Tonsor Stephen J
Barnes Laboratory, The University of Chicago, 5630 S. Ingleside Ave., 60637, Chicago, IL, USA.
Oecologia. 1985 Oct;67(3):442-446. doi: 10.1007/BF00384953.
The purpose of this study was to simultaneously measure pollen dispersal distance and actual pollen-mediated gene-flow distance in a wind-pollinated herb, Plantago lanceolata. The pollen dispersal distribution, measured as pollen deposition in a wind tunnel, is leptokurtic, as expected from previous studies of wind-pollinated plants. Gene-flow, measured as seeds produced on rows of male-sterile inflorescences in the wind tunnel, is non-leptokurtic, peaking at an intermediate distance. The difference between the two distributions results from the tendency of the pollen grains to cluster. These pollen clusters are the units of gene dispersal, with clusters of intermediate and large size contributing disproportionately to gene-flow. Since many wind-pollinated species show pollen clustering (see text), the common assumption for wind-pollinated plants that gene-flow is leptokurtic requires re-examination. Gene-flow was also measured in an artifical outdoor population of male-steriles, containing a single pollen source plant in the center of the array. The gene flow distribution is significantly platykurtic, and has the same general properties outdoors, where wind speed and turbulence are uncontrolled, as it does in the wind tunnel. I estimated genetic neighborhood size based on my measure of gene-flow in the outdoor population. The estimate shows that populations of Plantago lanceolata will vary in effective number from a few tens of plants to more than five hundred plants, depending on the density of the population in question. Thus, the measured pollen-mediated gene-flow distribution and population density will interact to produce effective population sizes ranging from those in which there is no random genetic drift to those in which random genetic drift plays an important role in determining gene frequencies within and among populations. Despite the platykurtosis in the distribution, pollen-mediated gene dispersal distances are still quite limited, and considerable within and among-population genetic differentiation is to be expected in this species.
本研究的目的是同时测量风媒草本植物披针叶车前（Plantago lanceolata）的花粉传播距离和实际花粉介导的基因流距离。以风洞中花粉沉积量衡量的花粉传播分布呈尖峰态，这与先前对风媒植物的研究预期一致。以风洞中雄性不育花序行上产生的种子衡量的基因流呈非尖峰态，在中间距离处达到峰值。这两种分布的差异源于花粉粒聚集的趋势。这些花粉簇是基因传播的单位，中等大小和大尺寸的簇对基因流的贡献不成比例。由于许多风媒物种都表现出花粉聚集（见正文），因此对于风媒植物基因流呈尖峰态的普遍假设需要重新审视。还在一个人工室外雄性不育种群中测量了基因流，该种群在阵列中心有一株单一花粉源植物。基因流分布显著呈低峰态，并且在室外风速和湍流不受控制的情况下，与在风洞中一样具有相同的一般特性。我根据在室外种群中测量的基因流来估计遗传邻域大小。估计结果表明，披针叶车前的种群有效数量会因所讨论种群的密度而有所不同，从几十株到五百多株不等。因此，所测量的花粉介导的基因流分布和种群密度将相互作用，产生有效种群大小范围，从不存在随机遗传漂变的情况到随机遗传漂变在决定种群内和种群间基因频率方面起重要作用的情况。尽管分布呈低峰态，但花粉介导的基因传播距离仍然相当有限，预计该物种在种群内和种群间会有相当大的遗传分化。
