RESEARCH ARTICLE Open Access

Tracing the legacy of the early Hainan Islanders-a perspective from mitochondrial DNAMin-Sheng Peng1,3,5†, Jun-Dong He1,2,3†, Hai-Xin Liu1,2,6, Ya-Ping Zhang1,3,4*

Abstract

Background: Hainan Island is located around the conjunction of East Asia and Southeast Asia, and during the LastGlacial Maximum (LGM) was connected with the mainland. This provided an opportunity for the colonization ofHainan Island by modern human in the Upper Pleistocene. Whether the ancient dispersal left any footprints in thecontemporary gene pool of Hainan islanders is debatable.

Results: We collected samples from 285 Li individuals and analyzed mitochondrial DNA (mtDNA) variations ofhypervariable sequence I and II (HVS-I and II), as well as partial coding regions. By incorporating previously reporteddata, the phylogeny of Hainan islanders was reconstructed. We found that Hainan islanders showed a closerelationship with the populations in mainland southern China, especially from Guangxi. Haplotype sharing analysessuggested that the recent gene flow from the mainland might play important roles in shaping the maternal pool ofHainan islanders. More importantly, haplogroups M12, M7e, and M7c1* might represent the genetic relics of theancient population that populated this region; thus, 14 representative complete mtDNA genomes were furthersequenced.

Conclusions: The detailed phylogeographic analyses of haplogroups M12, M7e, and M7c1* indicated that the earlypeopling of Hainan Island by modern human could be traced back to the early Holocene and/or even the lateUpper Pleistocene, around 7 - 27 kya. These results correspond to both Y-chromosome and archaeological studies.

BackgroundHainan Island, the second largest island of China, islocated in the Beibu Bay (Gulf of Tonkin) and separatedfrom Guangdong’s Leizhou Peninsula to the north by theQiongzhou Strait (Figure 1). During the Last GlacialMaximum (LGM), around 19 - 26.5 kya (thousand yearsago) [1], Hainan Island was connected with mainlandsouthern China and northern Vietnam, as the sea levelwas around 80 - 100 m below present day [2,3]. Thus,Hainan Island might lay on one of the modern humannorthward migration routes from Southeast Asia to EastAsia and it is likely that Hainan islanders may maintaincertain ancient footprints of these dispersals [4]. Thisscenario has been supported by some recent archaeologi-cal evidence, which suggested that Hainan Island might

have been colonized by human in the Upper Pleistoceneor the Upper Paleolithic period [5-8].Due to the post-glacial sea level rising and the forma-

tion of the Qiongzhou Strait, Hainan Island has beenisolated from the mainland for at least 6 thousand years[3,9]. Presently, Hainan Island is home to people withmany different languages and/or cultures. Comparedwith other ethnic/linguistic groups (e.g. Lingao, Han,and Hmong) - the recent immigrants from mainlandsouthern China [10], Li (Hlai) people were suggested tobe the earliest settlers, having arrived in Hainan Islandat least 3 kya [11]. In terms of linguistic analyses, theHlai language, used by the Li people was suggested tosplit from other languages within the Tai-Kadai (Daic)family ~ 3 - 4 kya [12]. Meanwhile, some current Lipopulations still maintain some ancient cultures of theNeolithic, e.g. bark cloth and original ceramic making[10]. Therefore, colonization of Hainan Island by theancestors of the Li people can be at least traced back tothe Neolithic period (~ 2 - 6 kya) [11,13]. However,whether the ancestor of the modern human had settled

* Correspondence: zhangyp@mail.kiz.ac.cn† Contributed equally1State Key Laboratory of Genetic Resources and Evolution, Kunming Instituteof Zoology, Chinese Academy of Sciences, Kunming, P.R. ChinaFull list of author information is available at the end of the article

Peng et al. BMC Evolutionary Biology 2011, 11:46http://www.biomedcentral.com/1471-2148/11/46

© 2011 Peng et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited.

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in this region in the Upper Pleistocene and contributedto the gene pool of modern Li populations in HainanIsland is unclear.To depict the prehistoric peopling events in this region,

human genetic approaches based on the uniparentalgenetic systems - mitochondrial DNA (mtDNA) and thenonrecombining region of the Y chromosome (NRY) -have been widely adopted [14]. By analyzing the domi-nant NRY haplogroups (paragroups) O1a* and O2a* inHainan aborigines (five Li populations and one Cunpopulation), Li et al. suggested that Hainan aborigineshad been isolated at the entrance to East Asia for ~ 20thousand years [4]. However, because of the relativelypoor resolution of phylogeny based on limited numbersof Y-SNPs, the candidate founders of the ancient disper-sal were still ambiguous. Moreover, in their later workabout O1a*, wide connections among the populationsaround the Beibu Bay (i.e. Guangxi and Hainan) andother populations from southern China and SoutheastAsia were observed [15]. This implies that the effect ofsome recent gene flows between Hainan islanders andthe populations in the mainland could not be ignored.In this study, we adopted mtDNA analyses to trace the

ancient peopling of Hainan Island in a maternal perspec-tive, because: 1) the phylogeny of mtDNA in context ofEast Asian and Southeast Asian has been improvedthanks to large scale complete mtDNA genome sequen-cing [16-28]; 2) mtDNA data of many ethnic/linguisticgroups in the neighboring regions of Hainan Island (i.e.southern China [29-36] and northern Vietnam [23,37])have been reported. Given that the maternal structures ofthe Li populations were poorly characterized in previous

work [30], we collected new samples from 285 Li indivi-duals. With comprehensive phylogeographic analysesbased on complete mtDNA genomes sequencing, weidentified some potential candidate markers for the earlypeopling of Hainan Island, which could be traced back to~ 7 - 27 kya.

ResultsThe phylogeny of mtDNA in Hainan IslandHypervariable sequence (HVS) analysis and partial cod-ing region testing indicated that all mtDNA lineages ofthe 285 Li individuals were unambiguously assigned intothe previously defined haplogroups in East and SoutheastAsians (see Additional file 1). The predominant hap-logroups in southern China and Southeast Asia: hap-logroups B, F, and M7 together account for ~ 69%, 71%,and 63% of the maternal gene pools of the populationsLi-BT, Li-LD, and Li-QZ, respectively (Table 1). The pre-vailing haplogroups in northern China, such as hap-logroups A, D4, G, and Z, were rare or even absent in thethree Li populations. Meanwhile, the previously reported162 sequences from five populations (Li-TZ, Jiamao,Cun, Danga, and Lingao) in Hainan Island [30] were re-evaluated and incorporated into further analyses. Theskeleton of the resulting phylogeny of 447 individualsfrom Hainan Island was constructed (Figure 2). ThemtDNA haplogroups profiles of the Hainan islanderswere similar to the patterns observed in the populationsfrom the mainland southern China and northern Viet-nam (Table 1). However, haplogroups M12 and M7e hadhigher frequencies (~ 6.3% and ~ 4.5%, respectively) inthe Hainan islanders than those of the populations in themainland, whose average were less than 1%.

Comparison of the Hainan islanders with otherpopulations in the mainlandTo compare the Hainan Islanders with other populationsin the mainland (see Additional file 2), the principal com-ponents (PC) analysis based on haplogroup frequencies(see Additional file 3) was performed (Figure 3). In thefirst PC, some Sinitic populations (Han-DG, HK, Hakka,and Chaoshan) clustered in one pole. In the other pole,except Lingao and Danga, most Hainan islanders wereclustered with some populations from Guangxi, whichwere distinguished from the other populations in themainland by the second PC. The genetic differencebetween Hainan islanders and populations from themainland was statistically significant (p < 0.001, Analysisof molecular variance, AMOVA), whereas the differencebetween the Li populations (Li-BT, Li-LD, Li-QZ, Li-TZ,and Jiamao) and non-Li populations (Cun, Danga, andLingao) was not (p = 0.147 ± 0.010, AMOVA). Then, weused the regression method to estimate the contributionof each haplogroup to the PCs [38]. The haplogroups

Figure 1 Map of Hainan Island and its surrounding regions,showing elevation relative to modern sea level. Map outlinewas kindly provided by YT. Yao, CAS Key Laboratory of Marginal SeaGeology, South China Sea Institute of Oceanology, Guangzhou [3].

