Using a cost-benefit approach to understand the evolution of self-fertilization in plants: the perplexing case of Aquilegia canadensis (Ranunculaceae)
Using a cost-benefit approach to understand the evolution of self-fertilization in plants: the perplexing case of Aquilegia canadensis (Ranunculaceae)
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DOI：
10.1111/j.1442-1984.2004.00112.x
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发表时间：
2004-12-01
影响因子：
1.4
通讯作者：
Herlihy, Christopher R.
中科院分区：
文献类型：
--
作者：
Eckert, Christopher G.;Herlihy, Christopher R.
植物表现出巨大的差异，无论是通过自花受精还是通过异交交配，许多物种都是两者的混合。从理论上讲，自交的进化受到一些大的成本和收益的影响，在平衡时，自交的收益应该与其成本相平衡。我们尝试了自交的成本效益分析，使用人口遗传调查，实验操作和数量遗传学的春天开花，短命的多年生植物，Aquilegia canadensis。本种在大的、花蜜丰富的花朵上投入大量资金，但在没有传粉者的情况下通过自花自熟获得完全的种子，并且在自然种群中自交76%的种子。花去雄表明，75%的自交通过自花受精发生，这增加了每花种子产量（生殖保证），但抢占了可用于制造异交种子的胚珠和资源（种子折扣）。这是昂贵的，因为异交后代似乎比自交后代存活到成熟的频率高10倍。几乎所有明显的非自花受精都涉及到近亲间的异花授粉（双亲近交）。这可能有助于混合交配的进化，但在近亲繁殖如此强烈的情况下就不行了。虽然自交似乎非常不利，A. canadensis在花内花药和柱头分离（herkogamy）方面表现出显著的可遗传变异，这与自交呈负相关。这表明交配系统处于平衡状态。对于在许多植物中发生的强烈的近交衰退面前的高自交没有适用的理论解释。了解这些神秘的交配系统的进化仍然是一个重大挑战。
Plants exhibit tremendous variation in whether mating occurs via self-fertilization versus outcrossing, and many species practice a mixture of both. In theory, the evolution of selfing is influenced by a few large costs and benefits, and the benefits of selfing should be balanced by its costs at equilibrium. We have attempted a cost-benefit analysis of selfing, using population genetic surveys, experimental manipulations and quantitative genetics to a spring-flowering, short-lived perennial, Aquilegia canadensis. This species invests heavily in large, nectar-rich flowers but achieves full seed set in the absence of pollinators by automonous autogamy, and selfs 76% of its seed in natural populations. Floral emasculations reveal that 75% of selfing occurs via autogamy, which increases per-flower seed production (reproductive assurance), but pre-empts ovules and resources that could be used to make outcrossed seed (seed discounting). This is costly because outcrossed progeny appear to survive to maturity 10-fold more often than selfed progeny. Almost all the apparent nonautogamous selfing involves cross-pollination between relatives (biparental inbreeding). This could facilitate the evolution of mixed mating, but not when inbreeding is so strong. Though selfing seems strongly disadvantageous, A. canadensis exhibits striking heritable variation in the separation between anthers and stigmas within flowers (herkogamy), which correlates negatively with selfing. This suggests that the mating system is at equilibrium. There is no applicable theoretical explanation for high selfing in the face of strong inbreeding depression, which occurs in a variety of plants. Understanding the evolution of these enigmatic mating systems remains a major challenge.