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BMC Evol Biol. 2017 Dec 7;17(1):246. doi: 10.1186/s12862-017-1089-6.

Historical isolation and contemporary gene flow drive population diversity of the brown alga Sargassum thunbergii along the coast of China.

Li JJ1,2,3, Hu ZM4,5, Sun ZM6, Yao JT1,2, Liu FL7, Fresia P8, Duan DL1,2.

Author information

1
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
2
Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China.
3
Institute of Marine Biology, College of Oceanography, Hohai University, Nanjing, 210098, China.
4
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. huzm@qdio.ac.cn.
5
Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China. huzm@qdio.ac.cn.
6
Laboratory of Marine Organism Taxonomy & Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
7
Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China.
8
Unidad de Bioinform atica, Institut Pasteur de Montevideo, Mataojo, 2020, Montevideo, Uruguay.

Abstract

BACKGROUND:

Long-term survival in isolated marginal seas of the China coast during the late Pleistocene ice ages is widely believed to be an important historical factor contributing to population genetic structure in coastal marine species. Whether or not contemporary factors (e.g. long-distance dispersal via coastal currents) continue to shape diversity gradients in marine organisms with high dispersal capability remains poorly understood. Our aim was to explore how historical and contemporary factors influenced the genetic diversity and distribution of the brown alga Sargassum thunbergii, which can drift on surface water, leading to long-distance dispersal.

RESULTS:

We used 11 microsatellites and the plastid RuBisCo spacer to evaluate the genetic diversity of 22 Sargassum thunbergii populations sampled along the China coast. Population structure and differentiation was inferred based on genotype clustering and pairwise F ST and allele-frequency analyses. Integrated genetic analyses revealed two genetic clusters in S. thunbergii that dominated in the Yellow-Bohai Sea (YBS) and East China Sea (ECS) respectively. Higher levels of genetic diversity and variation were detected among populations in the YBS than in the ECS. Bayesian coalescent theory was used to estimate contemporary and historical gene flow. High levels of contemporary gene flow were detected from the YBS (north) to the ECS (south), whereas low levels of historical gene flow occurred between the two regions.

CONCLUSIONS:

Our results suggest that the deep genetic divergence in S. thunbergii along the China coast may result from long-term geographic isolation during glacial periods. The dispersal of S. thunbergii driven by coastal currents may facilitate the admixture between southern and northern regimes. Our findings exemplify how both historical and contemporary forces are needed to understand phylogeographical patterns in coastal marine species with long-distance dispersal.

KEYWORDS:

Gene flow; Historical isolation; Long-distance dispersal; Microsatellite; Plastid RuBisCo spacer; Population genetic diversity; Sargassum thunbergii

PMID:
29216823
PMCID:
PMC5721624
DOI:
10.1186/s12862-017-1089-6
[Indexed for MEDLINE]
Free PMC Article

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