mean the new population must have had something going on where the new trait spread enough to become another species.
What am I not getting here?
07/17/09
And how sure are we of their models?
07/17/09
07/17/09
SPIDER-MAN = Menace or Pest?
07/17/09
07/17/09
But from the abstract it looks like they didn’t include environmental selection in the model.
I think where they’re going with this is that environmental/geographical selection might not be necessary for evolution, but that doesn’t mean it doesn’t play a role. The evolution of most new species probably occurs due to environmental/geographical selection (as well as other factors ie. genetic drift, bottle necking etc) but there are exceptions to the rule (such as the species mentioned at the end of the abstract) which could have evolved by the process demonstrated in the model.
07/17/09
07/17/09
I'm not sure there's anything "natural" about models, though I'm down with them being a different species.
07/17/09
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07/17/09
I guess it's important to watch what you say about evolution around science-y people.
07/17/09
07/17/09
07/17/09
07/17/09
07/17/09
Damn you Annalee, making me think and stuff!
07/17/09
I haven't read the actual article yet (I'm going to go do that now) but from what I can tell the results are all based on mathematical modelling which isn’t always entirely translatable to the real world.
07/17/09
07/17/09
07/17/09
07/17/09
Here here.
I mean, there is literally no reason for the peacock outside of sexual selection. You can't tell me that tail was actually good for anything but impressing the ladies.
07/17/09
It's this.... http://www.theonion.com/content/news/7_million_people_direct?utm_source=a-section
07/17/09
I think these guys have stumbled on a matter of phraseology, not anything particularly different.
07/17/09
07/17/09
I do believe that being able to carry such a tail (and be alive while doing it) it's a living proof of the male's speed, strength or wits; thus, females find him attractive.
07/17/09
It's all due to the intelligent designer!! IT'S THE INTELLIGENT DEEEEEEEESSSSSSIGNNNNNNNNNNNER!!!!!!!!!!
But seriously, who knew that entropy applies to biology?
07/17/09
07/17/09
Only in reference to "disorder" in genetics and not energy. As creatures reproduce, we get variants due to the inherent messiness of DNA combining from the egg and sperm. These variants start off small but over time they increase due to breeding patterns till eventually it becomes a new species.
07/17/09