If you find a robber fly in Tenerife, you will be face to face with an insect that is found nowhere else – and whose evolution may be a direct consequence of the great wealth of species on the Canary Islands, according to new research.
Posted on 04/20/2005 5:17:33 PM PDT by PatrickHenry
A unique fly from the Canary Islands has helped shed light on one driving force behind the birth of new species, Nature magazine reports this week.
The robber fly is found nowhere else, and scientists speculate that the rich biodiversity on the islands may actually have led to its emergence.
The researchers think sharing an island with a myriad of other lifeforms may push one species to evolve into another.
This new theory adds fresh insight into how biodiversity arises.
"Why some areas contain greater species diversity than others has been a fundamental question in evolutionary ecology and conservation biology," said co-author Brent Emerson, of the University of East Anglia, UK.
Genetic drift
It is thought "speciation" -- the evolution of a new species -- can occur when two populations of the same species become isolated, allowing them to "grow apart" genetically over the course of many generations.
Eventually, the two populations become so different that if they were to meet again they would no longer be able to breed, meaning they had become separate species.
One species can also evolve into another if strong selective forces are placed upon it (where certain genes or genetic traits are favoured by natural selection), or if its population is small enough to allow for "genetic drift", which happens when certain traits are lost -- or become proportionately more common -- simply because the gene pool has shrunk.
But exactly what drives speciation is still not fully understood by scientists, and it is an area of intense research.
By carefully studying animals and plants in the Canary and Hawaiian Islands, Dr Emerson and his colleague Niclas Kolm were able to show an apparent link between biodiversity and the evolution of new species.
If you find a robber fly in Tenerife, you will be face to face with an insect that is found nowhere else – and whose evolution may be a direct consequence of the great wealth of species on the Canary Islands, according to new research.
They found that endemic species, such as the predatory robber fly (Promachus vexator), are more common in places that are bustling with many different species. Therefore, they speculate, new species are more likely to evolve if they are surrounded by an already rich biodiversity.
Species competition
"Imagine you have an island colonised 100 species and a similar island colonised by 10 species," explained Dr Emerson. "If you leave that for a period of evolutionary time, the percentage of entirely new forms will be higher on the island with 100 species on it."
The researchers can think of three reasons why this might be the case. First, species that are forced to share a space with a lot of other species usually have smaller population sizes. That means they are more susceptible to genetic drift, which can speed up speciation.
Secondly, islands with a rich biodiversity have more habitat complexity. In other words, instead of just one habitat -- say, grass -- there is, for example, grass, shrubs and trees. That means species are more likely to evolve new adaptations and, eventually, become different species.
Thirdly and, the researchers believe, most importantly, competition between species can encourage speciation.
"We think the islands with more species have an increased interaction effect - and that is the most significant thing," said Dr Emerson. "So the more species you have, the more, as an individual species, competitors and predators you are facing.
"And that puts pressure on you that can lead to your extinction or you can adapt to that pressure and survive and that would result in a new species forming."
Tropical diversity
This new research could help explain why islands in warm areas (which tend to start off with a richer biodiversity than colder areas), like Hawaii and the Canary Islands, tend to have a high proportion of totally unique species.
Professor Axel Meyer, of Konstanz University in Germany, who is eminent in the field of speciation, says the research is very interesting -- if it stands further scrutiny.
"It is very thought provoking," he told the BBC News website. "I'm sure it will have people rushing to their computers to see whether this pattern holds up and it will be interesting to see if it does hold up in other systems."
He also stressed that a rich biodiversity could not entirely explain a rich biodiversity because, of course, you had to start somewhere.
"They are saying that if you have biodiversity it will create more biodiversity - I can buy that. But it still doesn't explain the initial step: how do you get more biodiversity in the first place?"
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Brilliant...
It pays to check your fly
Very nice photograph of that fly though. That's hard to do.
I don't know. Some of these things seem obvious. But that's always easy to say in hindsight. (The same is true of natural selection.) One test of this is to see if it's geographically true. I assume that's already the situation. So we have no counter-examples. Still, although it seems to explain a lot, I don't know where we go with this. But it's interesting.
I'm concerned that this could give a lot of ammo to environmentalists.
Not if the fly is stuffed
"...and scientists speculate..."
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"The researchers think..."
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"This new theory..."
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"It is thought..."
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"...still not fully understood by scientists..."
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"Therefore, they speculate,..."
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"...if it stands further scrutiny."
All this is is speculative guesswork. Yawn.
For that matter, a skilled person can argue a dumb point better than an unskilled person can argue a good one. Then it becomes a silly game of showing how smart you are, not how right you are.
Axel Meyer needs to read Schopf's Cradle of Life. OK, he probably has. But I don't see his objection as much of an objection. It did take a long time to grow enough biodiversity for things to take off. It also took a long time to invent sexual reproduction, which was a big breakthrough in speeding up evolution.
I guess you think all science then is speculative guesswork?
With what can we contrast this? ID or creation science? My guess is that many adherents to these beliefs would not have any questions or doubts about them, and would not be trying to disprove (falsify) them. And that is precisely why they are not science.
When creationists try to destroy the credibility of evolution, they undercut the entire credibility of science in the minds of many people. No wonder the junk science used by the extreme environmentalists is so widely accepted.
Better leave science to the scientists.
I hate to stomp too hard, but I actually have seen robber flies here in southeastern Va. I was so startled by the first one I saw that I took it to our local nature museum for ID, and the zoologist there did not seem at all surprised by it.
It's possible it drifted on the trades from the canaries, since we also get our hurricans from there, but for the record, I have seen this critter outside of the Canary Islands.
Who knows, maybe I was witnessing the beginning of a variant in the species.
Axel Meyer needs to read Schopf's Cradle of Life. OK, he probably has. But I don't see his objection as much of an objection. It did take a long time to grow enough biodiversity for things to take off. It also took a long time to invent sexual reproduction, which was a big breakthrough in speeding up evolution.
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You would be assuming that there was long enough span of time for these evolutionary miracles to occur in the correct order in the necessary location. That takes to much faith for me.
"They are saying that if you have biodiversity it will create more biodiversity - I can buy that. But it still doesn't explain the initial step: how do you get more biodiversity in the first place?"
Legislate from the Bench?
That's the problem with common names. There's more than one species of Robber Fly.
Link:
http://www.geller-grimm.de/asilidae.htm
You have no idea of the difficulties inherent in the "not enough time" (6-10 thousand years) hypothesis in explaining the world we see. No doubt this is a conscious decision on your own part not to know some things.
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The only difficulty would be for you because it would involve God.
But please, let us keep focused on the topic at hand and not on personal attacks.
Who could have made the world looking old. Last Thursday.
Please provide us with detailed reasoning on this important subject, that supports your hypothesis on this specific case.
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