Krauss S L, He T, Barrett L G, Lamont B B, Enright N J, Miller B P, Hanley M E
Botanic Gardens and Parks Authority, Kings Park and Botanic Garden, Fraser Avenue, Perth, Western Australia, Australia.
Heredity (Edinb). 2009 Mar;102(3):274-85. doi: 10.1038/hdy.2008.118. Epub 2008 Nov 12.
In plants, pollen- and seed-dispersal distributions are characteristically leptokurtic, with significant consequences for spatial genetic structure and nearest-neighbour mating. However, most studies to date have been on wind- or insect-pollinated species. Here, we assigned paternity to quantify effective pollen dispersal over 9 years of mating, contrasted this to seed dispersal and examined their effects on fine-scale spatial genetic structure, within the bird-pollinated shrub Banksia hookeriana (Proteaceae). We used 163 polymorphic amplified fragment length polymorphism markers to assess genetic structure and pollen dispersal in a spatially discrete population of 112 plants covering 0.56 ha. Spatial autocorrelation analysis detected spatial genetic structure in the smallest distance class of 0-5 m (r=0.025), with no significant structure beyond 8 m. Experimentally quantified seed-dispersal distances for 337 seedlings showed a leptokurtic distribution around a median of 5 m, reaching a distance of 36 m. In marked contrast, patterns of pollen dispersal for 274 seeds departed strikingly from typical near-neighbour pollination, with a distribution largely corresponding to the spatial distribution of plants. We found very high multiple paternity, very low correlated paternity and an equal probability of siring for the 50 closest potential mates. Extensive pollen carryover was demonstrated by multiple siring in 83 of 86 (96.5%) two-seeded fruits. Highly mobile nectar-feeding birds facilitate this promiscuity through observed movements that were effectively random. As the incidence of bird-pollination is markedly greater in the Southwest Australian Floristic Region than elsewhere, our results have broad and novel significance for the evolution and conservation for many species in Gondwanan lineages.
在植物中，花粉和种子的传播分布通常呈尖峰态，这对空间遗传结构和最近邻交配具有重要影响。然而，迄今为止，大多数研究都集中在风媒或虫媒授粉的物种上。在这里，我们通过确定父本关系来量化9年交配过程中的有效花粉传播情况，并将其与种子传播进行对比，同时研究它们对细尺度空间遗传结构的影响，研究对象是鸟媒授粉的灌木胡克山龙眼（山龙眼科）。我们使用163个多态性扩增片段长度多态性标记，在一个覆盖0.56公顷、由112株植物组成的空间离散种群中评估遗传结构和花粉传播。空间自相关分析在0 - 5米的最小距离类别中检测到空间遗传结构（r = 0.025），在8米以外没有显著结构。对337株幼苗进行实验量化的种子传播距离显示，其分布呈尖峰态，中位数为5米，最远达到36米。与之形成鲜明对比的是，274粒种子的花粉传播模式与典型的近邻授粉显著不同，其分布在很大程度上与植物的空间分布相对应。我们发现多重父本关系非常高，相关父本关系非常低，并且50个最接近的潜在配偶的授精概率相等。在86个双种子果实中的83个（96.5%）中，通过多重父本关系证明了广泛的花粉残留。高度移动的食蜜鸟类通过观察到的有效随机移动促进了这种杂交现象。由于西南澳大利亚植物区系中鸟媒授粉的发生率明显高于其他地区，我们研究结果对冈瓦纳谱系中许多物种的进化和保护具有广泛而新颖的意义。
