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Publication
Reproduction in context: field testing a laboratory model of socially controlled sex change in Lythrypnus dalli (Gilbert)
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Advisor(s)
Abstract(s)
Social interactions can have profound effects on reproduction and the proximate mechanisms involved are just beginning
to be understood. Lythrypnus dalli, the bluebanded goby, is an ideal organism for analyzing the dynamics of socially
controlled sex change both in the laboratory and field. As with most research species, the majority of its behavioural and
physiologic study has been performed in the laboratory. The goal of our study was to induce sex change of L. dalli in a more
natural environment and compare field dynamics with our laboratory-based model. Groups of L. dalli, composed of one large male and three females of varying sizes, were introduced into artificial habitats in the field. After male removal, the dominant, largest female underwent protogynous sex change in the majority of the groups. Within 15 days, 9 of 15 of the dominant females (focal fish) successfully fertilized eggs as males, compared to 13 of 17 in the laboratory. Focal fish displayed the distinctive temporal sequence of behaviour changes consisting of a dominance, quiescent, and courtship phase. In addition, focal fish had gonads, genital papillae, and accessory gonadal structures with morphology in between that of females and males. Those fish that fertilized eggs had this transitional morphology, but were functionally male. Steroids of focal fish were assayed by water sample, and morning samples of free 11-ketotestosterone (11-KT) positively correlated with the percent of male tissue in the gonad, with the size of the accessory gonadal structure but not the genitalia (genital papilla), and with aggressive displacement behaviour on the last day before the fish were sacrificed. These morphological, physiological, and behavioural patterns parallel those seen in the laboratory. Lower rates of behaviour and the dramatic effects of ambient temperature in the field provide insights as to how the environmental context modifies the behaviour and, subsequently, the reproductive function of individuals within a social group.
Description
Keywords
Sex reversal Gonad Genitalia Androgen Aggression 11-Ketotestosterone
Citation
Black, M. P.; Moore, B.; Canario, A. V. M.; Ford, D.; Reavis, R. H.; Grober, M. S. Reproduction in context: Field testing a laboratory model of socially controlled sex change in Lythrypnus dalli (Gilbert), Journal of Experimental Marine Biology and Ecology, 318, 2, 127-143, 2005.
Publisher
Elsevier