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A community split among dolphins: the effect of social relationships on the membership of new communities.

Nishita M, Shirakihara M, Amano M - Sci Rep (2015)

Bottom Line: Before the split, the males in the same community after the split more often associated with each other than they did with those in different community.These results indicate that the males of new community were socially different from the other males for a long time before the split, but the females might not have been different.The long-term social relationships among males could be maintained in the subsequent communities.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Fisheries and Environmental Science, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JAPAN.

ABSTRACT
Little is known about community splitting among dolphins because such events are rare in dolphin populations. A case of a community split was confirmed in a population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Japan, where a group of approximately 30 dolphins moved to a new habitat some 60 km from the original habitat. We examined the associations among the dolphins before the community split to determine whether the new community members were already socially different before the split, using 7-year identification data. Before the split, the males in the same community after the split more often associated with each other than they did with those in different community. In contrast, the association patterns among females and between sexes showed no relationships with their post-split community membership. These results indicate that the males of new community were socially different from the other males for a long time before the split, but the females might not have been different. Our findings suggest that at time of the community split, the factors determining the memberships of the subsequent communities are sex-linked. The long-term social relationships among males could be maintained in the subsequent communities.

No MeSH data available.


Standardized lagged association rates (SLAR) for the NC and SC males, with jack-knifed estimates of precision.The  associations (the theoretical SLAR if the individuals are randomly associated) and the best fitting models are shown for the NC and SC males. The supported models for the SC males are also shown.
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f6: Standardized lagged association rates (SLAR) for the NC and SC males, with jack-knifed estimates of precision.The associations (the theoretical SLAR if the individuals are randomly associated) and the best fitting models are shown for the NC and SC males. The supported models for the SC males are also shown.

Mentions: To examine the temporal patterns of the associations, we calculated the standardized lagged association rate (which is “an estimate of the probability that if two individuals are associated at any time, then, after the specified lag, the second individual is a randomly chosen associate of the first”) for the NC and SC males and fitted four models to the data3435. These four models and their quasi Akaike Information Criterion (QAIC) values are shown in Table 1 and the best fitting models and supported models are shown in Fig. 6. Based on the lowest QAIC value, the “casual acquaintances” model was chosen for NC males, and the duration of the associations was estimated to be on the order of several decades. The “preferred companions” model was chosen as the best-fitting model for SC males, with minimum QAIC value. However, the “casual acquaintances” and “constant companions and casual acquaintance” models, whose ΔQAIC were 1.7051 and 1.1699, respectively, were also strongly supported models, because the models with ΔQAIC = 0–2 are considered to be strongly supported models in addition to the best fit model (Table 1). As shown in Fig. 6, the graphs of best two models for the SC males (“preferred companions” and “constant companions and casual acquaintances”) were very close to each other and there was no or very little slope in the graph, indicating that the association relationships among SC males rarely changed with time.


A community split among dolphins: the effect of social relationships on the membership of new communities.

Nishita M, Shirakihara M, Amano M - Sci Rep (2015)

Standardized lagged association rates (SLAR) for the NC and SC males, with jack-knifed estimates of precision.The  associations (the theoretical SLAR if the individuals are randomly associated) and the best fitting models are shown for the NC and SC males. The supported models for the SC males are also shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660307&req=5

f6: Standardized lagged association rates (SLAR) for the NC and SC males, with jack-knifed estimates of precision.The associations (the theoretical SLAR if the individuals are randomly associated) and the best fitting models are shown for the NC and SC males. The supported models for the SC males are also shown.
Mentions: To examine the temporal patterns of the associations, we calculated the standardized lagged association rate (which is “an estimate of the probability that if two individuals are associated at any time, then, after the specified lag, the second individual is a randomly chosen associate of the first”) for the NC and SC males and fitted four models to the data3435. These four models and their quasi Akaike Information Criterion (QAIC) values are shown in Table 1 and the best fitting models and supported models are shown in Fig. 6. Based on the lowest QAIC value, the “casual acquaintances” model was chosen for NC males, and the duration of the associations was estimated to be on the order of several decades. The “preferred companions” model was chosen as the best-fitting model for SC males, with minimum QAIC value. However, the “casual acquaintances” and “constant companions and casual acquaintance” models, whose ΔQAIC were 1.7051 and 1.1699, respectively, were also strongly supported models, because the models with ΔQAIC = 0–2 are considered to be strongly supported models in addition to the best fit model (Table 1). As shown in Fig. 6, the graphs of best two models for the SC males (“preferred companions” and “constant companions and casual acquaintances”) were very close to each other and there was no or very little slope in the graph, indicating that the association relationships among SC males rarely changed with time.

Bottom Line: Before the split, the males in the same community after the split more often associated with each other than they did with those in different community.These results indicate that the males of new community were socially different from the other males for a long time before the split, but the females might not have been different.The long-term social relationships among males could be maintained in the subsequent communities.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Fisheries and Environmental Science, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JAPAN.

ABSTRACT
Little is known about community splitting among dolphins because such events are rare in dolphin populations. A case of a community split was confirmed in a population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Japan, where a group of approximately 30 dolphins moved to a new habitat some 60 km from the original habitat. We examined the associations among the dolphins before the community split to determine whether the new community members were already socially different before the split, using 7-year identification data. Before the split, the males in the same community after the split more often associated with each other than they did with those in different community. In contrast, the association patterns among females and between sexes showed no relationships with their post-split community membership. These results indicate that the males of new community were socially different from the other males for a long time before the split, but the females might not have been different. Our findings suggest that at time of the community split, the factors determining the memberships of the subsequent communities are sex-linked. The long-term social relationships among males could be maintained in the subsequent communities.

No MeSH data available.