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Sex differences in the repeatability of boldness over metamorphosis

Hedrick, Ann V., Kortet, Raine
Behavioral ecology and sociobiology 2012 v.66 no.3 pp. 407-412
Gryllidae, adults, animals, females, gender differences, hormones, juveniles, males, metamorphosis, nymphs, ontogeny, predation, risk
Consistent individual differences in boldness have been identified in many species and can have important effects on fitness. In most animals, juveniles face different costs and benefits of risk-taking behavior than do adults. Furthermore, profound changes in hormones, morphology and environment often occur when juveniles become adults. Therefore, the boldness of individuals might change with ontogeny. In field crickets, adult males call to attract sexually receptive females, and male calling increases predation risk. We measured the repeatability of boldness (latency to emerge from a safe refuge) in both male and female crickets. Each cricket was tested once as a small nymph and once as an adult. We found that boldness was repeatable across metamorphosis in females, but not in males. Males became less bold with maturation, a result that we predicted because of the risk associated with calling for mates. We also found that in general, nymphs were bolder than adults and that individuals spent more time immobile in response to a predator cue when they were nymphs, versus when they were adults.