We are fascinated by the evolution of behavior and amazing animal shapes. We have worked topics ranging from from weapon biomechanics and trade-offs, to context-dependent mate choice, to phenotypic plasticity in feeding morphology. Most of our research is conducted with Hemipterans in the Family Coreidae, the Leaf-Footed Bugs. Although our research interests are broad, two recent themes are described below. See the Publications page for more!
Resource allocation tradeoffs: Males in many species use weapons such as horns, antlers, and spurs to compete with other males for access to females. Larger weapons often allow males to win high-quality territories and mating opportunities. However, many of these weapons are costly to produce and maintain, competing for a limited supply of resources within the body. Through experimentation, we have discovered weapons-testes trade-offs in the leaf-footed bugs. Interestingly, such trade-offs are not limited to males; we have found leg-ovary trade-offs in females. The female trade-offs provide insights into the nature of resource allocation within the bodies of individual animals. This is an active current area of our research program, with more papers to come soon.
FEATURED PAPERS Miller CW, Joseph PN, Kilner RM, Emberts Z (2019). A weapons–testes trade-off in males is amplified in female traits. Proceedings of the Royal Society of London (B). 286: 20190906. http://dx.doi.org/10.1098/rspb.2019.0906.
Joseph PN, Emberts Z, Sasson DA, & Miller CW (2018). Males that drop a sexually-selected weapon grow larger testes. Evolution. 72: 113–122. DOI: 10.1111/evo.13387. PDF.
Somjee U, Miller CW, Tatarnic NJ, & Simmons LW (2018). Experimental manipulation reveals a trade-off between weapons and testes. Journal of Evolutionary Biology. 31: 57–65. DOI: 10.1111/jeb.13193. PDF.
Functional performance and diversity in the weapons of sexual selection: A trip to Yellowstone National Park can reveal male elk sparing with their antlers, pronghorn trying to edge out other males, and dung flies competing for mates on bison dung. In fact, any trip to the wilderness easily shows us many examples of male-male competition or, in some cases, female-female competition over access to mates. People have been fascinated by animal weapons and their fighting behaviors for centuries. In spite of the interest, we still do not know why there is such amazing weapon diversity. Why do some species use tusks to fight over females, while others use their legs? Why do even closely-related species often have such striking differences in their weapons? We tackle this problem using the striking diversity of weapons in the leaf-footed bugs and their relatives (Superfamily Coreoidea). We have partnered with the Insect Biomechanics Group at the University of Cambridge to better understand how biomechanics shape weapon diversification. We have also reconstructed the phylogeny of these insects so that we can map their amazing weapons and trace the evolutionary process. Our research takes us to Panama, Kenya, Swaziland, South Africa, Australia, Singapore, and across the insect-rich state of Florida. This work is funded by a NSF CAREER Award, 2016 - 2022.
FEATURED PAPERS Emberts Z, St. Mary CM, Howard CC, Forthman MP, Bateman B, Somjee U, Hwang W, Li D, Kimball R, Miller CW (2020). The evolution of autotomy in leaf-footed bugs. Evolution. 74: 897-910 open-access link.
Forthman M, Miller CW, Kimball RT. Phylogenomics of the leaf-footed bug subfamily Coreinae (Hemiptera: Coreidae) (2020). Insect Systematics and Diversity. 4:1-15 https://doi.org/10.1093/isd/ixaa009 Forthman M, Miller CW, Kimball RT (2019) Phylogenomic analysis suggests Coreidae and Alydidae (Hemiptera: Heteroptera) are not monophyletic. Zoologica Scripta. 48: 520-534.
Photo: A hind leg of one of our local species, Acanthocephala femorata. Males in this species wrestle on plants such as sunflower, pressing that prominent spine into the abdomen of their opponents. Successful males become territory holders and interact with females. Weapon reconstruction image courtesy of Dr. Josh Yarrow, UF.
The Superfamily Coreoidea: There are more than 3000 species of these insects worldwide, and male hind femurs (a sexually-selected weapon) are impressively diverse in size and shape. Males in many species (but not all) use their hind legs as weapons to wrestle over access to females and territories. Males with larger legs are often more likely to win male-male contests and have greater mating success.
Florida is a haven for coreoid researchers! We have dozens of local species, each with its own unique fighting style and weapon shape.
On the right, two male leaf-footed cactus bugs, Narnia femorata, compete over a territory on a flowering cactus. Males often turn around and wrestle with their hind legs whilst fighting.
Photo and content credit: The Miller Lab at the University of Florida/IFAS