近亲幽灵蛛用于兼性群居生活的时间消耗

Time Allocation of Costly Behavior in Group-living Spider Pholcus affinis

所谓近亲幽灵蛛(Pholcus affinis)的兼性群居生活,是指他们可以单独生活,也可以几个个体共栖于一张网上成为一组.本文使用焦点动物追踪法,研究不同大小的组(指组内个体数量多少)、不同年龄阶段的蜘蛛在组内生活中用于'消耗性'行为(移动、织网、弹跳、拨丝或种内相互作用)的时间耗费.主要结论包括:蜘蛛的年龄和组的大小影响组内成员的付出.在不同大小的组里,2～3龄幼蛛(S型)、亚成体或成体(L型)用在'消耗性'行为上所用的时间百分率没有显著性差异,但4～5龄幼蛛(M型)随着组内成员的增多而要花费更多的时间.当组内个体数量超过3个,L型和M型蜘蛛之间有着更多的相互作用,而S型蜘蛛不论组内个体多少,其个体之间相互作用都很少.研究结果同时显示,近亲幽灵蛛在不同发育阶段有不同的群居生活策略.

Pholcus affinis spiders （Araneae： Pholcidae） live in both solitary and group. Group membership is flexible and individuals move frequently among groups, We investigated the time allocation of costly behavior of P. affinis in group-living. Among groups of various sizes, there was no significant difference in the percentage of time that an S （up to 3rd instar） or L （subadult or adult） spider spent in costly behaviours, such as web maintenance, move, bounce or pluck, interactions. However, M （4 - 5th instars） spider spent more time engaging in costly behaviors with larger group size. When the groups were larger than three, L and M spiders had more interactions, whereas S spiders interacted rarely with conspecifics. These results suggest that both age and group size affect the costs incurred by group-living spiders and individuals of P. affinis may use different group living strategies in different growth phases.