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Table 1 mtDNA haplogroup frequencies in Hainan Island, Taiwan, mainland southern China, and Vietnam

Hainan Hainan Taiwan Guangxi Guangdong HongKong

Yunnan-SE

N-Vietnam

M-Vietnam

Mainland

Li-BT Li-LD Li-QZ Li-TZ Jiamao Cun Lingao Danga Total Total Total Total Total Total Total Total Total

Haplogroups n = 99 n =100

n =86

n =34

n = 27 n =30

n = 31 n =40

n =447

n =640

n =1111

n = 546 n = 337 n = 158 n = 326 n = 66 n = 2584

A 1.16 5.00 0.67 1.71 2.56 3.98 0.63 0.92 2.01

B* 2.94 3.70 3.33 6.45 2.50 1.34 1.08 0.55 0.80 1.90 0.92 4.55 1.04

B4* 1.00 3.70 0.45 1.71 2.20 1.86 1.27 2.76 1.52 1.93

B4a 2.02 1.00 5.81 8.82 11.11 13.33 3.23 7.50 4.92 15.63 6.03 5.13 2.65 4.43 3.37 1.52 4.80

B4b1 9.09 11.00 6.98 8.82 3.33 3.23 6.94 7.34 3.24 3.48 2.39 2.53 0.61 2.71

B4c1b 2.33 3.70 6.67 7.50 1.79 3.91 0.72 2.75 2.39 2.15 1.52 1.55

B4c2 2.50 0.22 0.36 0.55 3.16 1.23 4.55 0.74

B4g 2.02 1.16 2.94 0.89 2.16 1.47 0.80 0.63 3.07 1.78

B5a 10.10 10.00 8.14 8.82 17.50 8.28 5.16 7.92 4.40 5.57 5.70 11.66 3.03 7.04

B5b 1.00 1.16 3.70 0.67 0.72 1.65 0.61 1.52 0.77

C 6.06 1.16 10.00 6.45 7.50 3.36 4.32 2.38 3.71 6.96 3.68 3.03 3.87

D4 2.00 2.33 2.94 3.33 1.34 1.25 4.77 10.62 11.41 6.96 2.76 1.52 6.77

D5’6 7.07 3.00 3.49 2.91 4.06 1.89 5.13 6.37 2.53 2.15 1.52 3.29

E 12.03 0.18 0.04

F* 2.94 6.45 0.67 0.63 0.18 0.31

F1* 3.03 1.16 3.23 1.12 2.07 3.48 1.59 4.43 2.15 1.52 2.44

F1a* 3.00 1.16 0.89 2.19 4.05 4.95 3.71 3.16 7.36 9.09 4.68

F1a1* 9.09 16.00 5.81 3.33 3.23 2.50 7.38 3.28 3.42 4.03 5.04 4.43 4.29 6.06 4.02

F1a1a 2.00 1.16 3.23 0.89 3.51 3.11 2.92 2.53 5.83 9.09 3.72

F2 4.04 6.00 3.49 25.93 6.45 2.50 5.15 0.16 1.62 3.30 3.45 0.63 0.61 2.01

F3 3.03 3.23 2.50 1.12 8.44 3.96 3.48 2.12 5.70 0.92 3.21

F4 1.16 5.88 10.00 3.23 1.57 11.25 0.72 0.92 0.53 0.31 0.62

G 8.82 3.33 3.23 2.50 1.34 0.16 2.07 2.38 1.06 7.59 0.92 3.03 2.21

M* 2.94 3.23 0.45 2.88 0.92 3.18 3.16 3.37 7.58 2.71

M10 1.01 1.16 3.33 7.50 1.34 0.63 1.08 2.01 1.86 0.63 0.92 1.32

M12 11.11 4.00 9.30 5.88 3.70 5.00 6.26 0.31 0.72 0.73 3.16 1.53 1.52 0.89

M20 1.16 0.22 0.09 0.37 0.61 0.19

M33 3.33 9.68 0.89 1.17 0.92 1.33 0.61 0.97

M71 3.23 0.22 0.54 0.37 0.27 1.27 0.92 3.03 0.62

M74 2.00 3.23 0.67 0.54 0.18 0.80 0.63 3.03 0.50

M7b* 5.05 3.00 3.49 3.70 3.33 6.45 3.36 11.56 6.75 4.95 5.84 9.49 5.83 6.06 6.27

M7b1 10.10 9.00 1.16 5.88 7.41 6.67 3.23 10.00 6.94 0.78 9.09 3.66 6.63 5.70 6.75 6.06 7.00

M7c1’2 3.03 6.98 5.88 2.50 2.68 6.56 1.89 2.56 1.33 2.76 1.52 1.93

M7c3 6.06 1.00 2.33 2.01 1.44 1.83 1.59 1.23 1.39

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Table 1 mtDNA haplogroup frequencies in Hainan Island, Taiwan, mainland southern China, and Vietnam (Continued)

M7c* 2.00 4.65 2.94 1.57 0.09 0.04

M7e 2.02 5.00 4.65 14.71 13.33 4.47 0.18 0.53 0.61 0.23

M8a 3.03 4.00 1.16 2.94 7.41 3.33 6.45 3.13 1.08 2.38 1.06 0.92 1.52 1.28

M9a’b 4.65 0.89 1.53 0.73 1.59 1.27 1.53 1.52 1.35

N* 0.99 0.18 0.63 1.23 0.66

N10 3.23 0.22 0.09 0.37 0.53 0.61 0.27

N9a 2.02 3.49 2.94 3.23 2.50 1.79 1.56 3.42 3.85 2.12 3.37 1.52 3.06

R* 3.33 3.23 5.00 0.89 1.08 0.18 1.59 1.27 0.92 0.93

R11 1.01 2.33 3.70 2.50 1.12 1.08 0.55 0.80 0.70

R9* 0.27 1.27 0.92 3.03 0.39

R9b 8.00 5.81 2.94 18.52 6.67 2.50 4.92 3.96 1.47 2.12 3.16 3.37 7.58 3.13

R9c 6.00 3.70 3.23 1.79 2.34 0.63 0.73 2.12 1.27 1.53 3.03 1.08

Y 1.41 0.36 0.37 0.53 0.31

Z 2.50 0.22 0.36 1.83 1.86 1.90 2.15 1.20

HaplotypeDiversities

0.976 0.966 0.982 0.980 0.960 0.972 0.996 0.986 0.987 0.966 0.989 0.996 0.994 0.991 0.992 0.988 –

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16298 @16304 16355

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16095A 16242 16301

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@16304

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12705 16223

N16257A 16261

16142 16176

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10398 10873

489 10400

M

16234

9824

16297

146

1636516129

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16172 16311

16291

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16266Y

@162954163622

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2

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4715 16298

249d16184 16319

16185 16260

16327

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16095A 16217Y 16242

16262A 16298Y 16240

16129 16148

16171 16344 16357

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1614516311 16390

16229

16175 16311

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16468 16470 16471 16473

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M8

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2

16274

1620116234 16290 16258T

7

16094

163623

3 2

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2

16362

16189

16311

16195

32

16190 16234

16360

316126 16174 16192 16343

2

1609316129 16263

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4833

4883

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4491 16234

M9

3

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D5’6

2

2 16274

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16290 16319

A 1636216092 16145

16126 16235

16172

N10

16129 16311

2

16093 16193 16357

M10

16162 16172 16209 16272

M20

16213

16271M71

16111

16104

16235

M33

1631116093M74

Cun (Dongfang)

Danga (Lingshui)

Lingao (Lingao)

Li-TZ (Wuzhishan)

Li-QZ (Qiongzhong)

Li-LD (Ledong)

Li-BT (Baoting)

Jiamao (Baoting)

16093 16287

16093

M7bM7c1’2

M7e

M7b1

4 3

16136 16319

16274

16274R

16311

16249A

2

16274

16093

16167 16203 16318

2

16154Y

16093Y

16086

16269 16292 16300

16362

16294

2 16311R11

2

B5bF1a

F1a1

2

Non-Li Populations:Li (Hlai) Populations:

