A genetic study to evaluate dispersal between North and South america has identified potential new species among American doves.
The formation of the Central American land bridge around 3.5 million years ago has long been known as the main instrument by which the faunas of North and South America have mingled, particularly among mammals.
Less well-known is the influence this major geographical event has had on the actual diversification of the two continents' faunas. To investigate this, a team from the Field Museum of Natural History in Chicago performed a genetic analysis 32 individuals of 24 species (and the attendant subspecies of four of them), on one nuclear and three mitochondrial genes extracted from the museum. All species from the genera Geotrygon, Leptotila and Zenaida.
The team's results to indeed seem to suggest that dispersal after the connection of the two continents is the major driver of diversification among these dove genera. Interestingly - perhaps because of the recentness of the radiations - no clear direction of invasion could be inferred, and the authors propose that dispersal may have gone in both directions over the time period in question, and occur individually and independently rather than in one prolonged invasive movement.
One species in particular - White-tipped Dove Leptotila verreauxi, found from Mexico to southern Argentina - had diverged in a 'stepping stone'-like fashion across the Panama Isthmus and down into South America. The five subspecies (out of 14) analysed were as divergent genetically as many good dove species, and certainly warrant further scrutiny with a larger sample. White-throated Quail-dove G frenata, Zenaida Dove Z aurita, Grey-chested Dove L cassini and Grey-fronted Dove L rufaxilla may also warrant deeper investigation.
Reference: Johnson, K P and Weckstein, J D. 2011. The Central American land bridge as an engine of diversification in New World doves. Journal of Biogeography DOI: 10.1111/j.1365-2699.2011.02501.x
