Degen B, Bandou E, Caron H
INRA, Campus agronomique, BP 709, 9738 - Kourou cedex, French Guiana.
Heredity (Edinb). 2004 Dec;93(6):585-91. doi: 10.1038/sj.hdy.6800560.
In this paper, we report a study of the mating system and gene flow of Symphonia globulifera, a hermaphroditic, mainly bird-pollinated tree species with a large geographic distribution in the tropical Americas and Africa. Using three microsatellites, we analysed 534 seeds of 28 open pollinated families and 164 adults at the experimental site 'Paracou' in French Guiana. We observed, compared to other tropical tree species, relatively high values for the effective number of alleles. Significant spatial genetic structure was detected, with trees at distances up to 150 m more genetically similar than expected at random. We estimated parameters of the mating system and gene flow by using the mixed mating model and the TwoGener approach. The estimated multilocus outcrossing rate, tm, was 0.920. A significant level of biparental inbreeding and a high proportion of full-sibs were estimated for the 28 seed arrays. We estimated mean pollen dispersal distances between 27 and 53 m according to the dispersal models used. Although the adult population density of S. globulifera in Paracou was relatively high, the joint estimation of pollen dispersal and density of reproductive trees gave effective density estimates of 1.6 and 1.3 trees/ha. The parameters of the mating system and gene flow are discussed in the context of spatial genetic and demographic structures, flowering phenology and pollinator composition and behaviour.
在本文中，我们报告了一项关于球花豆（Symphonia globulifera）交配系统和基因流的研究。球花豆是一种雌雄同株的树种，主要靠鸟类传粉，在热带美洲和非洲有着广泛的地理分布。我们利用三个微卫星，对法属圭亚那“帕拉库”实验点的28个开放授粉家系的534粒种子和164株成年植株进行了分析。与其他热带树种相比，我们观察到等位基因有效数量的值相对较高。检测到显著的空间遗传结构，距离达150米的树木在遗传上比随机预期的更为相似。我们使用混合交配模型和双代方法估计了交配系统和基因流的参数。估计的多位点异交率tm为0.920。对28个种子阵列估计出显著水平的双亲近亲繁殖和高比例的全同胞。根据所使用的扩散模型，我们估计平均花粉扩散距离在27米至53米之间。尽管帕拉库的球花豆成年种群密度相对较高，但对花粉扩散和生殖树密度的联合估计得出有效密度估计值为每公顷1.6株和1.3株。我们在空间遗传和种群结构、开花物候以及传粉者组成和行为的背景下讨论了交配系统和基因流的参数。
