In two bird populations, differences in social traits, rather than just physical ones, are enough to generate new species.
Jay McEntee at the University of California, Berkeley, and his colleagues set out to understand how two species of sunbird that live side by side in East Africa, Nectarinia moreaui (pictured) and Nectarinia fuelleborni, evolved into separate species. The team compared the animals' genetics, physical traits, habitat preferences and songs, which are used by males to compete for territory and possibly for mates. They found that the species are physically similar and prefer the same types of food and habitat. However, the birds' songs differ in duration and structure.
Genetic predispositions for different songs may have split the two species even though the birds share common habitats, the authors say.
Evolution http://doi.org/bhpx (2016)