The agricultural contaminant 17β-trenbolone disrupts male-male competition in the guppy (Poecilia reticulata). (November 2017)

• Record Type: Journal Article
• Authors: Tomkins, Patrick; Saaristo, Minna; Bertram, Michael G.; Tomkins, Raymond B.; Allinson, Mayumi; Wong, Bob B.M.
• Is Part Of: Chemosphere. Volume 187(2017)
• Page Start: 286
• Page End: 293
• Publication Date: 2017-11
• Subjects: 17β-trenbolone -- Endocrine-disrupting chemical -- Guppy -- Hormonal growth promotant -- Sexual selection; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2017.08.125
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Despite a growing literature highlighting the potential impact of human-induced environmental change on mechanisms of sexual selection, relatively little is known about the effects of chemical pollutants on male-male competition. One class of environmental pollutant likely to impact male competitive interactions is the endocrine-disrupting chemicals (EDCs), a large and heterogeneous group of chemical contaminants with the potential to influence morphology, physiology and behaviour at minute concentrations. One EDC of increasing concern is the synthetic, androgenic steroid 17β-trenbolone, which is used globally to promote growth in beef cattle. Although 17β-trenbolone has been found to cause severe morphological and behavioural abnormalities in fish, its potential impact on male-male competition has yet to be investigated. To address this, we exposed wild male guppies ( Poecilia reticulata ) to an environmentally realistic concentration of 17β-trenbolone (average measured concentration: 8 ng/L) for 21 days using a flow-through system. We found that, in the presence of a competitor, 17β-trenbolone-exposed males carried out more frequent aggressive behaviours towards rival males than did unexposed males, as well as performing less courting behaviour and more sneak (i.e., coercive) mating attempts towards females. Considering that, by influencing mating outcomes, male-male competition has important consequences for population dynamics and broader evolutionary processes, this study highlights the need for greater understanding of the potential impact of EDCs on the mechanisms of sexual selection. Highlights: 17β-trenbolone (TB) is a widespread agricultural contaminant used in cattle farming. Male guppies were exposed to TB at an environmentally relevant level for 21 days. TB increased male aggression towards a rival and decreased courting of a female. Males exposed to TB performed more 'sneak' mating attempts towards females. First study to show disruption of male-male competition by exposure to TB.