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NOVA Online: Island Creatures
Ken collecting NOVA: And what about the stability of the habitat? Is this a stable or instable habitat, volcanic activity?

KANESHIRO: Well the volcanic activity in the Hawaiian Islands, especially on the island of Hawaii where we have constant volcanic activity, we constantly have change in the landscape of the forests. So many of these forests, I think the geologists will tell you, are probably no more than two thousand or four thousand years old and so the forests are continuously being burned by new lava flows. So the populations of flies or other organisms that may be trapped in these forests are continuously subjected to small population sizes. So what we have here is a situation where you have volcanic activity creating kapukas which results in small population sizes in these flies which then causes a shift in the mating system which then results in a shift in the genetic system, the genetic background of the population which then leads the population in a different evolutionary pathway.

NOVA: Going back to something we touched on a minute ago, does what you're learning about the speed with which evolution takes place in Hawaii, give new insights into the overall nature of evolution in general and, and the way people have always thought it worked?

KANESHIRO: The Hawaiian Islands and especially the flies, have given us the opportunity not only to test some of the classical ideas of evolution but also to formulate new ideas of evolutionary processes. And the recent work on the mating behavior and the sexual selection process in these flies, for example, have challenged some of Darwin's classical ideas about natural selection being the most dominant force in the evolutionary processes. We believe now that perhaps sexual selection plays a much more important role in at least the initial stages of speciation.

forest NOVA: Anywhere else in the tropics, if we were sitting here, we would be eaten alive by mosquitoes and other biting insects. Why aren't there any mosquitoes or gnats in Hawaii?

KANESHIRO: Good question. They never made it here. There are mosquitoes of course in the Hawaiian Islands, but most of these are restricted to the lowlands. They're not species that are adapted to the higher elevations so we're very fortunate in Hawaii where there are very few biting insects—mosquitoes and gnats and things like that in the native ecosystem.

NOVA: Because they never arrived and nothing else that got here ever evolved into something like that?

KANESHIRO: Apparently not. I have no answer for that, I mean they're just not here.



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