%0 Journal Article
%T Sex£¿ and species£¿biased gene flow in a spotted eagle hybrid zone
%A Niclas Backstr£¿m
%A ¨¹lo V£¿li
%J BMC Evolutionary Biology
%D 2011
%I BioMed Central
%R 10.1186/1471-2148-11-100
%X Our data suggest that there is a directional bias in migration rates between hybridizing spotted eagles in eastern Europe. We find that a model including post divergence gene flow fits our data best for both autosomal and Z-chromosome linked loci but, for the Z-chromosome, the rate is reduced in the direction from A. pomarina to A. clanga.The fact that some introgression still occurs on the Z-chromosome between these species suggests that the differentiation process is in a more premature phase in our study system than in previously studied avian species pairs and that could be explained by a shorter divergence time and/or a longer average generation time in the spotted eagles. The results are in agreement with field observations and provide further insight into the role of sex-linked loci for the build-up of barriers to gene flow among diverging populations and species.To get deeper insight into the mechanisms behind population differentiation and speciation, a crucial step is to understand the genetic underpinnings of reproductive isolation. Earlier efforts have revealed that, given the proportion of the genome covered by the physical size of sex-chromosomes, loci located on these chromosomes may contribute appreciably more than expected to reduced fitness in hybrids [1]. Most of the evidence spring from analyses of species with male heterogamety (XY-systems), where advanced genetic or genomic tools have been available for some time. It has for example been shown that regions on the X-chromosome affect hybrid fitness in Drosophila crosses or introgression lines [2-4], that several genes that cause hybrid breakdown or hybrid sterility in Mus species map to the X-chromosome [5-8], and also that the relative size of the X-chromosome compared to the autosomes affects the rate whereby reproductive isolation evolves in Drosophila [9]. Recently, there has been an accumulation of evidence that points to that the Z-chromosome plays a correspondingly important role in organ
%U http://www.biomedcentral.com/1471-2148/11/100