16298 @16304 16355

16213

16129 @16223 16232 16390

16129

16355

16274 16381

16129 16233C

16399

16092 16136

16259 16278 16294 16319

16172 16271 16278

16291A16298 16362

16225 16271

16234 16311@16234

16291

16224 16260 16266

16344T

16093

16129

16168 16256

16258C

16297

16111 16234

16103 16214

16092 16291 16319 16390

16242A

1631116140 16274 16335

16147 16184A 16235

16179

16299

16240

16361 16399

16209

16154

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16178

16093

16189

16140

16243

16266A

3

1636216294

16217

1626116338R

16136

2

16129

2

16362

16311

3

16309 16354

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16390 16399

16245

16093

16298

5

16092

2

7

8

3

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2

16280

216092 16172

16284

3

2

2

2

16095A 16242 16301

2

16291 16301 16463

R

B

2

2

16292

22

16189

16192Y

16325

16218G

16192G

16266

16304

12406 16309

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4

16299

16362

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16399

161923

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16260

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16192

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16218

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R9b

F

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16291

16311

74

12705 16223

N16257A 16261

16142 16176

16311

3

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L3

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489 10400

M

16234

9824

16297

146

1636516129

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16176

16295

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16291

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16256

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5

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4715 16298

249d16184 16319

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16095A 16217Y 16242

16262A 16298Y 16240

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16229

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16468 16470 16471 16473

4

M8

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16362

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316126 16174 16192 16343

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4883

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M9

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D

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16189

16290 16319

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16126 16235

16172

N10

16129 16311

2

16093 16193 16357

M10

16162 16172 16209 16272

M20

16213

16271M71

16111

16104

16235

M33

1631116093M74

Cun (Dongfang)

Danga (Lingshui)

Lingao (Lingao)

Li-TZ (Wuzhishan)

Li-QZ (Qiongzhong)

Li-LD (Ledong)

Li-BT (Baoting)

Jiamao (Baoting)

16093 16287

16093

M7bM7c1’2

M7e

M7b1

4 3

16136 16319

16274

16274R

16311

16249A

2

16274

16093

16167 16203 16318

2

16154Y

16093Y

16086

16269 16292 16300

16362

16294

2 16311R11

2

B5bF1a

F1a1

2

Non-Li Populations:Li (Hlai) Populations:

Figure 2 Tree drawn from a median-joining network of 180 mtDNA haplotypes observed in Hainan Island. mtDNA motifs of HVS-I(16080-16488) combined with HVS-II and/or certain coding region sites were considered to improve the resolution of the tree which wasconstructed manually and checked by using the Network 4.510. The circles represent mtDNA sequence types, shaded according to populationwith an area proportional to their absolute frequency. The geographic sources of populations were also noted. These are transitions whilesuffixes A, C, G and T refer to transversions, “Y” specifies heteroplasmic status C/T at the site, and “@” means a reverse mutation. Sevenhaplotypes were determined as the existing of heteroplasmic sites.

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M12, M7e, M7b1, M7c*, and B4b1 were found to contri-bute most to the pole consisting of Hainan islanders andthe populations from Guangxi (Figure 4).

Dissection of mtDNA haplotypes in Hainan IslandTo analyze mtDNA variation at a finer level, we dis-sected the haplotype information mainly based on HVS-I segment 16080 - 16488 (Figure 2). In general, the Hai-nan Island populations showed fairly high haplotypediversities compared with Taiwan aborigines or otherpopulations from the mainland (Table 1). Some haplo-types were shared by the Li and non-Li populationswithin Hainan Island. In total of 178 haplotypes (16090- 16365) observed in Hainan islanders, 80 types couldbe found the identical counterparts in the mainland (seeAdditional file 4). In addition, the median-joining net-works of the most frequent haplogroups (B4b1, B5a,F1a1, R9b, and M7b1) were unable to identify candidatefounder types which were suitable to date the relatedpeopling of Hainan Island (see Additional file 5).For the rest of the three haplogroups (i.e. M12, M7e,

and M7c*) contributing most to the pole of Hainan islan-ders in PCA (Figure 4), some interesting patterns wereobserved. With HVS-I motifs as 16223-16234-16258T-16290, 16189-16223-16278 and 16166C-16172-16223-16311, three lineages assigned within haplogroups M12,M7c* and M7e, respectively, were restricted in Hainan

Island. Meanwhile, the lineages of 16223-16234-16258T-16290 and 16166C-16172-16223-16311 underwent cer-tain sub-differentiation to generate the derived lineages(Figure 2). Moreover, haplogroups M12, M7c* and M7ewere more concentrated in the Li populations than thosein other non-Li populations (Table 1). Hence, this impliesthat the three haplogroups might be useful to trace theearly peopling of Hainan Island.

Candidate markers for the early peopling of HainanIslandAs the available phylogeny of haplogroups M12, M7e,and M7c* has not been well depicted at a fine-grainedlevel, we sequenced 14 complete mtDNA genomes: ele-ven from haplogroup M12, two from haplogroup M7eand one from haplogroup M7c* (Figure 5). The phylo-geny of haplogroup M12 was much improved comparedto previous work [20,39]. As the result of the earliestsplit, haplogroup M12b was defined by mutations11359-16129-16172 and haplogroup M12a was deter-mined by 318-12358. Within haplogroup M12a, hap-logroup M12a2 was newly determined by two sequencesfrom Vietnam as sharing mutations 463-16261 and Cinsertion at 573. Haplogroup M12a1 was defined by thesequence variation motif in HVS-II as 125-127-128 andthen was further divided into two clades as M12a1a andM12a1b. All sequences from Hainan Island were

Figure 3 Principle components analysis (PCA) of populations in southern China and Vietnam. The detailed information of 50 populationsemployed and their haplogroup profiles was indicated in Additional file 2 and 3.

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clustered with the sequences from Guangdong and Viet-nam into haplogroup M12a1a defined by transitions15463-15651. The unique lineage of Hainan islanderswith HVS-I motif as 16223-16234-16258T-16290 wasderived directly from the root of M12a1a suggestingthat the modern human colonization of Hainan Islandwas likely to be associated with the differentiation ofM12a1a around 17 - 20 kya.To characterize the phylogeographic pattern of hap-

logroup M12, the median-joining network was con-structed with all available M12 mtDNAs (Figure 6; seeAdditional file 6). Haplogroup M12 was widely distribu-ted in southern China, Southeast Asia and the easternpart of India, but relatively concentrated in Yunnan andHainan Island (Figure 6). The network suggested hap-logroup M12 was likely to originate from mainlandsouthern China and Southeast Asia. The estimatedexpansion time of M12a1*, which includes the lineages

from Hainan Island, was 24.2 ± 10.0 kya. The expansionof M12a1-16362 lineages in Hainan Island was esti-mated as 6.9 ± 3.4 kya. The results were largely inagreement with the results from the complete mtDNAgenomes (Figure 5). The two ages would be consideredas the potential upper (~ 24 kya) and lower (~ 7 kya)limits for the peopling of Hainan Island represented byhaplogroup M12, respectively.The phylogeny of haplogroup M7e based on complete

mtDNA genomes revealed that the sequence (Li241)with 16166C-16172-16223-16311 was directly derivedfrom the root of haplogroup M7e around 6.5 - 8.0 kya(Figure 5). As the lineages with the proto haplotypesdefined by HVS-I variations 16172-16223-16311 weremainly found in southern China and Vietnam (see Addi-tional file 7), the colonization of Hainan Island repre-sented by haplogroup M7e would be probably from thisregion around 15.1 ± 11.5 kya (Figure 7). However, as

Figure 4 Plot of the haplogroup contribution of the first and second PC. The contribution of each haplogroup was calculated as the factorscores for PC1 and PC2 with regression method (REGR) in SPSS13.0 software.

