Institute of Biology I, University of Freiburg, D-79104 Freiburg, Germany.
Department of Biological and Environmental Science, University of Jyväskylä, FI-40014 Jyväskylä, Finland.
Proc Natl Acad Sci U S A. 2022 Aug 16;119(33):e2206262119. doi: 10.1073/pnas.2206262119. Epub 2022 Aug 8.
The aesthetic preferences of potential mates have driven the evolution of a baffling diversity of elaborate ornaments. Which fitness benefit-if any-choosers gain from expressing such preferences is controversial, however. Here, we simulate the evolution of preferences for multiple ornament types (e.g., "Fisherian," "handicap," and "indicator" ornaments) that differ in their associations with genes for attractiveness and other components of fitness. We model the costs of preference expression in a biologically plausible way, which decouples costly mate search from cost-free preferences. Ornaments of all types evolved in our model, but their occurrence was far from random. Females typically preferred ornaments that carried information about a male's quality, defined here as his ability to acquire and metabolize resources. Highly salient ornaments, which key into preexisting perceptual biases, were also more likely to evolve. When males expressed quality-dependent ornaments, females invested readily in costly mate search to locate preferred males. In contrast, the genetic benefits associated with purely arbitrary ornaments were insufficient to sustain highly costly mate search. Arbitrary ornaments could nonetheless "piggyback" on mate-search effort favored by other, quality-dependent ornaments. We further show that the potential to produce attractive male offspring ("sexy sons") can be as important as producing offspring of high general quality ("good genes") in shaping female preferences, even when preferred ornaments are quality dependent. Our model highlights the importance of mate-search effort as a driver of aesthetic coevolution.
潜在配偶的审美偏好推动了各种精心制作的装饰物的惊人多样性进化。然而，选择者表达这些偏好会带来什么适应益处（如果有的话）是有争议的。在这里，我们模拟了对多种装饰物类型（例如“费雪式”、“累赘”和“指示剂”装饰物）偏好的进化，这些装饰物在与吸引力和其他适应成分的基因的关联上存在差异。我们以一种生物学上合理的方式模拟了偏好表达的成本，这种方式将昂贵的配偶搜索与无成本的偏好分离开来。在我们的模型中，所有类型的装饰物都进化了，但它们的出现远非随机。雌性通常更喜欢携带关于雄性质量信息的装饰物，这里定义的质量是指雄性获取和代谢资源的能力。高度显著的装饰物，即与预先存在的感知偏见相吻合的装饰物，也更有可能进化。当雄性表达依赖质量的装饰物时，雌性会欣然投入昂贵的配偶搜索中，以找到偏好的雄性。相比之下，与纯粹任意装饰物相关的遗传益处不足以维持高度昂贵的配偶搜索。然而，任意装饰物仍然可以“搭便车”，利用其他依赖质量的装饰物所偏好的配偶搜索努力。我们进一步表明，即使偏好的装饰物是依赖质量的，产生有吸引力的雄性后代（“性感儿子”）的潜力在塑造雌性偏好方面与产生高总体质量后代（“良好基因”）同样重要。我们的模型强调了配偶搜索努力作为审美共同进化的驱动力的重要性。
