Kinship and familiarity affect recognition and foraging in the wolf spider, Pardosa milvina (Araneae: Lycosidae).

Abstract

Recognition of familiar and related conspecifics can be crucial for altruistic behaviors. In spiders, a reduction in cannibalism has previously been used as evidence of kin recognition. The goal of this study was to examine the changes in activity and foraging for the non-social wolf spider, Pardosa milvina (Araneae: Lycosidae), as novel proxies for recognition and to provide evidence for altruism. Activity and foraging by juvenile spiders were explored on chemotactile cues (silk, excreta, feces) from related and/or familiar spiders. The activity of spiders included time spent moving, speed, and duration on familiar or kin cues. Foraging included the maximum consumption of crickets and rate of capture on non-kin, kin, familiar non-kin, and familiar kin cues. Pardosa spent more time ambulatory on kin cues than familiar cues. Additionally, animals foraging on kin cues decreased consumption while those foraging on familiar cues increased consumption. Capture rates increased on familiar cues, but tended to decrease on kin cues. These results suggest that immature Pardosa utilize chemotactile cues to distinguish kin and familiar conspecifics and may exploit this recognition to increase their indirect fitness. These results also align with a recent producer-scrounger foraging model that considers within-group relatedness as a key to understanding exploitation by kin. Together these results indicate a foraging strategy that may help to explain the early evolution of sociality in spiders.