Armin P. Moczek

Moczek.JPG (25599 bytes)

Armin P. Moczek


My primary interest is the origin of morphological and behavioral diversity
and the reasons why we observe those patterns of variation in the natural world and not others. In particular, I am interested in phenotypically plastic trait-complexes, such as polyphenisms, because of the bewildering diversity of forms and behaviors they account for and their vastly unexplored role in the evolution of morphological and behavioral novelties.

I currently focus on scarab beetles of the genus Onthophagus. Males
of many species in this genus express exuberant secondary sexual traits such as horns. Horns develop in response to larval feeding conditions and are used as weapons in aggressive interactions. In many species, horn expression is discontinuous, and male populations are composed of two alternative, discrete shapes. In other words, many species exhibit a polyphenism for male morphology. I discovered several exotic dung beetle populations that have diverged dramatically in certain components of polyphenic trait expression. I use these divergent populations as a tool to study the genetic, developmental, and ecological underpinnings of polyphenism evolution in natural populations.

I use quantitative genetic approaches and controlled breeding experiments to quantify the relative contributions of genetic and environmental conditions to phenotype expression. I also use a combination of behavioral observation techniques and controlled behavioral experiments to describe male and female reproductive behavior in Onthophagus beetles and to quantify the performance of males with varying phenotype and reproductive tactic in male-male competition for access to females. In addition, I use morphometric techniques to quantify allometries in exotic and native, as well as past and present populations, using museum and field collections. Furthermore, I employ common breeding methods to quantify the extent of genetic differentiation between phenotypically divergent populations. I use controlled breeding experiments as well as hormone manipulation experiments to identify those developmental control mechanisms whose modifications have permitted the evolution of divergent allometries in exotic populations. Drawing from my insights into the mating system of onthophagine beetles and the behavioral context within which alternative male phenotypes function, I contrast ecological and demographic conditions of phenotypically divergent populations in the field.

Armin P. Moczek
Department of Biology
Indiana University
915 E. Third Street
Myers Hall 150
Bloomington, IN 47405-7107

TEL: (812) 856-1468 (office), (812) 856-1783 (lab)
FAX: (812) 855-6082

Moczek AP, Nijhout HF (2000). The evolution of polyphenic development and its consequences: rapid allometric divergence between exotic populations of the scarab beetle Onthophagus taurus. American Zoologist 39: 12A.

Moczek AP, Emlen DJ (2000). Male horn dimorphism in the scarab beetle Onthophagus taurus: do alternative reproductive tactics favor alternative phenotypes? Animal Behaviour 59: 459 - 466. (

Moczek AP (1999). Facultative paternal investment in the polyphenic beetle Onthophagus taurus : the role of male morphology and social context. Behavioral Ecology 10: 641-647. (

Moczek AP, Emlen DJ (1999). Proximate determination of male horn dimorphism in the beetle Onthophagus taurus (Coleoptera: Scarabaeidae). Journal of Evolutionary Biology 12: 27-37. ( &filetype= abstracts&article=43549&year=&journal=)

Moczek AP (1998). Horn polyphenism in the beetle Onthophagus taurus: diet quality and plasticity in parental investment determine adult body size and male horn morphology. Behavioral Ecology 9: 636-641. (

Moczek AP (1996). Male dimorphism in the scarab beetle Onthophagus taurus Schreber, 1759 (Scarabaeidae, Onthophagini): Evolution and plasticity in a variable environment. MS thesis submitted to the Department of Behavioral Physiology and Sociobiology, Julius-Maximilians University, W¸rzburg, Germany.

Moczek AP (in press). Allometric plasticity in a polyphenic beetle. Ecological Entomology.

Moczek AP, Nijhout HF (in press). A method for sexing third instar larvae of the genus Onthophagus Latreille (Coleoptera: Scarabaeidae). Coleopterists Bulletin.

Shafiei M, Moczek AP, Nijhout HF (in press). Food availability controls onset of metamorphosis in the dung beetle Onthophagus taurus (Coleoptera: Scarabaeidae). Physiological Entomology.

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University of Nebraska-Lincoln State Museum - Division of Entomology