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Abstract Aposematic signals often allow chemically defended prey to avoid attack from generalist predators, including jumping spiders. However, not all individual predators in a population behave in the same way. Here, in laboratory trials, we document that most individualPhidippus regiusjumping spiders attack and reject chemically defended milkweed bugs (Oncopeltus fasciatus), immediately releasing them unharmed. However, a small number of individuals within the population kill and completely consume these presumably toxic prey items. This phenomenon was infrequent with only 14% of our sample (17/122) consuming the milkweed bugs over the course of the study. Individuals that killed and consumed bugs often did so repeatedly; specifically, individuals that consumed a bug in their first test were more likely to kill a bug in their second test and also tended to consume them again. We explored what might drive some (but not all) individuals to consume these bugs and found that neither sex, sexual maturity, body size, laboratory housing type, nor being wild‐caught or being laboratory‐reared, predicted milkweed bug consumption. Consuming bugs had no negative effects on spider mass or body condition; contrary to expectations, individuals that consumed milkweed bugs actually gained more body mass and increased in body condition. We discuss potential behavioural and physiological variation between individuals that may drive these rare behaviours and the implications for the evolution of prey defences.
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Beyond the burrow: Body condition and sex influence exploratory behavior in desert kangaroo rats ( Dipodomys deserti )
ABSTRACT Behavioral variation within a population can be influenced by physical factors such as size, sex, and body condition. This variation may contribute to intraspecific niche breadth by enabling individuals to exploit different niches. To examine how anatomy shapes behavior, we conducted open field tests on desert kangaroo rats (Dipodomys deserti, n=16) and compared their activity to sex, morphology, and body condition. We constructed an arena within the species' natural habitat to simulate ecologically relevant conditions and recorded behavior over 15 min. We quantified speed and distance traveled, used principal component analysis to explore behavioral patterns, and used linear models to test for associations between behavior, locomotor traits, and anatomical variables. We found that individuals with lower body condition scores spent more time exploring, males were more exploratory than females, and individuals with longer feet – a proxy for skeletal size – traveled further. However, behavior and locomotor performance were not significantly correlated. Lastly, individuals moved faster and farther on full moon nights compared to new moon nights, indicating that moonlight influences movement strategy – potentially reflecting trade-offs between foraging and predation risk. These findings highlight species-specific drivers of behavioral variation and underscore the importance of understanding behavioral variability of desert mammals.
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- Award ID(s):
- 2319710
- PAR ID:
- 10642193
- Publisher / Repository:
- The Company of Biologists
- Date Published:
- Journal Name:
- Biology Open
- Volume:
- 14
- Issue:
- 10
- ISSN:
- 2046-6390
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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