Kelley Steven E
Department of Botany, Duke University, Durham, NC, 27706.
Evolution. 1989 Aug;43(5):1054-1065. doi: 10.1111/j.1558-5646.1989.tb02550.x.
Sexually and asexually derived tillers of Anthoxanthum odoratum were planted directly in the field to test the hypothesis that competition among groups of sexual and asexual siblings favors the maintenance of sexual reproduction in populations. The results showed a substantial fitness advantage for sexual tillers. However, in contrast with the models, the advantage of sex did not increase with increasing numbers of colonists in the patch, there were multiple survivors among colonists, and an advantage was observed even for singly planted tillers. When a truncation-selection scheme was imposed ex post facto on the data, the relative performance of sexual tillers was similar to that predicted by the Bulmer (1980) model, suggesting that sib-competition models fail due to the violation of the assumption of truncation selection. The advantage of sex was not correlated with the presence of other species, total percentage cover, or species diversity, although sites where sex was favored were physically clustered.
将香茅有性繁殖和无性繁殖产生的分蘖直接种植在田间，以检验以下假设：有性和无性同胞群体之间的竞争有利于种群中维持有性繁殖。结果显示有性分蘖具有显著的适合度优势。然而，与模型相反的是，有性繁殖的优势并没有随着斑块中殖民者数量的增加而增加，殖民者中有多个存活个体，甚至单株种植的分蘖也观察到了优势。当对数据事后施加截断选择方案时，有性分蘖的相对表现与布尔默（1980年）模型预测的相似，这表明同胞竞争模型由于违反了截断选择的假设而失效。有性繁殖的优势与其他物种的存在、总盖度百分比或物种多样性无关，尽管有性繁殖占优势的地点在地理上是聚集的。
