Increased seed dispersal potential towards geographic range limits in a Pacific coast dune plant
Increased seed dispersal potential towards geographic range limits in a Pacific coast dune plant
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DOI：
10.1111/j.1469-8137.2007.02349.x
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发表时间：
2008-01-01
期刊：
影响因子：
9.4
通讯作者：
Eckert, Christopher G.
中科院分区：
文献类型：
--
作者：
Darling, Emily;Samis, Karen E.;Eckert, Christopher G.
分散可能有利于在地理范围的边缘不稳定的人口和集合种群动态。然而，扩散也可能演变的其他生活史特征，特别是交配系统的地理变异。在这里，增加的范围内的边缘扩散进行了测试，种子传播和交配系统性状的范围内的分析在Abronia umbellata，植物特有的太平洋沿岸沙丘的北美。34个种群的花果在翅的大小（质量校正翅指数）上差异很大。在风洞试验中，翼指数与扩散的临界风速呈负相关，表明翼有利于翻滚开放的桑迪基板。如预测的那样，翅指数增加和阈值速度下降向两个范围的限制。花大小，herkogamy和自交不亲和性下降向范围的限制，表明转向自交，花大小和翅指数呈负相关。然而，在统计控制花的大小后，翅指数对范围限制的增加仍然存在。这些结果与选择有利于在范围边缘的传播是一致的。在整个范围内扩散的进化不稳定性可能会影响选择和基因流动之间的相互作用，在建立和维持地理范围的限制。
Dispersal may be favoured at geographic range edges by unstable population and metapopulation dynamics. However, dispersal may also evolve in response to geographic variation in other life-history traits, especially the mating system. Here, increased dispersal at range margins was tested for with a range-wide analysis of seed dispersal and mating system traits in Abronia umbellata, a plant endemic to Pacific coastal dunes of North America.Seeds disperse within winged anthocarps. Anthocarps from 34 populations varied widely in wing size (mass-corrected wing index). Wing index correlated negatively with threshold wind velocity for dispersal in wind tunnel tests, suggesting that wings facilitate tumbling over open sandy substrate. As predicted, wing index increased and threshold velocity decreased towards both range limits.Flower size, herkogamy and self-incompatibility declined towards range limits, indicating a shift to self-fertilization, and flower size and wing index correlated negatively. However, the increase in wing index towards range limits remained after statistically controlling flower size.These results are consistent with selection favouring dispersal at range margins. The evolutionary lability of dispersal across the range may affect the interaction between selection and gene flow in the establishment and maintenance of geographic range limits.