Preventing behavioural interactions with a male facilitates sex change in female bluebanded gobies, Lythrypnus dalli
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Sex change in marine teleost fishes is commonly regulated by social factors. In species that exhibit protogynous sex change, such as the bluebanded goby Lythrypnus dalli, the most dominant female typically initiates sex change when a male is removed from the social group. Females can use visual, chemical or tactile cues to assess the presence or absence of a male. The primary goal of our study was to determine whether the olfactory and visual presence of a male versus its behavioural interactions with females were important for mediating sex change. We exposed females to three different treatments: absence of a male, presence of a male that could physically interact with her and presence of a male behind a barrier that allowed visual and olfactory interactions but prohibited physical interactions. Sex change occurred in the absence of a male but not in the presence of a male that could physically interact with the female. The presence of a male behind the barrier did not prevent sex change but affected the timing of sex change. Season appeared to affect the latency to initiate male typical courtship, with a delay at the end of the reproductive season only when the male was present behind the barrier. We discuss the seasonal results in terms of L. dalli life history and the potential benefits and costs of changing sex late in the season in the presence or absence of aggressive reinforcement by the male. Our results identify direct behavioural interactions as an important proximate mechanism in the social regulation of sex change in L. dalli.
KeywordsSex reversal Proximate mechanism Sensory cues Social interactions
We thank J. Pylkkanen for collecting the fish used in this study, E. Rodgers for assistance in the experimental design and M.B. Rasotto, M. Black and the Grober laboratory discussion group for providing insights. We also thank two anonymous referees for comments that significantly improved an earlier version of the manuscript. Experimental conditions and manipulations were approved by the Georgia State University IACUC (protocol no. A02011). This work was supported by the Center for Behavioral Neuroscience, an STC Program of the NSF under agreement no. IBN-9876754 to MSG, the Georgia Research Alliance, Georgia State University and an NIH award 1-F32-HD046240-01 to RLE.
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