Forbes LS, Mock DW
Department of Biology, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, Canada R3B 2E9
J Theor Biol. 1998 May 7;192(1):3-14. doi: 10.1006/jtbi.1997.0596.
Three general classes of fitness incentives have been proposed for parental overproduction of offspring: (1) tracking environmental variation; (2) developmental facilitation; and (3) replacements for failed or defective members of the core brood. In one version of this last category, called the progeny choice hypothesis, parents are seen as creating an enlarged array of offspring from which a genetically superior subset is chosen for full investment. In the selection process, parents may eliminate the victims either through personal effort (filial infanticide) or by proxy (by allowing or even encouraging fatal sibling rivalry). Because the culling process is non-random, it can elevate average offspring quality. Progeny choice, however, is only cost-effective if the expenses of early overproduction (including elevated levels of sibling competition) do not outweigh the eventual upgrade in offspring quality. A fair competition within the offspring "arena" offers the greatest potential for discriminating on the basis of intrinsic quality, but may be overwhelmed by high costs of sibling rivalry. Conversely, while parentally managed competition (conferring handicaps to some and advantages to others) can discount those rivalry costs, it simultaneously diminishes the system's capacity for distinguishing good offspring from bad. Ceteris paribus, one would expect to find progeny choice mechanisms in species with cheap sibling rivalry, large cohorts of evenly matched offspring, and exaggerated variation in offspring genetic quality. Conversely, this class of incentives of parental overproduction seems least suited to taxa in which parents dole out marked advantages or handicaps to various concurrent offspring (e.g. asynchronously hatching birds).Copyright 1998 Academic Press Limited
针对亲代过度繁殖后代的情况，人们提出了三类普遍的适应性激励因素：（1）追踪环境变化；（2）促进发育；（3）替代核心育雏中失败或有缺陷的成员。在最后一类的一个版本中，即后代选择假说，亲代被视为创造了大量的后代，从中挑选出一个基因上更优越的子集进行全力投资。在选择过程中，亲代可能通过自身努力（杀婴）或通过代理（允许甚至鼓励致命的同胞竞争）来淘汰牺牲品。由于淘汰过程是非随机的，它可以提高后代的平均质量。然而，只有当早期过度繁殖的成本（包括同胞竞争加剧）不超过后代质量的最终提升时，后代选择才具有成本效益。后代“竞技场”内的公平竞争为根据内在质量进行区分提供了最大潜力，但可能会被同胞竞争的高成本所压倒。相反，虽然亲代管理的竞争（给一些后代设置障碍，给另一些后代优势）可以降低这些竞争成本，但同时也会削弱系统区分好后代和坏后代的能力。在其他条件相同的情况下，人们会期望在同胞竞争成本低、大量后代实力相当且后代遗传质量差异大的物种中发现后代选择机制。相反，这类亲代过度繁殖的激励因素似乎最不适合亲代给不同同时出生的后代（如异步孵化的鸟类）明显优势或障碍的分类群。版权所有1998年学术出版社有限公司
