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Vol. 45 No. 2, 2006
Phylogeographic Structure of Lenok (Brachymystax lenok Pallas) (Salmoninae, Salmonidae) Populations in Water Systems of Eastern China, Inferred from Mitochondrial DNA Sequences
Ying-Zhe Xia1,2, Yi-Yu Chen3, and Yan Sheng1,*
1School of Environment and Natural Resource, Renmin University of China, Beijing 100872, China
2Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
3Chinese Academy of Sciences, Beijing 100864, China
Ying-Zhe Xia, Yi-Yu Chen, and Yan Sheng (2006)
Salmonid fishes represent a model system for addressing a wide range of
biogeographic, evolutionary, and conservation questions. Studies on the
genetic structure and phylogeographic pattern of Brachymystax lenok
Pallas (Salmoninae, Salmonidae) populations are important for
addressing the systematics, evolution, and effective conservation of
the species. Partial sequences of the mitochondrial control region (835
bp) and cytochrome (cyt) b
(1069 bp) were obtained by PCR amplification from 71 B. lenok
individuals from 7 populations in the river systems of northern China.
Analysis of molecular variance indicated that a high proportion of the
total genetic variance was distributed among regions, supporting strong
geographic structuring of mtDNA polymorphism. Phylogenetic analysis was
conducted using Neighbor-joining (NJ), maximum likelihood (ML), and
Bayesian approaches, based on the combined control region and cyt b
sequences. Seventeen haplotypes were assigned to 3 clades that were
related to geographic regions. No shared haplotypes were found among
regions. The pattern of phylogenetic discontinuity, which is associated
with spatial separation, is a result of both historical (long-term,
zoogeographic barriers to gene flow) and contemporary (limited
dispersal and gene flow capabilities) components. Based on our results,
together with geological age data, we inferred that after entering the
Amur River drainage, lenoks spread southwardly along inland drainages
and hypothesize the dispersal route of the species in the water systems
of eastern China. We further propose that each of the 3 evolutionarily
distinct groups of lenok populations should be protected in order to
avoid the loss of biodiversity. It is highly recommended that
management efforts focus on riverine conservation, and avoid
translocations among populations of different regions.
Key words: Phylogeography, Mitochondrial DNA, Control region, Cytochrome b, Brachymystax lenok.
*Correspondence: Tel: 86-10-62563057. Fax: 86-10-62565689. E-mail: wawa4257@hotmail.com
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