Money David A, Ingley Spencer J, Johnson Jerald B
Rev Biol Trop. 2017 Mar;65(1):267-77. doi: 10.15517/rbt.v65i1.23861.
Predators can influence a variety of prey traits, including behavior. Traits such as boldness, activity rate, and tendency to explore can all be shaped by predation risk. Our study examines the effects of predation on these behaviors by considering a natural system in which two sister species of livebearing fishes, Brachyrhaphis roseni and B. terrabensis, experience divergent predation environments. In February of 2013, we collected fish in the Río Chiriquí Nuevo drainage, Chiriquí, Panama, and conducted behavioral assays. Using open-field behavioral assays, we evaluated both juveniles and adults, and males and females, to determine if there were differences in behavior between ontogenetic stages or between sexes. We assessed boldness as ‘time to emerge’ from a shelter into a novel environment, and subsequently measured activity and exploration within that novel environment. We predicted that B. roseni (a species that co-occurs with predators) would be more bold, more active, and more prone to explore, than B. terrabensis (a species that does not co-occur with predators). In total, we tested 17 juveniles, 21 adult males, and 20 adult females of B. roseni, and 19 juveniles, 19 adult males, and 18 adult females of B. terrabensis. We collected all animals from streams in Chiriquí, Panama in February 2013, and tested them following a short acclimation period to laboratory conditions. As predicted, we found that predation environment was associated with several differences in behavior. Both adult and juvenile B. roseni were more active and more prone to explore than B. terrabensis. However, we found no differences in boldness in either adults or juveniles. We also found a significant interaction between ‘sex’ and ‘species’ as predictors of boldness and exploration, indicating that predation environment can affect behaviors of males and females differently in each species. Our work demonstrates the importance of considering sex and life history stage when evaluating the evolution of behavior.
捕食者能够影响猎物的多种特征，包括行为。诸如胆量、活动率以及探索倾向等特征都可能受到捕食风险的影响。我们的研究通过考察一个自然系统来探究捕食对这些行为的影响，在这个自然系统中，胎生鱼类的两个姐妹物种——罗森氏短颌鳉（Brachyrhaphis roseni）和巴拿马短颌鳉（B. terrabensis）——经历不同的捕食环境。2013年2月，我们在巴拿马奇里基省的奇里基新河中收集鱼类，并进行行为测定。通过旷场行为测定，我们对幼鱼和成鱼、雄性和雌性进行了评估，以确定个体发育阶段之间或性别之间在行为上是否存在差异。我们将胆量评估为从遮蔽处进入新环境的“出现时间”，随后在该新环境中测量活动和探索情况。我们预测，与巴拿马短颌鳉（一种不与捕食者共存的物种）相比，罗森氏短颌鳉（一种与捕食者共存的物种）会更大胆、更活跃，也更倾向于探索。我们总共测试了17条罗森氏短颌鳉幼鱼、21条成年雄性罗森氏短颌鳉和20条成年雌性罗森氏短颌鳉，以及19条巴拿马短颌鳉幼鱼、19条成年雄性巴拿马短颌鳉和18条成年雌性巴拿马短颌鳉。2013年2月，我们从巴拿马奇里基省的溪流中收集了所有动物，并在使其短暂适应实验室条件后对它们进行了测试。正如预测的那样，我们发现捕食环境与行为上的若干差异相关。罗森氏短颌鳉的成年个体和幼年个体都比巴拿马短颌鳉更活跃，也更倾向于探索。然而，我们发现成年个体和幼年个体在胆量方面均无差异。我们还发现，作为胆量和探索行为预测指标的“性别”和“物种”之间存在显著交互作用，这表明捕食环境对每个物种中雄性和雌性的行为影响可能不同。我们的研究表明，在评估行为进化时考虑性别和生活史阶段具有重要意义。
