Julie Smith (PhD, spring 2005)
I will start in September 2006 as a Assistant Professor at Pacific Lutheran University.
My PhD research examined the ecological and behavioral processes promoting speciation in North American Red Crossbills. My work centered on a newly discovered population of crossbills in the South Hills, Idaho where in the absence of squirrels, crossbills and lodgepole pine have coevolved. This has resulted in divergent selection between crossbills in the South Hills and the Rocky Mountains. My work shows that mate choice is highly assortative in the South Hills, indicating that reproductive isolation is evolving between these recently diverged populations (perhaps in only the last 3,000 years).
Several ecological and behavioral factors act to promote reproductive isolation.
For example, Rocky Mountain crossbills (mostly call types 2 and 5) are rare
in the South Hills when South Hills crossbills begin pairing in February, presumably
because Rocky Mountain crossbills have relatively low feeding rates on the well-defended
cones in the South Hills. Not until later in the spring and summer, when seed
availability increases, do Rocky Mountain crossbills become common. Then, interbreeding
can and does occasionally occur. This suggests that temporal isolation may reduce
gene flow, but it is not the only reproductive barrier.
Ecology-based selection also favors assortative grouping in Red Crossbills and
may promote reproductive isolation as a by-product. Public information use in
which individuals estimate patch quality by using the success of group mates
foraging in the same patch is important to Red Crossbills (Smith et al. 1999).
Effective use of public information by foraging Red Crossbills depends on similarities
in feeding abilities among flock mates, which in turn depends upon flock mates
having similar bill structures. Thus, public information use should favor assortative
flocking by trophic phenotype. My data suggests that public information use
promotes assortative flocking and may have favored the divergence of flight
calls among the visually similar Red Crossbills call types. Moreover, assortative
flocking may promote reproductive isolation because mates are often (usually?)
chosen from within flocks.
Below are my publications:
Smith, J. W., R. Powell, Jr., D. D. Smith,
and A. Lanthrop. 1994. Natural history notes on a population of grass anoles,
Anolis olssoni (Sauria: Polychrotidae), from the Dominican Republic.
Bull. Maryland Herpetol. Soc. 30:67-75.
Smith, J.W., J. S. Parmerlee, Jr., and
R. Powell. 1995. Anolis olssoni. Catalogue of American Amphibians and
Reptiles. 611.1-611.5.
Smith, J. W., C. W. Benkman and K. Coffey.
1999. The use and mis-use of public information by foraging red crossbills.
Behavioral Ecology 10:54 -62. PDF
Benkman, C. W., W. C. Holimon, and J. W. Smith. 2001. The influence of a competitor on the geographic mosaic of coevolution between crossbills and lodgepole pine. Evolution 55:282-294. PDF