Gerber Sophie, Chadœuf Joël, Gugerli Felix, Lascoux Martin, Buiteveld Joukje, Cottrell Joan, Dounavi Aikaterini, Fineschi Silvia, Forrest Laura L, Fogelqvist Johan, Goicoechea Pablo G, Jensen Jan Svejgaard, Salvini Daniela, Vendramin Giovanni G, Kremer Antoine
BIOGECO, UMR1202, INRA, Cestas, France ; BIOGECO, UMR1202, University of Bordeaux, Talence, France.
UR 1052, INRA, Montfavet, France.
PLoS One. 2014 Jan 13;9(1):e85130. doi: 10.1371/journal.pone.0085130. eCollection 2014.
Gene flow is a key factor in the evolution of species, influencing effective population size, hybridisation and local adaptation. We analysed local gene flow in eight stands of white oak (mostly Quercus petraea and Q. robur, but also Q. pubescens and Q. faginea) distributed across Europe. Adult trees within a given area in each stand were exhaustively sampled (range [239, 754], mean 423), mapped, and acorns were collected ([17,147], 51) from several mother trees ([3], [47], 23). Seedlings ([65,387], 178) were harvested and geo-referenced in six of the eight stands. Genetic information was obtained from screening distinct molecular markers spread across the genome, genotyping each tree, acorn or seedling. All samples were thus genotyped at 5-8 nuclear microsatellite loci. Fathers/parents were assigned to acorns and seedlings using likelihood methods. Mating success of male and female parents, pollen and seed dispersal curves, and also hybridisation rates were estimated in each stand and compared on a continental scale. On average, the percentage of the wind-borne pollen from outside the stand was 60%, with large variation among stands (21-88%). Mean seed immigration into the stand was 40%, a high value for oaks that are generally considered to have limited seed dispersal. However, this estimate varied greatly among stands (20-66%). Gene flow was mostly intraspecific, with large variation, as some trees and stands showed particularly high rates of hybridisation. Our results show that mating success was unevenly distributed among trees. The high levels of gene flow suggest that geographically remote oak stands are unlikely to be genetically isolated, questioning the static definition of gene reserves and seed stands.
基因流是物种进化中的一个关键因素，影响有效种群大小、杂交和局部适应性。我们分析了分布在欧洲的八个白栎林分（主要是栓皮栎和欧洲栎，也有柔毛栎和欧洲水青冈）中的局部基因流。对每个林分给定区域内的成年树木进行了详尽采样（范围[239, 754]，平均423），绘制了地图，并从几棵母树（[3]，[47]，23）收集了橡子（[17,147]，51）。在八个林分中的六个林分中收获了幼苗（[65,387]，178）并进行了地理定位。通过筛选分布在基因组中的不同分子标记，对每棵树、橡子或幼苗进行基因分型，从而获得遗传信息。因此，所有样本都在5 - 8个核微卫星位点进行了基因分型。使用似然方法将父本/亲本分配给橡子和幼苗。估计了每个林分中雄雌亲本的交配成功率、花粉和种子传播曲线以及杂交率，并在大陆尺度上进行了比较。平均而言，来自林分外部的风媒花粉百分比为60%，林分之间差异很大（21 - 88%）。进入林分的种子平均迁入率为40%，对于通常被认为种子传播有限的橡树来说，这是一个很高的值。然而，这个估计在林分之间差异很大（20 - 66%）。基因流大多是种内的，差异很大，因为一些树木和林分显示出特别高的杂交率。我们的结果表明，交配成功率在树木之间分布不均。高水平的基因流表明，地理上偏远的橡树林分不太可能在基因上隔离，这对基因库和种子林的静态定义提出了质疑。
