MITOCHONDRIAL GENE GENEALOGY AND GENE FLOW AMONG ISLAND AND MAINLAND POPULATIONS OF A SEDENTARY SONGBIRD, THE GREY-CROWNED BABBLER (POMATOSTOMUS TEMPORALIS) - PubMed (original) (raw)

MITOCHONDRIAL GENE GENEALOGY AND GENE FLOW AMONG ISLAND AND MAINLAND POPULATIONS OF A SEDENTARY SONGBIRD, THE GREY-CROWNED BABBLER (POMATOSTOMUS TEMPORALIS)

Scott V Edwards. Evolution. 1993 Aug.

Abstract

Distinguishing between ongoing gene flow and purely historical association of populations can be difficult without data on times of population separation and effective population sizes. To help discriminate between these two scenarios, I examined mitochondrial DNA sequence diversity in three geographically close populations of the grey-crowned babbler (Pomatostomus temporalis) separated by water barriers of known age in the Northern Territory, Australia, using the polymerase chain reaction (PCR), direct sequencing, and genealogical methods of inference. PCR primers were designed to obtain sequences from region I, a highly variable segment of the control region. Sequence diversity in all populations was consistent with neutrality. In the population on Melville Island, a Pleistocene land-bridge island, sequence variability is as high as on the mainland and consists of two mitochondrial lineages differing by 2%. Phylogenetic analyses of the sequence variation observed among 44 individuals suggest that the number of times lineages in one population trace back to ancestors of a different population (between-population coalescent events) was too high to be compatible with a model of population divergence solely by drift since rising of the water barriers, implying instead recent or ongoing gene flow across water barriers. Similar estimates of Fst , the fraction of genetic diversity apportioned among populations, were obtained when calculated using the divergence times of alleles and when estimated from Nm values derived from trees and ranging from 0.29-0.55. Both the phylogenies and patterns of allelic divergence suggest that the population on Melville Island exchanges migrants with both continental populations, although statistical tests indicated that some alternative phylogenies implying restricted gene flow among the populations could not be discounted.

Keywords: Coalescent process; control-region sequences; intraspecific phylogeny; island populations; mitochondrial DNA.

© 1993 The Society for the Study of Evolution.

PubMed Disclaimer

Similar articles

Cited by

LinkOut - more resources