Moleón Marcos, Martínez-Carrasco Carlos, Muellerklein Oliver C, Getz Wayne M, Muñoz-Lozano Carlos, Sánchez-Zapata José A
Departamento de Biología Aplicada, Universidad Miguel Hernández, Elche, Spain.
Departamento de Biología de la Conservación, Estación Biológica de Doñana-CSIC, Sevilla, Spain.
J Anim Ecol. 2017 Sep;86(5):1179-1191. doi: 10.1111/1365-2656.12714. Epub 2017 Jul 17.
Ecologists have traditionally focused on herbivore carcasses as study models in scavenging research. However, some observations of scavengers avoiding feeding on carnivore carrion suggest that different types of carrion may lead to differential pressures. Untested assumptions about carrion produced at different trophic levels could therefore lead ecologists to overlook important evolutionary processes and their ecological consequences. Our general goal was to investigate the use of mammalian carnivore carrion by vertebrate scavengers. In particular, we aimed to test the hypothesis that carnivore carcasses are avoided by other carnivores, especially at the intraspecific level, most likely to reduce exposure to parasitism. We take a three-pronged approach to study this principle by: (i) providing data from field experiments, (ii) carrying out evolutionary simulations of carnivore scavenging strategies under risks of parasitic infection, and (iii) conducting a literature-review to test two predictions regarding parasite life-history strategies. First, our field experiments showed that the mean number of species observed feeding at carcasses and the percentage of consumed carrion biomass were substantially higher at herbivore carcasses than at carnivore carcasses. This occurred even though the number of scavenger species visiting carcasses and the time needed by scavengers to detect carcasses were similar between both types of carcasses. In addition, we did not observe cannibalism. Second, our evolutionary simulations demonstrated that a risk of parasite transmission leads to the evolution of scavengers with generally low cannibalistic tendencies, and that the emergence of cannibalism-avoidance behaviour depends strongly on assumptions about parasite-based mortality rates. Third, our literature review indicated that parasite species potentially able to follow a carnivore-carnivore indirect cycle, as well as those transmitted via meat consumption, are rare in our study system. Our findings support the existence of a novel coevolutionary relation between carnivores and their parasites, and suggest that carnivore and herbivore carcasses play very different roles in food webs and ecosystems.
传统上，生态学家在食腐研究中一直将食草动物尸体作为研究模型。然而，一些关于食腐动物避免取食食肉动物尸体的观察表明，不同类型的尸体可能导致不同的压力。因此，关于不同营养级产生的尸体的未经检验的假设可能会导致生态学家忽视重要的进化过程及其生态后果。我们的总体目标是研究脊椎动物食腐动物对哺乳动物食肉动物尸体的利用情况。具体而言，我们旨在检验这样一个假设，即其他食肉动物会避免食用食肉动物尸体，尤其是在种内层面，最有可能是为了减少寄生虫感染的风险。我们采用三管齐下的方法来研究这一原理：（i）提供野外实验数据；（ii）在寄生虫感染风险下对食肉动物的食腐策略进行进化模拟；（iii）进行文献综述以检验关于寄生虫生活史策略的两个预测。首先，我们的野外实验表明，在食草动物尸体上观察到的取食物种的平均数量以及消耗的尸体生物量百分比显著高于食肉动物尸体。即使两种类型的尸体之间，访问尸体的食腐动物物种数量以及食腐动物检测到尸体所需的时间相似，这种情况仍然发生。此外，我们没有观察到同类相食现象。其次，我们的进化模拟表明，寄生虫传播的风险会导致食腐动物进化出普遍较低的同类相食倾向，并且避免同类相食行为的出现强烈依赖于基于寄生虫的死亡率假设。第三，我们的文献综述表明，在我们的研究系统中，可能能够遵循食肉动物 - 食肉动物间接循环的寄生虫物种以及通过食用肉类传播的寄生虫物种很少见。我们的研究结果支持食肉动物与其寄生虫之间存在一种新的协同进化关系，并表明食肉动物和食草动物尸体在食物网和生态系统中发挥着非常不同的作用。
