Meeting Abstract

35.6  Monday, Jan. 5  Aggression and the diversification of Lake Malawis rock-dwelling cichlids DANLEY, Patrick D; Baylor University patrick_danley@baylor.edu

Among the rock-dwelling Haplochromine cichlids of Lake Malawi, males must obtain and defend a territory to secure access to females. As a result, aggression plays a critical role in mbuna territoriality. This study examined the patterns of aggression in four sibling species within the mbuna genus Metriaclima at two locations in the southern Lake Malawi. The number of aggressive acts of two sympatric species was examined at each location. At each site, one species defends territories over bedrock and the other over cobble. The number of aggressive acts across the four species was compared. The influence of habitat type on male aggression was examined and the targets of male aggression were identified to evaluate several hypotheses concerning the evolution of male aggression. The results show that aggression quantitatively varied among species, was largely directed towards heterospecifics, and was strongly influenced by habitat type. The aggressive behavior of one sympatric species pair, Metriaclima benetos and Metriaclima zebra, was observed under controlled laboratory conditions. Laboratory results support field observations: the bedrock associated species performed more aggressive acts and aggressive acts were directed primarily at heterospecifics. The results of this study provide further evidence that behavioral evolution has contributed to the most recent speciation events among Lake Malawis cichlid fish.