Solitary versus group living lifestyles, social group composition and cooperation in otters

摘要: Increased reproduction success, enhanced foraging and reduced predation risk are usually regarded as major factors favouring the evolution of social behaviour. Here we formulate a series hypotheses relating sexual, ecological behavioural to evaluate their explanatory value for 13 extant otter species, estimating extent which each factor contributes sociality species. We also compare individual behaviours within some Four species obligatory social; four solitary; five present both types organization. Social organizations not related phylogenetic relationships. However, many exhibit intra-species patterns flexible lifestyles. Both solitary otters adjust in response chiefly food availability, but habitat features competition.Group living is more common when intraspecific competition or trophic resources replenish rapidly. Under these circumstances, group members often forage individually. When individually, they switch prey type compete with other conspecifics. structures fall into seven types: (1) family groups; (2) extended groups, an alpha dominant pair; (3) highly groups helpers; (4) collective hunting (5) lifestyle; (6) unstable mixed-sex (7) single-sex bachelor groups. variable adopts one sociality, this may be only temporary. Variations life actually based on events that induce individuals make decisions taking account.Although ontogenetic can influence delayed dispersal otters, rather than could play important role formation cohesiveness kinship appear secondary effects primary causes group. Appropriate adjustment behaviour reduces cost because avoid interactions benefits low gather together provides real advantages. Although any model unlikely explicate all facets towards results mainly from family.