Animal and plant genes create new species

The genes of plants and animals act as engines for speciation, that is, they are “programmed” to cause the development of new species, according to investigations on two very different groups of organisms.

When two diverging populations of organisms do not interbreed — a phenomenon of hybrid sterility or incompatibility — the number of genes that prevent them from producing new organisms starts to grow very fast. This process promotes the evolution of new species.

In the first of the studies, Daniel Matute and his colleagues at the University of Chicago counted the number of genes in species incompatibility between fruitflies that belong to three species: Drosophila melanogaster, Drosophila simulans and Drosophila santomea. These three species can interbreed, but the new organisms are sterile.

The team created two hybrid populations — one by crossing D. melanogaster with D. simulans and the other by crossing D. melanogaster with D. santomea — and counted the number of incompatibilities in the hybrid chromosomes.

They found 65 incompatibilities in the hybrids between D. melanogaster and D. santomea, while there were just ten in the hybrids between D. melanogaster and D. simulans. Taking into account the relative number of genetic changes between species, this suggests that the number of incompatibilities does not increase in a linear way, but is accelerating.

Similar results were found out when studying the plant genus “solanum”, which includes potatoes and tomatoes. A lot of genes contributing to sterility were growing faster than the linear rate, while genes that had nothing to do with sterility were not.
Adapted from an article by Joseph Milton in Nature. Picture by Stockphoto.