http://informahealthcare.com/mdn ISSN: 1940-1736 (print), 1940-1744 (electronic) Mitochondrial DNA, Early Online: 1–6 ! 2014 Informa UK Ltd. DOI: 10.3109/19401736.2013.861424 ORIGINAL ARTICLE Genetic diversity analysis of mitochondrial DNA control region in artificially propagated Chinese sucker Myxocyprinus asiaticus Yuan Wan 1,2 , Chun-hua Zhou 1,2 , Shan Ouyang 2 , Xiao-chen Huang 1,2 , Yang Zhan 3 , Ping Zhou 4 , Jun Rong 1 , and Xiao-ping Wu 1,2 1 Center for Watershed Ecology, Institute of Life Science, Nanchang University, Nanchang, China, 2 College of Life Sciences and Food Engineering, Nanchang University, Nanchang, China, 3 Jiangxi Aquaculture Technology Spreading Center, Nanchang, China, and 4 Yongfeng County Aquaculture Technology Spreading Center, Nanchang, China Abstract The genetic diversity of the three major artificially propagated populations of Chinese sucker, an endangered freshwater fish species, was investigated using the sequences of mitochondrial DNA (mtDNA) control regions. Among the 89 individuals tested, 66 variable sites (7.26%) and 10 haplotypes were detected (Haplotype diversity Hd ¼ 0.805, Nucleotide diversity  ¼ 0.0287). In general, genetic diversity was lower in artificially propagated populations than in wild populations. This reduction in genetic diversity may be due to population bottlenecks, genetic drift and human selection. A stepping-stone pattern of gene flow was detected in the populations studied, showing much higher gene flow between neighbouring populations. To increase the genetic diversity, wild lineages should be introduced, and more lineages should be shared among artificially propagated populations. Keywords Artificial propagation, Chinese sucker, control region, genetic diversity, mitochondrial DNA History Received 15 August 2013 Revised 17 October 2013 Accepted 24 October 2013 Published online 10 January 2014 Introduction Chinese sucker, Myxocyprinus asiaticus, is an endangered fresh- water fish species belonging to the family Catostomidae of the order Cypriniformes. Most species in Catostomidae are distrib- uted in North America and Chinese sucker is the only represen- tative of the family in Asia (Nelson, 1976). Therefore, Chinese sucker plays an important role in studies based on taxonomic classification and zoogeography (Wang et al., 1998; Zhang et al., 2009a). Historically, this fish species was widely distributed in the Yangtze river and the Minjiang river, and it was an economically important fish in China (Gao et al., 2008; Yuan et al., 2010). However, due to over-fishing, dam construction, water pollution and other anthropogenic disturbances, the natural populations of this species have been declining dramatically over the past decades (Zhang & Zhao, 2000). Currently, Chinese sucker is an endangered species and is listed in the second class of preserved animals in China (Wang & Xie, 2004). To preserve this rare species, artificial propagation programs have been carried out (Zhang et al., 2009b). Genetic diversity is fundamental for species protection (Avise, 2000; Xia, 1999). Generally, rare species with low genetic diversity may have low potential for population recovery and high risk of extinction because population genetic diversity can reflect the ability of species to adapt to the environmental changes (Frankham et al., 2002; Vrijenhoek, 1994). Chinese sucker is an endangered species; its natural populations are shrinking and it is very hard to find wild populations of Chinese sucker. Therefore, ex situ conservation is considered to be the most important complement to in situ conservation of Chinese sucker. Understanding the genetic diversity and genetic structure in artificially propagated Chinese sucker populations can provide insights into how to maintain the genetic diversity of this rare species ex situ. Although such information is essential for artificial propagation programs, it is still lacking for Chinese sucker. Mitochondrial DNA (mtDNA) has become a popular genetic marker for the study of animal population genetics, especially for quantifying intraspecific genetic differentiation (Carvalho, 2004; Ludwig et al., 2008; Quattro et al., 2002) because it is maternally inherited and has relatively high mutation rates compared to those of the nuclear protein-coding genes in animals. Animal mtDNA genome consists of 37 coding genes and a noncoding region, with variable rates of evolution in different regions. The displacement loop (D-loop) region in mtDNA is a noncoding control region. As a noncoding region, the D-loop region may not be directly targeted in natural selection, and its rate of evolution is therefore 5 to 10 times higher than that of coding regions of mtDNA (Cheng et al., 2011; Elisabeth et al., 2011). Xiao et al. (2009) observed relatively high variation in a 457 bp segment of the mtDNA control region in small yellow croaker and indicated that there was no significant genetic structure throughout eight sample localities from the Yellow Sea and the northern East China Sea. Klaus & Petra (2013) observed high variability in a 928 bp fragment of the control region in Cyprinus carpio and concluded that the European and Central Asian populations shared the same ancestor. In our study, a control region of mtDNA was used as a genetic marker to explore genetic diversity in Chinese sucker. The main objective of this study is to examine the genetic diversity and structure of the artificially propagated Chinese Correspondence: Xiao-ping Wu and Jun Rong, Center for Watershed Ecology, Institute of Life Science, College of Life Sciences and Food Engineering, Nanchang University, Xuefu Road 999, Nanchang, 330031 China. Tel: +86 079183969531. E-mail: xpwu@ncu.edu.cn (X.-p. Wu); rong_jun@hotmail.com (J. Rong) Mitochondrial DNA Downloaded from informahealthcare.com by Nanchang University on 04/09/14 For personal use only.