Tree DNA tests prove that Benjamin Franklin isn't ruining the Gulf Coast

Much of the southeastern US is struggling with Chinese tallow trees, an invasive species that is overrunning the Gulf Coast and wreaking havoc on the natural habitat. And, until now, people figured it was that big jerk Benjamin Franklin's fault.

While Franklin was living in Europe, he arranged to have some of these tallow trees shipped to friends of his in Georgia. Franklin and his business partners were intrigued by the ultra-fertility of the trees - they produce a million seeds every two years, and those seeds can be harvested to make soap, candles, and other goods. The problem is that there's just no way to harvest enough seeds to keep the trees themselves under control, and in the ensuing centuries tallow trees have run wild throughout the southeastern US.

Now, biologist Evan Siemann and his colleagues at Rice University have cleared Franklin's name. They ran genetic tests on over a thousand of these trees, and it turns out that none of the trees that overrunning the Gulf Coast came from Franklin's original batch - the descendants of Franklin's trees are completely confined to the coastal plains of Georgia and South Carolina. Instead, the tallow tree invasion began in 1905, when federal biologists imported some new tallow trees from China.

What's particularly interesting about the American tallow trees is just how ridiculously successful they are. They grow about 30% faster than their Chinese counterparts. Because the insects that keep the Chinese trees in check don't exist in the United States, they don't have to devote nearly as much energy to produce chemicals that can fight them off.

These are supercharged trees, and Siemann says it's unclear precisely why that is:

"This raises some interesting scientific questions. Are tallow trees in the U.S. undergoing evolutionary selection? Did those original plants brought from China have the traits to be successful or did they change after they arrived? Does it matter where they came from in China, or would any tallow tree do just as well in the U.S.?

Even when the Americanized trees were brought back to China and brought into contact with their insect predators, they still massively outgrew their native counterparts, as Siemann explains:

"They suffered twice the damage from insects that the natives did, but they grew so much faster that they still retained a competitive edge. In some ways, this raises even more questions, but it clearly shows that if you are going to explore control methods for an invasive species, you to need to use appropriate genetic material to make certain your tests are valid."

But let's not lose sight of the real takeaway here: as far as tallow trees are concerned, Benjamin Franklin was innocent of spreading his seeds to places he shouldn't have. And, based on everything I've read about him that's got to be the first time anyone could say that about Benjamin Franklin.

Via the American Journal of Botany. Image via.