A global model for the origin of species independent of geographical isolation

Jul 17, 2009

(PhysOrg.com) -- The tremendous diversity of life continues to puzzle scientists, long after the 200 years since Charles Darwin's birth. However, in recent years, consistent patterns of biodiversity have been identified over space, time organism type and geographical region.

Two views of the process of "speciation" -- the evolutionary process by which new biological arise -- dominates evolutionary theory. The first requires a physical barrier such as a glacier, mountain or body of water to separate organisms enabling groups to diverge until they become separate species. In the second, an environment favors specific characteristics within a species, which encourages divergence as members fill different roles in an ecosystem.

In a new study, "Global patterns of speciation and diversity," just published in Nature, Les Kaufman, Boston University professor of biology and associate director of the BU Marine Program along with a team of researchers from The New England Complex Systems Institute, have collaborated and found a way to settle the debate which deals with the origin of species independent of geographic isolation.

They demonstrated, using a computer model, how diverse species can arise from the arrangement of organisms across an area, without any influence from geographical barriers or even natural selection. Over generations, the genetic distance between organisms in different regions increases, the study noted. Organisms spontaneously form groups that can no longer mate resulting in a patchwork of species across the area. Thus the number of species increases rapidly until it reaches a relatively steady state.

"Our results provide additional evidence that arises without specific physical barriers," the study states.

The , the authors, note showed the distribution of species formed patterns similar to those that have occurred with real organisms all around the world.

"The model we put forward in the paper lays the groundwork for more powerful tests of the role played by natural and sexual selection, as well as habitat complexity in shaping the patterns of biological diversity that we see around us today," said Kaufman. Our insights can be applied to the immense challenge that we now face -- not only to prevent the extinction of a large chunk of life, but also to prevent ourselves from quenching the very forces that fuel the continuous creation of new life forms on earth."

This study is also the fourth in a series from The New England Complex Systems Institute on the role of complexity in species coexistence and evolutionary diversification.

"One can think about the creation of species on the genetic level in the same way we think about the appearance of many patterns, including traffic jams," said Yaneer Bar-Yam, president of The New England Institute and a senior author of the study. "While the spatial environment may vary, specific physical barriers aren't necessary. Just as traffic jams can form from the flow of traffic itself without an accident, the formation of many species can occur as generations evolve across the organisms' spatial habitat."

Source: Boston University Medical Center

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Azpod
not rated yet Jul 17, 2009
? This isn't a new theory. I heard of it in my evolutionary biology class in college back in 1995!
defunctdiety
not rated yet Jul 17, 2009
? This isn't a new theory. I heard of it in my evolutionary biology class in college back in 1995!


Yeah, it sounds suspiciously exactly like genetic drift via mutation... which I think has been around for a good 70 yrs?
PinkElephant
5 / 5 (1) Jul 17, 2009
Yeah, it sounds suspiciously exactly like genetic drift via mutation... which I think has been around for a good 70 yrs?


Not exactly. In its classical formulation, genetic drift should act on the entire population. It also has problems among populations that are too large (unless a mutation produces strong reproductive advantage, statistically it will tend to get bred out of the population simply due to chance -- unless the population is very small.)

This study postulates how genetic drift (as well as plain old natural selection) could evolve a population into sub-species, without need for any explicit physical barriers to first create small sub-populations.
defunctdiety
1 / 5 (1) Jul 17, 2009
genetic drift (as well as plain old natural selection) could evolve a population ...


The following is from the article:
"They demonstrated, using a computer model, how diverse species can arise from the arrangement of organisms across an area, WITHOUT any INFLUENCE FROM geographical barriers or even NATURAL SELECTION."

They're saying no natural selection needed.

It's the founder effect, except "between organisms in different regions", instead of absolute isolation. All they did was change "isolation" to "different regions" or "across an area"... lame. And questionable. Sounds to me like semantic horse-puckey.
PinkElephant
5 / 5 (1) Jul 17, 2009
All they did was change "isolation" to "different regions" or "across an area"... lame. And questionable.


I don't think it's lame at all. The very reason people were postulating a necessity of physical barriers and isolation, is because they didn't think such speciation would be possible otherwise. The models described here show, at least theoretically, that no such barriers or isolation would in fact be necessary (though I don't suppose it would hurt, either.)

