The Central American land bridge as an engine of diversification in New World doves


Kevin P. Johnson, Illinois Natural History Survey, University of Illinois, 1816 South Oak Street, Champaign, IL 61820, USA.


Aim  The closure of the Central American land-bridge connection between North and South America 3.5 million years ago was a major biogeographic event that allowed considerable interchange of the previously isolated faunas of these continents. However, the role that this connection may have had in diversification of North and South American faunas is less well understood. The goal of this study was to evaluate the potential role of the formation of this land connection in generating diversity, through repeated rare dispersal events followed by isolation.

Location  North and South America.

Methods  We evaluated the role of the Central American land-bridge connection in avian diversification using a molecular phylogeny based on four gene regions for mid-sized New World doves. Diversification events were dated using a Bayesian relaxed clock analysis and internal calibration points for endemic island taxa with known island ages.

Results  The reconstructed phylogenetic tree was well supported and recovered monophyly of the genera Leptotila and Zenaida, but the quail-doves (Geotrygon) were paraphyletic, falling into three separate lineages. The phylogeny indicated at least nine dispersal-driven divergence events between North and South America. There were also five dispersal events in the recent past that have not yet led to differentiation of taxa (polymorphic taxa).

Main conclusions  Most of these dispersal-driven diversification events occurred at the time of or after the formation of the Central American land bridge, indicating that this land connection played a role in facilitating divergence via dispersal of doves between continents.