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the network of haplogroup M7e was not in the ideallystar-like structure, the time estimates with a huge stan-dard error should be treated with caution. When weestimated the expansion time of M7e without the Hai-nan data, the age (9.4 ± 5.9 kya; Figure 7) seemed morecompatible with the result based on mtDNA genomes(Figure 5).For the sequences of M7c* with HVS-I motif as 16189-16223-16278, the complete mtDNA sequence (Li152)could be assigned into M7c1 but did not cluster withany known lineages of M7c1. This pattern implied thatthe related peopling of Hainan Island was likely to betraced back to the initial differentiation of haplogroupM7c1 as early as ~ 18 - 27 kya (Figure 5).

DiscussionIn general, the mtDNA haplogroup profiles of Hainanislanders are similar to the profiles of the populationsfrom mainland southern China. This pattern is consis-tent with the previous work on NRY [4,40-43]. It

suggests the Hainan islanders should have derived frommainland southern China and/or have had a commonorigin with the populations from this region [30]. Espe-cially, most Hainan islanders were clustered with somepopulations from Guangxi (Figure 3). This pattern wasalso reflected by the genome-wide data: the Jiamaopopulation in Hainan Island was clustered with theZhuang population (i.e. the dominant minority ethnicgroup in Guangxi) as a branch in the tree of the “Pan-Asian” [44]. Thus, the ancestors of the Li populationswere likely from Guangxi.As the prevailing haplotype sharing has been found

between the Hainan islanders and the populations fromthe mainland, the role of the recent gene flow from themainland in shaping the maternal pool of Hainan islan-ders can not be ignored. This result is in agreement withthe archaeological research, which revealed that the tightlinks between Hainan Island and mainland southernChina existed during the Neolithic period [5,10,13].Meanwhile, some haplotypes were shared by the Li

16258T 15530 s

15204 I~T 14182 s 11965 s 4242 s 3450 s 3010 r

151 146

HainanLi200

7220 s

15043 s14783 s10400 s

489

M

16290 16234

15010 s 14727 t 12372 s

12030 N~S 5580

4170 s

M12

128 127 125

M12a1

1617211353 s 5492 s @318

14016 s 194 189

16209 12699 s

@11353 s 152

1631115344 s 14774 s 5814 t 5288 s 1888 r 633 t 523-524d @128

15951 t 15236 I~V 14788 s

13708 A~T7080 F~L

1331 r

7166 s523-524d374

QK1# Guangdong

GD7825 AY255172

AC# India GL31

FJ383651

FamilyTree# Hakka

EU294322

AC# India

PB119 FJ383653

AC# India PB8

FJ383652

14569 s

15651 A~V 15463 s

12358 T~A 318

16362 9490 A~V 4048 D~N 523-524d

513

8472 P~L 1664 t

@1623414383 s 12067 s 3736 V~I

@1623416093

14693 t 8005 s

150

16320 9101 I~T

5744

1614814377 s 12285 t

7270 V~A 7196 s 4973 s

Vietnam Kinh004

Vietnam Cham

146

Vietnam Kinh129

HainanLi352

HainanLi273

M12a1a

16274 16262 1612914691 t 2405A r 1719 r

152143

Vietnam Cham058

M12a2

16261 573+C

463

1617216129

11359 s

16354 16325 16305

@1623415884T A~S 10923 T~I

7337 s 3337 V~M

573+C152

Thailand Thai24

M12b

1618912616 s

11025 L~P 9755 s 3621 s

195 146

1626116148

15894 t15424 s 13914 s 11172R

11016 S~N 6446 s 6314 s 4562 s 979 r

Yunnan Lisu40

M12a

16201

HainanLi256

G

93 16094 15894 t

13708 A~T9966 V~I 5899+C 4853 s

HainanLi351

9824 s 6455 s

M7

12091 s 11665 s 4850 s 4071 s

523-524d199 146

1631116172

15338 s 14053 T~A

11932 s 10897 s 9449 s 5378 s 3912 s @199

MD# Czech

Cz32_III EF153810

1618911084 T~A

6713 s 5174 s

15301 s 10873 s

10398 A~T 9540 s

8701 A~T

N

16223 12705 s

R

14766 I~T11719 s 7028 s 2706 r

73

H

15326 A~T 8860 A~T

4769 s 1438 r 750 r 263

rCRS

L3

HainanLi348

M7e

5442 F~L 3882 s

16278 16189

14766 I~T9629 s 7546 t 2768 r 2755 r 1420 r

M7c1

HainanLi152

SP: 6.5 2.3 kyLE: 8.0 4.0 ky

SP: 19.0 3.0 kyLE: 27.4 6.5 ky

M7c’e

M12a1b

SP: 41.7 6.4 kyLE: 28.5 6.1 ky

SP: 21.2 3.8 kyLE: 17.0 5.4 ky

16291

QK1# Yunnan Dai125

HM030509

16166C 14552 V~A

10897 s

7909 s

HainanLi241

SP: 6.1 2.3 kyLE: 5.3 3.8 ky

16258T 15530 s

15204 I~T 14182 s 11965 s 4242 s 3450 s 3010 r

151 146

HainanLi200

7220 s

15043 s14783 s10400 s

489

M

16290 16234

15010 s 14727 t 12372 s

12030 N~S 5580

4170 s

M12

128 127 125

M12a1

1617211353 s 5492 s @318

14016 s 194 189

16209 12699 s

@11353 s 152

1631115344 s 14774 s 5814 t 5288 s 1888 r 633 t 523-524d @128

15951 t 15236 I~V 14788 s

13708 A~T7080 F~L

1331 r

7166 s523-524d374

QK1# Guangdong

GD7825 AY255172

AC# India GL31

FJ383651

FamilyTree# Hakka

EU294322

AC# India

PB119 FJ383653

AC# India PB8

FJ383652

14569 s

15651 A~V 15463 s

12358 T~A 318

16362 9490 A~V 4048 D~N 523-524d

513

8472 P~L 1664 t

@1623414383 s 12067 s 3736 V~I

@1623416093

14693 t 8005 s

150

16320 9101 I~T

5744

1614814377 s 12285 t

7270 V~A 7196 s 4973 s

Vietnam Kinh004

Vietnam Cham

146

Vietnam Kinh129

HainanLi352

HainanLi273

M12a1a

16274 16262 1612914691 t 2405A r 1719 r

152143

Vietnam Cham058

M12a2

16261 573+C

463

1617216129

11359 s

16354 16325 16305

@1623415884T A~S 10923 T~I

7337 s 3337 V~M

573+C152

Thailand Thai24

M12b

1618912616 s

11025 L~P 9755 s 3621 s

195 146

1626116148

15894 t15424 s 13914 s 11172R

11016 S~N 6446 s 6314 s 4562 s 979 r

Yunnan Lisu40

M12a

16201

HainanLi256

G

93 16094 15894 t

13708 A~T9966 V~I 5899+C 4853 s

HainanLi351

9824 s 6455 s

M7

12091 s 11665 s 4850 s 4071 s

523-524d199 146

1631116172

15338 s 14053 T~A

11932 s 10897 s 9449 s 5378 s 3912 s @199

MD# Czech

Cz32_III EF153810

1618911084 T~A

6713 s 5174 s

15301 s 10873 s

10398 A~T 9540 s

8701 A~T

N

16223 12705 s

R

14766 I~T11719 s 7028 s 2706 r

73

H

15326 A~T 8860 A~T

4769 s 1438 r 750 r 263

rCRS

L3

HainanLi348

M7e

5442 F~L 3882 s

16278 16189

14766 I~T9629 s 7546 t 2768 r 2755 r 1420 r

M7c1

HainanLi152

SP: 6.5 2.3 kyLE: 8.0 4.0 ky

SP: 19.0 3.0 kyLE: 27.4 6.5 ky

M7c’e

M12a1b

SP: 41.7 6.4 kyLE: 28.5 6.1 ky

SP: 21.2 3.8 kyLE: 17.0 5.4 ky

16291

QK1# Yunnan Dai125

HM030509

16166C 14552 V~A

10897 s

7909 s

HainanLi241

SP: 6.1 2.3 kyLE: 5.3 3.8 ky

Figure 5 Reconstructed phylogenetic tree of 21 complete mtDNA genome sequences from haplogroups M12 and M7c’e. The sixreported sequences were taken from the literature and were further labeled by the symbols MD [18], AC [39], QK1 [20], and QK2 [28] followedby “#”, the geographic locations, and the sample codes or the access numbers in GenBank. One sequence (Accession No. EU294322) submittedby “Family Tree DNA” was retrieved from GenBank. Haplogroup age estimates (±standard errors) are indicated at the branch roots in terms ofthe calibrated mutation rate with symbols as SP [58] and LE [66], respectively. Mutations are transitions at the respective nucleotide positionunless otherwise specified. Letters following positions indicate transversions. Recurrent mutations are underlined. +: insertion; d: deletion; @:back-mutation. “R” specifies heteroplasmic status A/G and was also noted in italic. Amino acid replacements are specified by single-letter code; s,synonymous replacements; t, change in transfer RNA; r, change in ribosomal RNA gene.

