摘要
Aims Pluchea indica is a mangrove-associate species,known for its medicinal properties in its native range and being invasive in part of its introduced range.This study aimed to assess geographic distribution of genetic variation of this species across its distribution range,identify the factors influencing its genetic structure and use this information to suggest conservation and management strategies in its native and introduced ranges,respectively.Methods We assessed the genetic diversity and population structure of 348 individuals from 31 populations across its native(Asia)and introduced(USA)ranges for 15 nuclear microsatellite loci.The spatial pattern of genetic variation was investigated at both large and regional spatial scales with the hypothesis that geographic distance and natural geographic barriers would influence the population structure with varying levels of differentiation across spatial scales.Important Findings We found relatively high genetic diversity at the population level and pronounced genetic differentiation in P.indica,as compared with the genetic diversity parameters of mangroves and mangrove associates in this region.Most of the populations showed heterozygote deficiency,primarily due to inbreeding and impediment of gene flow.Analysis of population structures at large spatial scale revealed the presence of two major clusters across the species’natural range separating populations in China from those in Indonesia,Malaysia,Singapore,Thailand,Cambodia and Philippines,and that the USA population might have been introduced from the population cluster in China.Genetic differentiation between populations was also observed at the regional scale.A large number of populations showed evidence of genetic bottleneck,thereby emphasizing the risk of local extinction.Based on these findings,our study recommends in situ conservation strategies,such as to prioritize populations for conservation actions and to maintain genetic diversity.
阔苞菊(Pluchea indica)是一种红树林伴生植物,以其在原产地的药用特性和部分引入地的入侵性而闻名。本研究旨在评估阔苞菊在其分布范围内遗传变异的地理分布,确定影响其遗传结构的因素,并利用这些信息对阔苞菊在原产地和引入地的保护和管理策略提出建议。我们以来自阔苞菊原产地(亚洲)和引入地(美国)的31个种群共348个个体的15个核微卫星位点数据对阔苞菊的遗传多样性和种群结构进行了评估。在大尺度范围以及局部区域两种空间尺度上对阔苞菊遗传变异的空间格局进行了探讨,并验证了以下假说:地理距离和自然地理屏障将影响种群结构并在空间尺度上产生不同程度的分化。研究结果表明,与所研究区域内的其它红树林物种的遗传多样性参数相比,我们发现阔苞菊在种群水平上具有相对较高的遗传多样性以及在物种水平上具有明显的遗传分化。大多数阔苞菊种群显示杂合子缺失,这主要是由于近交和有限的基因流所导致。在较大空间尺度上进行的种群结构分析显示,该物种自然分布范围内存在两个主要遗传谱系,中国的种群与印度尼西亚、马来西亚、新加坡、泰国、柬埔寨和菲律宾的种群分别属于不同的谱系,而美国的种群可能来自于中国的谱系。此外,在局部区域范围内也同样检测到种群之间的遗传分化。大部分阔苞菊种群所表现出的遗传瓶颈效应强调了其具有本地灭绝的风险。基于上述研究结果,我们建议采用原位保护策略对阔苞菊进行管理,并开展对优先保护种群的保护行动以维持遗传多样性。
基金
supported by grants from the National Natural Science Foundation of China(grant no.41776166,31700178)
the Natural Science Foundation of Guangdong Province(grant no.2017A030313189)
Guangdong Basic and Applied Basic Research Foundation(grant no.2019A1515012221)
the Fundamental Research Funds for the Central Universities(grant no.20lgpy103)
the Chang Hungta Science Foundation of Sun Yat-sen University.
