Glorious giants of the Appalachians are being killed off by insignificant-looking Asian females. And this has nothing to do with outsourcing, job losses, small towns, bitterness, guns or religion.
The Eastern Hemlock, a glorious native American tree that grows to a stature of 100m, the Sequoia of the Appalachians, is being wiped out by a tiny parasite, an aphid called the Woolly Adelgid. This has been observed and mourned in the New Yorker (I found the story thumbing through a back issue), the New York Times (way back in 1991) and in various pamphlets accessible with a Google search. However, what doesn't seem to have attracted comment is that the attacker is fatally flawed.
The aphids first came to America on decorative Japanese trees which were planted at Maymont, a public park in Richmond, VA. All the male aphids died. They feed exclusively on spruce sap and the males could not digest American spruce. A few females survived. Sans males, they had to reproduce by cloning. So, the threat to the Eastern Hemlock comes from clones of a very small number of individual female aphids. The clones were fantastically successful because they could colonize the Eastern Hemlock. As a predator gets established in America, or worst-case, as the Hemlock populations in the wild die out, the clones will also die. Clones are evolutionary dead-ends.
Should conservationists freeze Hemlock gene-plasm to re-populate the Applachians once the Woolly Adenids clones inevitably die? Makes sense. Just be sure to freeze a diverse pool of Hemlock gene-plasm. And establish an Eastern Hemlock worshipping cult whose rituals will remind initiates to perform this sacred task when evolution plays out and the clones finally die.
No comments:
Post a Comment