December 1 2009
12:00 154 BSRB
Center for Tropical Research, Institute of Environment, UCLA
A Global Perspective on Speciation in the Mallard Complex: New Insights on Parapatric Speciation and Incomplete Lineage Sorting
Summary:
While the mallard complex (genus: Anas) was used as an early example of incomplete lineage sorting in closely related species, and several hypotheses have been suggested to explain the origins of this group in the New World, little genetic evidence has been collected to date to address the global phylogeography of mallards. We used a large multi-species sample set and sequenced mitochondrial and nuclear DNA to investigate both the historical and contemporary phylogenetic patterns of the mallard complex, in order to understand the role that hybridization, ancestral polymorphism, and anthropogenic influences have contributed to the paraphyly observed among species within this group. Two large mtDNA haplotype groups were recovered corresponding to Avise et al.’s (1990) group A and B haplotypes, and these haplotypes were found to be distributed in striking patterns across the holarctic range of mallards. Both natural range expansion followed by introgression, and the artificial introduction of species to new areas, have the ability to erase morphological and genetic differences between sister species, as exemplified in the mallard complex in North America.