Mentor effects in wild species of Helianthus (Asteraceae)
Mentor effects in wild species of Helianthus (Asteraceae)
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DOI：
10.2307/2446411
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发表时间：
1998-06-01
影响因子：
3
通讯作者：
Rieseberg, LH
中科院分区：
文献类型：
--
作者：
Desrochers, AM;Rieseberg, LH
自交不亲和性（SI）是限制开花植物自交受精的有效方法，但在某些情况下，其他功能的SI系统可能会失效。其中最有趣的是诱导自交的混合负荷的自我和异源花粉（导师效应），因为它很可能发生在自然条件下，如在杂交区。在这里，我们进行了一系列的控制杂交，以确定是否导师效应在两个SI一年生物种，向日葵和H，petiolaris，以及是否SI的失败导致这两个物种之间的杂交频率下降。从花粉混合物中检查了1396个瘦果，其中包括不同比例的自交、种内亲和和种间花粉，其中71个（5.1%）是自交的。自交频率显着低于预期的花粉比例的基础上，除了种内兼容的花粉比例低。在相同花粉比例下，与H. annuus为母本，13.3%为H. petiolaris作为母亲。对排除自花花粉的1404个花粉混合物的分析表明，H。annuus（42.2%）和H. petiolaris（18.2%）与包括自花花粉的花粉没有显著差异。因此，导师效应似乎没有发挥重要作用，这些物种之间的生殖隔离。另一方面，即使杂交种群中自花受精的适度增加，例如由于导师效应，也可以提高杂交物种建立的可能性。
Self-incompatibility (SI) is an effective method for limiting self-fertilization in flowering plant species, but there are circumstances in which an otherwise functional SI system may fail. One of the most intriguing of these is the induction of selfing by mixed loads of self and heterospecific pollen (the mentor effect) because it is likely to occur under natural conditions, such as in hybrid zones. Here we conducted a series of controlled crosses to determine whether mentor effects operate in two SI annual species, Helianthus annuus and H, petiolaris, and whether the failure of SI results in a decrease in the frequency of hybridization between these two species. Of the 1396 achenes examined from pollen mixtures that included varying ratios of self, intraspecific compatible, and interspecific pollen, 71 (5.1%) were selfed. Selfing frequencies were significantly less than expected based on pollen ratios, except when the proportion of intraspecific compatible pollen was low. Hybridization frequencies from these same pollen ratios averaged 41.8% with H. annuus as the maternal species and 13.3% with H. petiolaris as the mother. Analysis of 1404 achenes from pollen mixtures that excluded self pollen resulted in hybridization frequencies for H. annuus (42.2%) and H, petiolaris (18.2%) that do not differ significantly from those including self pollen. Thus, mentor effects do not appear to play an important role in reproductive isolation between these species. On the other hand, even a modest increase in self-fertilization in hybrid populations, such as that due to mentor effects, could enhance the probability of hybrid species establishment.