A team led by UC San Francisco researchers has discovered a sensory system in the foreleg of the fruit fly that tells male flies whether a potential mate is from a different species. The work addresses a central problem in evolution that is poorly understood: how animals of one species know not to mate with animals of other species.
For the common fruit fly D. melanogaster, the answer lies in the chemoreceptor Gr32a, located on sensory neurons on the male fly’s foreleg. “In nature, this sensory system would prevent the creation of hybrids that may not survive or cannot propagate, thereby helping the species preserve its identity,” said senior author Nirao M. Shah, MD, PhD, a UCSF associate professor of anatomy.
The work is reported in a paper published online in Cell on June 27, 2013.
Before mating, the researchers found, the male approaches a prospective female and taps her repeatedly on the side with his foreleg. “As he does so, he is using Gr32a to detect, or actually taste, unpleasant-tasting waxy chemicals on the cuticle, or outer skin, of individuals of other species, said co-author Devanand S. Manoli, MD, PhD, a UCSF postdoctoral fellow in anatomy and fellow in child and adolescent psychiatry. “If the prospective mate is not of the same species, and Gr32a is activated, the mating ritual stops right there, even if the male has never encountered a female of another species before.”
The researchers also found that if the male fly’s Gr32a neurons are activated directly, courtship with other species can be suppressed in these male flies. “These and other findings show that Gr32a neurons are both necessary, in terms of having this taste receptor, and sufficient, in terms of their activity, to prevent males from courting females of other species,” said Manoli.
Read more at: Phys.org