Trapnell Dorset W, Hamrick J L, Nason John D
Department of Plant Biology, University of Georgia, Athens, Georgia 30602, USA.
Mol Ecol. 2004 May;13(5):1111-8. doi: 10.1111/j.1365-294X.2004.02148.x.
Epiphytic plants occupy three-dimensional space, which allows more individuals to be closely clustered spatially than is possible for populations occupying two dimensions. The unique characteristics of epiphytes can act in concert to influence the fine-scale genetic structure of their populations which can, in turn, influence mating patterns and other population phenomena. Three large populations of Laelia rubescens (Orchidaceae) in the Costa Rican seasonal dry forest were sampled at two levels of intensity to determine: (i) whether individual clusters contain more than one genotype, and (ii) the spatial distribution and fine-scale genetic structure of genotypes within populations. Samples were assayed for their multilocus allozyme genotypes and spatial autocorrelation analyses were performed. High levels of genetic diversity, high genotypic diversity and low among-population variation were found. In the larger clusters, multiple genets per cluster were common with discrete clusters containing up to nine genotypes. Spatial autocorrelation analyses indicated significant positive genetic structure at distances of </= 45 cm. This result is likely due to the formation of discrete clusters by vegetative reproduction, as well as the establishment of sexually derived progeny within and near maternal clusters.
附生植物占据三维空间，这使得与占据二维空间的种群相比，更多个体能够在空间上紧密聚集。附生植物的独特特征可以共同作用，影响其种群的精细尺度遗传结构，进而影响交配模式和其他种群现象。对哥斯达黎加季节性干燥森林中的三个大花莱丽兰（兰科）种群进行了两个强度水平的采样，以确定：（i）单个集群是否包含不止一种基因型，以及（ii）种群内基因型的空间分布和精细尺度遗传结构。对样本进行多位点等位酶基因型分析，并进行空间自相关分析。发现了高水平的遗传多样性、高基因型多样性和低种群间变异。在较大的集群中，每个集群有多个基因是常见的，离散集群中包含多达九种基因型。空间自相关分析表明，在距离≤45厘米时存在显著的正遗传结构。这一结果可能是由于营养繁殖形成离散集群，以及有性繁殖产生的后代在母本集群内部和附近定居所致。
