Date of Award


Degree Type


Degree Name

Master of Science




Dr. Beth MacDougall-Shackleton



Correlations between heterozygosity and fitness are commonly reported in the literature, but there is disagreement about the frequency of such correlations and the mechanisms which underlie them. Using a multi-year data set acquired from a wild population of song sparrows I investigated the relationship between heterozygosity and song complexity, an important sexually selected trait thought to be an indicator of genetic quality. Heterozygosity was determined at 17 putatively neutral microsatellites and 5 microsatellites derived from the expressed sequence tag of zebra finch brain proteins. Song and syllable repertoire size were taken as measures of song complexity. Neither genetic marker type was predictive of song complexity. A further test failed to support the hypothesis that heterozygosity-fitness correlations at marker loci are due to closely linked coding genes. These results indicate that heterozygosity is unlikely to play a major role in individual song complexity in this outbred population of song sparrows.



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