Selection for reduced male size in raptorial birds: the possible roles of female choice and mate guarding
Selection for reduced male size in raptorial birds: the possible roles of female choice and mate guarding
复制标题
猛禽中雄性尺寸减小的选择：雌性选择和配偶保护的可能作用
作者：
C. Safina
许多关于猛禽“反向”大小二态性的论文引起了很多讨论，但很少有一致意见。然而，一些人同意，猛禽鸟类性别大小二态性的程度与猎物的敏捷性有关。基于较小的猎物比较大的猎物更丰富以及较小的猛禽比较大的猛禽更频繁地捕获猎物的假设，我提出了三种假设机制来提高小型雄性的适应性：雌性在求偶期间评估狩猎能力的性选择，如按需生产食物的能力和展示时的机动性，可能偶然地选择雄性体型变小。2. 更频繁的求偶喂养可以更有效地刺激雌性的生殖同步和交配接受性，因此体型较小的雄性在繁殖中会更成功。3. 较小的雄性可能会遇到最佳尺寸（最成功的追捕）的猎物，搜寻时间更短，使它们能够更接近巢穴，更有效地防御其他雄性和捕食者。与之前的理论不同，这些机制将在配对和卵子受精过程中发挥主要作用。
Numerous papers on the subject of "reversed" size dimorphism in raptors have generated much discussion and little concurrence. Some have agreed, however, that the degree of sexual size dimorphism in raptorial bird species is related to the agility of their prey. Based on the assumptions that smaller prey is more abundant than larger prey and that smaller raptors capture prey more frequently than larger ones, I present three hypothetical mechanisms which would increase the fitness of small males: 1. Sexual selection for indications of hunting proficiency as assessed by the female during courtship, such as the ability to produce food on demand and maneuverability during displays, may incidently select for decreased male size. 2. More frequent courtship feeding may more effectively stimulate reproductive synchrony and copulatory receptiveness in the female, thus smaller males would be more successful in breeding. 3. Smaller males might encounter optimally sized (most successfully pursued) prey with less searching time, allowing them to remain closer to the nest for more efficient guarding against other males and predators. Unlike previous theories, these mechanisms would have their principal effect during pairing and egg fertilization.