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Evolution Of New Species Slows Down As Number Of Competitors Increases
by Science Daily
Thanks to SPS for the link.
http://www.sciencedaily.com/releases/2008/03/080325083359.htm
Evolution Of New Species Slows Down As Number Of Competitors Increases
ScienceDaily (Mar. 25, 2008) — The rate at which new species are formed in a group of closely related animals decreases as the total number of different species in that group goes up, according to new research.
The research team believes these findings suggest that new species appear less and less as the number of species in a region approaches the maximum number that it can support.
In order for new species to thrive, they need to evolve to occupy their own niche in the ecosystem, relying on certain foods and habitats for survival that are sufficiently different from those of other closely related species.
Competition between closely related species for food and habitat becomes more intense the more species there are, and researchers believe this could be the reason for the drop-off in the appearance of new species over time.
Dr. Albert Phillimore, from Imperial College London's NERC Centre for Population Biology, lead author on the paper, explains: "The number of niches in any given region is finite, and our research supports the idea that the rate of speciation slows down as the number of niches begins to run out.
"In essence, it seems like increased competition between species could place limits on the number of species that evolve."
The new study used detailed analysis of the family trees, or phylogenies, of 45 different bird families. By examining the rate at which new species have arisen in each of these trees over a period of millions of years, scientists saw that the rate of appearance of new species seemed to be much higher in the early stages of the family tree, compared to more recent lower rates.
For example, when the researchers examined the phylogeny of tit birds they found that some 10 million years ago, species formed rapidly but this rate has slowed over time to perhaps a quarter of the initial rate.
Journal reference: Phillimore AB, Price TD (2008) Density-dependent cladogenesis in birds. PLoS Biol 6(3): e71. doi:10.1371/journal.pbio.0060071
Adapted from materials provided by PLoS Biology, via EurekAlert!, a service of AAAS.
http://www.sciencedaily.com/releases/2008/03/080325083359.htm
Evolution Of New Species Slows Down As Number Of Competitors Increases
ScienceDaily (Mar. 25, 2008) — The rate at which new species are formed in a group of closely related animals decreases as the total number of different species in that group goes up, according to new research.
The research team believes these findings suggest that new species appear less and less as the number of species in a region approaches the maximum number that it can support.
In order for new species to thrive, they need to evolve to occupy their own niche in the ecosystem, relying on certain foods and habitats for survival that are sufficiently different from those of other closely related species.
Competition between closely related species for food and habitat becomes more intense the more species there are, and researchers believe this could be the reason for the drop-off in the appearance of new species over time.
Dr. Albert Phillimore, from Imperial College London's NERC Centre for Population Biology, lead author on the paper, explains: "The number of niches in any given region is finite, and our research supports the idea that the rate of speciation slows down as the number of niches begins to run out.
"In essence, it seems like increased competition between species could place limits on the number of species that evolve."
The new study used detailed analysis of the family trees, or phylogenies, of 45 different bird families. By examining the rate at which new species have arisen in each of these trees over a period of millions of years, scientists saw that the rate of appearance of new species seemed to be much higher in the early stages of the family tree, compared to more recent lower rates.
For example, when the researchers examined the phylogeny of tit birds they found that some 10 million years ago, species formed rapidly but this rate has slowed over time to perhaps a quarter of the initial rate.
Journal reference: Phillimore AB, Price TD (2008) Density-dependent cladogenesis in birds. PLoS Biol 6(3): e71. doi:10.1371/journal.pbio.0060071
Adapted from materials provided by PLoS Biology, via EurekAlert!, a service of AAAS.
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Posted: Tuesday, March 25, 2008 | PermalinkComments 1 - 11 of 11 |
Reload Comments | Back to Top | Page Numbers2. Comment #149264 by sarah95 on March 25, 2008 at 11:04 am
Great article! Ecology has always been one of the most interesting areas of biology to me.
This reminds me of something that was said during a recorded discussion on evolution at the Natural History Museum between Richard Dawkins, Lewis Wolpert and Steve Jones. In talking about complexity, they mentioned the fact that a finite number of supportable niches may be what drove evolution towards complexity. Niches for simple organisms were simply running out.
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3. Comment #149287 by davem on March 25, 2008 at 11:50 am
Didn't we always know this? I certainly thought that this was obvious stuff.Other Comments by davem
4. Comment #149385 by AtheistAspy on March 25, 2008 at 2:29 pm
Maybe this is the reason for the Cambrian explosion (there were niches before then). Other Comments by AtheistAspy
5. Comment #149406 by sarah95 on March 25, 2008 at 3:06 pm
Comment #149287 by davem
Didn't we always know this? I certainly thought that this was obvious stuff.
I think you're right. I learned this in Ecology and Biology classes a while ago, and the discussion I referenced in my last comment mentioned this concept.
It's still interesting to hear about research and new evidence for it though...
The new study used detailed analysis of the family trees, or phylogenies, of 45 different bird families. By examining the rate at which new species have arisen in each of these trees over a period of millions of years, scientists saw that the rate of appearance of new species seemed to be much higher in the early stages of the family tree, compared to more recent lower rates.
Other Comments by sarah95
6. Comment #149655 by Geoff on March 26, 2008 at 4:01 am
3. Comment #149287 by davem Didn't we always know this? I certainly thought that this was obvious stuff.
That was my thought, too, Dave.
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7. Comment #149694 by j.mills on March 26, 2008 at 6:20 am
'Obvious' stuff still requires evidence. Assumptions must be tested, and in this case quantified too. Good to know that intuition hasn't led biologists astray in this. Other Comments by j.mills
8. Comment #150294 by Andrew Stich on March 26, 2008 at 4:59 pm
Precisely what does it mean by species? And what does it mean by "a group of closely related animals"? Doesn't this imply that evolution is slowing down? Isn't that not the case?Not saying that this is wrong, but how does it not imply that evolution is slowing down if less and less "species" are forming?
Other Comments by Andrew Stich
9. Comment #150310 by Mitchell Gilks on March 26, 2008 at 5:23 pm
This seems like basic economics to me. Though it clearly does still need to be tested and varified, no matter how intuitive it may appear. Other Comments by Mitchell Gilks
10. Comment #150606 by Azven on March 27, 2008 at 6:58 am
I'd like to echo Andrew Stich here.
What, exactly, is a 'group'? What does speeding up or slowing down of evolution mean? If we're talking about the rate of increase in the number of species then what has this got to do with evolution's speed?
'Niches' implies species that are not in competition for resourses. It's fairly tautological that this means that there are a fixed number of niches. species that are competing for resources should evolve faster - but note - the number of species competing for over-lapping resouces will DECREASE over time.
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11. Comment #151882 by RightWingAtheist on March 29, 2008 at 3:58 pm
Andrew Stich said "how does it not imply that evolution is slowing down if less and less "species" are forming?"
Maybe they are referring to less diversification, while still allowing for succession within a single niche-focused species. There is still competition among members of the species, as well as predator vs. prey pressures.
But I do have a nagging feeling that there must be some kind of reduction, as the premise seems [to me] to be that we are comparing pre- and post-adaptation.
Other Comments by RightWingAtheist
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1. Comment #149261 by HumanisticJones on March 25, 2008 at 10:52 am
It does make sense. If there is a pre-existing species filling a niche in the ecosystem already, the statistical chance that another species slightly varied to exploit the same niche would be as well adapted and able to compete for resources.It really fits in well with punctuated equilibrium where drastic, sudden changes to the ecosystem of the organisms would close old niches down and leave new niches unfilled promoting new species to fill them.
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