Posted on 08/23/2004 6:06:04 PM PDT by PatrickHenry
Being kicked out of its coral home may have forced the evolution of a new species of fish, say Australian scientists.
Research published in today's issue of the journal Current Biology provides more support for the idea that geographic isolation is not always needed for new species to develop.
Marine biologist, Dr Philip Munday of James Cook University in Townsville and team studied a new species of coral-dwelling goby fish found in southern Papua New Guinea to try and see how it evolved.
The most established doctrine of how new species form is that a group of organisms becomes separated and geographically isolated from the rest of a population.
But there is another idea that has been around, even since the time of Darwin, that a new species can arise without geographic isolation. This theory of sympatric speciation is controversial, not least because there have been few convincing cases.
The new species of coral-dwelling goby could have evolved according to the common wisdom, as the fish has a larval stage that spends time in the plankton and can easily float far away from the original population.
But there were other clues that suggested sympatric speciation was at work.
First, genetic studies showed the new species was a recent descendant of another species that lived on the same reef. The new species was estimated to have diverged from its ancestor between 200,000 and 700,000 years ago.
Second, the new species of goby inhabited a different species of coral not inhabited by the ancestral goby or any other goby species.
"Even though there are lots of fish that live on coral reefs, these particular gobies have a very intimate association with the corals," Munday told ABC Science Online. "They live among the branches of small coral colonies and they rely on them for shelter and breeding.
"They have to live in these corals to survive and they compete quite strongly for access to these corals."
Munday and team theorised that a group of ancestral gobies could have been essentially kicked out of their normal coral home and sought refuge in another species of coral that wasn't being used at the time.
"If they continued to colonise that coral there would be very little gene flow between the new fish and the ancestor, and the new environment would then select for traits that favoured its survival in the new coral," said Munday.
A third piece of evidence for sympatric speciation was the distribution of the new species, which appeared to be a small 'bullseye' at the centre of the range of the ancestral species.
"If this new species evolved from geographic isolation, you might expect that their ranges wouldn't overlap," said Munday.
Before this case, there had only been a few good examples of sympatric speciation, said Munday. One example involved leaf-eating insects which, like the coral-dwelling gobies, had very precise and close associations with their host.
Munday and team said it was possible that the new goby species arose from geographic isolation, but if it did, more steps would have been required.
First a part of the population of the ancestor would have to become geographically isolated, become established into a new species and changed its coral habitat. After that there would had to have been a shift in the new species' geographic range so it came back to a bullseye distribution at the centre of the range of the ancestor.
"There are other possibilities and we recognise that, this is probably just the simplest explanation," said Munday.
Speciation without the usual geographical isolation (which would make it "allopatric" speciation). One part of the population starts making a living in a new way, experimenting with eating something different. For a while, the populations stay completely intermingled, but after a time divergent selection pressures make them look and act differently. Interbreeding stops. Eventually it becomes impossible.
This particular scenario is not thought to account for that much of the diversity we see.
The passive voice--always the friend of the scientist making unaccountable and unverifiable claims. Also useful for shamans and witch doctors who want grants, too.
Thanks, I appreciate learning that.
It's just one fish becoming another fish. Nothing to see here. No evidence for evolution </creationist mode>
HERE (3 months after a thread died).
HERE (6 months after the thread died).
HERE (7 months after it died).
HERE (in another thread).
HERE.
HERE. And now ...
HERE (in yet another thread -- this thread).
This sort of stalking behavior can mean only one thing: she thinks you are an astronaut!
Given her obsession with the rocket men, it is no wonder she cyber-stalks you on FR, if she's managed to convince herself that you are one.
OK--I'll never direct a post directly to Patrick Henry again.
p>
But, unless I'm instructed otherwise by authorities, I'll continue to post to the many, many, many regular threads that Patrick Henry begins on the subject of claiming bogus speciation, to others who may be unafraid of challenges.
I presume you are still available for comment--but let me know if you're not...
The whole point of the Fruit Fly thread and my later participation (I never meant to *scare* anyone, not even a wee timorous scientist) was to establish a record and a history. The article claimed a new species almost nine months ago. However, no new species was in the article, nor have any emerged in the nine months hence.
Fruit flies have very a brief generation--24 hours. Each new day is the chance at a new species. Approx 270 potential new generations and potential new speciation. Yet--none.
The fruit fly has been used for hundreds of years, across many continents, every experiment a variation in selecting out for genetic variety. High schools in Kansas do it. Universities in Asia do it. Down to Patagonia and out to the Caribbean...
How much more ideal a lab can there be to reproduce this thing that supposedly happens so easily by accident?
Slow thread? OK, I'll play for a while.
700,000-800,000 years for one species of Gobie to split into two visibly indistinguishable forms is a great example of speciation, but not of the kind of leaps you need to make macroevolution a plausable hypothesis. To get that, you would have to find examples of where new FAMILIES formed every four or five centuries. That is based on estimates of the number of families there have been on Earth since the Cambrian explosion (1.25 million) divided by the number of years since that explosion (543 million). I am using your sides numbers for all of this, and the numbers don't add up if all you can show me is a species split in 700,000 years.
Even that is weak, because the genes of the original host may have had the latent genes all along. There is no evidence that any "new" functioning gobi genes are required to become the "new" species. Those genes could well have been a subset of the original group. THAT does not prove macroevolution.
It's not that so much, grammaticaly speaking, as the idea of putting the object first in the sentence for clarity. A different sentence structure would feature the writer or the scientists and technicians, which would put the main attention on the scientist rather than the science. Featuring the actor rather than the object might be appropriate for a politician, but science requires an impersonal mode.
The student of rhetoric will also tell you that the passive voice deflects more than just immodesty. It functions as an oblique way for the reader to slide over what might otherwise prove uncomfortable for the writer--asking "who came up with that 200M or 700M figure--kind of outlandish, don't you think"? There's a heap of "surmisin'" that slips by with the use of the passive voice.
It's not modesty at all. The science is the center of interest and any suitably equipped scientist should be able to reproduce the results if it is good science.
As to whether the passive voice is just as suitable for other areas such as the annual laboratory budget, well, that would be an affectation. But for science as a discipline, the passive voice should be perfectly acceptable.
Is this related to another thread here on convergent evolution?
Maybe this explains vegans.
AW, don't give in so easy - I like watching.
Science is influenced by nuance.
The passive voice is almost always used in scientific writing to emphasize results rather than personalities. If you read scientific journals regularly, this would be obvious.
My aunt tried to dissuade me from studying physics, but otherwise she had no influence on science.
Now that the background noise has subsided on the issue he is not heard from.
I wish I could remember his name.
Global Climate Change is the new mantra and it is every bit as dogmatic for publication and peer respect as was ozone depletion then; but the primary advocates for change are still nameworthy.
Evolution is a deep subject that rankles people at a gut level, even more than imminent annihilation.
There will never be a consensus.
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