Circulating androgens are influenced by parental nest defense in a wild teleost fish
- 145 Downloads
While social interactions influence vertebrate endocrine regulation, the dynamics of regulation in relation to specific behaviors have not been clearly elucidated. In the current study, we investigated whether androgens (testosterone) or glucocorticoids (cortisol) play a functional role in aggressive offspring defense behavior in wild smallmouth bass (Micropterus dolomieu), a teleost fish with sole paternal care. We measured circulating testosterone and cortisol concentrations in plasma samples taken from parental males following a simulated nest intrusion by a common nest predator, the bluegill sunfish (Lepomis macrochirus). To understand whether endocrine regulation changes across the parental care period, we looked both at males guarding fresh eggs and at males guarding hatched embryos. Plasma testosterone levels increased in males subjected to a simulated nest intrusion when compared to sham controls. Testosterone concentrations in males guarding embryos were lower than in males guarding fresh eggs, but circulating testosterone was positively correlated with the level of aggression towards the nest predator at both offspring development stages. However, there was no increase in cortisol levels following a simulated nest intrusion, and no relationship between cortisol and any measured parameter. These results suggest that androgens play an important role in promoting aggressive nest defense behavior in teleost fish.
KeywordsCortisol Androgens Testosterone Challenge hypothesis Parental care
All fish were sampled under an Ontario Ministry of Natural Resources Scientific Collection Permit and handled in accordance with the guidelines of the Canadian Council on Animal Care as administered by Carleton University and the Queen’s University Biological Station. This research was supported by NSERC Discovery Grants to S.J.C., K.M.G., and G.V.D.K., and a Research Achievement Award from Carleton University to S.J.C. C.M.O. was supported by an Ontario Graduate Scholarship, and by Carleton University. The authors also wish to thank members and friends of “Cooke Country” for assistance with fieldwork, particularly Jake Davis, Cody Dey, Eric Fontaine, Marie-Ange Gravel, Kyle Hanson, Sean Landsman, Sarah McConnachie, Rana Sunder, Alex Wilson, Samantha Wilson, and Claire Yick. Finally, many thanks to Cody Dey and Jacquie Matsumoto for their invaluable assistance with androgen assays.
- Coble DW (1975) Smallmouth bass. In: Clepper H (ed) Black bass ecology and management. Sport Fishing Institute, Washington, DC, pp 21–33Google Scholar
- Fuzzen M, Bernier NJ, Van Der Kraak G (2011) Stress and reproduction. In: Norris DO, Lopez KH (eds) Hormones and reproduction in vertebrates, vol 1: Fishes. Elsevier, Toronto, pp103–117Google Scholar
- Gross MR, Sargent RC (1985) The evolution of male and female parental care in fishes. Am Zool 25:807–822Google Scholar
- Hegner RE, Wingfield JC (1987) Effects of brood-size manipulation on parental investment, breeding success, and reproductive endocrinology of house sparrows. Auk 104:470–480Google Scholar
- McMaster M, Munkittrick K, Van Der Kraak G (1992) Protocol for measuring circulating levels of gonadal sex steroids in fish. Can Tech Rep Fish Aquat Sci 1836Google Scholar
- Nelson RJ (2000) Homeostasis and behaviour. In: Nelson RJ (ed) An introduction to behavioural endocrinology. Sinauer Associates, Massachusetts, pp 447–496Google Scholar
- O’Connor CM, Yick CY, Gilmour KM, Van Der Kraak G, Cooke SJ (2011) The glucocorticoid stress response is attenuated but unrelated to reproductive investment during parental care in a teleost fish. Gen Comp Endocrinol 170:215–221Google Scholar
- Zar JH (1999) Biostatistical analysis, 4th edn. Prentice-Hall, Upper Saddle RiverGoogle Scholar