Fighting and assessment in male cichlid fish: the effects of asymmetries in gonadal state and body size

@article{citeulike:2551989, abstract = {In fights between animals over limited resources, the larger contestant often wins. Game theoretical models of animal fighting predict that relative body size is assessed during the fight and thus determines fight duration and intensity. In addition, if the contestants differ in the value they place on the disputed resource, this can also influence the outcome, duration and intensity of the fight. We studied territorial fighting in a cichlid fish,Tilapia zillii, in relation to relative body size and gonad weight. Relative gonad weight was a much stronger predictor of fight outcome than relative body size, even when body weight asymmetries were as large as 30\%. This suggested that males with large gonads were fighting harder to defend their territory, perhaps because the value of a territory correlates with the gonadal state of the individual. A detailed analysis of mouth wrestling observed during fighting suggested that relative body size is assessed. However, contestants smaller than their opponent often continued to fight in spite of their size disadvantage. Weight disadvantaged winners appeared to fight more fiercely as suggested by a negative correlation between weight asymmetry and the proportion of bites inflicted by the winner. During escalated fighting, winners and losers differed consistently with regard to a behaviour termed mouth locking. Although neither biting nor persistence in mouth locking was related to gonad weight, we propose that the fish may have been assessing asymmetries unrelated to relative body size and possibly more related to levels of cost and the motivation to persist.}, author = {Neat, Francis C. and Huntingford, Felicity A. and Beveridge, Malcolm M. }, citeulike-article-id = {2551989}, comment = {Gonadal size predicts fight outcome much better than body size even up to body size differentials of 30\%. Territories may be more valuable to fish with enlarged gonads (i.e. depending on their reproductive state).}, doi = {http://dx.doi.org/10.1006/anbe.1997.0669}, journal = {Animal Behaviour}, keywords = {contest, dominance, endocrine, experiment, fish, loss, model, rhp, win}, month = {April}, number = {4}, pages = {883--891}, posted-at = {2008-03-18 16:22:13}, priority = {2}, title = {Fighting and assessment in male cichlid fish: the effects of asymmetries in gonadal state and body size}, url = {http://dx.doi.org/10.1006/anbe.1997.0669}, volume = {55}, year = {1998} }

TY - JOUR ID - citeulike:2551989 L3 - citeulike-article-id:2551989 TI - Fighting and assessment in male cichlid fish: the effects of asymmetries in gonadal state and body size JF - Animal Behaviour VL - 55 IS - 4 SP - 883 EP - 891 N2 - In fights between animals over limited resources, the larger contestant often wins. Game theoretical models of animal fighting predict that relative body size is assessed during the fight and thus determines fight duration and intensity. In addition, if the contestants differ in the value they place on the disputed resource, this can also influence the outcome, duration and intensity of the fight. We studied territorial fighting in a cichlid fish,Tilapia zillii, in relation to relative body size and gonad weight. Relative gonad weight was a much stronger predictor of fight outcome than relative body size, even when body weight asymmetries were as large as 30%. This suggested that males with large gonads were fighting harder to defend their territory, perhaps because the value of a territory correlates with the gonadal state of the individual. A detailed analysis of mouth wrestling observed during fighting suggested that relative body size is assessed. However, contestants smaller than their opponent often continued to fight in spite of their size disadvantage. Weight disadvantaged winners appeared to fight more fiercely as suggested by a negative correlation between weight asymmetry and the proportion of bites inflicted by the winner. During escalated fighting, winners and losers differed consistently with regard to a behaviour termed mouth locking. Although neither biting nor persistence in mouth locking was related to gonad weight, we propose that the fish may have been assessing asymmetries unrelated to relative body size and possibly more related to levels of cost and the motivation to persist. KW - contest KW - dominance KW - endocrine KW - experiment KW - fish KW - loss KW - model KW - rhp KW - win N1 - Gonadal size predicts fight outcome much better than body size even up to body size differentials of 30%. Territories may be more valuable to fish with enlarged gonads (i.e. depending on their reproductive state). AU - Neat, Francis AU - Huntingford, Felicity AU - Beveridge, Malcolm PY - 1998/04// UR - http://dx.doi.org/10.1006/anbe.1997.0669 ER -