Melvin Rouse, Jr., Ph.D.
Assistant Professor, University of Puget Sound

Asymmetric Differences in Acoustic Characteristics and Recognition in a New White-Crowned Sparrow (Zonotrichia leucophrys) Hybrid Zone
o Secondary contact zones can be used to examine the mechanisms affecting reproductive isolation. In the Cascade Mountains (Washington state), the first known contact between the Pacific (Zonotrichia leucophrys pugetensis) and Interior (Z.l. gambelii) white-crowned sparrows occurred within the past thirty years. Using citizen science data from eBird and Breeding Bird Surveys, and field site confirmation of white-crowned sparrow distribution, phenotype, as well as song recognition from inside and outside the contact zone, our analysis suggests that white-crowned sparrows have expanded their range into the Cascade Mountains, resulting in increased secondary contact. Likewise, there appears to be hybridization occurring, with some birds possessing plumage and song characteristics intermediate between the two subspecies. That being said, we observed an asymmetric song recognition pattern. Male Z.l. pugetensis demonstrated greater recognition to their own song than Z.l. gambelii song. Z.l. gambelii did not discriminate significantly. We suggest that this difference in recognition stems from differences in dialect structure. Individual Z.l. gambelii songs were found to be less similar to one another, whereas, individual Z.l. pugetensis songs were more similar to one another. Lastly, hybrid songs were found to share greater similarity to Z.l. pugetensis song relative to Z.I. gambelii. The Pacific population (Z.I. pugetensis) has a complex dialect structure, whereas the Interior population (Z.I. gambelii) has much less of a dialect structure and recognizes multiple song-types within a given area. In this novel hybrid zone, it may be that this behavioral asymmetry is due to Z.I. pugetensis invasion, sex biased dispersal, and/or adaptive introgression.

This lecture made possible in part by a generous endowment from Professor Allen L. Edwards. 
Faculty host: Joe Sisneros, sisneros@uw.edu.

Accommodation requests related to a disability should be made by 2/19/20 to chairpsy@uw.edu.