Detecting evolutionary rate heterogeneity among mangroves and their close terrestrial relatives

Authors

  • Yang Zhong,

    Corresponding author
    1. Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, and Institute of Biodiversity Science, Fudan University, Shanghai 200433, People's Republic of China.,
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  • Qiong Zhao,

    1. Department of Genetics, University of Wisconsin-Madison, WI 53706, USA.,
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  • Suhua Shi,

    1. Key Laboratory of Gene Engineering of Ministry of Education, School of Life Sciences, Zhongshan University, Guangzhou 510275, People's Republic of China.,
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  • Yelin Huang,

    1. Key Laboratory of Gene Engineering of Ministry of Education, School of Life Sciences, Zhongshan University, Guangzhou 510275, People's Republic of China.,
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  • Masami Hasegawa

    1. The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato-ku, Tokyo 106, Japan
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  • Editor, R. Crozier

Yang Zhong Institute of Biodiversity Science, Fudan University, Shanghai 200433, People's Republic of China. E-mail: yangzhong@fudan.edu.cn

Abstract

Mangroves form the dominant intertidal ecosystems and differ morphologically and physiologically from their close terrestrial relatives. We investigate the molecular evolutionary pattern of the typical mangrove family, i.e. Rhizophoraceae, and rate heterogeneity for the plastid matK and rbcL genes in different species of the family, as revealed by phylogenetic analyses and relative-rate tests. Our study documents evolutionary rate heterogeneity in the Rhizophoraceae for the two genes: the mangrove genus Bruguiera has relatively slow substitution rates compared to the terrestrial genus Carallia at both synonymous and non-synonymous sites in the matK sequences, and the synonymous and non-synonymous substitution matrices are correlated. However, the rbcL non-synonymous sites exhibit a high degree of rate heterogeneity among mangroves and related terrestrial groups, and uncoupling of rates with the synonymous sites. Selection is probably an important influence on the rate variation, suggesting further investigation for better understanding of various forces contributing to the rate heterogeneity and molecular adaptation in mangroves.

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