Guo Wuxia, Banerjee Achyut Kumar, Wu Haidan, Ng Wei Lun, Feng Hui, Qiao Sitan, Liu Ying, Huang Yelin
Department of Bioengineering, Zhuhai Campus of Zunyi Medical University, Zhuhai, China.
State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
Front Plant Sci. 2021 Jun 23;12:637009. doi: 10.3389/fpls.2021.637009. eCollection 2021.
Mangroves are ecologically important forest communities in tropical and subtropical coasts, the effective management of which requires understanding of their phylogeographic patterns. However, these patterns often vary among different species, even among ecologically similar taxa or congeneric species. Here, we investigated the levels and patterns of genetic variation within consisting of two species ( and ) with nearly sympatric ranges across the Indo-West Pacific (IWP) region by sequencing three chloroplast DNA regions (for both species) and genotyping 11 nuclear microsatellite loci (for ). Consistent with findings in studies on other mangrove species, we found that both and showed relatively high genetic variation among populations but low genetic variation within populations. Haplotype network and genetic clustering analyses indicated two well-differentiated clades in both and . The relationship between geographic and genetic distances and divergence time estimates of the haplotypes indicated that limited dispersal ability of the propagules, emergence of land barriers during ancient sea-level changes, and contemporary oceanic circulation pattern in the IWP influenced the current population structure of the two species. However, the position of genetic break was found to vary between the two species: in , strong divergence was observed between populations from the Indian Ocean and the Pacific Ocean possibly due to land barrier effect of the Malay Peninsula; in , the phylogeographic pattern was created by a more eastward genetic break along the biogeographic barrier identified as the Huxley's line. Overall, our findings strongly supported previous hypothesis of mangrove species divergence and revealed that the two species have different phylogeographic patterns despite their close genetic relationship and similar current geographic distribution. The findings also provided references for the management of mangroves, especially for the threatened .
红树林是热带和亚热带海岸具有重要生态意义的森林群落，对其进行有效管理需要了解其系统发育地理格局。然而，这些格局在不同物种间往往存在差异，即使是在生态相似的分类群或同属物种之间。在这里，我们通过对三个叶绿体DNA区域（两个物种都测）进行测序以及对11个核微卫星位点（仅对[某一物种]进行基因分型），研究了在印度 - 西太平洋（IWP）区域具有近乎同域分布的两个物种（[物种名称1]和[物种名称2]）的遗传变异水平和格局。与其他红树林物种研究结果一致，我们发现[物种名称1]和[物种名称2]在种群间均表现出相对较高的遗传变异，但种群内遗传变异较低。单倍型网络和遗传聚类分析表明，[物种名称1]和[物种名称2]均有两个分化明显的分支。单倍型的地理距离与遗传距离之间的关系以及分化时间估计表明，繁殖体有限的扩散能力、古代海平面变化期间陆地屏障的出现以及IWP区域当前的海洋环流模式影响了这两个物种当前的种群结构。然而，发现两个物种的遗传间断位置有所不同：在[物种名称1]中，印度洋和太平洋种群之间观察到强烈分化，这可能是由于马来半岛的陆地屏障效应；在[物种名称2]中，系统发育地理格局是由沿着被确定为赫胥黎线的生物地理屏障更向东的遗传间断形成的。总体而言，我们的研究结果有力地支持了先前关于红树林物种分化的假设，并表明这两个[物种名称]物种尽管遗传关系密切且当前地理分布相似，但具有不同的系统发育地理格局。这些发现也为[物种名称]红树林的管理提供了参考，特别是对于受威胁的[物种名称]。
