by Carl Strang
This week’s peek at the scientific literature is a recent study published in the journal Science. My source is an article about that study in the science review site ScienceDaily.
Y. Zhen, M. L. Aardema, E. M. Medina, M. Schumer, P. Andolfatto. Parallel Molecular Evolution in an Herbivore Community. Science, 2012; 337 (6102): 1634 DOI: 10.1126/science.1226630
They examined genes of insects from several orders that feed on milkweed and dogbane plants. Though the insects (butterflies, moths, beetles, true bugs, aphids) are well separated from one another in their taxonomy and evolutionary history, they share the basic genes regulating cellular exchange of sodium and potassium, the proteins for which are affected by the plants’ poisons. A common pattern was gene duplication, with one copy available to mutate into a resistant form that allowed normal exchange of those ions within gut cells. The same gene was involved in all those diverse species, indicating the course of evolution was somewhat predictable.
Here is a gallery of local insects which eat milkweed and dogbane leaves, illustrating the diversity.
Monarch
Large milkweed bug
Red milkweed beetle
Milkweed tussock moth caterpillar
Milkweed leaf beetle
Dogbane beetle
Note how common orange appears among the milkweed insects’ colors. Is there a common genetic factor there as well?
