Krauss S L
Division of Botany and Zoology, The Australian National University, Canberra, ACT.
Proc Biol Sci. 2000 Oct 7;267(1456):1925-9. doi: 10.1098/rspb.2000.1231.
The ultimate importance of postpollination sexual selection has remained elusive, largely because of the difficulty of assigning paternity in the field. Here I use a powerful new molecular marker (AFLP) for paternity analysis in a natural population of the outcrossing angiosperm Persoonia mollis (Proteaceae) to assess male reproductive success following equal pollination of 15 pollen donors on each of 6310 pistils. These results were contrasted with male reproductive success of these same plants following natural mating. Following equal pollination, there was a significant departure from equal siring success, indicating a potential for postpollination sexual selection. The most successful pollen donor sired more than twice the expected number of seeds, and this was largely consistent across recipient plants. However, siring success following natural mating was significantly different from siring success following artificial pollination and showed that the reproductive gains to be made from superior pollen performance did not translate into increased reproductive success following natural mating. As the ecological context for post-pollination sexual selection is strong in P. mollis, I suggest that pollen competition may ultimately have only a weak effect on non-random male mating success under natural conditions because the realized opportunities for pollen competition within pistils are limited.
授粉后性选择的最终重要性一直难以捉摸，这主要是因为在野外确定父本关系存在困难。在此，我使用一种强大的新分子标记（扩增片段长度多态性，AFLP），对异交被子植物柔毛波斯铁木（山龙眼科）的一个自然种群进行父本分析，以评估在6310枚雌蕊上对15个花粉供体进行等量授粉后雄性的繁殖成功率。这些结果与这些相同植株在自然交配后的雄性繁殖成功率形成对比。在等量授粉后，父本成功情况显著偏离均等，这表明存在授粉后性选择的可能性。最成功的花粉供体产生的种子数量超过预期数量的两倍，并且在受体植株中情况基本一致。然而，自然交配后的父本成功情况与人工授粉后的父本成功情况显著不同，这表明花粉表现优异所带来的繁殖优势在自然交配后并未转化为更高的繁殖成功率。由于在柔毛波斯铁木中授粉后性选择的生态背景很强，我认为在自然条件下，花粉竞争最终可能对非随机的雄性交配成功影响甚微，因为雌蕊内实际发生花粉竞争的机会有限。
