中甸灯台报春与鹅黄灯台报春的系统演化

Phylogenetic analysis of Primula chungensis and P. cockburniana

关键词:  中甸灯台报春, 鹅黄灯台报春, 姐妹种, SSR, 生态位

Key words:  Primula chungensis, P. cockburniana, sister species, SSR, ecological niche

摘要:

中甸灯台报春和鹅黄灯台报春在形态上较为相似,通常被认为是亲缘关系较近的物种。该研究选取核基因ITS序列和叶绿体trnL-F为分子标记,利用贝叶斯的方法构建系统树,在用两种分子标记构建的系统树中,两种报春均以0.81的支持率聚成一个分支,明确了两种报春的姐妹种关系。首先,通过选取两个物种的五个形态学性状,进行主成分分析,聚类结果中两种报春各自的个体分别聚在两块区域,表明两种报春的形态学性状产生了明显的分化,且中甸灯台报春的花部各性状值明显大于鹅黄灯台报春,表明花部综合征和繁育系统间的相关联系。然后,通过用8对SSR分子标记对两种报春进行STRUCTURE聚类分析,结果检测K的最适值为2,此时中甸灯台报春和鹅黄灯台报春的个体各自以不同颜色聚成界限清晰的两块区域,揭示了两种报春在分子水平上也产生了显著而稳定的分化,通过Ima2软件,依据叶绿体联合序列,计算了两种报春的分化时间大约是在更新世,推测这两个姐妹种的物种分化受更新世气候动荡和一些地质历史事件的影响。最后,运用maxent软件分析两个物种的生态位差异,结果表明最干季节降水量、年均降水量和季节性降水量对中甸灯台报春的分布有重要影响,最冷季节平均温度、最干月降水量、年均降水量和季节性降水量对鹅黄灯台报春的分布有重要影响,两个物种间的生态位产生了分化。由此推测,这种生态位的差异是物种分化的结果,同时也是物种间系统演化的重要驱动力。

Abstract:

Primula chungensis and P. cockburniana, are usually considered as close species for the similar morphological traits. We reconstructed the phylogenetic trees with the Bayesian inference method based on two DNA fragments, the molecular marker we chose was internal transcribed spacer and chloroplast fragment trnL-F, among the two phylogenetic trees we reconstructed, P. chungensis and P. cockburniana got into a branch with 0.81 support, which indicated that P. chungensis and P. cockburniana were sister species. we also utilized principle component analysis based on five morphological traits, and the two species got into two clusters, which indicated that in term of the morphology, there was significant differentiation between the two species, and this differentiation had an important relationship with the mating system, and we discussed the relationship between flora syndrome and breeding system of these two species. We chose eight pairs of SSR primers and sent the polymerase chain reaction production to the company to measure the peak value, according to the anlysis of the softwae STRUCTUER based on the nuclear microsatellite marker, the appropriate value of K was two, the result of structure consisted of two area and with different colors, the red area represented the population of P. cockburniana, and the green area represented the populations of P. chungensis, which meant that there was significant and stable differentiations between the two species on the molecular level. Then we calculated the differentiation time between the two species with Ima2 based on the united chloroplast fragments, which showed turbulent environment and geological and historical accidents in Pleistocene may have an important effect on the differentiation of the two species. Finally we analysed the ecological niches of the two species with the software maxent. The results indicated that the precipitation of the driest quarter, range of annual temperature, isothermality and the annual average precipitation had important effects on the distribution of P. chungensis,the mean temperature of the coldest quarter, precipitation of the driest month, annual average precipitation and the precipitation seasonality had an important effect on the distribution of P. cockburniana. We speculate that the different ecological niches had been influenced by the phylogenetic evolution of the species, and in turn the different niches can also promote the phylogenetic evolution process.