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Metabolic divergence between sibling species of cichlids Pundamilia nyererei and Pundamilia pundamilia

Authors

  • P. D. Dijkstra,

    Corresponding author
    • Institute of Biodiversity, Animal Health and Comparative Medicine, Graham Kerr Building, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, U.K.
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  • O. Seehausen,

    1. Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute for Aquatic Sciences, Kastanienbaum, Switzerland
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  • N. B. Metcalfe

    1. Institute of Biodiversity, Animal Health and Comparative Medicine, Graham Kerr Building, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, U.K.
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Author to whom correspondence should be addressed at present address: The University of Texas at Austin, Section of Integrative Biology, Institute for Cellular and Molecular Biology, 1 University Station–C0930, Austin, TX 78712, U.S.A. Tel.: +1 512 475 7318; email: pddijkstra@gmail.com

Abstract

This study compared Pundamilia nyererei and Pundamilia pundamilia males in routine metabolic rate (RR) and in the metabolic costs males pay during territorial interactions (active metabolic rate, RA). Pundamilia nyererei and P. pundamilia males housed in social isolation did not differ in RR. In contrast to expectation, however, P. nyererei males used less oxygen than P. pundamilia males, for a given mass and level of agonistic activity. This increased metabolic efficiency may be an adaptation to limit the metabolic cost that P. nyererei males pay for their higher rate of aggressiveness compared to P. pundamilia males. Thus, the divergence between the species in agonistic behaviour is correlated with metabolic differentiation. Such concerted divergence in physiology and behaviour might be widespread in the dramatically diverse cichlid radiations in East African lakes and may be an important factor in the remarkably rapid speciation of these fishes. The results did not support the hypothesis that higher metabolic rates caused a physiological cost to P. nyererei males that would offset their dominance advantage.

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