Tsitrone Anne, Duperron Sébastien, David Patrice
Section of Integrative Biology C0930, University of Texas, Austin, Texas 78712, USA.
Am Nat. 2003 Sep;162(3):318-31. doi: 10.1086/375542. Epub 2003 Sep 5.
The evolution of mating systems and that of life history have usually been modeled separately. However, they may be to some extent coupled in natural situations because they rely on the same phenotypic traits. Here, we focus on one of these traits, the age at first reproduction, in a species able to self- and cross-fertilize. When inbreeding depression is strong, self-fertile species preferentially cross-fertilize. However, outcrossing is not always possible when the availability of sexual partners is limited. The optimal reproductive strategy in this case would be to wait for a sexual partner for a certain period of time (the waiting time) and then switch to selfing if no mates have been encountered (reproductive assurance strategy). We predict the evolution of an optimal waiting time depending on the efficiency of resource reallocation to late fecundity, on the inbreeding depression, and on the instantaneous probability of encountering a partner versus dying. As a consequence of reduced mate availability, intermediate selfing rates can be generated in preferentially outcrossing populations, but they are lowered by the existence of a waiting time. Our model may thus explain low selfing rates observed in natural populations of many self-fertile, preferentially outcrossing plants or animal species.
交配系统的演化和生活史的演化通常是分别建模的。然而，在自然情况下，它们可能在一定程度上相互关联，因为它们依赖于相同的表型特征。在此，我们聚焦于其中一个特征，即首次繁殖的年龄，研究对象是一个能够进行自花授粉和异花授粉的物种。当近亲繁殖衰退强烈时，自花可育物种优先进行异花授粉。然而，当性伴侣的可获得性有限时，异花授粉并不总是可行的。在这种情况下，最优的繁殖策略是等待性伴侣一段时间（等待时间），如果没有遇到配偶，则转向自花授粉（繁殖保障策略）。我们预测最优等待时间的演化取决于资源重新分配到后期繁殖力的效率、近亲繁殖衰退以及遇到伴侣与死亡的瞬时概率。由于配偶可获得性降低，在优先进行异花授粉的种群中会产生中等程度的自花授粉率，但等待时间的存在会降低这些自花授粉率。因此，我们的模型可以解释在许多自花可育、优先进行异花授粉的植物或动物物种的自然种群中观察到的低自花授粉率。
