Date of Award


Degree Type


Degree Name

Master of Science




Dr. Elizabeth Macdougall-Shackleton

Second Advisor

Dr. Bryan Neff

Third Advisor

Dr. Liana Zanette


In many species, both females and males may adjust mating and parental investment tactics in response to the perceived attractiveness of their social mate. I examined how mate attractiveness (based on song complexity and genetic dissimilarity) affects female mating tactics, offspring sex allocation, offspring growth rates and parental feeding rates in a wild population of song sparrows (Melospiza melodia melodia). Male song complexity appeared to affect female mating tactics, as males that had smaller song repertoires lost paternity more frequently than did males retaining full paternity within the offspring of their social mate. Paternal song complexity was also predictive of male-biased offspring sex ratios near the end of the nestling period, although not earlier in the nestling period. Males with complex songs also provisioned offspring at higher rates, and consequently their nestlings grew at faster rates than offspring in nests of less complex singers. The degree to which social mates were genetically dissimilar to one another was positively related to rates of offspring growth and female nest visitation. This study contributes to the growing literature focused on the indirect and direct benefits females may receive by mating with highly ornamented or genetically dissimilar males.



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