Differences in Repertoire Size, Singing Behavior, and Associated Neuroanatomy Among Marsh Wren Populations Have a Genetic Basis

Abstract

Among songbirds, adult song forms usually are determined culturally during an individual's early experience. In the Marsh Wren (Cistothorus palustris), we have demonstrated that the quantity of this learned behavior (i.e. song repertoire size), its style of delivery, and the size of controlling nuclei in the forebrain have a genetic basis. Nestling males taken from New York and California and reared under standardized conditions in the laboratory still develop population-typical behavior and neuroanatomy. We do not know the developmental mechanisms responsible for these differences, but we believe that year-round residency, high densities, and polygynous mating systems are likely factors contributing to an escalation of vocal abilities in the western populations.