tailieunhanh - Variation in Helper Type Affects Group Stability and Reproductive Decisions in a Cooperative Breeder

Recent studies have shown that differences in life history may lead to consistent inter-individual variation in behavioural traits, so-called behavioural syndromes, animal personalities or temperaments. Consis- tencies of behaviours and behavioural syndromes have mainly been studied in non-cooperative species. Insights on the evolution of coopera- tion could be gained from studying individual differences in life histories and behavioural traits. Kin selection theory predicts that if an individ- ual’s reproductive ability is low, it had to aim at gaining inclusive fitness benefits by helping others. We tested this prediction in the cooperatively breeding cichlid Neolamprologus pulcher, by assessing reproductive parameters of adults that had been tested earlier for aggressiveness and for their. | ethology international journal of behavioural biology Ethology RESEARCH PAPER Variation in Helper Type Affects Group Stability and Reproductive Decisions in a Cooperative Breeder Roger Schurch t Dik Heg Department of Behavioural Ecology Institute of Ecology and Evolution University of Bern Hinterkappelen Switzerland t Department of Evolution Ecology and Organismal Biology The Ohio State University Columbus OH USA Correspondence Roger Schurch Department of Evolution Ecology and Organismal Biology The Ohio State University Columbus OH 43210 USA. E-mail Received September 30 2009 Initial acceptance November 3 2009 Final acceptance December 9 2009 J. Wright doi Abstract Recent studies have shown that differences in life history may lead to consistent inter-individual variation in behavioural traits so-called behavioural syndromes animal personalities or temperaments. Consistencies of behaviours and behavioural syndromes have mainly been studied in non-cooperative species. Insights on the evolution of cooperation could be gained from studying individual differences in life histories and behavioural traits. Kin selection theory predicts that if an individual s reproductive ability is low it had to aim at gaining inclusive fitness benefits by helping others. We tested this prediction in the cooperatively breeding cichlid Neolamprologus pulcher by assessing reproductive parameters of adults that had been tested earlier for aggressiveness and for their propensity to assist breeders when they had been young juveniles . We found that juvenile aggression levels predicted the acceptance of a subordinate in the group when adult. Males which were aggressive as juveniles were significantly more likely to tolerate a subordinate in the group when compared with males which were peaceful as juveniles whereas females which were more aggressive as juveniles tended to expel subordinates more often. Females produced significantly smaller