Dark-Eyed Junco Song: Linking Ontogeny and Function with a Potential Role in Reproductive Isolation
Snowbird: Integrative Biology and Evolutionary Diversity in the Junco
The elaborate songs produced by many songbirds during the breeding season play an integral role in mate attraction and courtship. Depending on how song is learned and develops, it may diverge rapidly across space and promote reproductive isolation. Here we review the function, ontogeny and geographic divergence of dark-eyed junco song, to evaluate its potential as an isolating mechanism. Dark-eyed juncos share long-range songs (LRS) minimally with other males within populations, populations harbor high diversity of LRS, acoustic properties of LRS vary little across subspecies, and males respond aggressively to songs from distant populations. We suggest that a high input of novel song types during song development has a homogenizing effect on song properties across populations, which hinders reproductive isolation. In contrast, junco short-range songs (SRS) are much more complex than LRS, and may be less constrained by acoustic transmission properties because they are close-proximity signals. Thus, the acoustic properties of SRS may be more evolutionarily labile in response to changes in female preference or other selective pressures, and could play a greater role promoting divergence among populations. We also discuss functionally puzzling aspects of dark-eyed junco song development, and emphasize the importance of addressing entire vocal repertoires when investigating sexual selection and reproductive isolation.
Reichard, Dustin; Cardoso, Gonçalo C. Dark-Eyed Junco Song: Linking Ontogeny and Function with a Potential Role in Reproductive Isolation. In Snowbird: Integrative Biology and Evolutionary Diversity in the Junco; Ketterson, Ellen D., Atwell, Jonathan W., Eds.; University of Chicago Press: Chicago, 2016; 310-337. DOI: 10.7208/chicago/9780226330808.003.0013
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