摘要
濒危植物鹅掌楸(Liriodendron chinense)目前仅零散分布于我国亚热带及越南北部地区,残存居群生境片断化较为严重。研究濒危植物片断化居群的遗传多样性及小尺度空间遗传结构(spatial genetic structure)有助于了解物种的生态进化过程以及制定相关的保育策略。本研究采用13对微卫星引物,对鹅掌楸的1个片断化居群进行了遗传多样性及空间遗传结构的研究,旨在揭示生境片断化条件下鹅掌楸的遗传多样性及基因流状况。研究结果表明:鹅掌楸烂木山居群内不同生境斑块及不同年龄阶段植株的遗传多样性水平差异不显著(P>0.05),居群内存在寨内和山林2个遗传分化明显的亚居群。烂木山居群个体在200 m以内呈现显著的空间遗传结构,而2个亚居群内的个体仅在20 m的距离范围内存在微弱或不显著的空间遗传结构。鹅掌楸的空间遗传结构强度较低(Sp=0.0090),且寨内亚居群的空间遗传结构强度(Sp=0.0067)要高于山林亚居群(Sp=0.0053)。鹅掌楸以异交为主,种子较轻且具翅,借助风力传播,在一定程度上降低了空间遗传结构的强度。此外,居群内个体密度及生境特征也对鹅掌楸的空间遗传结构产生了一定影响。该居群出现显著的杂合子缺失,近交系数(FIS)为0.099(P<0.01),表明生境片断化的遗传效应正逐渐显现。因此,对鹅掌楸的就地保护应注意维护与强化生境的连续性,促进基因交流。迁地保护时,取样距离应不小于20 m,以涵盖足够多的遗传变异。
The Chinese tulip tree（Liriodendron chinense）,an endangered species scattered throughout subtropical China and northern Vietnam,suffers from severe habitat fragmentation.Understanding the genetic diversity and fine-scale spatial genetic structure（SGS） of fragmented populations is critical for developing successful conservation strategies for endangered species.In this study,we investigated the population genetic diversity and fine-scale spatial genetic structure in a wild,fragmented population of L.chinense using 13 polymorphic microsatellite loci.No significant differences in genetic diversity were found among habitat fragments or age classes（P 0.05）.Two genetically heterogeneous subpopulations were revealed through Bayesian assignment analysis and Principal Coordinates Analysis（PCoA）.Significant SGS was found within the whole population within 200 m,while weak spatial aggregation of related individuals in the two subpopulations was found within 20 m.SGS intensity was weak in this population（Sp = 0.0090）,and it was stronger in the village subpopulation（Sp = 0.0067） than in the hill subpopulation（Sp = 0.0053）.Liriodendron chinense is a predominantly outcrossing tree and its winged seeds are wind-dispersed,a fact that may reduce SGS intensity in the species.Furthermore,low population density and flat hypsography also likely influence the SGS of L.chinense.The presence of significant heterozygote deficiency in the population（FIS = 0.099,P 0.01） suggests a genetic signal of habitat fragmentation.Therefore,measures for promoting pollen flow should be taken for in situ conservation.For ex situ conservation,individuals should be sampled at 20 m apart to efficiently capture genetic diversity of wild populations.
出处
《生物多样性》
CAS
CSCD
北大核心
2014年第3期375-384,共10页
Biodiversity Science
基金
国家自然科学基金(31270384)
中国科学院优秀青年科技专项(KSCX2-EW-Q-16)
