10 May 2006

The Land of the Endangered.

The State of Hawaii is one of the smaller states in the Union. According to Wikipedia, we're 43rd out of 50 in size, 42nd in population, and, at 3000km from the nearest continent, we're as isloated as you can get. We may be small and out of the way, but there's a lot that we have. We've got a great climate - we're the only state that's entirely in the tropics. Being in the middle of the ocean helps there, too, since all that water helps to moderate the climate even more. It also gives us some really great beaches, world-class surf spots, and truly excellent snorkling and diving.

There's something else that being isolated does for us. It's the reason that we're the endangered species capital of the United States. We're so far out in the middle of the ocean that it is very difficult for new species to get here. The few that have made it have become the founders for evolutionary radiations, resulting in the origin of thousands of species unique to Hawaii. These species have been hit hard as a result of human actions. One in four species (329/1312) on the United States endangered species list is endemic to the Hawaiian Islands.

Yesterday, the list of endangered species in Hawaii got longer. The United States Fish and Wildlife Service added eleven species of Drosphila to the endangered species list, with one more species being listed as threatened. Each of the twelve species is found on only on a single island.

For those of you not familiar with the Hawaiian Drosophila, let me provide a quick intro. The genus Drosophila is best known because of Drosophila melanogaster, the legendary "fruit fly" that geneticists and students of biology have worked with for decades. ("Fruit fly" is in quotes because Drosophila are not actually fruit flies, but I'll refrain [for now] from descending to the depths of dorkdom necessary to go into detail on the difference. For now, suffice it to say that the distinction is at least semi-important to people who work with the group in the field.)

As I was saying, D. melanogaster is the best known member of the group, but it is far from the only one. There are literally thousands of species in the genus. Almost a quarter of them are found only in the Hawaiian Islands. The twelve flies being listed are members of a group of the Hawaiian Drosophila known as the picture-wings. (Pictures of two picture wings, one of which [D. heteroneura] is one of the newly-listed species, can be found in an earlier post here.) Each of the listed species has a range restricted to a single island. Most of them will only breed on a small number of plant species (1-3). They are extremely rare - surveys in their habitat areas don't turn up more than a couple of flies. Listing these species as endangered, under the circumstances, is such a complete no brainer that it's a wonder that it only took five years of work and a lawsuit to get it done.

But here's the kicker - the only thing that really distinguishes these twelve picture wings from the other hundred or so in the group is that they are a bit more rare. The vast majority of the group are limited to one island, and the vast majority are limited to a small number of plants. It's possible to catch a few more during surveys, but the difference isn't really all that much - none of these insects are what anyone would consider to be common.

It gets even better. The picture wings, ironically enough, haven't been the focus of this attention because they are the rarest of the Hawaiian Drosophilids. They've gotten the attention because they're the best studied group. The truth is, we don't actually even know how many species there are for sure. Entirely new species have been described within the last few years, and it is quite probable that there are more to be found.

Described species or not, formally listed or not, there are a lot of species in Hawaii that are very rare and at risk of extinction. Listing these twelve species is good, especially since the lawsuit settlement also mandates that critical habitat be designated for these species. It's good, but it's hardly enough. Unless we want to lose biodiversity faster than we can discover and describe it, we need to do far more to protect the native Hawaiian species. And, of course, we need to put more time, effort, and money into studying our ecosystems while we still have them.

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