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Riebli, T., Avgan, B., Bottini, A. - M., Duc, C., Taborsky, M., & Heg, D. (2011). Behavioural type affects dominance and growth in staged encounters of cooperatively breeding cichlids. Anim. Behav., 81(1), 313–323.
Abstract: In animals, behavioural properties such as aggressive propensity are often consistent over a life span, and they may form part of a behavioural syndrome. We studied how aggressive propensity influences dominance, contest behaviour and growth in the cooperatively breeding cichlid fish Neolamprologus pulcher. We tested whether intrinsic aggressive propensity (1) influences dominance in paired contests, (2) causes different aggression levels in contests with partners matched for aggressive propensity compared to unmatched partners, and how it (3) affects growth rate in groups that were either matched or unmatched for aggressive propensity. Intrinsic aggressive propensity was first scored with a mirror test and classified as high, medium or low. Thereafter we tested fish with either high or low aggressive propensity with partners matched for size and either matched or unmatched for aggressive type in a paired contest for a shelter. We scored dominance, aggression and submission. As predicted, (1) dominance was more clearly established in unmatched than in matched contests and (2) individuals with high aggressive propensity launched more attacks overall than fish with low intrinsic aggressiveness, suggesting a higher propensity to escalate independently of winning or losing the paired contest. However, contrary to expectation, (3) individuals with low aggressiveness grew faster than aggressive ones in unmatched groups, whereas the opposite occurred in matched groups. This suggests that individuals with low aggressive propensity may benefit from conflict evasion, which might allow them to gain dominance in the future owing to larger body size.
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Dall, S. R. X., Houston, A. I., & McNamara, J. M. (2004). The behavioural ecology of personality: consistent individual differences from an adaptive perspective. Ecol. Letters, 7, 734–739.
Abstract: Individual humans, and members of diverse other species, show consistent differences in
aggressiveness, shyness, sociability and activity. Such intraspecific differences in
behaviour have been widely assumed to be non-adaptive variation surrounding
(possibly) adaptive population-average behaviour. Nevertheless, in keeping with recent
calls to apply Darwinian reasoning to ever-finer scales of biological variation, we sketch
the fundamentals of an adaptive theory of consistent individual differences in behaviour.
Our thesis is based on the notion that such .personality differences. can be selected for if
fitness payoffs are dependent on both the frequencies with which competing strategies
are played and an individual`s behavioural history. To this end, we review existing models
that illustrate this and propose a game theoretic approach to analyzing personality
differences that is both dynamic and state-dependent. Our motivation is to provide
insights into the evolution and maintenance of an apparently common animal trait:
personality, which has far reaching ecological and evolutionary implications.
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