The evolution of self-compatibility in geographically peripheral populations of Leavenworthia alabamica (Brassicaceae)
The evolution of self-compatibility in geographically peripheral populations of Leavenworthia alabamica (Brassicaceae)
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DOI：
10.3732/ajb.92.9.1503
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发表时间：
2005-09-01
影响因子：
3
通讯作者：
Busch, JW
中科院分区：
文献类型：
--
作者：
Busch, JW
自交亲和和自体受精的适应经常出现在物种分布范围外围或岛屿上的植物种群中。在这些环境中，自交亲和性可能占主导地位，因为当传粉者或配偶的可用性限制种子生产时，它可以提供繁殖保证。在美国东南部特有的一种开花植物莱文沃斯亚拉巴米卡（Leavenworthia alabamica）中研究了这种可能性。该物种范围中心的种群保留了孢子体自交不亲和性，但外围种群较小，自交亲和，并且具有自体受精的适应性。设计了相互移植实验来测试种子集是否存在花粉限制并检查其在中心群体和外围群体中的强度。在所有环境中，自交亲和基因型比自交不亲和基因型产生更多的果实和多 17-22% 的种子，这表明阿拉巴马乳杆菌栖息的所有种群中的自然选择可能有利于向自交亲和基因型的转变。序列分析表明，两个外围种群的遗传变异减少了 90-100%，这与种群规模较小或历史瓶颈的影响一致。尽管种子集花粉限制在所有环境中都会发生，但阿拉巴马乳杆菌的自交亲和性可能会在外围进化，因为繁殖保证的好处受到种群规模或灭绝和殖民化后瓶颈的影响。
Self-compatibility and adaptations to self-fertilization are often found in plant populations at the periphery of species' ranges or on islands. Self-compatibility may predominate in these environments because it provides reproductive assurance when pollinators or availability of mates limits seed production. This possibility was studied in Leavenworthia alabamica, a flowering plant endemic to the southeastern United States. Populations at the center of the species' range retain sporophytic self-incompatibility, but peripheral populations are smaller, self-compatible, and have adaptations for self-fertilization. A reciprocal-transplant experiment was designed to test whether there is pollen limitation of seed set and to examine its strength in central and peripheral populations. Self-compatible genotypes produced more fruit and 17-22% more seed than self-incompatible genotypes in all environments, suggesting that the transition to self-compatibility may be favored by natural selection in all populations inhabited by L. alabamica. Sequence analyses demonstrated that two peripheral populations have 90-100% reductions in genetic variation, consistent with the effects of small population size or historical bottlenecks. Although pollen limitation of seed set occurs in all environments, self-compatibility may evolve at the periphery in L. alabamica because the benefits of reproductive assurance are influenced by Population size or bottlenecks following extinction and colonization.