Foraging specialization and the evolution of life histories in Argyrodes spider.

本研究的目的是阐明盗寄生银蛛的觅食专门化和生活史特征的进化。为此，我研究了1)觅食模式和宿主范围，2)觅食模式的可塑性，3)生活史特征，4)分子系统发育树的构建。1)以寄主为食和以猎物/蚕丝为食是银蛉的两种主要觅食方式。除裂裂蛛外，其他以捕食为主要觅食方式的有居圆网蜘蛛。这可能与球状蛛网上留下的大量小猎物有关。2) A. flavescens只在猎物丰富时偷食猎物，而在其他季节则经常吃丝。在食物供应不足的情况下，食丝似乎是另一种觅食方式。先前的研究表明，寄主进食是生活在三维网络中的物种的另一种策略。(3)食宿主和裂丝拟南蚕为单伏特生命周期，盗食猎物和蚕丝的小物种为多伏特生命周期。这可能与猎物的可用性有关。4)测定了6种Argyrodes和2种Achaearanea的线粒体DNA序列，并构建了系统发育树。saganus和a . fur形成了一个分支，表明捕食宿主和捕食猎物/偷丝是独立进化的。瓢虫的觅食方式从捕食宿主转变为捕食猎物，从而形成了多伏特的生命周期。

The objective of this study is to clarify foraging specialization and the evolution of life history traits in kleptoparasitic Argyrodes spiders. To achieve this, I examined 1) foraging mode and host range, 2) plasticity in foraging mode, 3) life history traits, 4) construction of molecular phylogenetic tree.1) Host eating and prey / silk eating were the two major foraging modes in Argyrodes. Species whose main foraging mode was prey stealing inhabited orb-web spiders, except for A. fissifrons. This may be related to the abundant small prey left on orb-webs.2) A. flavescens exclusively steal prey when prey were abundant, while it often eat silk in other seasons. Silk eating appears to be the alternative foraging mode under poor food availability. Previous studies suggested that host eating was the alternative tactics in species living in three-dimensional webs.3) Host eaters and A. fissifrons had a univoltine life cycle, while small species stealing prey and silk showed a multivoltine life cycle. Probably this is related to the prey availability.4) We determined the sequence of mitochondrial DNA for six species of Argyrodes and two species of Achaearanea and constructed the phylogenetic tree. A. saganus and A. fur formed a clade, suggesting that host eating and prey / silk stealing evolved independently.It appears that Argyrodes developed multivoltine life cycle by changing its foraging mode from host eating to prey stealing.