Mating under the influence: male Siamese fighting fish prefer EE2-exposed females
Countless pharmaceuticals and endocrine disrupting chemicals (EDCs) exist on the market with more added each day. Many of these compounds are not removed during the wastewater treatment process and enter bodies of water in their active form. EDCs are known to have physiological and behavioral effects in exposed organisms. Exposure to the synthetic estrogen 17α-ethinylestradiol (EE2), a common EDC found in birth control pills, has been found to lead to population collapse after only a few generations in some fish species. Mechanisms identified as potential driving forces for collapse include feminization of males and altered fecundity in both sexes. However, an additional way in which EE2 could lead to population collapse is by altering courtship behavior, which could then change mating preferences and decrease mating opportunities. The current study had the following objectives: determine if exposing female Siamese fighting fish, Betta splendens, to EE2 changes mate choice in males; assess if the dose and duration of female exposure matters; and examine if exposing males to EE2 influences their mating preferences. Both unexposed and exposed males were presented with pairs of females that differed in EE2 dose and exposure duration. The results indicate that males were more responsive to EE2-exposed females than unexposed females, with males being most responsive to females exposed to the low versus high dose. Furthermore, exposed males responded less overall than unexposed males. If EE2 concentration increases in the environment, the likelihood of successful mating could decrease and, therefore, potentially lead to adverse population impacts.
KeywordsEndocrine disrupting chemicals Mate choice 17α-ethinylestradiol Courtship
The authors would like to thank Haley LaMonica for her assistance in running behavioral trials. They also thank Jessica Kane, Kelley Portrais, Megan Stevens, and two anonymous reviewers for their feedback on a previous version of this manuscript. Amy Keirstead and Molly Wright were instrumental in creating the EE2 solution and analyzing EE2 in water samples.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. Animal care and experimental protocols were approved by the UNE IACUC and covered under protocol UNE-20130910DZIET.
All authors have approved this version of the work.
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