Paleoceanographic changes in the late Pliocene promoted rapid
diversification in pelagic seabirds
Abstract
In marine environments, paleoceanographic changes can act as drivers of
diversification and speciation, even in highly mobile marine organisms.
Shearwaters are a group of pelagic seabirds with a well-resolved
phylogeny that are globally distributed and show periods of both slow
and rapid diversification. Using reduced representation sequencing data,
we explored the role of paleoceanographic changes on diversification and
speciation in these highly mobile pelagic seabirds. We performed
molecular dating, applying a multispecies coalescent approach (MSC) to
account for the high levels of incomplete lineage sorting (ILS). We
identified a major effect of the Pliocene marine megafauna extinction,
followed by a period of high dispersal and rapid speciation.
Biogeographic analyses showed that dispersal appears to be favoured by
surface ocean currents, and we found that founder and vicariant events
are the main processes of diversification. Body mass appears to be a key
phenotypic trait potentially under selection during shearwater
diversification, and it shows significant associations with life
strategies and local conditions. We also found incongruences between the
current taxonomy and patterns of genomic divergence, suggesting
revisions to alpha taxonomy. Globally, our findings extend our
understanding on the drivers of speciation and dispersal of highly
mobile pelagic seabirds and shed new light on the important role of
paleoceanographic events.