Long-tailed macaques (Macaca fascicularis Raffles, 1821) were captured at various locations in th... more Long-tailed macaques (Macaca fascicularis Raffles, 1821) were captured at various locations in the north of Sumatra as part of a study on social behaviour and genetic relationships. We used individual cage traps, a group trap, a blowpipe and an air-pressure rifle. Provided that the monkeys were willing to take bait, individual cage traps proved most successful; they gave a high capture rate with minimal disturbance of the group. Success with young juveniles and peripheral animals could be improved by placing elevated traps in the centre and in clusters at the periphery of the trapping site. Trapping had no clear lasting effect on the natural behaviour of the animals.
Proceedings of the Royal Society B: Biological Sciences, 1998
Genealogical relatedness is thought to be an important causal factor in the evolution of cooperat... more Genealogical relatedness is thought to be an important causal factor in the evolution of cooperation. We inferred relatedness on the basis of 11 blood protein markers using the Queller and Goodnight index of relatedness in a macaque population with long-term demographic records. This estimate reflected independently determined pedigree relationships in our data set. Mean relatedness among all members of a social group was 0.10 but much higher levels of relatedness (0.30-0.47) were found among the members of matrilineal families with a high or intermediate social rank. Groups of dispersing males that had been born into the same social group were sometimes closely related (0.43 and 0.58), but they could also be less related (0.08). We found that the pattern of distribution of relatedness was associated with gene flow and differential reproduction in males, rather than with group fission and the presence of geographical barriers.
Long-tailed macaques (Macaca fascicularis Raffles, 1821) were captured at various locations in th... more Long-tailed macaques (Macaca fascicularis Raffles, 1821) were captured at various locations in the north of Sumatra as part of a study on social behaviour and genetic relationships. We used individual cage traps, a group trap, a blowpipe and an air-pressure rifle. Provided that the monkeys were willing to take bait, individual cage traps proved most successful; they gave a high capture rate with minimal disturbance of the group. Success with young juveniles and peripheral animals could be improved by placing elevated traps in the centre and in clusters at the periphery of the trapping site. Trapping had no clear lasting effect on the natural behaviour of the animals.
Proceedings of the Royal Society B: Biological Sciences, 1998
Genealogical relatedness is thought to be an important causal factor in the evolution of cooperat... more Genealogical relatedness is thought to be an important causal factor in the evolution of cooperation. We inferred relatedness on the basis of 11 blood protein markers using the Queller and Goodnight index of relatedness in a macaque population with long-term demographic records. This estimate reflected independently determined pedigree relationships in our data set. Mean relatedness among all members of a social group was 0.10 but much higher levels of relatedness (0.30-0.47) were found among the members of matrilineal families with a high or intermediate social rank. Groups of dispersing males that had been born into the same social group were sometimes closely related (0.43 and 0.58), but they could also be less related (0.08). We found that the pattern of distribution of relatedness was associated with gene flow and differential reproduction in males, rather than with group fission and the presence of geographical barriers.
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Papers by Jan De Ruiter