Meeting Abstract

P2.110  Sunday, Jan. 5 15:30  An intrasexual comparison of tyrosine hydroxylase fiber innervation of the vocal motor system in a teleost with alternative reproductive tactics GHAHRAMANI, Z.N.*; TIMOTHY, M.; KIM, S.; FORLANO, P.M.; CUNY Brooklyn College; CUNY Brooklyn College; CUNY Brooklyn College; CUNY Brooklyn College zackgmani@gmail.com

The plainfin midshipman, Porichthys notatus, is a seasonal breeding marine teleost that produces vocal signals for intraspecific communication. There are two distinct reproductive male morphs: Type I males establish nests and vocally court females while type II males, incapable of vocal courtship, sneak-spawn to steal fertilizations from type I males. Previously established sexual polymorphisms in the hindbrain-spinal vocal circuitry of midshipman are related to divergence of male reproductive tactics, specifically the ability to produce long-duration advertisement calls. Catecholamines, including the neurotransmitters dopamine and noradrenaline, are known regulators of reproduction and sexually motivated behaviors across vertebrates, including vocal-acoustic communication. We tested the hypothesis that there are intrasexual differences between the two males in the catecholaminergic fiber innervation of the vocal motor circuitry. Animals were collected from nesting sites in Tomales Bay, CA during the summer nesting season. Subjects were sacrificed by transcardial perfusion and brains were labeled for tyrosine hydroxylase (TH, rate-limiting enzyme in catecholamine synthesis) by immunofluorescence (-ir). Preliminary results demonstrate that type II males have a greater total intensity and density of TH-ir fibers within the vocal motor nucleus (VMN), and greater numbers of TH-ir varicosities contacting vocal motoneurons. Our findings support the hypothesis that catecholamines are direct modulators of vocal behavior and are additional substrates underlying social and reproductive behavioral divergence between male midshipman morphs.