中国东部沿海水仙归化群体的遗传多样性

Genetic Diversity of Narcissus tazetta var. chinensis Populations in Eastern Coast of China

摘要:

为揭示我国东部归化水仙（Narcissus tazetta var. chinensis）的群体遗传多样性，利用2个叶绿体基因matK和trnH-psbA片段对采自沪、浙、闽的5个代表群体的49株水仙进行了评估。结果表明，双基因联合序列的总长为1 443 bp，共定义6个单倍型，各归化群体的遗传多样性水平为DLSY > PTD > NJD=ZZ > CMD。AMOVA分析表明，群体内变异为遗传变异的主要来源（91.98%），群体间的遗传分化较低（F_st=0.080 22）。群体物种水平上的谱系结构不显著（N_st=0.020 < G_st=0.031；P< 0.05）。Mantel检验表明水仙群体间的遗传距离与地理距离呈显著的线性相关（r=0.929，P=0.02<0.05）。中性检验和错配分布分析结果均暗示水仙群体背离了快速扩张模型的假设。单倍型分布的中介网络图结合系统发育NJ树均将所有群体划分为2大分支。因此，我国东部沿海水仙归化群体整体遗传多样性水平较低，各群体间遗传分化较弱，遗传变异主要来自群体内，物种近期未经历扩张事件，可能是基因流受海岛隔离、自身生物学特征、生境异质性与及人为干扰的综合作用影响。

关键词:水仙;中国东部沿海;归化群体;叶绿体DNA;遗传结构

Abstract:

To reveal the genetic diversity of naturalized Narcissus tazetta var. chinensis populations in eastern coast of China, 49 individuals from five representative populations distributed in Shanghai, Zhejiang and Fujian Proviences were evaluated by using two chloroplast DNA matK and trnH-psbA fragments. The results showed that total of six haplotypes were identified from the combined two sequences with an alignment length of 1 443 bp. The genetic diversity of naturalized population was in order of DLSY > PTD > NJD=ZZ > CMD. AMOVA analysis showed that the variation within populations was the main source of the genetic variation (91.98%) and low genetic differentiation between populations (F_st=0.080 22). Insignificant phylogeographic structure was detected at species level (N_st=0.020 < G_st=0.031; P<0.05). Mantel test showed a significant linear correlation between genetic distance and geographical distance (r=0.929, P=0.02<0.05). The neutrality test combined bimodal curve in mismatch distribution analysis both rejected the hypothesis of the demographic expansion of these populations. Analysis of median network and phylogenetic NJ tree based on the distribution of haplotype both divided all the populations into two major branches. These indicated a low level of genetic diversity with a weak genetic differentiation among Narcissus tazetta var. chinensis populations in eastern coast of China. Genetic variation mainly occurs in populations, while species had experienced no demographic expansion. These might likely owing to the gene flows which were caused by the combination of islands segregation, biological characteristics, habitat heterogeneity as well as human disturbance.

Key words:Narcissus tazetta var. chinensis;Eastern coast of China;Naturalized population;cpDNA;Genetic structure