Data from: Spatial genetic structure in continuous and fragmented populations of Pinus pinaster Aiton

Habitat fragmentation, i.e., the reduction of populations into small isolated remnants, is expected to increase spatial genetic structure (SGS) in plant populations through non-random mating, lower population densities and potential aggregation of reproductive individuals. We investigated the effects of population size reduction and genetic isolation on SGS in maritime pine (Pinus pinaster Aiton) using a combined experimental and simulation approach. Maritime pine is a wind-pollinated conifer which has a scattered distribution in the Iberian Peninsula due to forest fires and habitat fragmentation. Five highly polymorphic nuclear microsatellites were genotyped in a total of 394 individuals from two population pairs from the Iberian Peninsula, formed by one continuous and one fragmented population each. In agreement with predictions, SGS was significant and stronger in fragments (Sp=0.020 and Sp=0.026) than in continuous populations, where significant SGS was detected for one population only (Sp=0.010). Simulations suggested that under fat-tailed dispersal, small population size is a stronger determinant of SGS than genetic isolation, while under normal dispersal, genetic isolation has a stronger effect. SGS was always stronger in real populations than in simulations, except if unrealistically narrow dispersal and/or high variance of reproductive success were modelled (even when accounting for potential overestimation of SGS in real populations due to short-distance sampling). This suggests that factors such as non-random mating or selection not considered in the simulations were additionally operating on SGS in Iberian maritime pine populations.

生境破碎化（habitat fragmentation），即种群被分割为小型孤立残存斑块的过程，预计会通过非随机交配、种群密度降低以及繁殖个体潜在的聚集现象，提升植物种群的空间遗传结构（spatial genetic structure，SGS）。本研究结合实验与模拟手段，探究了种群规模缩减与遗传隔离对滨海松（Pinus pinaster Aiton）空间遗传结构的影响。滨海松为风媒传粉的针叶树种，受森林火灾与生境破碎化影响，在伊比利亚半岛呈零散分布格局。研究共对来自伊比利亚半岛的2个种群对（每个种群对分别包含1个连续种群与1个破碎化种群）的总计394个个体，开展了5个高度多态性核微卫星（nuclear microsatellites）的基因分型工作。
与理论预测相符，破碎化种群的空间遗传结构更为显著且强度更高（Sp值分别为0.020与0.026），而连续种群中仅在1个种群中检测到显著的空间遗传结构（Sp值为0.010）。模拟结果显示，在肥尾扩散（fat-tailed dispersal）模式下，种群规模偏小对空间遗传结构的影响强于遗传隔离；而在正态扩散（normal dispersal）模式下，遗传隔离的作用更为显著。除了在模拟中设置极窄的扩散距离和/或较高的繁殖成功方差（即便考虑到真实种群中因近距离采样可能导致的空间遗传结构高估情况）之外，真实种群的空间遗传结构强度始终高于模拟结果。这表明，诸如模拟研究未纳入的非随机交配或自然选择等额外因素，正在对伊比利亚半岛滨海松种群的空间遗传结构产生调控作用。