Mixed genetic and environmental sex determination in an androdioecious population of Mercurialis annua
Mixed genetic and environmental sex determination in an androdioecious population of Mercurialis annua
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DOI：
10.1038/hdy.1997.6
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发表时间：
1997-01-01
期刊：
影响因子：
3.8
通讯作者：
Pannell, J
中科院分区：
文献类型：
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作者：
Pannell, J
金银花是泛欧分布的一种植物。在西班牙南部、葡萄牙南部和摩洛哥北部，雄性与雌雄同株（双性）个体共存的频率在零到30%之间变化。在这里，我报告了两个温室实验的结果，旨在描述一个这样的雌雄同株种群的性别决定模式。在一项繁殖实验中，与雄性分离的同性只产生同性后代，而与雄性交配的同性既产生同性后代，也产生雄性后代。结果与性别遗传的单位点模型一致，雄性由显性等位基因决定。在密度实验中，雄鼠出现的频率与密度呈正相关，证实了实地观察结果。实验设计排除了两性之间的死亡率或萌发差异，因此结果支持密度依赖性别选择的假设。密度与“晚期同性别”（在发育后期变成同性的男性）的比例呈负相关，而纯（未改变的）同性别的比例在密度之间没有任何差异，这表明只有男性能够改变性别。这种解释与繁殖实验的结果是一致的，在实验中，晚期同一性只发生在被允许与雄性交配的同一性的后代中。我认为这些发现有助于解释M. annua雄性不育的维持。
Mercurialis annua is a ruderal of pan-European distribution. In southern Spain, southern Portugal and northern Morocco, males coexist with monoecious (cosex) individuals at frequencies which vary between zero and about 30 per cent, Were, I report the results of two glasshouse experiments which aimed to characterize the mode of sex determination in one such androsdioecious population. In a breeding experiment, cosexes isolated from males produced only cosexual progeny, whereas those allowed to mate with males produced both cosexual and male offspring. The results are consistent with a single-locus model of sex inheritance, with maleness determined by a dominant allele. In a density experiment, the frequency of males correlated positively with density, confirming field observations. Differential mortality or germination between the sexes was excluded by experimental design, so that the result supports the hypothesis of density-dependent gender choice. A negative correlation between density and the proportion of 'late cosexes' (males which turned cosexual late in their development), and the lack of any differences in the proportion of pure (unchanged) cosexes between density, suggest that only males were capable of sex change. This interpretation is consistent with the results of the breeding experiment, in which late cosexes occurred only in the offspring of cosexes allowed to mate with males. I argue that these findings help to explain the maintenance of androdioecy in M. annua.