García Luis Fernando, Viera Carmen, Pekár Stano
Grupo Multidisciplinario en Ecología para la Agricultura, Centro Universitario Regional Este, Universidad de la República, Treinta y Tres, Uruguay.
Sección Entomología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
Naturwissenschaften. 2018 Apr 2;105(3-4):30. doi: 10.1007/s00114-018-1555-z.
Predators are traditionally classified as generalists and specialists based on the presence of adaptations that increase efficiency of prey capture and consumption and selection of particular prey types. Nevertheless, empirical evidence comparing foraging efficiency between generalist and specialist carnivores is scarce. We compared the prey-capture and feeding efficiency in a generalist and a specialist (araneophagous) spider predator. By using two related species, the generalist Harpactea rubicunda (Dysderidae) and the specialist Nops cf. variabilis (Caponiidae), we evaluated their fundamental trophic niche by studying the acceptance of different prey. Then, we compared their predatory behavior, efficiency in capturing prey of varying sizes, feeding efficiency, and nutrient extraction. Nops accepted only spiders as prey, while Harpactea accepted all offered prey, confirming that Nops is stenophagous, while Harpactea is euryphagous. Further, Nops displayed more specialized (stereotyped) capture behavior than Harpactea, suggesting that Nops is a specialist, while Harpactea is a generalist. The specialist immobilized prey faster, overcame much larger prey, and gained more mass (due to feeding on larger prey) than the generalist. Both the specialist and the generalist spider extracted more proteins than lipids, but the extraction of macronutrients in the specialist was achieved mainly by consuming the prosoma of the focal prey. We show that the specialist has more efficient foraging strategy than the generalist.
传统上，捕食者根据是否存在能提高猎物捕获和消耗效率以及特定猎物类型选择的适应性特征，被分为广食性和狭食性两类。然而，比较广食性和狭食性食肉动物觅食效率的实证证据却很稀少。我们比较了一种广食性蜘蛛捕食者和一种狭食性（食蛛性）蜘蛛捕食者在猎物捕获和进食方面的效率。通过使用两个近缘物种，即广食性的红螯蛛（管巢蛛科）和狭食性的似多变管巢蛛（卡波蛛科），我们通过研究它们对不同猎物的接受情况来评估它们的基础营养生态位。然后，我们比较了它们的捕食行为、捕获不同大小猎物的效率、进食效率和营养物质提取情况。似多变管巢蛛只接受蜘蛛作为猎物，而红螯蛛接受所有提供的猎物，这证实了似多变管巢蛛是狭食性的，而红螯蛛是广食性的。此外，似多变管巢蛛表现出比红螯蛛更具专业性（刻板）的捕获行为，这表明似多变管巢蛛是狭食性的，而红螯蛛是广食性的。与广食性蜘蛛相比，狭食性蜘蛛使猎物更快地失去活动能力，能制服大得多的猎物，并获得更多的体重（因为以更大的猎物为食）。狭食性蜘蛛和广食性蜘蛛都提取了比脂质更多的蛋白质，但狭食性蜘蛛对大量营养素的提取主要是通过消耗目标猎物的头胸部来实现的。我们表明，狭食性蜘蛛比广食性蜘蛛具有更有效的觅食策略。