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http://www.ncbi.nlm.nih.gov/pubmed/294322?dopt=Abstract

(original aborigines) and the non-Li (recent immigrants)populations (Figure 2). It suggests that intermarriagesamong different populations might be common andcould strengthen the effect of recent demographic events.As a result, although certain haplogroups in Hainanislanders present the star-like phylogeny in the network(e.g. B5a and M7b1, Figure 2; see Additional file 5) andthe characteristics of the candidate founders [45],whether their expansion time estimates (Table 2) could

be associated with the early peopling of Hainan Island isstill elusive.To trace the early peopling of Hainan Island, we paid

more attention to haplogroups M12 M7c1*, and M7e,because: 1) they have relatively high frequencies in Hai-nan Island and are relatively concentrated in the Lipopulations; 2) some lineages within these haplogroupsare only found in Hainan Island; 3) certain sub-differen-tiation within these haplogroups are observed. Detailed

M12b (N=28)

16278

M12a2

M12a1M12a (N=70)

@16234 16093

16311 16266

16239

16225 16093

16309

16274 16262 16129

16148

16261

16172

16311

16249

16261 16148

16189

16209

16094

16258T

16311

@16234

16129

1627416189

16362

1620116287

16093

(128 127 125)

16311

16093

16223 16111

16108

16305

@16234

16312

16290 16234

16172 16129

16320 (318)

† 16223-73-263M

Yunnan

Vietnam

South China (Guangxi, Guangdong, and Taiwan )

Thailand

Hainan Island

Malaysia, Singapore, and Indonesia

South Asia

151

@16172

M12a1b

M12a1* (w/o M12a1b) 24.2 10.0 kya

16354 1632516220

M12 (N=98)

M12a1-16362 12.6 7.4 kyaM12a1-16362 (only Hainan Island)

6.9 3.4 kya

M12

Figure 6 Median-joining network of HVS-I sequences of haplogroup M12 and the spatial frequency distribution. The circles representmtDNA HVS-I (16090 - 16365) sequence types, shaded according to region with an area proportional to their absolute frequency which is alsoindicated by the number in the circle. Mutations are transitions unless the base change is explicitly indicated. Heteroplasmic positions areindicated by an “H” after the nucleotide positions. Some HVS-II sites were employed to improve the resolution and were noted in parentheses.

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phylogeographic analyses based on mtDNA genomessuggested the initial peopling of Hainan Island was likelyto be around 7 - 27 kya (Figure 5 - 6) when HainanIsland was connected with the mainland southern Chinaand/or northern Vietnam [3,9]. The long-standing con-nection between Hainan Island and the mainland fromthe LGM to 6 - 7 kya [3,9] could provide the opportu-nity for some of the dispersals of modern human. Ourresults are largely in agreement with the time estimatesfrom NRY [4] and are supported by the recent archeolo-gical findings [5-8]. However, as mentioned above, thegene pool of Hainan islanders was likely to be affectedby the recent immigrants from the mainland. To pindown the recent gene flow and the ancient componentsin detail, it is necessary to improve the resolution ofmolecular markers, together with extensive sampling,and even to employ genome-wide autosomal markers,which could be the future direction and would providemore details about the peopling of Hainan Island.

ConclusionsCombining the fresh data of the mtDNA variation of the285 Li individuals and those from previous study, we

not only help to further understand the mtDNA phylo-geny in Hainan Island but also provide deeper insightsinto the peopling of Hainan Island. Although somegenetic differentiations from the populations in themainland did emerge, in general, the mtDNA phylogenyin Hainan Island was represented as a subset in the con-text of East Asian and Southeast Asian. The ancestors ofthe Li people were likely from the populations in main-land southern China, especially in Guangxi. The recentgene flow from the mainland might play important rolesin shaping the maternal pool of Hainan islanders. Basedon the mtDNA genome sequencing, the phylogeo-graphic analyses of haplogroups M12, M7e, and M7c1*suggested that the related immigration from mainlandsouthern China and Vietnam could be trace back toaround 7 - 27 kya, which largely corresponds to theresults from NRY and archaeology.

MethodsPopulation samples and DNA extractionIn total, we collected samples from 285 unrelated Liindividuals residing in Hainan Island (Figure 2): 86 fromQiongzhong Li and Miao Autonomous County (Li-QZ);99 from Baoting Li and Miao Autonomous County (Li-BT); and 100 from Ledong Li Autonomous County (Li-LD). All subjects were interviewed to ascertain their eth-nic affiliations and to obtain informed consent beforeblood collection. Comparative mtDNA data from south-ern China and Vietnam were taken from previous pub-lished literature (see Additional file 2). Genomic DNAwas extracted from whole blood samples by the stan-dard phenol/chloroform methods.

MtDNA typingThe mtDNA control region sequences were amplified bythe PCR method previously reported [46]. HVS-I (mini-mum length sequenced was nucleotide positions (np)16080-16569; maximum length sequenced np 16001-16569) and HVS-II (minimum length sequenced np 1-207;maximum length sequenced np 1-575) were sequenced inall samples as described elsewhere [47]. We performedhaplogroup-specific control region motif recognition and

16274

16166C

16291

16287 16086

Northern China

Other

Southern China

Hainan Island

1631116172@199

1609316298

16189

161

M7e (N=35)

† 16223-73-146-199-263M7c’e

15.1 11.5 kya

Vietnam

M7e (the mainland only) 9.4 5.9 kya

Figure 7 Median-joining network of HVS-I sequences ofhaplogroup M7e. The circles represent mtDNA HVS-I (16085 -16365) sequence types, shaded according to region with an areaproportional to their absolute frequency which is also indicated bythe number in the circle. Mutations are transitions unless the basechange is explicitly indicated. Heteroplasmic positions are indicatedby an “H” after the nucleotide position.

Table 2 Coalescence ages of the most frequent mtDNA haplogroups in Hainan Island

Total Li

Haplogroups Individuals r s T ΔT Individuals r s T ΔT

B5a 37 1.03 0.32 19.4 5.9 30 1.07 0.35 20.1 6.6

B4b1 31 0.45 0.26 8.5 4.9 29 0.45 0.27 8.4 5.2

F1a1-16399 31 0.13 0.07 2.4 1.2 30 0.13 0.07 2.5 1.3

M7b1 31 0.45 0.22 8.5 4.2 24 0.54 0.29 10.2 5.0

M12 28 0.61 0.40 11.4 7.6 26 0.54 0.39 10.1 7.4

R9b 21 1.67 1.00 31.4 18.8 19 1.21 1.10 31.7 20.7

M7e 20 1.00 0.82 18.8 15.4 16 1.00 0.78 18.8 14.6

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(near-) matching search with the published mtDNA datato assign each mtDNA into specific, named haplogroups[46]. Then we selected certain mtDNAs from sequenceshaving similar HVS motifs to genotype the related diag-nostic sites in the coding region to confirm their hap-logroup status (see Additional file 1). Moreover, 14 wholemtDNA genomes were sequenced following protocolsreported elsewhere [48-50]. The sequences generated inthis study have been deposited in GenBank database(Accession Nos. HQ156470-HQ156754 for HVS andHQ157971-HQ157984 for mtDNA genome sequences).Sequences were edited and aligned by Lasergene

(DNAStar Inc., Madison, Wisconsin, USA) and muta-tions were scored relative to the revised Cambridgesequence (rCRS) [51]. For the length variants in thecontrol region, we followed the rules proposed by Ban-delt and Parson (2008) [52]. The transition at 16519 andthe C-length polymorphisms in regions 16180-16193and 303-315 were disregarded in the analyses. The clas-sification of the mutations of each mtDNA genomeswas performed with mtDNA GeneSyn 1.0 http://www.ipatimup.pt/downloads/mtDNAGeneSyn.zip [53]. Toavoid any nomenclature conflicts, we followed the cri-terion of PhyloTree (http://www.phylotree.org, mtDNAtree Build 10) [54] and the recent updating mtDNAphylogeny in East Asia [28].

