Development of geographic song preferences and the neural responses to local geographic song in songbirds.

摘要

This thesis examined the role of early song experience on the development of geographic song preferences in female songbirds and the neural responses to local geographic song in adult birds. By hand-rearing nestlings to control song exposure early in life I was able to look at the role of experience versus inherited factors on local song preferences. After tutoring with local, foreign or no song, female hand-reared house finches (Carpodacus mexicanus ) were found to have an experience-independent preference for local geographic song, and no differential Zenk activation to songs heard early in life (tutor) over song from a distant location. Song did have a general effect on auditory areas, with isolate birds not exposed to song having higher Zenk activation to song than tutored birds. In hand-reared song sparrows (Melospiza melodia), I found similar evidence that song exposure has a general effect on Zenk response to song in auditory areas and no effect of early experience modulating Zenk responses in auditory regions to local tutor songs. Yet unlike in house finches, I found a preference for songs heard early in life in female song sparrows, as indicated by greater time spent in approach arms in an automated choice test, suggesting early learning of tutor songs does not modulate neural responses to specific songs in adulthood. We also failed to find higher Zenk response when hand-reared male song sparrows were exposed to tutor songs over non-tutor songs, and did not replicate previous findings showing that Zenk activation in auditory areas following tutor song presentation is correlated with how well males learned tutor song. In addition, I found small biases in Zenk activation to genetic song in males, and non-genetic song in females, suggesting that auditory responses in auditory areas in songbirds can be pre-tuned and differentially pre-tuned in the two sexes. Taken together, song preference development seems to be guided both by experience-expectant learning and song exposure early in life, and neural responses in auditory areas do not seem to be modulated by song learning early in life.;Keywords: song preferences, female songbirds, dialects, auditory learning, auditory regions, CMM, NCM, ZENK, immediate-early gene, early experience.