Large group size yields group stability in the cooperatively breeding cichlid Neolamprologus pulcher
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Abstract
Group size has been shown to positively influence survival of group members in many cooperatively breeding vertebrates, including the Lake Tanganyika cichlid Neolamprologus pulcher, suggesting Allee effects. However, long-term data are scarce to test how these survival differences translate into changes in group extinction risk, group size and composition. We show in a field study of 117 groups from six different colonies (three from two populations each), that group size critically influences these parameters between years. Within one year, 34% of the groups went extinct. Group size correlated positively between years and large groups did not go extinct. The latter were more likely to contain small helpers the subsequent year, which is a cumulative measure of the previous months' reproductive success. Finally, there was a tendency that large groups were more likely to contain a breeding male and female still a year after the first check. The breeder male size, breeder female size, and largest helper size did not influence these parameters, and also did not correlate with the sizes of these categories of fish after one year. This suggests that group size, and not the body size or fighting ability of group members, was the critical variable determining the success of groups. In total, seven groups had fused with other groups between years. To our knowledge, this is the first study showing long-term benefits of large group size in a cooperatively breeding fish. We discuss the importance of differential survival and dispersal of group members for the demonstrated group size effects.
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| All Time | Past 365 days | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 1334 | 223 | 18 |
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Large group size yields group stability in the cooperatively breeding cichlid Neolamprologus pulcher
In: BehaviourSearch for other papers by Dik Heg in
Current site
Google Scholar
PubMed
Search for other papers by Lyanne Brouwer in
Current site
Google Scholar
PubMed
Search for other papers by Zina Bachar in
Current site
Google Scholar
PubMed
Search for other papers by Michael Taborsky in
Current site
Google Scholar
PubMed
Abstract
Group size has been shown to positively influence survival of group members in many cooperatively breeding vertebrates, including the Lake Tanganyika cichlid Neolamprologus pulcher, suggesting Allee effects. However, long-term data are scarce to test how these survival differences translate into changes in group extinction risk, group size and composition. We show in a field study of 117 groups from six different colonies (three from two populations each), that group size critically influences these parameters between years. Within one year, 34% of the groups went extinct. Group size correlated positively between years and large groups did not go extinct. The latter were more likely to contain small helpers the subsequent year, which is a cumulative measure of the previous months' reproductive success. Finally, there was a tendency that large groups were more likely to contain a breeding male and female still a year after the first check. The breeder male size, breeder female size, and largest helper size did not influence these parameters, and also did not correlate with the sizes of these categories of fish after one year. This suggests that group size, and not the body size or fighting ability of group members, was the critical variable determining the success of groups. In total, seven groups had fused with other groups between years. To our knowledge, this is the first study showing long-term benefits of large group size in a cooperatively breeding fish. We discuss the importance of differential survival and dispersal of group members for the demonstrated group size effects.
| All Time | Past 365 days | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 1334 | 223 | 18 |
| Full Text Views | 405 | 46 | 5 |
| PDF Views & Downloads | 416 | 89 | 9 |