Abstract
Sex allocation theory for sequential hermaphrodites predicts the size at which an individual should change sex, given the different relationships between individual size and reproductive success in the two sexes. We studied a host-parasite system where the myxozoan Kudoa ovivora infects the ovaries of the reef fish Thalassoma bifasciatum, a protogynous sequential hermaphrodite. The parasite sporulates in the host’s eggs and renders them infertile. It is thus expected to reduce the female’s reproductive success, and could thereby influence host sex change. We present data from marked fish we observed in the field over 4 months. The data suggest that females infected with Kudoa ovivora have a lower reproductive success, change sex earlier and at a smaller size than uninfected females. These results are in agreement with predictions from sex allocation theory, and provide the first example of a possible parasitic influence on the sex allocation of its host.
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Acknowledgements
We thank Todd Catalini, Arturo Dominici, Trimurti Irzan, Caroline Joris, Kuno von Wattenwyl, and Jono Wilson for excellent field assistance, and the Smith family for their hospitality at Crawl Cay. Furthermore, we would like to thank the staff of the Smithsonian Tropical Research Institute for invaluable support, particularly Harry Barnes and Luis Mou Sue for support in Bocas del Toro, and John Christy, Arturo Dominici, Allen Herre, Bailey Kessing, Harilaos Lessios and Ross Robertson for support in Panama City. This project profited greatly from discussions with Jacob Koella, Nico Michiels, Steve Swearer, and the participants of the 1998 Population Biology Seminar in Guarda, particularly Mette Hansen. We also thank Anders Berglund, Jacob Koella, Nico Michiels, and Steve Swearer for helpful comments on the manuscript. During this study L.S. was supported by a poste rouge (CNRS, France), an IHP fellowship (SNF, Switzerland), and research funds from the Novartis Foundation, the Janggen-Pöhn-Stiftung, and the Kommission für Reisestipendien of the Swiss Academy of Natural Sciences. D.B.V. was supported by CONICIT (Venezuela). The research was carried out in accordance to Panamanian law.
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Schärer, L., Vizoso, D.B. Earlier sex change in infected individuals of the protogynous reef fish Thalassoma bifasciatum . Behav Ecol Sociobiol 55, 137–143 (2003). https://doi.org/10.1007/s00265-003-0694-0
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DOI: https://doi.org/10.1007/s00265-003-0694-0