Phylogeography of a Marsh Herb Sagittaria Trifolia (Alismataceae) in China Inferred from Cpdna Atpb–Rbcl Intergenic Spacers
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Molecular Phylogenetics and Evolution xxx (2008) xxx–xxx http://www.paper.edu.cn Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev Phylogeography of a marsh herb Sagittaria trifolia (Alismataceae) in China inferred from cpDNA atpB–rbcL intergenic spacers Jin-Ming Chen a, Fan Liu a, Qing-Feng Wang a,b,*, Timothy J. Motley b a Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, PR China b Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529-0266, USA article info abstract Article history: Sagittaria trifolia L. is a perennial, erect herb that is confined to ponds, rice fields, ditches, and freshwater Received 27 October 2007 wetlands. Using chloroplast DNA (cpDNA) atpB–rbcL intergenic spacer sequences, we studied the phylog- Revised 2 March 2008 eographic pattern and demographic history of S. trifolia with 108 samples from 42 populations represent- Accepted 4 March 2008 ing the entire geographic range in China. Twenty-seven haplotypes were characterized and two of them Available online xxxx were widely distributed in the populations. In the minimum-spanning network, all tip haplotypes were unique to a particular population, while the interior nodes represented widespread haplotypes. Nested Keywords: clade analysis (NCA) of cpDNA haplotypes indicated that long distance dispersal characterized the cpDNA atpB–rbcL noncoding spacer post-glacial recolonization of S. trifolia in China. No specific refugia areas were suggested because genetic sequence Marsh herb differentiation was low among the sampled regions and among populations within regions although a Nested clade analysis large number of the haplotypes were unique to a single population. The present data support that the Phylogeography unique haplotypes in individual population most likely represent recent mutational derivatives after long Sagittaria trifolia distance dispersal rather than the relics in refugia. These results for S. trifolia represent the first phylog- eographic analysis of a widespread marsh herb in China and support the importance of long distance dis- persal events in the post-glacial migrations of plants. Ó 2008 Published by Elsevier Inc. 1. Introduction (Cox and Moore, 2000; Hewitt, 2000, 2004). Most of these studies have been concerned with the patterns of distributional changes In the evolutionary history of a species, the distribution of pop- following climatic oscillations in Europe and the North America ulations could be constricted or expanded due to the environmen- (Soltis et al., 1997; Taberlet et al., 1998; Griffin and Barrett, tal changes. The climatic oscillations during the Quaternary ice age 2004; Schonswetter et al., 2005). have been considered to play a major role in changing the geo- China has some distinctive biogeographical features. The Qing- graphical distribution of plant and animal species (Hewitt, 1996, hai–Tibet (Q–T) Plateau located in the western China is the highest 2000; Comes and Kadereit, 1998). The climatic oscillations of the and the largest plateau in the world. The Q–T Plateau was a part of Quaternary, 2 million years ago, resulted in several glacial and the Ancient Tethys Sea and began to uplift about 50 million years interglacial cycles (Shackleton and Opdyke, 1973). In general, the ago in the Eocene of the Lower Tertiary (Harrison et al., 1992; An distribution of organisms shifted across latitudes and elevations et al., 2001). With the large-scale intense uplift of the Q–T Plateau, in response to these paleoclimatic cycles, contributing to species the Chinese three-step land features were formed (Zhang et al., distributions being restricted to refugia during cold, glacial periods 2000). The formation of the Q–T Plateau has dramatically influ- and rapidly range expansions with the onset of interglacial warm- enced the natural environments of the East Asia and the East Asia ing (Hewitt, 1996; Taberlet et al., 1998). flora (Coleman and Hodges, 1995; Zheng and Li, 1999; An et al., Although the effects of glacial–interglacial cycling of the Qua- 2001; Sun, 2002; Shi et al., 1998). Although no massive ice sheet ternary were global, the biological response appears to vary with developed in most parts of China during glacial periods, the tre- locality and taxa (Cox and Moore, 2000; Hewitt, 1996; Taberlet mendous global climatic changes combined with the local climatic et al., 1998). Recent progress in the use of molecular markers has changes caused by the Q–T Plateau uplift, particularly during Qua- facilitated many phylogeographic studies in northern hemisphere ternary glaciations, have influenced the distribution and evolution of many plant species in China and its neighboring areas (Zhang et al., 2005; Wang and Ge, 2006). In contrast to the numerous * Corresponding author. Address: Laboratory of Plant Systematics and Evolution- investigations on plants of Europe and North America, understand- ary Biology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, PR China. Fax: +86 27 68752560. ing of the effects of past climate events on the current distribution E-mail address: [email protected] (Q.