Condition-dependent auditory function and reproductive development in the round goby, Neogobius melanostomus
Neural responses to sensory stimuli often differ between sexes and can be regulated by endocrine activity. This thesis examines the effects of sex, reproductive condition, female plasma 17b-estradiol level, and saccule hair cell density on auditory function in the round goby (Neogobius melanostomus). Relative to males, females had greater auditory sensitivity in the upper range of their hearing (300-600 Hz) and a higher density of hair cells. Female 17b-estradiol was associated with changes in auditory filtering properties at low frequencies (100-200 Hz). Additionally, I examined associations between gonadosomatic index, reproductive hormones, and stage of gonadal development in the round goby. Gonadasomatic indices provided limited resolution on reproductive condition in males and females; these categories encompassed individuals in varied endocrine and gonadal conditions. The results demonstrate auditory sexual dimorphism, elucidate the physiological mechanisms regulating auditory function, and present a framework for future studies on the reproductive cycle in the round goby.