SIGNAL DIVERGENCE AND
REPRODUCTIVE ISOLATION IN A SONGBIRD, JUNCO
HYEMALIS
Divergence
in mating signals can promote diversification and reproductive
isolation through assortative mating. In many taxa, acoustic
signals are essential for mate attraction and choice and are known to
diverge in response to both sexual selection and natural selection for
efficient sound transmission. Previous research on song
divergence and mate choice in birds has focused exclusively on high
amplitude, “long-range songs” (LRS) important in territoriality and
mate attraction. However, many species also produce low
amplitude, “short-range songs” (SRS) associated with male-female
interactions during courtship, the function of which is poorly
understood. My dissertation research seeks to determine the role
of SRS in assortative mating and promoting reproductive isolation.
Recent molecular evidence indicates the Dark-eyed
Junco (Junco hyemalis)
radiated into five distinct subspecies as recently as 5,000 years
ago. During this radiation, each subspecies developed a unique
range, plumage, and morphology, making the junco an informative case of
rapid divergence and potentially incipient speciation. Dark-eyed
junco song consists of distinct LRS and SRS types that differ
substantially in length, complexity, and frequency bandwidth, all of
which are greater in SRS. Initial results suggest that LRS is
relatively unimportant in subspecies divergence. However, in the junco
and most passerines, little is known about within and/or between
subspecies variation in SRS or its role in species recognition and
assortative mating.
PRESENTED PAPERS
Reichard,
D.G. and Ketterson, E.D. Geographic
variation in Dark-eyed Junco song: potential for reproductive
isolation?
American Ornithologists’ Union Conference, Portland, OR,
August 2008. (Oral Presentation)
