Researcher Profile

Erin McCullough

Erin McCullough

Ph.D. Student



2008 – present: University of Montana, PhD Candidate
Diversity of animal weapons: Insights from the functional costs of rhinoceros beetle horns

B.S. 2006 University of Puget Sound, Tacoma, Washington

Research Interests

One of the fundamental, and most exciting questions for evolutionary biologists is explaining the incredible amount of morphological variation that is found among organisms. My dissertation focuses on the evolution and diversification of animal weapons, and specifically, how the functional consequences of different horn types may have shaped the evolution of weapons among rhinoceros beetle species. I explore the hypothesis that the different sizes, shapes, and architectures of horns in rhinoceros beetles may reflect the functional and mechanical constraints on different weapon designs. That is, selection to minimize the functional costs of carrying and producing horns may explain why beetles living in different habitats have different horn morphologies; and selection to maximize the function of horns, or how well horns perform during combat, may help explain why beetles that have different fighting tactics, or that fight on different substrates have different types of horns. I hope to explore how mechanical and functional constraints have influenced the evolution of weapon morphology among rhinoceros beetles in order to better understand the diversity of some of Nature’s most elaborate body forms.


McCullough, E.L. and Tobalske, B.W. 2013. Elaborate horns in a giant rhinoceros beetle incur negligible aerodynamic costs. Proceedings of theRoyal Society B 280: 20130197.

McCullough, E. L. 2013. Using radio telemetry to assess movement patterns in a giant rhinoceros beetle: Are there differences among majors, minors, and females? Journal of Insect Behavior 26: 51-56.

McCullough, E. L., Weingarden, P. R., Emlen, D. J. 2012. Costs of elaborate weapons in a rhinoceros beetle: How difficult is it to fly with abig horn? Behavioral Ecology 23: 1042-1048.

Bai, M. E. McCullough, K-Q. Song, W-G. Liu, X-K. Yang. 2011. Evolutionary constraints in hind wing shape in Chinese dung beetles (Coleoptera: Scarabaeinae). PLoS ONE 6(6): e21600. doi:10.1371/journal.pone.002160

McCullough, E., K. M. Wright, A. Alvarez, C. P. Clark, W. L. Rickoll, and A. Madlung. 2010. Photoperiod-dependent floral reversion in the natural allopolyploid Arabidopsis suecica. New Phytologist 186: 239-250.


Media Coverage

“Rhinoceros beetles’ horns are not costly during flight.”
“Beetle horns not so cumbersome: Males’ outrageous head spikes don’t impede flight.” February 11, 2012. ScienceNews.
“Flying rhinos: Studying big beetles in Taiwan. 2009. Vision (University of Montana’s Research, Scholarship, and Innovation Magazine)




Grants / Fellowships/ Awards 

  • 2011, Society for Integrative and Comparative Biology, Fellowship for Graduate Student Travel ($1055)
  • 2011, Sigma Xi Grant in Aid of Research ($1000)
  • 2011, Teaching Innovation Award, University of Montana OREOS ($1000)
  • 2010, Sigma Xi Grant in Aid of Research ($800)
  • 2009, NSF Graduate Research Fellowship ($121,500)
  • 2009, National Academy of Sciences Ford Foundation Diversity Fellowship ($66,000)
  • 2009, NSF East Asia and Pacific Summer InstituteFellowship, Taiwan ($8610)



Professional Experience

2007-2008: University of Puget Sound, Research Technician  
Floral meristem reversion in the natural allotetraploid Arabidopsis suecica
Supervisor: Andreas Madlung 

2006-2007: Phu Khieo Wildlife Sanctuary, Thailand, Field Assistant
Patch depletion and scramble competition in Phayre’s leaf monkeys
Advisors: Andreas Koenig and Carola Borries

2004: University of Kansas, Research Experience for Undergraduates 
Spatial and temporal memory and decision making in foraging honeybees
Advisor: Rudolf Jander