Fernández-M J F, Sork V L
Laboratoire d'Ecologie, Systématique et Evolution, Bât 360, Université Paris Sud XI, 91405 Orsay Cedex, France.
J Hered. 2005 Nov-Dec;96(6):635-43. doi: 10.1093/jhered/esi104. Epub 2005 Sep 8.
Mating patterns play a critical role in the maintenance of genetic variation. We analyzed the mating system in a recently fragmented population of the Andean oak (Quercus humboldtii) using four microsatellite loci. Five fragments in northeastern Colombia, South America, were selected consisting of 30.4 trees on average. We sampled about 30 seeds from three target trees in each fragment and genotyped them with four microsatellite loci with a total of 40 alleles across loci. Progenies were analyzed under the mixed mating system model (MLTR program) and the TwoGener pollen pool structure analyses. The number of unshared pollen donors per family (Nu) was estimated using gametotypic counts with the program HAPLOTYPES. Low selfing (3%) is occurring at the population and fragment level. Biparental inbreeding is present (4.9%), but reduced, in the largest fragment. The average pollen neighborhood size (Nep = 5.1 to 6.1) appears comparable to other oak species in sparse landscapes. In contrast, Nu consists of 2 to 4 main donors, although up to 12 are possible, with the mode positively correlated with fragment size. The Andean oak appears to be a resilient species capable of tolerating population subdivision, provided landscapes include large fragments.
交配模式在维持遗传变异方面起着关键作用。我们使用四个微卫星位点分析了最近碎片化的安第斯橡树（Quercus humboldtii）种群的交配系统。在南美洲哥伦比亚东北部选择了五个片段，平均每个片段有30.4棵树。我们从每个片段中的三棵目标树上采集了约30粒种子，并使用四个微卫星位点对它们进行基因分型，这些位点总共具有40个等位基因。根据混合交配系统模型（MLTR程序）和双代花粉库结构分析对后代进行了分析。使用HAPLOTYPES程序通过配子型计数估计每个家族未共享花粉供体的数量（Nu）。在种群和片段水平上都出现了低自交率（3%）。双亲近亲繁殖存在（4.9%），但在最大的片段中有所减少。平均花粉邻域大小（Nep = 5.1至6.1）似乎与稀疏景观中的其他橡树种相当。相比之下，Nu由2至4个主要供体组成，尽管最多可能有12个，其模式与片段大小呈正相关。安第斯橡树似乎是一个有韧性的物种，能够容忍种群细分，前提是景观中包括大片段。
