Oral Presentation Society of Environmental Toxicology and Chemistry Australasia 2021

Disruption of male mating strategies in a chemically compromised environment (#150)

Michael G Bertram 1 , Patrick Tomkins 2 , Minna Saaristo 2 3 , Jake M Martin 2 , Marcus Michelangeli 2 4 , Raymond B Tomkins 5 , Bob BM Wong 2
  1. Swedish University of Agricultural Sciences, Umeå, VäSTERBOTTEN, Sweden
  2. Monash University, Melbourne, VICTORIA, Australia
  3. Åbo Akademi University, Turku, Finland
  4. University of California, Davis, Davis, California, United States
  5. Department of Environment, Land, Water and Planning, Melbourne, Victoria, Australia

Pharmaceuticals are accumulating in environments globally. This includes trenbolone, a potent growth-promoting hormone that enters waterways in agricultural run-off. However, whether and how drugs like trenbolone impact complex behaviours in wildlife remain largely unknown. We exposed male guppies (Poecilia reticulata) to trenbolone and compared the response of exposed and unexposed males to sequentially presented large and small females. Due to a positive size-fecundity relationship, larger females are generally expected to be preferred by males. While we found no evidence that the size of a previously encountered female affected the amount of mating behaviour performed by males during the second presentation, males from both exposure treatments conducted more frequent courting events towards larger females during both presentations, suggesting an absolute preference for greater female size. Further, across both presentations, trenbolone exposure caused a shift in male mating strategy towards increased sneaking behaviour, although male sequential investment into mating effort was not impacted. Our findings contribute to a growing understanding of impacts of pharmaceuticals on wildlife behaviour.