Data analysesFor HVS data, we constructed the median-joining net-work using Network 4.510 http://www.fluxus-engineer-ing.com/sharenet.htm [55]. The coalescent age of ahaplogroup of interest was estimated by statistics r ±s [56,57] and the rate of 18,845 years per transitionfor control region (16090-16365) [58] was used (Table2). Principal components analysis (PCA) followed themethod developed by Richards et al. with SPSS13.0software (SPSS) [38]. Analysis of molecular variance(AMOVA) was computed with the package Arlequin3.11 http://cmpg.unibe.ch/software/arlequin3/ [59].The counter map of spatial frequency was created byusing the Kriging algorithm of the Surfer 8.0 package(Golden Software Inc., Golden, Colorado, USA) [60].To detect the recent gene flow, haplotypes sharinganalyses between the Hainan islanders and the popula-tions from the mainland were carried out based onphylogeny [61].For complete mtDNA sequences, the phylogeny was

reconstructed manually and checked by Network 4.510.Six reported sequences were employed for tree recon-structed (Figure 5). To estimate the coalescence time ofhaplogroup M7c1, additional 13 complete mtDNA gen-omes from the published literature (Accession Nos.EF153823, EF397561, EU007890, EU597541, AP008755,

AP008336, AP008647, AP008886, AP010681, AP010827,HM030514, HM030523, and HM030547) [18,27,28,62-65] were employed but not displayed in thetree. The coalescent age was also estimated by statisticsr ± s [56,57]. The recent calibrated rates for the entiremtDNA genome [58] and for only the synonymousmutation [66] were adopted, respectively (Figure 5).

Additional material

Additional file 1: mtDNA control and coding region information of285 Li individuals from three populations. The data provide themarkers examined in the subjects of the present study.

Additional file 2: Information of comparative populations used inthis study. The information includes ethnic groups, sample sizes,geographic locations, language affinities, and the references for alladditional files.

Additional file 3: mtDNA haplogroup frequencies of 50 populationsfrom Hainan Island, mainland southern China, and Vietnam. Thedata were used in the PCA and AMOVA.

Additional file 4: Haplotype sharing between Hainan islanders andthe populations in the neighboring mainland region. The haplotypesharing was calculated with the fragment 16090 - 16365 in HVS-I.

Additional file 5: Median-joining network of HVS-I sequences ofhaplogroups B4b1, B5a, F1a1, R9b, and M7b1. The information referssequences from populations in Hainan Island and its neighboring regionsin the mainland.

Additional file 6: mtDNA sequences of haplogroup M12. Theinformation refers 98 sequences of haplogroup M12 used to reconstructthe median-joining network.

Additional file 7: mtDNA sequences of haplogroup M7e. Theinformation refers 35 sequences of haplogroup M7e used to reconstructthe median-joining network.

AcknowledgementsWe are grateful to all the donors for providing blood samples. We thankChun-Ling Zhu, Shi-Fang Wu, and Ji-Shan Wang for technical assistance andYan-Tao Yao for providing the map of Hainan Island. And we thank Dr. ChadL. Samuelsen for language editing. This study was supported by grants fromNational Natural Science Foundation of China (30621092 and 30900797), andBureau of Science and Technology of Yunnan Province (2009CI119).

Author details1State Key Laboratory of Genetic Resources and Evolution, Kunming Instituteof Zoology, Chinese Academy of Sciences, Kunming, P.R. China. 2School ofLife Science, University of Science and Technology of China, Hefei, P.R.China. 3KIZ/CUHK Joint Laboratory of Bioresources and Molecular Research inCommon Diseases, Kunming, P.R. China. 4Laboratory for Conservation andUtilization of Bio-resources, Yunnan University, Kunming, P.R. China.5Graduate School of the Chinese Academy of Sciences, Beijing, P.R. China.6Current address: Program in Neuroscience, SUNY at Stony Brook, StonyBrook, New York, USA.

Authors’ contributionsMSP: contributed to the experiment work, data analysis and manuscriptwriting; JDH: carried out the experiment work and data analysis; HXL:performed the experiment work and commented the manuscript; YPZ:designed the study and prepared the manuscript; and all authors have readand approved the final manuscript.

Received: 30 September 2010 Accepted: 15 February 2011Published: 15 February 2011

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http://www.ncbi.nih.gov/entrez/query.fcgi?db=Nucleotide&cmd=search&term=HQ156470http://www.ncbi.nih.gov/entrez/query.fcgi?db=Nucleotide&cmd=search&term=HQ156754http://www.ncbi.nih.gov/entrez/query.fcgi?db=Nucleotide&cmd=search&term=HQ157971http://www.ncbi.nih.gov/entrez/query.fcgi?db=Nucleotide&cmd=search&term=HQ157984http://www.ipatimup.pt/downloads/mtDNAGeneSyn.ziphttp://www.ipatimup.pt/downloads/mtDNAGeneSyn.ziphttp://www.phylotree.orghttp://www.fluxus-engineering.com/sharenet.htmhttp://www.fluxus-engineering.com/sharenet.htmhttp://cmpg.unibe.ch/software/arlequin3/http://www.biomedcentral.com/content/supplementary/1471-2148-11-46-S1.XLShttp://www.biomedcentral.com/content/supplementary/1471-2148-11-46-S2.DOChttp://www.biomedcentral.com/content/supplementary/1471-2148-11-46-S3.XLShttp://www.biomedcentral.com/content/supplementary/1471-2148-11-46-S4.XLShttp://www.biomedcentral.com/content/supplementary/1471-2148-11-46-S5.PDFhttp://www.biomedcentral.com/content/supplementary/1471-2148-11-46-S6.XLShttp://www.biomedcentral.com/content/supplementary/1471-2148-11-46-S7.XLS

References1. Clark PU, Dyke AS, Shakun JD, Carlson AE, Clark J, Wohlfarth B, Mitrovica JX,

Hostetler SW, McCabe AM: The Last Glacial Maximum. Science 2009,325:710-714.

2. Huang ZG, Zhang WQ, Chai FX, Xu QH: On the lowest sea level duringthe culmination of the lastest glacial period in South China. Acta GeogrSin 1995, 50:385-393.

3. Yao YT, Harff J, Meyer M, Zhan WH: Reconstruction of paleocoastlines forthe northwestern South China Sea since the Last Glacial Maximum. SciChina Ser D-Earth Sci 2009, 52:1127-1136.

4. Li D, Li H, Ou C, Lu Y, Sun Y, Yang B, Qin Z, Zhou Z, Li S, Jin L: Paternalgenetic structure of Hainan aborigines isolated at the entrance to EastAsia. PLoS ONE 2008, 14:e2168.

5. Hao SD, Wang DX: Hainan archaeology: retrospect and prospect. Kaogu2003, 291-299.

6. Li CR, Li Z, Wang DX, Hao SD, Wang MZ, Jiang B, Huang ZX, Fang XL:Some stone artifacts discovered in Changjiang, Hainan. Acta AnthropolSin 2008, 27:66-69.

7. Li Z, Li CR, Wang DX: Paleolithic archaeology in Hainan Province. InProceedings of the Eleventh Annual Meeting of the Chinese Society ofVertebrate Paleontology. Edited by: Dong W. Beijing: China Ocean Press;2008:167-172.

8. Wang DX: The Hunyaling zoolite of Changjiang Country. In ArchaeologyAlmanac (1999). Edited by: Chinese Society of Archaeology. Beijing: CultureRelics Publishing House; 2001:267-268.

