High gene flow on a continental scale in the polyandrous Kentish plover Charadrius alexandrinus CLEMENS KU ¨ PPER,* † SCOTT V. EDWARDS,* ANDRA ´ S KOSZTOLA ´ NYI, ‡ MONIF ALRASHIDI, § TERRY BURKE, † PHILIPP HERRMANN, ¶ ARACELI ARGU ¨ ELLES-TICO, ¶ JUAN A. AMAT,** MOHAMED AMEZIAN, †† AFONSO ROCHA, ‡‡ HERMANN HO ¨ TKER, §§ ANTON IVANOV, ¶¶ JOSEPH CHERNICKO*** and TAMA ´ S SZE ´ KELY ¶ *Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA, †Department of Animal and Plant Sciences, NERC Biomolecular Analysis Facility, University of Sheffield, Sheffield, S10 2TN, UK, ‡Department of Ethology, Eo ¨tvo ¨s Lora ´nd University, Pa ´zma ´ny Pe ´ter se ´ta ´ny 1/c., H-1117, Budapest, Hungary, §Department of Biology, Faculty of Science, University of Hail, PO Box 2440, Hail, Saudi Arabia, ¶Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK, **Department of Wetland Ecology, Estacio ´n Biolo ´gica de Don ˜ ana (EBD- CSIC), Calle Ame ´rico Vespucio s/n, 41092 Seville, Spain, ††Department of Biology, Faculty of Sciences, University of Abdelmalek Essaa ˆdi, PO Box 2121, Te ´touan, Morocco, ‡‡Fundac ¸a ˜o das Salinas do Samouco, 2890, Alcochete, Portugal, §§Michael-Otto-Institut im NABU, Goosstroot 1, D-24861, Bergenhusen, Germany, ¶¶Timiryazev State Biological Museum, Malaya Grusinskaya, 15, Moscow 123242, Russia, ***Azov-Black Sea Ornithological Station, Lenin Street 20, Melitopol, Ukraine Abstract Gene flow promotes genetic homogeneity of species in time and space. Gene flow can be modulated by sex-biased dispersal that links population genetics to mating systems. We investigated the phylogeography of the widely distributed Kentish plover Charadrius al- exandrinus. This small shorebird has a large breeding range spanning from Western Eur- ope to Japan and exhibits an unusually flexible mating system with high female breeding dispersal. We analysed genetic structure and gene flow using a 427-bp fragment of the mitochondrial (mtDNA) control region, 21 autosomal microsatellite markers and a Z microsatellite marker in 397 unrelated individuals from 21 locations. We found no structure or isolation-by-distance over the continental range. However, island popula- tions had low genetic diversity and were moderately differentiated from mainland loca- tions. Genetic differentiation based on autosomal markers was positively correlated with distance between mainland and each island. Comparisons of uniparentally and biparen- tally inherited markers were consistent with female-biased gene flow. Maternally inher- ited mtDNA was less structured, whereas the Z-chromosomal marker was more structured than autosomal microsatellites. Adult males were more related than females within genetic clusters. Taken together, our results suggest a prominent role for polyan- drous females in maintaining genetic homogeneity across large geographic distances. Keywords: gene flow, genetic differentiation, genetic diversity, microsatellites, sex-biased dis- persal Received 4 June 2012; revision received 24 August 2012; accepted 29 August 2012 Introduction Investigating the link between ecology and evolution is a central challenge of population biology. Dispersal has a strong influence on gene flow, genetic diversity and population structure which may in turn affect the effi- ciency of selection and local adaptation (Bohonak 1999; Clobert et al. 2004). However, dispersal is a complex process that is often difficult to assess (Edwards 1993; Okamura & Freeland 2002). For each individual, the motivation to disperse often depends on age (i.e. natal or breeding dispersal) and may differ between sexes. Sex-biased dispersal has been related to mating Correspondence: Clemens Ku ¨ pper, Fax: +1 617 495 5667; E-mail: ckuepper@oeb.harvard.edu © 2012 Blackwell Publishing Ltd Molecular Ecology (2012) 21, 5864–5879 doi: 10.1111/mec.12064