Increased selfing and correlated paternity in a small population of a predominantly outcrossing conifer, Pinus sylvestris
Increased selfing and correlated paternity in a small population of a predominantly outcrossing conifer, Pinus sylvestris
复制标题
以异交为主的针叶树 Pinus sylvestris 的小种群中自交和相关亲子关系的增加
作者：
J. J. Robledo;R. Alía;Luis Gil
对樟子松小种群的异交率、胚珠败育率和种子败育率以及父子关系水平进行了估计，并与同一树种的两个广泛分布的林地的估计值进行了比较，显示出不同的密度范围。平均而言，小种群的种子树的自交率(25%比3%)是大种群树的8倍，亲子关系相关的发生率(19.6%比0.2%)是大种群树的100倍。根据胚珠败育率，没有发现残留林内花粉限制的证据。基于778个自由授粉种子明确的系谱，对小群体的交配模式进行了调查，结果表明，与随机交配有很大的背离。只观察到8%的可能的交配对在林内。母系亲缘关系内的父亲率与到最近邻的距离呈负相关(rS=−0.398，P<；0.050)，母系间的父子关系与种子树之间的距离负相关(rS=−0.704，P<；0.001)。基于估计的个体花粉散布核的数值模拟表明，有限的散布可能是影响小种群交配模式的关键因素，与低种群密度一起，可能解释了观察到的小种群和大种群之间的交配系统差异。这项研究的结果表明，严重的尺寸缩小可能会对风媒授粉的典型异交植物物种的交配系统产生重大影响。
Outcrossing rate, the rates of ovule and seed abortion, and levels of correlated paternity were estimated in a small population of Pinus sylvestris, a predominantly outcrossing conifer, and were compared with estimates from two widely dispersed woodlands of the same species, showing a range of densities. On average, seed trees of the small population showed an eight‐fold higher selfing rate (25 vs. 3%) and a 100‐fold greater incidence of correlated paternity (19.6 vs. 0.2%) than did trees from the large populations. No evidence was found of pollen limitation within the remnant stand, as suggested by ovule abortion rates. Investigation of the mating patterns in the small population, based on the unambiguous genealogy of 778 open‐pollinated seeds, showed a large departure from random mating. Only 8% of the possible mating pairs within the stand were observed. Correlated paternity rate within a maternal sibship was negatively associated (rs = −0.398, P < 0.050) with the distance to the nearest neighbour, and shared paternity among maternal sibships was negatively correlated (rs = −0.704, P < 0.001) with the distance between seed trees. Numerical simulations, based on the estimated individual pollen dispersal kernel, suggest that restricted dispersal might have been the key factor affecting mating patterns in the small population and, together with low population density, may account for the observed mating system variation between the small and the large populations. The results of this study show that a severe size reduction may substantially affect the mating system of a wind‐pollinated, typically outcrossed plant species.
影响因子：
56.9
作者：
LANDE, R
通讯作者：
LANDE, R