Phylogeographical pattern of Mazocraeoides gonialosae (Monogenea, Mazocraeidae) on the dotted gizzard shad, Konosirus punctatus, along the coast of China q Min Li a,1 , Su-Fen Shi a , Christopher L. Brown b , Ting-Bao Yang a,⇑ a State Key Laboratory of Biocontrol and Center for Parasitic Organisms, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China b National Oceanic and Atmospheric Administration, Aquaculture and Enhancement Division, The Milford Laboratory, 212 Rogers Avenue, Milford, CT 06460, USA article info Article history: Received 3 April 2011 Received in revised form 18 July 2011 Accepted 19 July 2011 Available online 3 September 2011 Keywords: Monogenea Mazocraeoides gonialosae Phylogeography Coast of China COI abstract In the present study, we examined the phylogeographical pattern of the monogenean, Mazocraeoides gonialosae, which parasitises the dotted gizzard shad (Konosirus punctatus) along the coast of China. Frag- ments of 756 bp of the mitochondrial cytochrome c oxidase subunit I gene were sequenced for 147 indi- viduals from seven localities along the coast of China. Phylogenetic analysis revealed no significant genealogical clades of samples corresponding to sampling localities. Analyses of molecular variance and pairwise F ST suggested a high rate of gene flow and the lack of a predictable genetic structure between different populations of this parasite. Both neutrality tests and mismatch distribution analyses indicated a recent population expansion in M. gonialosae after the last glacial maximum. Gradually decreasing genetic diversity in more northerly populations implied a historical south-to-north expansion of this parasite. Dispersal of eggs and larvae with ocean currents was considered to be associated with the genetic homogeneity of this species. The limited time to accumulate genetic variation after the last glacial maximum may also account in part for the lack of phylogeographical structure in the studied region. Ó 2011 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved. 1. Introduction Phylogeography aims to determine the principles and processes limiting the geographical distribution of genetic lineages, thereby allowing us to gain insights into processes such as population subdivision, gene flow, dispersion and ecological adaptation to past climatic changes (Avise et al., 1987; Avise, 2000). In the northwest Pacific Ocean, most of the phylogeographical analyses have concentrated on widely distributed free-living organisms such as molluscs (Yokogawa, 1997; Chang et al., 2010; Niu et al., 2010), crustaceans (Tzeng et al., 2004; Wang et al., 2008; Xu et al., 2009), and fishes (Liu et al., 2006a,b, 2007, 2009; Song et al., 2010). Results of these and other studies suggest that historical geographic events, as well as contemporary ecologies and behav- iours of organisms are likely to have played important roles in shaping the genetic structure of these species. However little attention has been paid to their parasites, which are closely associated with them. The colonising processes of oceanic parasites remain unclear, although the broad distributions of most parasites imply their facility in spreading into new habitats (Vignon and Sasal, 2010). Phylogeographical studies of parasites are intended to help gain in- sight into these characteristics. In addition, the pace of evolution for parasites is often thought to be greater than that of free-living species as a consequence of their particular life modes (De Meeûs et al., 1998; Huyse et al., 2005). Evolution of parasites is heavily influenced by both their life cycle and that of their hosts (Criscione et al., 2005). For these reasons, marine parasites may display un- ique phylogeographical patterns and provide alternative models of evolutionary biology (Plaisance et al., 2007). The Monogenea is one of the largest group of Platyhelminthes, mainly inhabiting the skin and gills of fishes, characterised by a high degree of host specificity and a direct life cycle (with no inter- mediate hosts) (Gusev, 1995; Zhang et al., 2001). Monogeneans are oviparous except for gyrodactylids (with polyembryony). Eggs of monogeneans may vary in both morphology and structure from species to species. Some may have filaments (e.g., Diclidophora lus- cae, see Whittington and Kearn, 1988; Branchotenthes octohamatus, see Glennon et al., 2006), whereas others may have no appendages (e.g., Calicotyle australis and Pseudoleptobothrium aptychotremae, see Glennon et al., 2006). The eggs hatch to release larvae known as oncomiracidia, which may disperse by actively swimming or passively drifting with the water current until they attach to 0020-7519/$36.00 Ó 2011 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijpara.2011.07.012 q Note: Nucleotide sequence data reported in this paper are available in the GenBank databases under the accession numbers JF773397–JF773482. ⇑ Corresponding author. Tel./fax: +86 020 84115126. E-mail address: tingbao123@gmail.com (T.-B. Yang). 1 Present address: South China Sea Fisheries Research Institute, Chinese Academy of Fishery Science, Guangzhou 510300, China. International Journal for Parasitology 41 (2011) 1263–1272 Contents lists available at SciVerse ScienceDirect International Journal for Parasitology journal homepage: www.elsevier.com/locate/ijpara