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Séminaire présenté par F.S Dobson

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Kin selection in Columbian ground squirrels : direct and indirect fitness benefits

Par : F. Stephen DOBSON (CEFE Montpellier et COSAM-University of Auburn, Alabama) invité par V. Viblanc
Date : Jeudi 10 novembre 2011 à 13h30
Lieu : Bibliothèque du DEPE

Résumé :

Empirical and theoretical studies have supported kin selection by demonstrating nepotism or modeling its conditions and consequences. As an alternative, we previously found that female Columbian ground squirrels had greater direct fitness when more close kin were present. Extending those results, we used population matrix methods to calculate minimum estimates of individual fitness, estimated direct and indirect components of fitness, estimated inclusive fitness by adding the direct fitness (stripped of estimated influences of the social environment) and indirect fitness components together, and finally looked for inclusive fitness benefits of associations with close kin who seem to be ‘genial neighbours’. We examined the estimated fitness of a sample of 35 females for which complete lifetimes were known for themselves, their mothers and their littermate sisters. Six of these females had no co-surviving adult close kin, and their direct fitness was significantly lower than 29 females with such kin (k = 0.66 vs. k = 1.23). The net fitness benefit of the presence of close kin was thus 0.57. The estimated indirect component of fitness through benefits to the direct fitness of close kin was 0.43. Thus, estimated inclusive fitness for females with co-surviving close kin (k = 1.09) was significantly greater than that for females without surviving close kin (viz., k = 0.66). The presence of closely related and philopatric female kin appeared to result in considerable fitness benefits for female ground squirrels, perhaps through the behavioural mechanisms of lowered aggression and other forms of behavioural cooperation.