Toyama Ken S
Am Nat. 2025 Jun;205(6):548-558. doi: 10.1086/735583. Epub 2025 Apr 23.
AbstractA pattern of allometry in which the degree of male-biased sexual size dimorphism (SSD) increases with species body size is known as "Rensch's rule." Over the past decades, a growing amount of Rensch's rule studies has advanced our understanding of SSD, our knowledge of its prevalence in nature, and our comprehension of the mechanisms underlying its evolution. However, Bernhard Rensch, when describing the pattern for the first time, considered the allometry of SSD only as a special case of a more general pattern in which dimorphism in any relative sexual difference increased with body size. In this perspective I revisit the history of Rensch's rule, starting with its popularization in recent decades, then diving into the original works by Rensch to rediscover his original observations, and finally discussing the implications of studying Rensch's pattern beyond its applications to SSD. The strong bias toward body size in the study of Rensch's rule has proven valuable regarding our understanding of the evolution of SSD. Using empirical examples, I propose, however, that expanding the study of the pattern to other traits might prove insightful for the general study of sexual dimorphism and phenotypic diversity.
一种异速生长模式，即雄性偏向的性大小二态性（SSD）程度随物种体型增大而增加，被称为“伦施法则”。在过去几十年里，越来越多关于伦施法则的研究增进了我们对SSD的理解、对其在自然界中普遍程度的认识以及对其进化潜在机制的理解。然而，伯恩哈德·伦施在首次描述这一模式时，将SSD的异速生长仅视为一种更普遍模式的特殊情况，在该普遍模式中，任何相对性差异中的二态性都随体型增大而增加。从这个角度出发，我重新审视了伦施法则的历史，首先从其在近几十年的普及说起，接着深入研究伦施的原著以重新发现他最初的观察结果，最后讨论研究伦施模式在SSD应用之外的意义。事实证明，在研究伦施法则时对体型的强烈偏向对于我们理解SSD的进化很有价值。然而，通过实证例子，我提出将该模式的研究扩展到其他性状可能对性二态性和表型多样性的一般研究具有启发性。
