[From the archives; originally posted November 25, 2005]
I discussed here new research on venom evolution that topples some old conventional wisdom. It seems this and another study are already making large waves in that field.
Genealogy of Scaly Reptiles Rewritten by New Research
The most comprehensive analysis ever performed of the genetic relationships among all the major groups of snakes, lizards, and other scaly reptiles has resulted in a radical reorganization of the family tree of these animals, requiring new names for many of the tree’s new branches. The research, reported in the current issue of the journal C. R. Biologies, was performed by two biologists working at Penn State University: S. Blair Hedges, professor of biology, and Nicolas Vidal, a postdoctoral fellow in Hedges’ research group at the time of the research who now is a curator at the National Museum in Paris.
Vidal and Hedges collected and analyzed the largest genetic data set ever assembled for the scaly reptiles known as squamates. The resulting family tree has revealed a number of surprising relationships. For example, “The overwhelming molecular-genetic evidence shows that the primitive-looking iguanian lizards are close relatives of two of the most advanced lineages, the snakes on the one hand and the monitor lizards and their relatives on the other,” Vidal says.
“We gave this group the new name, ‘Toxicofera’ because of another discovery, reported in a related paper, that some lizard species thought to be harmless actually produce toxic venom, as do some snakes–including some large monitor lizards in the same family as the giant Komodo Dragon and some large species of iguanians.”
Vidal, Hedges, and other researchers report this and other discoveries about the early evolution of the venom system in lizards and snakes in a paper led by Bryan G. Fry, of the University of Melbourne in Australia, published in the current issue of the journal Nature. “It’s a really startling thing that so many supposedly harmless lizards actually are venomous,” Vidal comments, “but their sharing of this characteristic makes sense now that our genetic studies have shown how closely they are related.”
This is a great example of how science works. Important new findings have come to light, and the rest of the evidence is re-examined in that light, to see what stays and what thinking may need to be revised. No one expects it to happen overnight, and a call is put out for others to investigate and test the new conclusions:
“Because the current tree has been widely accepted for nearly a century, I think there is going to be a delay of maybe a few years before the general scientific community gets used to the new tree,” Vidal says. “If other research groups working in this area find the same pattern with additional genes, then I believe the scientific community may accept these results more quickly.”
Note how there are no politics involved, no pressure to teach these new results. The investigators are confident enough in their own data that they can wait for other scientists to examine it, express skepticism, test it themselves, and add their own conclusions to the scientific literature. It may take several years, but if the data stand up and are repeated by others, the way students are taught *will* change–not because anyone was lobbied to do so, but because the evidence is strong and it would be folly not to acknowledge that. I look forward to following this in the coming years.
Images from http://www.science.psu.edu/alert/photos/miscphotos/Hedges/IguanaHead-Cyclura-FernandezSmall.jpg