From sneaker to parental male: Change of reproductive traits in the black goby, Gobius niger (Teleostei, Gobiidae)

Authors

  • Simone Immler,

    1. University of Basel, Zoological Institute, Rheinsprung 9, 4051 Basel, Switzerland
    Current affiliation:
    1. Present address for S. Immler: University of Bern, Dept. Behavioural Ecology, Wohlenstrasse 50A, 3032 Hinterkappelen, Switzerland
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  • Carlotta Mazzoldi,

    1. University of Padova, Dipartimento di Biologia, Via U. Bassi 58/B, 35131 Padova, Italy
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  • Maria Berica Rasotto

    Corresponding author
    1. University of Padova, Dipartimento di Biologia, Via U. Bassi 58/B, 35131 Padova, Italy
    • University of Padova, Dipartimento di Biologia, Via U. Bassi 58/B, 35131 Padova, Italy
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Abstract

This study focuses on the consequences of the switch of tactic from parasitic to parental male in the black goby, Gobius niger (Teleostei: Gobiidae), a species showing two alternative male mating tactics. Older and larger males defend nests, court, and perform parental care on eggs, while younger and smaller ones behave as parasites, sneaking into nests while spawning occurs. Males adopting different tactics are known to present differences in primary and secondary sex traits. The social context of sneaker males was manipulated to induce a tactic switch. Sneakers were kept under two different experimental treatments with or without a female, and under exclusion of male-male competition. Males changed tactics, courting females, spawning, and performing parental care. All males showed substantial changes in primary sexual traits, such as a reduction in gonadal development and an increase in the investment in accessory structures. The experimental groups differed in the functionality of gonads and accessory organs and in the development of the secondary sex traits. These results demonstrate that the moment of switching is not genetically fixed in the black goby. Sneaker males are able to quickly reallocate energy in primary and secondary sex traits, in accordance with the adopted tactic. Several aspects of this flexible reproductive pattern resemble the socially controlled sex change found in sequential hermaphrodites. J. Exp. Zool. 301A:177–185, 2004. © 2004 Wiley-Liss, Inc.

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