Gaiotti Milene G, Webster Michael S, Macedo Regina H
Programa de Pós-Graduação em Ecologia, and Laboratório de Comportamento Animal, Departamento de Zoologia, Universidade de Brasília, Brasília, Distrito Federal 70910-900, Brazil.
Cornell Lab of Ornithology, and Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14850, USA.
R Soc Open Sci. 2020 Jan 8;7(1):191548. doi: 10.1098/rsos.191548. eCollection 2020 Jan.
Most of the diversity in the mating systems of birds and other animals comes at higher taxonomic levels, such as across orders. Although divergent selective pressures should lead to animal mating systems that diverge sharply from those of close relatives, opportunities to examine the importance of such processes are scarce. We addressed this issue using the Araripe manakin (), a species endemic to a forest enclave surrounded by xeric shrublands in Brazil. Most manakins exhibit polygynous lekking mating systems that lack territoriality but exhibit strong sexual selection. In sharp contrast, we found that male Araripe manakins defended exclusive territories, and females nested within male territories. However, territoriality and offspring paternity were dissociated: males sired only 7% of nestlings from the nests within their territories and non-territorial males sired numerous nestlings. Moreover, female polyandry was widespread, with most broods exhibiting mixed paternity. Apparently, territories in this species function differently from both lekking arenas and resource-based territories of socially monogamous species. The unexpected territoriality of Araripe manakins and its dissociation from paternity is a unique evolutionary development within the manakin clade. Collectively, our findings underscore how divergences in mating systems might evolve based on selective pressures from novel environmental contexts.
鸟类和其他动物交配系统的多样性大多出现在较高的分类学层面，比如不同目之间。尽管不同的选择压力应会导致动物的交配系统与其近亲的交配系统产生显著差异，但检验此类过程重要性的机会却很少。我们利用阿腊里皮侏儒鸟（）解决了这个问题，该物种是巴西一片被干旱灌木丛环绕的森林飞地的特有物种。大多数侏儒鸟表现出一夫多妻制的求偶场交配系统，这种系统没有领地意识，但有强烈的性选择。与之形成鲜明对比的是，我们发现阿腊里皮侏儒鸟的雄性会捍卫专属领地，而雌性会在雄性领地内筑巢。然而，领地意识和后代父系关系是分离的：雄性仅使它们领地内巢穴中7%的雏鸟受孕，而非领地雄性使许多雏鸟受孕。此外，雌性一妻多夫制很普遍，大多数一窝雏鸟有不同的父系。显然，该物种的领地功能既不同于求偶场，也不同于社会一夫一妻制物种基于资源的领地。阿腊里皮侏儒鸟意外的领地意识及其与父系关系的分离是侏儒鸟进化枝内独特的进化发展。总的来说，我们的研究结果强调了交配系统的差异可能如何基于新环境背景下的选择压力而进化。
