Instituto de Biociências, Programa de Pós-Graduação em Biodiversidade, Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", São José do Rio Preto, São Paulo, Brazil.
Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, São Paulo, Brazil.
PLoS One. 2023 Oct 24;18(10):e0288826. doi: 10.1371/journal.pone.0288826. eCollection 2023.
The reduction of predation is a potentially important factor for the evolution of the traits of an island animal species. By relaxed selection, insular animals tend to lose their antipredator behaviors. A monophyletic group of pitvipers (genus Bothrops) in southeastern Brazil, which have high genetic affinity and dwell on the mainland and adjacent islands, provide an appropriate setting to study the evolution of antipredator behavior and how different predatory stimuli can influence this behavior. The mainland Bothrops jararaca has several terrestrial and aerial predators, whereas B. insularis and B. alcatraz, restricted to two small islands, Queimada Grande and Alcatrazes, respectively, have a smaller range of aerial predators. Terrestrial predators are absent on Queimada Grande, but one potential snake predator occurs on Alcatrazes. We observed that the defensive repertoire of island snakes has not been lost, but they display different frequencies of some antipredator behaviors. The type of predatory stimuli (terrestrial and aerial) influenced the defensive response. Bothrops insularis most often used the escape strategies, especially against terrestrial predatory stimuli. Bothrops alcatraz displayed the highest rate of strike for both terrestrial and aerial stimuli. Our results indicate that even though relaxed selection may occur in island environments as compared to mainland environments, these pitvipers still retain their antipredator behaviors but with different response degrees to the two predator types.
捕食减少是岛屿动物物种特征进化的一个潜在重要因素。通过放松选择，岛屿动物往往会失去它们的防御捕食行为。在巴西南部，有一个亲缘关系密切的矛头蝮属（Bothrops）单系群，它们生活在大陆和邻近岛屿上，为研究防御捕食行为的进化以及不同的捕食刺激如何影响这种行为提供了一个合适的环境。大陆矛头蝮（Bothrops jararaca）有几种陆地和空中捕食者，而仅限于两个小岛——大基埃马达格兰德岛（Queimada Grande）和阿尔卡特拉斯岛（Alcatrazes）的 B. insularis 和 B. alcatraz 则有较少的空中捕食者。大基埃马达格兰德岛上没有陆地捕食者，但在阿尔卡特拉斯岛上有一种潜在的蛇类捕食者。我们观察到，岛屿蛇类的防御 repertoire 并没有丧失，但它们对一些防御行为的表现频率不同。捕食刺激的类型（陆地和空中）影响防御反应。B. insularis 最常使用逃避策略，特别是针对陆地捕食刺激。B. alcatraz 对陆地和空中刺激都表现出最高的攻击率。我们的结果表明，即使在岛屿环境中可能会发生放松选择，这些矛头蝮仍然保留着它们的防御捕食行为，但对两种捕食者类型的反应程度不同。
