Bucci Gabriele, Menozzi Paolo
Istituto Miglioramento Genetico Piante Forestali, Consiglio Nazionale delle Richerche, Florence, Italy.
Mol Ecol. 2002 Mar;11(3):305-15. doi: 10.1046/j.1365-294x.2002.01444.x.
The spatial clustering of single- and di-locus genotypes in a natural, continuous population of Norway spruce was investigated using 69 Mendelian Random Amplified Polymorphic DNA (RAPD) markers that covered about 15 of the species genome, and whose linkage relationships were known. Spatial autocorrelation techniques and randomization tests, applied to both single- and di-locus genotypes, revealed a weak, though significant, spatial structure at the scale 0-200 m (5 of single-locus and 7 of di-locus genotypes). To assess the relative importance of isolation by distance and linkage between markers on their spatial genetic structuring, we grouped joins between sampled trees into equivalence categories expected to show similar, specific patterns of spatial distribution under isolation by distance. Results from both single- and di-locus analyses were consistent with the existence of patches of like homozygotes (about 8 and 11 of loci at the single- and di-locus level, respectively) surrounded by a mix of like heterozygotes. Similar structuring has been predicted by simulation models under isolation by distance and selective neutrality. Overall, linkage between markers accounted for an increase of spatial clumping of di-locus genotypes involving tightly linked loci with recombination fractions up to 0.1, a consequence of limited, stochastic spread of single-locus genotypes in space. Our results support the hypothesis that isolation by distance and linkage have a small, though significant, effect even within continuous forest tree populations. In general, the spatial distribution of multilocus genotypes within populations should be interpreted with caution when linkage relationships among the markers used are unknown.
利用69个孟德尔随机扩增多态性DNA（RAPD）标记对挪威云杉自然连续种群中单基因座和双基因座基因型的空间聚类进行了研究，这些标记覆盖了该物种约15%的基因组，且其连锁关系已知。应用于单基因座和双基因座基因型的空间自相关技术及随机化检验显示，在0 - 200米尺度上存在微弱但显著的空间结构（单基因座基因型有5种，双基因座基因型有7种）。为了评估距离隔离和标记间连锁对其空间遗传结构的相对重要性，我们将采样树木之间的连接分组为等效类别，预期在距离隔离下会呈现相似的特定空间分布模式。单基因座和双基因座分析的结果均与存在纯合子斑块（单基因座和双基因座水平分别约有8个和11个基因座）一致，这些斑块被杂合子混合体包围。在距离隔离和选择中性条件下的模拟模型也预测了类似的结构。总体而言，标记间的连锁导致了涉及紧密连锁基因座且重组率高达0.1的双基因座基因型空间聚集增加，这是单基因座基因型在空间中有限的随机扩散的结果。我们的结果支持这样的假设，即距离隔离和连锁即使在连续的林木种群中也有虽小但显著的影响。一般来说，当所用标记间的连锁关系未知时，对种群内多基因座基因型的空间分布应谨慎解释。
