Locomotor behaviour of tropical wolf spiders is affected by external temperature and body size, not load bearing

• Published in: Animal behaviour 2023-10
• Main Authors: Villaseñor-Amador, Damián, Vilas-Bôas M.P. de Cerqueira, Leonardo, Gómez, Quimey, Cornejo, Francisca Zamora, Paulucci, Julia, Escalante, Ignacio
• Format: Article
• Language: English
• Subjects: body size; Lycosidae; maternal care; movement rate; paramo; poikilothermy; trade-off
• ISSN: 0003-3472; 1095-8282
• DOI: 10.1016/j.anbehav.2023.10.003

Ectothermic animals depend on ambient temperature to regulate internal temperature. This dependence affects many aspects of their behaviour, including locomotion, foraging and reproduction. Additionally, ectotherms are more vulnerable in environments with extreme hourly temperature fluctuations and their activity patterns likely match those of favourable temperatures. Here, we studied Pardosa wolf spiders (Lycosidae) in the highland tropical paramos of Costa Rica. We tested two hypotheses to elucidate the factors that influence variation in locomotor behaviour. First, we tested whether locomotor behaviour is driven by temperature variation. Female spiders experimentally exposed to higher temperatures (30 °C) moved approximately four times faster than those exposed to lower temperatures (7 °C). Second, we tested whether locomotor behaviour is modulated by the maternal care strategy of these spiders. Females carry an eggsac externally by holding it with the distal spinnerets. The eggsac can represent up to 36% of the spider's body size. However, females moved at the same speed regardless of whether they carried an eggsac or not. This demonstrates that the maternal care strategy does not affect their locomotor performance. In contrast, temperature plays a crucial role in driving locomotion. Our findings expand our understanding of how temperature fluctuations in extreme environments challenge ectotherms’ ability to move and, by extension, escape predators and locate mates and food. •Ectotherms in tropical highlands experience high hourly temperature variations.•Female wolf spiders ran faster when in higher-than-average ambient temperatures.•Female wolf spiders carrying an eggsac moved as fast as females not carrying one.•External temperature, not maternal care, modulates locomotion of these arachnids.•Females with eggsacs might modify their posture to avoid biomechanical consequences.