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A test of the ‘challenge hypothesis’ in cichlid fish: simulated partner and territory intruder experiments
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Abstract(s)
In male birds, the responsiveness of androgens to sexual and territorial behaviour is predicted to vary with
mating system and the degree of paternal investment (‘challenge hypothesis’, CH; Wingfield et al. 1990,
American Naturalist, 136, 829–846). The CH predicts a higher and longer lasting ‘breeding baseline’
androgen level in males of polygynous species with no or only short-term paternal investment than in
males of monogamous species with a high degree of paternal investment. Since the applicability of the CH
to nonavian vertebrates has been unclear, we experimentally tested its predictions in several cichlid fish
(Neolamprologus pulcher, Lamprologus callipterus, Tropheus moorii, Pseudosimochromis curvifrons and
Oreochromis mossambicus) using a simulated territorial intruder protocol. Androgens (11-ketotestosterone:
11-KT; testosterone: T) were measured from fish-holding water. In all species sampled, the 11-KT patterns
confirmed the predictions of the CH originating from the avian literature, but T patterns did not. Males of
all species sampled were highly responsive to territorial intrusions; however, the magnitude and duration
of this response, that is, the rapid return to baseline 11-KT levels, could not clearly be explained by the
degree of paternal care. 11-KT responses to interactions with ovulating females were observed in maternal
mouthbrooders but not in biparental species (e.g. Lamprologini). At the interspecific level, androgen
responsiveness was greater among males of monogamous species, as predicted, but also in species with
more intense pair bonding (e.g. Tropheus moorii). Thus, this study confirms the predictions of the CH in
cichlid fish at both the intraspecific and the interspecific levels.
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Citation
Hirschenhauser, K.; Taborsky, M.; Oliveira, T.; Canário, A.V.M.; Oliveira, R.F.A test of the ‘challenge hypothesis’ in cichlid fish: simulated partner and territory intruder experiments, Animal Behaviour, 68, 4, 741-750, 2004