9. Zhao HT, Wang LR, Yuan JY: Origin and time of Qiongzhou Strait. MarGeol & Quaternary Geol 2007, 27:33-40.

10. Yan J: Eco-environmental changes in Hainan Island Beijing: Science Press;2008.

11. Du R, Yip VF: Ethnic groups in China Beijing and New York: Science Press;1993.

12. Ostapirat W: Kra-Dai and Austronesian: notes on phonologicalcorrespondences and vocabulary distribution. In The peopling of East Asia:putting together archaeology, linguistics and genetics. Edited by: Sagart L,Blench R, Sanchez-Mazas A. London and New York: RoutledgeCurzon;2005:107-131.

13. Wang HP: The Neolithic archaeological discoveries and researches inHainan. J Hainan Normal Univ 1990, 81-89.

14. Underhill PA, Kivisild T: Use of Y chromosome and mitochondrial DNApopulation structure in tracing human migrations. Annu Rev Genet 2007,41:539-564.

15. Li H, Wen B, Chen SJ, Su B, Pramoonjago P, Liu YF, Pan SL, Qin ZD, Liu W,Cheng X, et al: Paternal genetic affinity between western Austronesiansand Daic populations. BMC Evol Biol 2008, 8:146.

16. Ingman M, Kaessmann H, Pääbo S, Gyllensten U: Mitochondrial genomevariation and the origin of modern humans. Nature 2000, 408:708-713.

17. Dancause KN, Chan CW, Arunotai NH, Lum JK: Origins of the Moken SeaGypsies inferred from mitochondrial hypervariable region and wholegenome sequences. J Hum Genet 2009, 54:86-93.

18. Derenko M, Malyarchuk B, Grzybowski T, Denisova G, Dambueva I,Perkova M, Dorzhu C, Luzina F, Lee HK, Vanecek T, et al: Phylogeographicanalysis of mitochondrial DNA in northern Asian Populations. Am J HumGenet 2007, 81:1025-1041.

19. Hill C, Soares P, Mormina M, Macaulay V, Meehan W, Blackburn J, Clarke D,Raja JM, Ismail P, Bulbeck D, et al: Phylogeography and ethnogenesis ofaboriginal Southeast Asians. Mol Biol Evol 2006, 23:2480-2491.

20. Kong QP, Bandelt HJ, Sun C, Yao YG, Salas A, Achilli A, Wang CY, Zhong L,Zhu CL, Wu SF, et al: Updating the East Asian mtDNA phylogeny: aprerequisite for the identification of pathogenic mutations. Hum MolGenet 2006, 15:2076-2086.

21. Kong QP, Yao YG, Sun C, Bandelt HJ, Zhu CL, Zhang YP: Phylogeny of EastAsian mitochondrial DNA lineages inferred from complete sequences.Am J Hum Genet 2003, 73:671-676.

22. Macaulay V, Hill C, Achilli A, Rengo C, Clarke D, Meehan W, Blackburn J,Semino O, Scozzari R, Cruciani F, et al: Single, rapid coastal settlement ofAsia revealed by analysis of complete mitochondrial genomes. Science2005, 308:1034-1036.

23. Peng MS, Quang HH, Dang KP, Trieu AV, Wang HW, Yao YG, Kong QP,Zhang YP: Tracing the Austronesian footprint in Mainland SoutheastAsia: a perspective from mitochondrial DNA. Mol Biol Evol27:2417-2430.

24. Soares P, Trejaut JA, Loo JH, Hill C, Mormina M, Lee CL, Chen YM,Hudjashov G, Forster P, Macaulay V, et al: Climate change and postglacialhuman dispersals in Southeast Asia. Mol Biol Evol 2008, 25:1209-1218.

25. Tabbada KA, Trejaut J, Loo JH, Chen YM, Lin M, Mirazon-Lahr M, Kivisild T,De Ungria MC: Philippine mitochondrial DNA diversity: a populatedviaduct between Taiwan and Indonesia? Mol Biol Evol 2010, 27:21-31.

26. Trejaut JA, Kivisild T, Loo JH, Lee CL, He CL, Hsu CJ, Li ZY, Lin M: Traces ofarchaic mitochondrial lineages persist in Austronesian-speakingFormosan populations. PLoS Biol 2005, 3:1362-1372.

27. Tanaka M, Cabrera VM, González AM, Larruga JM, Takeyasu T, Fuku N,Guo LJ, Hirose R, Fujita Y, Kurata M, et al: Mitochondrial genome variationin Eastern Asia and the peopling of Japan. Genome Res 2004,14:1832-1850.

28. Kong QP, Sun C, Wang HW, Zhao M, Wang WZ, Zhong L, Hao XD, Pan H,Wang SY, Cheng YT, et al: Large-scale mtDNA screening reveals asurprising matrilineal complexity in East Asia and its implications to thepeopling of the region. Mol Biol Evol 2011, 28:513-522.

29. Gan RJ, Pan SL, Mustavich LF, Qin ZD, Cai XY, Qian J, Liu CW, Peng JH,Li SL, Xu JS, et al: Pinghua population as an exception of Han Chinese’scoherent genetic structure. J Hum Genet 2008, 53:303-313.

30. Li H, Cai X, Winograd-Cort ER, Wen B, Cheng X, Qin Z, Liu W, Liu Y, Pan S,Qian J, et al: Mitochondrial DNA diversity and population differentiationin Southern East Asia. Am J Phys Anthropol 2007, 134:481-488.

31. Wang WZ, Wang CY, Cheng YT, Xu AL, Zhu CL, Wu SF, Kong QP, Zhang YP:Tracing the origins of Hakka and Chaoshanese by mitochondrial DNAanalysis. Am J Phys Anthropol 2010, 141:124-130.

32. Wen B, Li H, Gao S, Mao X, Gao Y, Li F, Zhang F, He Y, Dong Y, Zhang Y,et al: Genetic structure of Hmong-Mien speaking populations in EastAsia as revealed by mtDNA lineages. Mol Biol Evol 2005, 22:725-734.

33. Wen B, Li H, Lu D, Song X, Zhang F, He Y, Li F, Gao Y, Mao X, Zhang L,et al: Genetic evidence supports demic diffusion of Han culture. Nature2004, 431:302-305.

34. Yao YG, Nie L, Harpending H, Fu YX, Yuan ZG, Zhang YP: Geneticrelationship of Chinese ethnic populations revealed by mtDNAsequence diversity. Am J Phys Anthropol 2002, 118:63-76.

35. Kivisild T, Tolk HV, Parik J, Wang YM, Papiha SS, Bandelt HJ, Villems R: Theemerging limbs and twigs of the East Asian mtDNA tree. Mol Biol Evol2002, 19:1737-1751.

36. Yao YG, Kong QP, Bandelt HJ, Kivisild T, Zhang YP: Phylogeographicdifferentiation of mitochondrial DNA in Han Chinese. Am J Hum Genet2002, 70:635-651.

37. Irwin JA, Saunier JL, Strouss KM, Diegoli TM, Sturk KA, O’Callaghan JE,Paintner CD, Hohoff C, Brinkmann B, Parsons TJ: Mitochondrial controlregion sequences from a Vietnamese population sample. Int J Legal Med2008, 122:257-259.

38. Richards M, Macaulay V, Torroni A, Bandelt HJ: In search of geographicalpatterns in European mitochondrial DNA. Am J Hum Genet 2002,71:1168-1174.

39. Chandrasekar A, Kumar S, Sreenath J, Sarkar BN, Urade BP, Mallick S,Bandopadhyay SS, Barua P, Barik SS, Basu D, et al: Updating phylogeny ofmitochondrial DNA macrohaplogroup M in India: dispersal of modernhuman in South Asian corridor. PLoS ONE 2009, 4:e7447.

40. Sun Y, Yang B, Ou C, Chen L, Su Z, Li D: Investigation into the origin of Liethnic group in China by genetic analysis of Y chromosome singlenucleotide polymorphism. China Trop Med 2007, 7:1527-1529.

41. Sun Y, Yang B, Ou C, Zhou Z, Su Z, Li D: Origins of the Three MinorityPopulations in Hainan Island as Seen from Y-SNP. Sci &Technol Rev 2007,25:44-47.

