海南坡鹿的起源、进化及保护

坡鹿是世界濒危物种,三个亚种分布在东南亚大陆,仅海南坡鹿种群分布在中国海南岛.2003年,国际社会的专家和学者提出了将海南坡鹿引入泰国亚种原分布区,重建已经绝灭野生种群的建议.在此种情况下,明确海南坡鹿的起源、与其它亚种间的系统发生关系、以及遗传多样性水平对有效保护坡鹿具有重要意义.本研究以线粒体DNA D-loop区490 bp基因片段为分子标记,比较分析了海南坡鹿、泰国亚种和缅甸亚种共35个样本的序列差异.我们所测的样本中,总共发现4种单倍型.所有21个海南坡鹿样品共享1种单倍型.利用最大似然法(ML)、最大简约法(MP)、邻接法(NJ)和贝叶斯法(Bayesian)构建的系统进化树表明海南坡鹿种群与泰国亚种的关系较近.但是,二者也发生一定程度的遗传分化.海南坡鹿与泰国亚种的遗传距离均值为0.026.我们推测海南坡鹿可能是在更新世冰期(69万年前)通过陆桥由东南亚大陆迁入中国海南岛.我们的结论说明海南坡鹿的遗传多样性很低,并且已独立进化很长时间.因此,我们不支持将海南坡鹿引入泰国亚种的原分布区,重建已经绝灭的野生种群的设想和建议.我们建议将海南坡鹿与泰国亚种分别作为两个独立的进化显著单元(ESUs)进行管理.

The origin and phylogenetics of Hainan Eld's deer and implications for Eld's deer conservation

Eld's deer (Cervus eldi) , a highly endangered cervid, includes three subspecies (C. e. eldi, C. e. siamensis and C. e, thamin) that distribute in Southeast Asia and one separated population of C. e. siamensii occurs in Hainan Island of China named Hainan Eld's deer. The endangered subspecies C. e. siamensis has been extinct in wild in Thailand over several dec-ades. Recently, a conservation program has been launched in Thailand to establish wild population of C. e. siamensis from cap-tive breeding deer in the zoo. Hainan Eld' s deer has been considered as supplement resource for the reestablish deer population. In this study, we analyzed variation in the mitochondria! DNA (mtDNA) D-loop sequences of 35 Eld's deer samples, including two Eld's deer subspecies (C e. siamensis and C. e. thamin) and Hainan Eld's deer to address the following questions: (1) where did the Hainan Eld's deer originate from; (2) the relationship between Hainan Eld's deer and subspecies C. e. siamen-sis , and (3) the genetic diversity of Hainan Eld' s deer population. Four haplotypes were observed in all samples, all the sam-ples of Hainan Eld's deer shared an identical haplotype. We constructed phylogenetic trees by Maximum likelihood (ML) , max-imum parsimony ( MP) , Neighbour-Joining ( NJ ) and Bayesian method using the results of this study with sequences data provid-ed by GenBank together. The Hainan Eld's deer and C. e. siamensis were clustered together by MP and NJ method, however, some genetic differentiation was detected between the Hainan Eld' s deer and C. e. siamensii. The average genetic distance is 0.026 between the Hainan Eld's deer and 6". e. siamensii. Our results suggest that Eld's deer could distribute via land bridge from the South-easten Asian mainland to the Hainan Island during the Pleistocene (0. 69 Mya) when the sea level of Beibu Gulf seacoast went down in glacier age. Our results indicate a long-term historical isolation of Hainan Eld's deer population from its original resource. Therefore, we do not recommend using Hainan Eld' s deer as supplement of C. e. siamensis. We recommend C. e. hainanus and C. e. siamensis should be both managed as evolutionarily significant units (ESUs).