1001 East Third St
Bloomington, IN 47405
I am interested in the role of migration and sexual selection in seasonally sympatric population divergence. Migration typically is thought to increase gene flow and therefore reduce population divergence, but this may not always be the case. Migration can also lead to seasonal sympatry, or ‘heteropatry’ (termed by Kevin Winker) in which populations are overlapping during the winter and early spring and then become allopatric during the summer. The overlap in early spring may allow for interbreeding, but instead this population distribution appears to contribute to divergence.
I study these questions in the dark-eyed junco. Within the slate-colored group of junco, there are seasonally sympatric subspecies: a migratory subspecies of dark-eyed junco co-exist with a sedentary subspecies on the wintering grounds in the Appalachians before departing for their breeding grounds in Canada. There may be a small window for interbreeding; the sedentary subspecies initiates breeding during the period of migration, but this does not appear to be occurring. I am interested in whether differences in timing of reproduction based on migratory phenotype or differences in morphology due to sexual selection in reproductively isolated populations are driving and maintaining population divergence. I have studied male and female choice based on morphology and reproductive timing between the two populations. I am also studying the difference in timing of reproductive development between the migratory and sedentary populations despite receiving the same environmental cues on the wintering grounds.