Body condition and food shapes group dispersal but not solitary dispersal in a social spider

Dispersal is important for exploitation of new habitat and for outbreeding. A precondition for sociality in spiders is reduced dispersal propensity leading to largely inbred societies. Despite this, social spiders have been observed to disperse from natal colonies and form new or satellite colonies. Proximate factors shaping dispersal, inter-individual variation in dispersal propensities and any advantages accrued from dispersal remain obscure. In the social spider Stegodyphus sarasinorum, we distinguish two types of dispersal: 1) group dispersal in which groups of sub-adult spiders move to form adjacent satellite colonies that are connected to the natal retreat by a shared capture web and 2) solitary dispersal, where a single mated female disperses from the natal colony and can potentially establish a new independent colony. Using experimental colonies that varied in size and subjected to long-term differential food treatment, we show that individuals that participate in group dispersa...

扩散行为对于新栖息地的开拓以及远交繁殖均具有重要意义。蜘蛛社会性演化的一项核心先决条件是扩散倾向的降低，这进而促使种群形成高度近交的社会结构。尽管存在这一规律，已有观测表明社会性蜘蛛仍会从其出生地种群中扩散出去，进而形成新的种群或卫星种群。然而，调控扩散的直接驱动因素、不同个体间扩散倾向的差异，以及扩散所能带来的适应性优势，目前仍未明确。在社会性蜘蛛萨氏纺器蛛（Stegodyphus sarasinorum）中，我们明确区分出两类扩散模式：1. 群体扩散：亚成体蜘蛛集群迁移，形成与出生地栖息巢通过共享捕猎网相连的邻近卫星种群；2. 单独扩散：单只已交配的雌蛛从出生地种群中迁出，并有潜力建立全新的独立种群。我们通过构建大小各异的实验种群，并对其施加长期差异化的食物处理条件，结果显示参与群体扩散的个体……