The opportunity for outcrossing varies across the geographic range of the primarily selfing Clarkia xantiana ssp. parviflora
The opportunity for outcrossing varies across the geographic range of the primarily selfing Clarkia xantiana ssp. parviflora
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在主要自交的 Clarkia xantiana ssp 的地理范围内，异交的机会各不相同。
DOI：
10.1002/ajb2.1510
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发表时间：
2020
影响因子：
3
通讯作者：
Moeller, David A.
中科院分区：
文献类型：
--
作者：
Ruane, Lauren G.;Mangum, Samantha M.;Horner, Kaitlyn M.;Moeller, David A.
自我受精的时机对交配系统进化的轨迹、异交的机会和维持种群中的遗传变异具有潜在的重要影响。对于主要自交的分类群，花的变异如何影响异交的机会，以及这些属性是否在不同地理范围的种群之间存在差异，仍然知之甚少。方法我们研究了分布在其分布的西部到东部边缘的7个种群的花卉性状(雌雄配子、雌雄配子、花大小、开花时的柱头阶段、柱头可接受性)的变异。我们还进行了实验性的去势和授粉(随后切断柱头)来量化异交在花发育中的机会的程度。结果所有的花性状在种群间都有明显的变异，特别是在远东和西部种群之间。去雄实验表明，东部种群的自主自交率最低，而西部种群在开花后24小时内的自交率较高。自交性的群体变异可以通过花的性状变异进行显著预测，特别是花性和花瓣大小。结论较大的花性既延长了可能发生异交的时间，又降低了自主自交的概率，这表明当传粉者不常见时，可能存在权衡，导致适合度下降。一些花卉性状的东西分化模式与冰期后的范围扩大相似，这表明在范围扩大的过程中，交配系统的选择可能是很强的。
PremiseThe timing of self‐fertilization has potentially important consequences for the trajectory of mating system evolution, the opportunity for outcrossing, and the maintenance of genetic variation in populations. For primarily selfing taxa, it remains poorly understood as to how floral variation influences the opportunity for outcrossing and whether those attributes vary among populations across geographic ranges.MethodsWe examined variation in floral traits (herkogamy, protandry, flower size, stigma stage at anthesis, timing of stigma receptivity) in seven populations ofClarkia xantianassp.parviflora, a primarily selfing taxon, spanning from the western to eastern margins of its distribution. We also performed experimental emasculations and pollinations (followed by stigma severing) to quantify the extent of opportunities for outcrossing across flower development.ResultsThere was marked among‐population variation in all floral traits, particularly between far eastern and western populations. Emasculation experiments showed that the eastern populations had minimal autonomous selfing, but western populations had high rates of selfing within 24 h after anthesis. Population variation in autofertility was significantly predicted by floral trait variation, especially protandry and petal size.ConclusionsGreater protandry both extended the time over which outcrossing could potentially occur and reduced the probability of autonomous selfing, suggesting that there may be a tradeoff that results in fitness loss when pollinator visits are not common. The east‐west pattern of differentiation in some floral traits parallels that of postglacial range expansion, suggesting that selection on the mating system may have been strong in the process of range expansion.