厚壳桂新微卫星体分子标记的开发与应用(英文)

Isolation and characterization of new set of microsatellite loci in Cryptocarya chinensis

关键词:  无性生殖  保育  森林片断化  遗传标记

Key words:  asexual reproduction  conservation  forest fragmentation  genetic marker

摘要:

生境破碎化是导致全球生物多样性危机的主要原因,即使常见物种也会受到很大影响。厚壳桂(Cryptocarya chinensis)是我国南亚热带季风常绿阔叶林群落演替顶极物种,由于这一森林植被的破坏而呈片断化分布。在以往的研究中,我们利用筛选到的一些微卫星体对其遗传多样性研究后发现其可能以无性生殖为主。为进一步证实这一发现,该文又报道了11个新微卫星体,这些新微卫星体和以往报道的微卫星体将有助于更好分辨厚壳桂的有性和无性生殖,特别是在空间小尺度(Fine spatial scale)。选取鼎湖山21个厚壳桂个体,对这11个新微卫星体进行多态性检测。结果表明,这些微卫星体位点所包含的等位基因数目为2～3个,观察杂合度(Observed heterozygosities)和期望杂合度(Expected heterozygosities)分别为:0.048～1.000,0.048～0.535。11个位点中有8个偏离哈迪—温伯格平衡,FIS在8个位点表现为负值,并极显著。所有两两位点在0.05水平上均表现出连锁不平衡,但这一不平衡在使用Bonferroni 校正(Bonferroni correction)后不显著。研究同时发现21个厚壳桂个体中20个有相同的多位点基因型(multilocus genotype)。上述遗传多样性结果符合无性生殖物种的遗传特征,表明厚壳桂以无性生殖为主。

Abstract:

Habitat fragmentation is the main threat to global biodiversity. Common species could also greatly suffer from habitat fragmentation. As a result of the destruction of the monsoon evergreen broad-leaved forest in South China,Cryptocarya chinensis,one of the climax species,is now patchily distributed. Because a few microsatellite loci reported previously might cause low resolution to detect asexual reproduction in this species,we reported a new set of microsatellite which will assist to detect the extensiveness of sexual and asexual reproduction at fine spatial scale in the future. Eleven microsatellite markers from repetitive DNA enriched libraries for C.chinensis were developed. Twenty-one individuals from Dinghu Mountain in South China were used to characterize their polymorphism. The number of alleles of 11 loci ranged from two to three,observed and expected heterozygosities ranged from 0.048 to 1.000,and 0.048 to 0.535,respectively. Deviations from Hardy-Weinberg equilibrium were detected in 8 loci due to heterozygote excess(highly significant negative Fis). All locus pairs showed significant linkage disequilibrium at the 0.05 significant level,but such significance disappeared after Bonferroni correction. 20 of 21 detected individuals showed identical multilocus genotype. All these results conformed to the genetic characteristic of clonal species,confirming extensive clonal growth in C.chinensis.