Filial cannibalism as a conditional strategy in males
of a paternal mouthbrooding fish |
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Authors: | Tomohiro Takeyama Noboru Okuda Yasunobu Yanagisawa |
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Institution: | (1) Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan;(2) Center for Ecological Research, Kyoto University, Otsu 520-2113, Japan;(3) Department of Biology and Earth Sciences, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan;(4) Present address: Center for Ecological Research, Kyoto University, 2-509-3, Hirano, Otsu 520-2113, Japan |
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Abstract: | Filial cannibalism is widespread in a variety of animal species and has been generally accepted as an adaptive behavior. Within
a population, some individuals adopt filial cannibalism and others do not, in spite of its adaptiveness. There is little knowledge
of how such a polymorphic trait is maintained in nature. To understand the underlying mechanism of cannibalistic polymorphism,
we conducted a long-term field study that involved monitoring of the reproductive experience of marked individuals in the
paternal mouthbrooding cardinalfish, Apogon doederleini, in which parental males sometimes cannibalize their entire broods. We assumed that filial cannibalism can be described as
one of three possible strategies: alternative, mixed or conditional. Individual cannibalistic tendencies, represented by the
number of entire brood cannibalism performed by each individual in one breeding season, showed a random distribution within
the study population. Moreover, the individual cannibalistic tendencies were not consistent between two successive seasons.
These results suggest that filial cannibalism is phenotypically plastic, thus eliminating the alternative strategy as a possible
mechanism. Comparison of variance in reproductive success between cannibals and non-cannibals showed that observations were
not in accordance with those expected in the case that males adopt filial cannibalism stochastically, that is, as a mixed
strategy. Our previous studies have indicated that filial cannibalism is affected by male status, such as age, somatic condition
and mate availability. In conclusion, filial cannibalism by male A. doederleini is carried out as a conditional strategy. |
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Keywords: | Alternative tactics Apogonidae Paternal cannibalism Mouthbrooder Phenotypic polymorphism |
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