Research in the Miller Lab

We aim to improve understanding of the role of the environment in the evolution of morphology, function, and behavior. We focus on sexual selection in insects, examining the importance of environmental variability both for the expression of sexually-selected traits and for the process of selection itself. Most of our research is conducted with Hemipterans in the Superfamily Coreoidae.

Christine W. Miller

Major Research Areas:


The Amazing Coreoidae


Male male competition

We work on insects in the Superfamily Coreoidae, which includes the leaf-footed bugs. There are more than 3000 species of these insects worldwide, and the shapes and sizes of male hind femurs are astonishingly diverse. Males in many species use their hind legs as weapons to squeeze each other in contests over access to females. Males with larger legs are often more likely to win male-male contests and have greater mating success.

Much of our work is conducted with the leaf-footed cactus bug, Narnia femorata (Hemiptera: Coreidae). One of the real strengths of working on this study species is that we can examine variation in sexual selection under realistic environmental conditions. Narnia lives on Opuntia sp. (cholla and prickly pear cactus) from the Southern U.S. to Central America, and is excellent for both field and laboratory study. Narnia routinely encounter two discrete natal environmental conditions. Some juveniles have access to cactus fruits for growth and development, while others only have access to cactus pads. Cactus with red fruit is a higher quality resource for these insects; insects reared with fruit develop faster (Nageon de Lestang & Miller 2009), grow larger, are more competitively successful, and are generally more attractive as adults.

Male Narnia compete with other males for territories on cactus. When a competition between males escalates, males turn around and squeeze each other with their exaggerated, spiny hind legs. Males with larger legs are more likely to win competitions and mate with females on the plant. We have found that the strength of sexual selection via male-male competitions varies according to the presence of absence of females (Procter et al. 2012).


Environmental effects on sexual selectionMarked Heliconia bug, Panama

A major focus of our research is the effects of diet quality, and resource quality more generally, on sexual selection. We have discovered that sexually-selected traits vary in expression over both space and time (Miller & Emlen 2010a). We have found effects of juvenile diet on male weapons (Miller & Emlen 2010b, Gillespie et al. 2014), testes (Ummat, Allen, & Miller in review), copulatory courtship behaviors, and mating receptivity (Miller 2008). We have followed the dynamic patterns of sexual selection over time (Somjee & Miller, in prep). We have found that the strength and form of sexual selection can be affected by context (Addesso et al. 2014, Gillespie et al. 2014). Currently, we are examining the extent to which inbreeding and resource quality interact to influence weapon size and sperm quality (in collaboration with graduate students Paul Joseph and Pablo Allen).


Functional performance and diversity in the weapons of sexual selection

Acanthocephala femorata

We are excited to undertake a new research direction, examining the extent to which fighting style has shaped weapon shape and functional performance across species in the Coreoidae. This work is in collaboration with Dr. Nam-Ho Kim (Mechanical and Aerospace Engineering), Marc Branham (Entomology and Nematology), Joshua Yarrow (Applied Physiology & Kinesiology), and Nikolai Tatarnic (Western Australia Museum).