Odd fly uncovers evolution secret [speciation]

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.

"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.

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.

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.

"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."

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?"

Creationism is not a wild guess. Creationism is the belief in a higher being (usually a supreme being) that exists somehow out of time and is responsible for bringing into being the physical universe as we know it.

I don't "guess" that I believe it, I either believe it or I do not. Science can not prove creation, nor can it disprove it. Science cannot prove the evolution of man from a non-living origin. Nor can science disprove it.

Science can prove or disprove specific mechanisms in the natural world which can be used to hypothesize an historic chain of events which have some non-zero probability of allowing human to come into being starting with non-living matter. But absent a recorded history, any such hypothesis is simply a guess as to what happened.

We know that there was non-living matter, because it still exists today. We know that there are humans now, because we can see them. We are pretty sure that there was a time when there were no humans, because we dig around in the ground and after some point we cease to find human remains.

But sometimes we dig farther and find human remains, and the "hypothesis" (guess) of the HISTORICAL EVOLUTION STORY is modified to take into account the scientific (observable historical) evidence which contradicts our previous guess.

Eveolution is a provable theory. We can observe evolution. We can perform repeatable experiments which replicate evolution.

An analogy. Gravity is a proven theory. We know that if we drop things, they fall to earth. But, that does not prove that the pencil fell off the table onto the floor. It is a valid hypothesis that the pencil fell to the floor because of the theory of gravity. But it is also possible that your 2-year-old walked over to your desk, TOOK your pencil, and placed it on the floor.

If your shoes end up on top of the TV, that does not disprove the theory of gravity. However, it is likely that your shoes were put there by your 2-year-old.

The only real problem with what seems otherwise to be an obvious conclusion (evolution=science, creation=belief, therefore teach evolution but not creation), is the pesky problem that, while not being scientific, creation could still in fact be true. And if it is in fact true, then the hypothesis of the mechanism by which humans evolved from non-living matter is false, even though the mechanisms themselves are observable and repeatable.

Just as you can't scientifically prove that your pencil was placed on the floor, or that your shoes were placed on your TV, by a 2-year-old, unless you have a recorded observation of the activity.

This is why I advocate teaching only science in science classes. This would include the science of evolution, but not the teaching of historical hypotheses such as the "origin" of man. Religion is not science. History is not science.

This of course is a generalization. It can be deduced from statements I have made in this article that "observable history" can be considered science of a kind. Would the term "forensic science" be the name for this kind of science? It isn't quite the same has hard science, the science of repeated observations of experiments with repeatable results. We have less of a problem if we don't try to equate "science" with "truth" (NOT meaning science isn't truth, but simply that determining the truth of something does not make that something "science" -- there is no "science" involved in saying "the pencil is on the floor").

For example, when we find a human fossil in close proximity with a fossil of another organism, we can state with reasonable certainty the "truth" that the two co-existed (this is not provable, as there are mechanism by which the proximity could be achieved without the organisms being co-located in time). That truth is not "science" in the sense that it is a repeatable experiment (it is trivially a repeatable observation). For example, suppose you were to try to use a rigorous scientific method. You hypothesize that other human remains will be found in the surrounding area, and that with those remains you will find the remains of the other organism. So now you seek to "repeat" the experiment by digging up all of the countryside. If you find 50 more sets of human remains, and not one of them shows the other organism, have you disproved your theory? Not really, just dropped the probability. What if you find the other organism at a few of the other sites? You raise the probability, but you still can't be sure. If you find the other organism at EVERY other site, you will feel pretty good about it, except that the very next site you dig up might not have it. Because you are not running a controlled experiment.

I've gone on too long. There is a lot to be said about the non-scientific nature of a manufactured historical record (maufactured meaning derived from a limited observation set grounded in the current time, rather than being directly observed through recorded historical documentation).

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