Return to search

Natural and Sexual Selection Shape the Acoustic Phenotype of Urban Birds

acase@tulane.edu / Anthropogenic noise is an evolutionarily recent phenomenon and many animals respond by changing the pitch and timing of their vocalizations to avoid masking. A benefit to modifying a vocal mating signal in the context of noise is increased transmission distance. This same modification may pose a fitness cost if that signal feature is also sexually selected. Bird song is a well-studied sexual signal used in territory defense and mate attraction. Physically difficult to produce components of song are thought to be honest signals of male quality. One such trait is a male's ability to maximize the rate of note production at a given frequency bandwidth; this tradeoff is known as vocal performance. Studies have shown modifications to song in the context of noise, specifically to trill rate and bandwidth. Costs of these modifications may include increased conflict with neighboring males, which could potentially lead to decreased body condition, loss of a territory, or less time spent attracting a female. Few studies have investigated this tradeoff between environmentally induced selection (i.e. natural selection) and social selection (i.e. sexual selection) on song in an urban landscape. Therefore, a gap remains in our knowledge of the consequences on fitness of urban song adaptation for signalers. Using the white-crowned sparrow (Zonotrichia leucophrys) in the San Francisco Bay Area of California, the objectives of my dissertation research include 1) testing if vocal performance is a salient signal for white-crowned sparrows, 2) testing if receivers are responding specifically to variation in trill rate or bandwidth, and 3) testing the effect of ambient noise level on receiver assessment of vocal performance. Overall, my dissertation research suggests that both anthropogenic and natural soundscapes shape the evolution of song and receiver behavior. Modifications to song structure that increase signal detection come at the cost of decreased signal salience for male competitors. Additionally, anthropogenic noise appears to change how males utilize vocal performance. Therefore, species living in noisy areas may face consequences of decreased fitness over time due to masked honest signals and increased male-male conflict. / 1 / Jennifer N. Phillips

  1. tulane:75601
Identiferoai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_75601
Date January 2017
ContributorsPhillips, Jennifer (author), (author), Derryberry, Elizabeth (Thesis advisor), (Thesis advisor), School of Science & Engineering Ecology and Evolutionary Biology (Degree granting institution)
PublisherTulane University
Source SetsTulane University
LanguageEnglish
Detected LanguageEnglish
TypeText
Formatelectronic, 103
RightsNo embargo, Copyright is in accordance with U.S. Copyright law.

Page generated in 0.002 seconds