-F. Wang). patterns of species in China is relatively limited. 1055-7903/$ - see front matter Ó 2008 Published by Elsevier Inc. doi:10.1016/j.ympev.2008.03.008 转载 Please cite this article in press as: Chen, J.-M. et al., Phylogeography of a marsh herb Sagittaria trifolia (Alismataceae) in China ..., Mol. Phylogenet. Evol. (2008), doi:10.1016/j.ympev.2008.03.008 中国科技论文在线 http://www.paper.edu.cn 2 J.-M. Chen et al. / Molecular Phylogenetics and Evolution xxx (2008) xxx–xxx Recent phylogeographical studies of Chinese plant species seven regions, i.e., Northeast China (JL-1–3, HLJ-1–8), Northwest have focused on the endangered or endemic species that with China (XJ-1 and GS-1), North China (HEB-1), Central China (HUB- narrow distribution ranges in China. Most phylogeographical 1–4, HEN-1, HUN-1), East China (JS-1 and 2, and JX-1–3), South studies of plant migration in China have dealt with woody, China (GX-1 and 2, and HAIN-1), and Southwest China (YN-1–10 long-lived tree and shrub species, e.g., Cathaya argyrophylla,an and GZH-1–4). The definition of regions in this study was followed endangered conifer restricted to subtropical mountains of China the criteria of Ren and Yang (1961), which was based on the differ- (Wang and Ge, 2006); Juniperus przewalskii, a tree endemic to ences of the altitude and latitude, the distribution of the flood and the Q–T Plateau region (Zhang et al., 2005); Alsophila spinulosa, field, the topography, the climate, and the distribution of vegeta- a relictual tree fern distributed in southern China (Su et al., tion. A total of 108 individuals from the 42 populations were in- 2005a,b) ; and Dunnia sinensis, an endangered, endemic shrub re- cluded in the study. Details on materials are given in Table 1. stricted to the southern part of Guangdong Province (Ge et al., About 5 g of fresh leaves per plant was collected and immediately 2002). Although these studies have enriched the knowledge of dried with silica gel. the effects of historical events on the current geographical distri- butions of several species in China, due to large gaps in taxo- 2.2. DNA extraction, PCR amplification, and sequencing nomic and habitat sampling, for example, as yet there are few published data examining phylogeographical patterns across a Total genomic DNA was isolated from 0.5 g of silica-dried leaf wide geographic range (Ran et al., 2006) and relating to herba- tissue following the procedure described by Fu et al. (2003). PCR ceous plant phylogeography (Huang et al., 2005), our understand- was performed in a reaction volume of 50 ll containing 0.25 mM ing of the historical biogeography events in China still remains of each dNTP, 2.5 llof10ÂTaq buffer [10 mM Tris–HCl (pH 8.3), incomplete. 1.5 mM MgCl2 and 50 mM KCl], 1 mM of each primer, 2 U Taq Poly- Sagittaria trifolia L. is a perennial, erect marsh herb that be- merase (Tian Yuan Biotech) and 60 ng of DNA template. Primers of longs to the family Alismataceae. It is a self-compatible species, Chiang et al. (1998) were used to amplify the cpDNA atpB–rbcL which can reproduce both sexually by selfed and out-crossed noncoding spacer. Amplification of genomic DNA was made on a seeds and vegetatively through corms (Chen, 1989). The species PTC-100TM thermocycler (MJ Research, Inc.), and commenced with is insect-pollinated by bees (Hymenoptera). Seeds are dispersed 4 min at 94 °C, followed by 35 cycles of 1 min at 94 °C, 1 min by water or animals (Cook, 1990). Most of the seeds drop and annealing at 50 °C and 2 min extension at 72 °C, and a final exten- germinate within populations (pers. obs. Chen J.M.). S. trifolia sion cycle of 7 min at 72 °C. The size of PCR products was deter- is one of the most widespread species in the genus Sagittaria mined by agarose electrophoresis. All PCR products were purified ranging from north Beikal in Russia to the Southeastern part of from an agarose gel using the PCR product purification kit (Shang- Asia and Europe. It is confined to ponds, rice fields, ditches, hai SBS, Biotech Ltd., China). The purified PCR products were se- and freshwater wetlands (Chen, 1989). In China, the distribution quenced in both directions by standard methods on an ABI 377 range of this species extends to most parts of the country except automated sequencer in Beijing Genomics Institute, Chinese Acad- for the Q–T Plateau and the western desert area. The current emy of Sciences. widespread distribution range probably spans the former glaci- ated (e.g., the Northeast and the Northeastern regions of China) 2.3.