Social tuco-tucos develop more variety

From Atlanta, Ga., at the annual meeting of the Animal Behavior Society

In mustachioed rodents called tuco-tucos, nature has set up a tidy test for the effect of social life on the immune system.

Group life boosts exposure to pathogens, explains Eileen A. Lacey of the University of California, Berkeley. Evolutionarily, that added exposure ought to be associated with more genetic variety in immune systems than solitary lifestyles show.

Lacey tested this proposition in two neighboring tuco-tuco species in Argentina. Ctenomys sociabilis cluster in groups, but Ctenomys haigi live solitary lives.

Lacey and her UC-Berkeley colleague Tina M. Hambuch analyzed DNA from 35 animals in one population of each species. The researchers compared the DNA sequences in a gene that encodes a molecule in the major histocompatibility complex, a key part of the immune system.

The social tuco-tucos consistently showed more variation at these spots than the solitary species did.

That difference seems to reflect a special richness of the immune system, Lacey suggests. A test section elsewhere in the salamanders’ genomes didn’t show differences in diversity between the two species.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.