RELATIONS BETWEEN SONG REPERTOIRE SIZE AND THE VOLUME OF BRAIN NUCLEIRELATED TO SONG - COMPARATIVE EVOLUTIONARY ANALYSES AMONGST OSCINE BIRDS

Song and brain structure are compared amongst 41 species of oscine bir ds by using the method of independent evolutionary contrasts. We find a significant correlation between the relative volume of the song cont rol centre, the high vocal centre (HVC), and the number of song types typically found in the repertoire. Relative Hvc volume is not correlat ed with the number of different syllable types per song bout. The rela tive volume of a second song nucleus, area X, is not significantly cor related with either measure. RelatiVe HVC Volume is uncorrelated with relative volume of the hippocampus, a brain area involved in other for ms of memory. This is the first evidence for repeated independent evol ution of an association between complexity of learned song and the rel ative volume of one of the song control nuclei thought to be involved in song learning.