Parental care behaviour in response to perceived paternity is not mediated by 11-ketotestosterone in bluegill sunfish

Parental care is critical for the survival of many young animals, but parental care can be costly to the individual providing care. To balance this cost, parents can allocate their care to offspring based on their value, which can be dependent on the offspring's relatedness to the parent. Bluegill (Lepomis macrochirus) is a fish characterized by uniparental male care and high levels of cuckoldry. While parental males of this species have been shown to adaptively adjust their care in response to paternity, the mechanisms for this adjustment are not well understood. Androgens are steroid hormones that are associated with parental care behaviours in many species including bluegill. Here, we test the hypothesis that circulating androgen concentrations mediate the adjustment in care provided by bluegill parental males by manipulating perceived paternity and then measuring circulating 11-ketotestosterone concentration and parental care behaviour. We show that males with higher perceived paternity provide higher levels of nurturing and nest defense behaviour, but contrary to expectations, we found that these males had lower concentrations of 11-ketotestosterone. Furthermore, we found positive correlations between individual circulating plasma 11-ketotestosterone concentrations and nurturing behaviour, but not with the aggressive behaviours that differed between paternity treatments. While bluegill make behavioural changes in response to perceived paternity, these changes do not appear to be modulated by 11-ketotestosterone.