Aggression in closely related Malawi cichlids varies inversely with habitat complexity
- 356 Downloads
Within the past 2 million years, the cichlids of Lake Malawi have diversified into well over 500 species resulting in one of the worlds largest lacustrine fish radiations. As a result, many of the habitats within the lake support a high diversity of species. In these highly species rich communities, male cichlids must acquire and defend a territory to successfully reproduce. Within the rock-dwelling cichlids of Lake Malawi (mbuna), this has resulted in the formation of polyspecific leks on the heterogeneous rocky benthos. Aggression is fairly common in these leks and has been tied not only to individual reproduction but to the larger phenomenon of community assembly and the maintenance of biological diversity. In this study, I examined the patterns of aggressive acts of four species within the mbuna genus Maylandia 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, Maylandia benetos and Maylandia 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 equally at con- and heterospecifics. The results of this study suggest that habitat complexity plays a larger role in shaping aggressive behavior than other suggested factors such as competition for resources.
KeywordsMbuna Aggressive behavior Speciation Habitat utilization Lake Malawi Metriaclima Pseudotropheus
I would like to thank Thomas D. Kocher, Michael Kidd and R. Craig Albertson for their help in collecting data on the aggressive behavior of fish in the wild. Additionally, T.D. Kocher, Gerald Borgia, and Tagide de Carvalho, and two anonymous reviewers made several valuable comments on previous versions of this manuscript. I am grateful to the University of Malawi and officials at Lake Malawi National Park for providing the facilities and permits necessary to conduct this work.
- Barley AJ, Coleman RM (2010) Habitat structure directly affects aggression in convict cichlids Archocentrus nigrofasciatus. Current Zoology 56(1):52–56Google Scholar
- Danley PD (2001) The ecological, behavioral, and genetic factors influencing the diversification of Lake Malawi’s Rock Dwelling Cichlids. University of New Hampshire, DurhamGoogle Scholar
- Fryer G, Iles TD (1972) The Cichlids of the Great Lakes of Africa. Their Biology and Evolution. TFH, Neptune CityGoogle Scholar
- Liem KF (1991) Functional morphology. In: Keenleyside MHA (ed) Cichlid fishes behavior, ecology and evolution. Chapman and Hall, New York, pp 129–150Google Scholar
- Ribbink AJ, Marsh BA, Marsh AC, Ribbink AC, Sharp BJ (1983) A preliminary survey of the cichlid fishes of rocky habitats in Lake Malawi. South African Journal of Zoology 18:149–310Google Scholar