Article révisé par les pairs
Résumé : This study highlights the influence of sampling size on the interpretation of between castes division of labour in the dimorphic ant genus Pheidole. We show that data analyses based on rarefaction curves provide better estimates of caste repertoire sizes. Weighted observations of the two worker castes of Pheidole pallidula reveals that the behavioural repertoire of majors is far more extended than expected. Indeed, majors are not restricted to defence, seed milling or food storage but can additionally participate to within nest activities by carrying out 69% of the minors' behavioural repertoire including brood care. Besides, we show that interspecific variation in the size of majors' behavioural repertoire could simply result from differences in the number of majors observed. Therefore, the ergonomic prediction that the repertoire size of one caste should be correlated to its numerical representation in the colony needs to be re-examined considering between-castes differences in the sampling effort.