Visual and chemical cues – does EE2 exposure affect male mate choice of a freshwater fish? (#437)
Aquatic habitats are increasingly being exposed to chemicals that, even at low levels, can disturb the endocrinology of organisms. The morphological and physiological consequences of exposure to these endocrine disrupting chemicals are well known, yet their effects on behavior have received less attention. The aim of this study was to investigate the impacts of short-term (24-day) exposure to an environmentally relevant concentration (5ng/L) of 17α-ethinyl estradiol (EE2) – the active ingredient of the oral contraceptive pill - on male mate choice in the guppy. To do this we asked: 1) Do males discriminate between exposed and control females when only presented with visual cues? 2) Do males discriminate between exposed and control females when presented only with chemical cues? To investigate the impact of EE2 on visual and chemical communication of guppies a male was presented with a choice between (1) the visual cues of an exposed and a control female, and the following day (2) the odour cues of an exposed and a control female. Behaviour of both sexes was video-recorded. We found that EE2-exposed males spent more time associating with exposed females when they could only use visual cues. By contrast, when they were given only chemical cues to choose from, EE2-exposed males visited control female chemical cue more often than EE2-female cue. Interestingly, control females spent significantly more time associating with control males and repeated that behaviour more often than EE2-exposed females. Our study shows that exposure to EE2 alters male mate choice and female behaviour in the guppy. This is the first study to show that EE2-exposure does not impair male ability to sense or respond to chemical cues. Not only does our study uncover a previously unknown behavioural impact of EE2-exposure on female behaviour, but highlights the need to study multiple mate choice cues contemporaneously.