42. Yang B, Li D, Sun Y, Ou C, Ying D: Genetic analysis of Y-chromosomalsingle nucleotide polymorphoism in three banches of Li ethnic groupsin Hainan Province. China Trop Med 2007, 7:341-356.

43. Li D, Sun Y, Lu Y, Mustavich LF, Ou C, Zhou Z, Li S, Jin L, Li H: Geneticorigin of Kadai-speaking Gelong people on Hainan island viewed from Ychromosomes. J Hum Genet 2010, 55:462-468.

44. Abdulla MA, Ahmed I, Assawamakin A, Bhak J, Brahmachari SK, Calacal GC,Chaurasia A, Chen CH, Chen JM, Chen YT, et al: Mapping human geneticdiversity in Asia. Science 2009, 326:1541-1545.

45. Richards M, Macaulay V, Hickey E, Vega E, Sykes B, Guida V, Rengo C,Sellitto D, Cruciani F, Kivisild T, et al: Tracing European founderlineages in the near eastern mtDNA pool. Am J Hum Genet 2000,67:1251-1276.

Peng et al. BMC Evolutionary Biology 2011, 11:46http://www.biomedcentral.com/1471-2148/11/46

Page 12 of 13

http://www.ncbi.nlm.nih.gov/pubmed/19661421?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18076332?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18076332?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18482451?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18482451?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11130070?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11130070?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19158811?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19158811?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19158811?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17924343?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17924343?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/16982817?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/16982817?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/16714301?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/16714301?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12870132?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12870132?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15890885?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15890885?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20513740?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20513740?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18359946?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18359946?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19755666?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19755666?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15466285?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15466285?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20713468?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20713468?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20713468?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18270655?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18270655?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17668442?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17668442?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19591216?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19591216?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15548747?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15548747?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15372031?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11953946?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11953946?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11953946?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12270900?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12270900?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11836649?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11836649?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17960413?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17960413?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12355353?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12355353?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19823670?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19823670?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19823670?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20485445?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20485445?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20485445?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20007900?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20007900?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11032788?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/11032788?dopt=Abstract

46. Yao YG, Kong QP, Wang CY, Zhu CL, Zhang YP: Different matrilinealcontributions to genetic structure of ethnic groups in the Silk Roadregion in China. Mol Biol Evol 2004, 21:2265-2280.

47. Yao YG, Kong QP, Man XY, Bandelt HJ, Zhang YP: Reconstructing theevolutionary history of China: a caveat about inferences drawn fromancient DNA. Mol Biol Evol 2003, 20:214-219.

48. Fendt L, Zimmermann B, Daniaux M, Parson W: Sequencing strategy forthe whole mitochondrial genome resulting in high quality sequences.BMC Genomics 2009, 10:139.

49. Wang HW, Jia XY, Ji YL, Kong QP, Zhang QJ, Yao YG, Zhang YP: Strikinglydifferent penetrance of LHON in two Chinese families with primarymutation G11778A is independent of mtDNA haplogroup backgroundand secondary mutation G13708A. Mutat Res 2008, 643:48-53.

50. Zhao M, Kong QP, Wang HW, Peng MS, Xie XD, Wang WZ, Duan JG,Cai MC, Zhao SN, et al: Mitochondrial genome evidence revealssuccessful Late Paleolithic settlement on the Tibetan Plateau. Proc NatlAcad Sci USA 2009, 106:21230-21235.

51. Andrews RM, Kubacka I, Chinnery PF, Lightowlers RN, Turnbull DM,Howell N: Reanalysis and revision of the Cambridge reference sequencefor human mitochondrial DNA. Nat Genet 1999, 23:147-147.

52. Bandelt HJ, Parson W: Consistent treatment of length variants in thehuman mtDNA control region: a reappraisal. Int J Legal Med 2008,122:11-21.

53. Pereira L, Freitas F, Fernandes V, Pereira JB, Costa MD, Costa S, Maximo V,Macaulay V, Rocha R, Samuels DC: The diversity present in 5140 humanmitochondrial genomes. Am J Hum Genet 2009, 84:628-640.

54. van Oven M, Kayser M: Updated comprehensive phylogenetic tree ofglobal human mitochondrial DNA variation. Hum Mutat 2009, 30:E386-E394.

55. Bandelt HJ, Forster P, Rohl A: Median-joining networks for inferringintraspecific phylogenies. Mol Biol Evol 1999, 16:37-48.

56. Forster P, Harding R, Torroni A, Bandelt HJ: Origin and evolution of nativeAmerican mtDNA variation: a reappraisal. Am J Hum Genet 1996,59:935-945.

57. Saillard J, Forster P, Lynnerup N, Bandelt HJ, Norby S: mtDNA variationamong Greenland Eskimos: the edge of the Beringian expansion. Am JHum Genet 2000, 67:718-726.

58. Soares P, Ermini L, Thomson N, Mormina M, Rito T, Rohl A, Salas A,Oppenheimer S, Macaulay V, Richards MB: Correcting for purifyingselection: an improved human mitochondrial molecular clock. Am J HumGenet 2009, 84:740-759.

59. Excoffier L, Laval G, Schneider S: Arlequin ver. 3.0: an integrated softwarepackage for population genetics data analysis. Evol Bioinform Online 2005,1:47-50.

60. Cavalli-Sforza LL, Menozzi P, Piazza A: The history and geography of humangenes Princeton: Princeton University Press; 1994.

61. Achilli A, Olivieri A, Pala M, Metspalu E, Fornarino S, Battaglia V,Accetturo M, Kutuev I, Khusnutdinova E, Pennarun E, et al: MitochondrialDNA variation of modern Tuscans supports the near eastern origin ofEtruscans. Am J Hum Genet 2007, 80:759-768.

62. Bilal E, Rabadan R, Alexe G, Fuku N, Ueno H, Nishigaki Y, Fujita Y, Ito M,Arai Y, Hirose N, et al: Mitochondrial DNA haplogroup D4a is a marker forextreme longevity in Japan. PLoS ONE 2008, 3:e2421.

63. Hartmann A, Thieme M, Nanduri LK, Stempfl T, Moehle C, Kivisild T,Oefner PJ: Validation of microarray-based resequencing of 93 worldwidemitochondrial genomes. Hum Mutat 2009, 30:115-122.

64. Ingman M, Gyllensten U: Rate variation between mitochondrial domainsand adaptive evolution in humans. Hum Mol Genet 2007, 16:2281-2287.

65. Nohira C, Maruyama S, Minaguchi K: Phylogenetic classification ofJapanese mtDNA assisted by complete mitochondrial DNA sequences.Int J Legal Med 2010, 124:7-12.

66. Loogväli EL, Kivisild T, Margus T, Villems R: Explaining the imperfection ofthe molecular clock of hominid mitochondria. PLoS ONE 2009, 4:e8260.

doi:10.1186/1471-2148-11-46Cite this article as: Peng et al.: Tracing the legacy of the early HainanIslanders- a perspective from mitochondrial DNA. BMC EvolutionaryBiology 2011 11:46.

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http://www.ncbi.nlm.nih.gov/pubmed/15317881?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15317881?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/15317881?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12598688?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12598688?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/12598688?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19331681?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19331681?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18619472?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18619472?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18619472?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18619472?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19955425?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19955425?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/10508508?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/10508508?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17347766?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17347766?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19426953?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19426953?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18853457?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18853457?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/10331250?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/10331250?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/8808611?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/8808611?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/10924403?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/10924403?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19500773?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19500773?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19325852?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19325852?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17357081?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17357081?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17357081?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18545700?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18545700?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18623076?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/18623076?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17617636?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/17617636?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19066930?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/19066930?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20041137?dopt=Abstracthttp://www.ncbi.nlm.nih.gov/pubmed/20041137?dopt=Abstract

AbstractBackgroundResultsConclusions

BackgroundResultsThe phylogeny of mtDNA in Hainan IslandComparison of the Hainan islanders with other populations in the mainlandDissection of mtDNA haplotypes in Hainan IslandCandidate markers for the early peopling of Hainan Island

DiscussionConclusionsMethodsPopulation samples and DNA extractionMtDNA typingData analyses

AcknowledgementsAuthor detailsAuthors' contributionsReferences

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