As for whether or not it's "questionable", well then that's exactly the reason why it's not lame. Any time some conclusion is not obvious a priori, it's a worthwhile conclusion stemming from a worthwhile investigation.

If I interpret the article correctly, this team has shown that even within a population that might appear interconnected and whole, local "eddies" naturally develop much like with turbulent flows, and within these eddies localized evolution can occur without any explicit separation from the rest of the population. I found this a rather interesting dynamical revelation.
otto1923
not rated yet Jul 17, 2009
Population pressure would force individuals into new niches, say ground squirrels to climb trees in search of food, or to eat different foods and to adapt accordingly? Is that it? Fluctuating predation and climate change could add to this impetus-
nkalanaga
not rated yet Jul 17, 2009
That's exactly it. Another way it could work is if a species relies on food A, and a second species eats food B. If something happens to the second species, food B would be abundant, and the first species could start eating it. If the two foods require different behaviors, or teeth, or digestion, those who eat more of one would evolve to better eat it, and those who eat the other would evolve in another direction. Eventually, they'd be different enough that they would be unlikely to interbreed, even if they were biologically able to do so.
Velanarris
not rated yet Jul 18, 2009


I don't think it's lame at all. The very reason people were postulating a necessity of physical barriers and isolation, is because they didn't think such speciation would be possible otherwise.
Yes but nowhere are geological or environmental barriers required for speciation, and that's what the article above is trying to reinforce. This isn't new, it's been around for a long long time. This is jsut a computer model of a theory that's all but been ratified.

Even Darwin postulated on it in his discussions of the red footed booby vs the blue footed booby.

One parent species that speciated not due to seperation but due to female sexual selection.
smiffy
not rated yet Jul 18, 2009
One parent species that speciated not due to seperation but due to female sexual selection.
I don't think you should confuse sexual selection with the effect that this article is talking about. They're clearly different. For a start although sexual selection clearly drives speciation once begun, it's not at all clear that it initiates speciation. This computer model is postulating speciation without any reference to sexual selection and is therefore quite novel - it demands further scrutiny to establish or discredit the claims.
defunctdiety
not rated yet Jul 20, 2009
...this team has shown that even within a population that might appear interconnected and whole, local "eddies" naturally develop much like with turbulent flows, and within these eddies localized evolution can occur without any explicit separation from the rest of the population...


Even if it's not "explicit separation" by a physical barrier (which their language use implies is still present: spacial separation = physical barrier) there is definitely an implicit separation of some nature, whether spacial, behavioral or phenotypical etc., and the difference between the two is, as considered by the mechanisms of evolution, non-existant.

Nothing novel or new to this.

If they're claiming this speciation occurs with no separation of any nature, they better get to proving it IN NATURE.
HenisDov
not rated yet Jul 27, 2009
Spontaneous Speciation?
Again And Again: It's Culture That Drives Evolution
Not Occasional Genetic Accidents


Re "Spontaneous speciation?"
http://www.the-sc...y/55825/

Again and again:

A. Earth's primal organisms, Genes, and their take-offs, all Earth organisms, are temporary energy packages. The more of them there are the more enhanced is the biosphere, Earth's life, Earth's storage of temporarily constrained energy. This Is Nature's Drive And Purpose Of Life. This Is The Origin, The Drive, The Archetype, Of Selected Modes Of Survival.

B. From http://www.physor...378.html
I have been presenting evidence for years that adaptation, i.e. culture, is the driver of evolution of all life including human and, yes, of all other, inanimate materials, and that genetic evolution is generally biased, not random.

NO NO NO. The drive of evolution is NOT RANDOM change followed by survival selection. It is biased, as explained in my "Updated Life's Manifest" and elaborated in my posts about the nature and role of culture in evolution. In evolution of ALL materials, including life.

C. From http://www.the-sc...age#2753
"Origin Of Origins"
Earth Life is but one specimen of myriad of materials being formed and attempting to survive for temporarily constraining energy. This is the essence of the ongoing Big Bang.


Dov Henis
(Comments From The 22nd Century)
Updated Life's Manifest May 2009
http://www.physfo...ic=14988&st=480&#entry412704
http://www.the-sc...age#2321
Velanarris
not rated yet Jul 27, 2009
Henis,

Culture is itself an evolved trait due to the selection advantage gained by strength in numbers.

Culture may drive some form of speciation now, but it didn't prior to it's inception. After all, you'd have to prove that every species has had some form of culture including the early microorganisms.