On the (in)stability of dominance hierarchies in the cichiid fish Oreochromis mossambicus

Oliveira, Rui Filipe; Almada, Vítor Carvalho

http://hdl.handle.net/10400.12/1319

Use this identifier to reference this record.

Name:	Description:	Size:	Format:
AB 22(1) 37-45.pdf		2.91 MB	Adobe PDF	Download

Send Feedback

Authors

Oliveira, Rui Filipe

Almada, Vítor Carvalho

Abstract(s)

Dominance hierarchies were studied during 8 weeks in eight heterosexual captive groups of Oreochromis mossambicus at Ihe unset of sexual maturity. Linearity was assessed for each group on a weekly basis based on the Landau's index (h) and on the procedure described by Appleby [Appleby MC (1983): Animal Behaviour 31:600-6081. Week-toweek stability of the hierarchical structures was measured using the Burk's stability index (b) and Spearman rank correlation coefficients for the ranks of fishe.s in consecutive weeks. The two measures of stability showed a high level of concordance but the Spearman rank correlations were more conservative in detecting cases of stability. Although most dominance structures were linear they were unstable frum week to week. Dominant individuals were less likely to experience rank reversals than subordinates. Rank reversals were especially likely among hierarchical neighbors. Dominance hierarchies did not -Stabilize in tbe time span of tbis study.