Empirical work

During my PhD my empirical work focused primarily on Orthoptera with nuptial gifts. I worked with the ground cricket (Allonemobius socius) to see what the effect of a trade-off between wing-morph and fecundity has on the strength of sexual selection. I have also estimated the upper limit on sexual selection for males and females using the meadow katydid Conocephalus nigropleurum.

After completing my PhD work, Darryl Gwynne and I radio-tracked female Mormon crickets in Utah and Colorado to demonstrate differences in migratory habits of two different morphs with different mating patterns. This work has led to continuing efforts to predict the direction and speed of moving bands of Mormon crickets during outbreaks that can lead to crop devastation.

Theoretical work

I have pursued several theoretical projects on the interaction of sexual and natural selection. Two related lines of research build on recent theoretical developments. The first devises a way to translate changes in life history traits into changes in the strength of sexual selection. This directional approach assumes that naturally selected changes in life history cause changes in the strength of sexual selection. This approach used "Bateman gradients" to quantify the strength of "causal" sexual selection. These gradients measure the relationship between fecundity and number of mates, separately for each sex which are believed to be the cause of sexual selection. I have also used Bateman gradients to develop an alternative measure of the "opportunity for sexual selection" that is more precise than older measures based on comparing variances in mating success for males and females.

The second line of research is coevolutionary, allowing a set of interconnected traits to evolve in response to both natural and sexual selection. This approach examines how existing sexual selection models are affected by allowing sexually selected display traits to develop dependence on condition (the pool of resources available for allocation to various traits).

These two approaches are part of a long term plan to better understand how natural and sexual selection interact.

Other theoretical aspects of my research include an paper with Lin Chao on selection for multiple mating in females due to mates that reduce female fitness. Also, I have written a power test of the Concentrated Changes Test, which quantifies the extent to which two characters evolve in a correlated fashion across a phylogenetic tree. I have also studied sperm competition in the Malaysian stalk-eyed fly Cyrtodiopsis whitei with Jerry Wilkinson.