
Contemporary divergence of island bird plumage
Author(s) -
Avery Julian D.,
Cassey Phillip,
Lockwood Julie L.
Publication year - 2014
Publication title -
journal of avian biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.022
H-Index - 76
eISSN - 1600-048X
pISSN - 0908-8857
DOI - 10.1111/jav.00300
Subject(s) - plumage , biology , population , divergence (linguistics) , zoology , sexual selection , ecology , demography , linguistics , philosophy , sociology
Although the diversity in avian plumage coloration is striking, there is little known about the rate with which colour diverges. Eastern bluebirds Sialia sialis bermudensis on the island of Bermuda are considered endemic based upon differences in coloration from the mainland, but recent molecular evidence suggests they established on the island only 400 yr ago. We explored sexual dichromatism and colour divergence in this isolated population, thus providing one of the few quantitative accounts of contemporary plumage change. Contrary to expectations that sexual dichromatism would decrease in this sedentary island population, we found that males and females have increased plumage ornamentation in a coordinated fashion that acts to preserve sexual dichromatism, while plumage colour is also altered to become brighter and bluer. These differences were in place at least 100 yr ago based upon a separate analysis of museum specimens. Our results provide insight into the divergence of plumage colour in an incipient species, and we show the remarkable extent to which plumage colour can change over contemporary time frames.