Entomology, Ornithology & Herpetology: Current Research
Open Access

Abstract

Fighting Performance of Female Chinese Wolf Spiders in Cannibalistic Contests in Relation to the Battlefield Size

Li-Li Xian, Li-Fang Gao, Chang-Jing Liu and Bo Du

Game theory models suggest that both the forms (ritualized display and real fighting) and outcome of animal contest can be influenced by the relative body size, fighting experience, and hunger level of contestants. However, whether a factor determining the outcome of a contest exhibits similar effects in different forms of the contest has not been highlighted. In a cavity-nesting predator, the Chinese wolf spider Lycosa sinensis (Araneae: Lycosidae) that frequently carries out cannibalism on the Tibetan Plateau, we addressed this question in female cannibalistic contests by designing three series of experiments (the first between large and small opponents, the second between experienced and inexperienced opponents, and the last between satiated and hungry opponents). By repeatedly performing these experiments in large and small artificial battlefields, we revealed that battlefield size determined whether these three factors came into play in the cannibalism of spiders. In asymmetric contest, big spiders always defeated their opponents in real fights. But the battlefield size determined whether a contest can be escalated into real fights. Experienced or satiated spiders can successfully escalate the contest into real fights by enhanced aggressiveness; however, they were unlikely to defeat their inexperienced or hungry opponents in a real fighting. This battlefield size effect may be a reason for Chinese wolf spiders to excavate a cave with themselves proportionally accommodated. Therefore, this effect of battlefield size needs to be considered in future studies of animal contests, especially for the spiders that cannibalism frequently occurs in natural environments.