Mike Dunford posted Entry 1357 on August 17, 2005 03:56 AM.
Trackback URL: http://www.pandasthumb.org/cgi-bin/mt/mt-tb.fcgi/1355

Invasive species are nothing new to the Islands of Hawai’i. The first invasive species arrived with, and included, the first Polynesian settlers. Although there does appear to be some evidence that they may have caused the extinction of a few endemic species, the effects of these invasions were most likely relatively minor. Since the first western contact with the islands, the number of invasive species present has skyrocketed, causing a massive ecological disaster. If you want proof of the severity, you need not look any farther than the fact that Hawaii contains well less than 1% of the total land area of the US, but has over a third of the listed endangered species in the US.

At the moment, there is a new invasive species that is making the news here in Hawai’i: a species of “gall wasp” that has been wrecking havoc on trees of the genus Erythrina in Singapore, Taiwan, and a number of other places was found in a valley on Oahu in April. Since then, it has been found in a large number of other places on Oahu, and has started to turn up on other islands, including Maui, and a number of scientists believe that it poses a serious threat to a culturally-significant endemic plant - the Wiliwili (Erythrina sandwichensis). The threat is being taken so seriously that scientists have reportedly begun to bank Wiliwlil seeds as a precaution in case the extant population is completely lost.

So what does this have to do with evolution?

Continue reading (and hopefully find out) at The Questionable Authority:

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Comment #43446

Posted by Carl Zimmer on August 17, 2005 8:27 AM (e)

History predicts that a parasite from the wasp’s original range could keep it in check in Hawaii. In Africa, for example, cassava mealybugs introduced from South America threatened to wipe out this staple crop in the 1970s. Scientists went to Paraguay and found a parasitic wasp that lives on the mealybug. They showered it down on African cassava fields by plane, and the mealybugs dwindled away. (Full details can be found in my book Parasite Rex.

Of course, this strategy also has its risks, because introduced parasites may also be able to attack native species.

Comment #43450

Posted by Alan on August 17, 2005 8:51 AM (e)

The Cane Toad and Australia being a prime example.

Also the evolutionary change that has selected reduced head size of a local predator snake, as smaller head size prevented them from swallowing the poisonous toads.

Comment #43456

Posted by Darkling on August 17, 2005 9:50 AM (e)

Introductions can quite easily have unexpected consequences as new organisms are introduced to novel (for them) environments.

Rabbits and mustelids in New Zealand are a prime example. Rabbits were introduced early on and started to ravage the country side so mustelids were introduced to control them. The problem is that now there is a major problem with stoats predating upon native (and now endangered) birds.

Comment #43497

Posted by Reed A. Cartwright on August 17, 2005 12:24 PM (e)

The problem many intoroduced contols have is that they didn’t think about what they introduced. In many situations they introduced predators that were generalists or didn’t even prey on what they wanted controled.

Comment #43500

Posted by Alan on August 17, 2005 12:33 PM (e)

Like the Cane Toad couldn’t jump high enough to get the cane beetles they were supposed to control. You’d think someone would have checked!

Comment #43505

Posted by Darkling on August 17, 2005 12:45 PM (e)

The problem many intoroduced contols have is that they didn’t think about what they introduced. In many situations they introduced predators that were generalists or didn’t even prey on what they wanted controled.

That was the point I was trying to make. Or more specifically that introductions of new species need to be very well thought out.

The main problem is that predators either witingly or unwitingly have been introduced to environments where the natives have evolved with out similar predators. Hence a lot of native NZ birds have become extinct or restricted to offshore islands (out of stoat swinning distance, about 1.2 km, don’t ask) within the geological blink of an eye. The introduction of brown tree snake to Guam might be a more familar example, which I think this one was a lot more recent (1940’s?). Again the native bird life has been devastated.

Comment #43522

Posted by Sir_Toejam on August 17, 2005 1:47 PM (e)

there was an old lady who swallowed a fly…

Comment #43536

Posted by Mike Dunford on August 17, 2005 2:46 PM (e)

Hawaii has a history of having poorly thought out biological control programs go hideously bad. The introduction of the Small Indian Mongoose during the 1880s is a prime example of this. Another is the more recent (1959) introduction of the Cattle Egret as a means of controlling insects. Both cases have resulted in far more harm to the Hawaiian ecosystem than they fixed.

Comment #43688

Posted by Loren Petrich on August 18, 2005 5:47 AM (e)

A creationist might respond “But those gall wasps are still gall wasps”. I wonder what would satisfy them short of going back in time in a time machine.

Comment #43764

Posted by Big Bill on August 18, 2005 2:13 PM (e)

C’mon, guys. It’s just diversity in action. Multiculturalism.

The Gall Wasp is eating plants that the Hawaiian animals are just to lazy to eat, kinda like the American Grey Squirrel in England an the Mexicans floding the USA.

Where does this moralistic “preserving diversity” stuff come from? God? Im mean where do you get that religion rom?

And anyway, letting in foreign plants andimals and peoples who can survive better and more efficiently is a good thing. It is survival of the fittest.

And further, letting foreign people plants and animals in always increases diversity. Sure, some native peoples, plants, and animals will die out, but it’s not like they have any right to the land. There is no God-given title. If the native peoples, plants and animals cannot compete and survive, that is their fault. It’s Darwin in action.

Comment #43831

Posted by Michael Hopkins on August 18, 2005 6:17 PM (e)

The creationists, if they acknowledge that “evolution” here had application, will undoubtedly say that it was “microevolution” that was applied.