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Award Detail

Doing Business As Name:Michigan State University
  • Ian M Dworkin
  • (517) 432-6733
Award Date:08/28/2009
Estimated Total Award Amount: $ 101,825
Funds Obligated to Date: $ 101,825
  • FY 2012=$53,875
  • FY 2009=$1,000
  • FY 2013=$46,950
Start Date:08/15/2009
End Date:06/30/2016
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.074
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Collaborative Research: Genetic mechanisms of conditional-expression and trait exaggeration in weapons of sexual selection
Federal Award ID Number:0920142
DUNS ID:193247145
Parent DUNS ID:053343976
Program:Integrtv Ecological Physiology
Program Officer:
  • Irwin Forseth
  • (703) 292-7862

Awardee Location

Street:Office of Sponsored Programs
City:East Lansing
County:East Lansing
Awardee Cong. District:08

Primary Place of Performance

Organization Name:Michigan State University
Street:Office of Sponsored Programs
City:East Lansing
County:East Lansing
Cong. District:08

Abstract at Time of Award

Animals produce a bewildering diversity of ornaments and weapons that function in male contests over reproductive access to females. Two characteristics are common in the most elaborate of these structures: disproportionate growth yielding exaggerated trait sizes, and growth that is more sensitive to nutrition than is the growth of other, non-sexually-selected, structures (e.g. antlers in moose or elk reach extreme sizes in the largest bulls, and antler growth is especially sensitive to the nutritional state of the animal). Despite intense interest in the evolution of these sexually selected traits, almost nothing is known of the genes or the developmental mechanisms responsible for disproportionate/ exaggerated growth, or of the mechanisms linking nutrition with the amount of trait growth. This proposal addresses a fundamental gap in understanding the evolutionary potential of ornaments and weapons of sexual selection: What are the genes and developmental/ physiological processes that underlie nutrition-dependent expression and exaggerated growth? The premise for this project is that to understand the evolution of these structures requires exploration of the details of how they develop. The long-term goal is to understand how physiology and development interact with the environment to generate diversity in morphological and behavioral phenotypes. The objectives are to identify genes and associated physiological pathways responsible for generating exaggerated weapon growth, and nutrition-dependent phenotypic plasticity. The investigators will (1) test whether the mechanisms generating nutrition-dependent expression are the same as those generating exaggerated growth, and (2) compare these mechanisms for two weapons (horns & mandibles) in three lineages of beetle representing three independent origins of enlarged male weapons (dung beetles, rhinoceros beetles, & stag beetles). The integrative approach utilized will shed light on physiological and developmental pathways involved with nutrition-dependent phenotypic plasticity in animals generally, and will provide one of the most comprehensive studies to date linking variation in male condition with the expression of sexually selected traits - a central tenet of current theories of sexual selection. A core objective is the cross-training of young scientists in genetics, development, physiology and evolution. The postdoc and students involved with this project will spend extensive periods in all three labs actively learning techniques and interacting and collaborating with all three PIs. The PIs are committed to training undergraduates in all aspects of the research process, and will incorporate innovative teaching methods in science that embrace diversity; the very nature of this system lends itself to learner-centered investigations. The focal species are a fantastic resource for outreach activities and the PIs will use these animals in educational programs designed to enhance STEM learning in K-12 students as well as in informal science education environments, including visiting local school classrooms in both WA and MT, supporting the WSU insect museum, and aiding with a new Montana insect zoo.

Publications Produced as a Result of this Research

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Lavine, L.C., Gotoh, H., Brent, C.S., Dworkin,I. & Emlen, D.J. "Exaggerated Trait Growth in Insect" Annual Review of Entomology, v.60, 2015, p.453. doi:10.1146/annurev-ento-010814-021045 

Gotoh, H., Zinna, R., Warren, I., DeNieu, M., Niimi., T., Dworkin, I., Emlen, D., Miura, T. & Lavine, L "Identification and functional analyses of sex determination genes in the sexually dimorphic stag beetle Cyclommatus metallifer." BMC Genomics, v., 2016, p..

Warren, Ian A and Gotoh, Hiroki and Dworkin, Ian M and Emlen, Douglas J and Lavine, Laura C "{A general mechanism for conditional expression of exaggerated sexually-selected traits.}" BioEssays : news and reviews in molecular, cellular and developmental biology, v., 2013, p..

Chandler, Christopher H.; Ofria, Charles; Dworkin, Ian "RUNAWAY SEXUAL SELECTION LEADS TO GOOD GENES" EVOLUTION, v.67, 2013, p.110-119.

Emlen, D.J., Warren, I., Johns, A., Dworkin, I. &, Corley-Lavine, L "A mechanism of extreme growth and reliable signaling in sexually selected ornaments and weapons" Science, v.337, 2012, p.860-864. doi:10.1126/science.1224286 

Lavine, Laura and Gotoh, Hiroki and Brent, Colin S and Dworkin, Ian and Emlen, Douglas J "{Exaggerated Trait Growth in Insects.}" Annual Review of Entomology, v., 2014, p..

Warren, Ian A and Vera, J Cristobal and Johns, Annika and Zinna, Robert and Marden, James H and Emlen, Douglas J and Dworkin, Ian and Lavine, Laura C "{Insights into the development and evolution of exaggerated traits using de novo transcriptomes of two species of horned scarab beetles.}" PLoS ONE, v., 2014, p..

Ingleby, F. C.; Hosken, D. J.; Flowers, K.; Hawkes, M. F.; Lane, S. M.; Rapkin, J.; Dworkin, I.; Hunt, J. "Genotype-by-environment interactions for cuticular hydrocarbon expression in Drosophila simulans" JOURNAL OF EVOLUTIONARY BIOLOGY, v.26, 2013, p.94-107.

Lavine, Laura Corley and Hahn, Laura L and Warren, Ian A and Garczynski, Stephen F and Dworkin, Ian and Emlen, Douglas J "{Cloning and characterization of an mRNA encoding an insulin receptor from the horned scarab beetle Onthophagus nigriventris (Coleoptera: Scarabaeidae).}" Archives of insect biochemistry and physiology, v., 2013, p..

Lavine, Laura Corley; Hahn, Laura L.; Warren, Ian A.; Garczynski, Stephen F.; Dworkin, Ian; Emlen, Douglas J. "CLONING AND CHARACTERIZATION OF AN mRNA ENCODING AN INSULIN RECEPTOR FROM THE HORNED SCARAB BEETLE Onthophagus nigriventris (COLEOPTERA: SCARABAEIDAE)" ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY, v.82, 2013, p.43-57.

Warren IA, Gotoh H, Dworkin IM, Emlen DJ, Lavine LC. "A general mechanism for conditional expression of exaggerated sexually-selected traits." Bioessays, v.35, 2013, p.1-11. doi:10.1002/bies.201300031 

Project Outcomes Report


This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

Sexual dimorphism, the measurable differences between the biological sexes (such as males and females in humans) are quite common throughout the animal kingdom.  While often such sexual dimorphism is very subtle (such as subtle differences in size or shape or physiology), in some species (such as Peacocks) the differences are quite substantial.

Biologists have been greatly fascinated in both the evolutionary and developmental mechanisms that facilitate such extreme differences in morphology among the sexes, and how these differences compare to more subtle differences.


Using a variety of species of beetles (including the Rhinocerous beetles with exaggerated horns on males, and stag beetles with large sexually dimorphic mandibles) we used genetic and genomic tools to investigate these sexually dimorphic traits. In particular we focused on how these large differences in exaggerated morphologies between the sexes also show parallel effects depending on the overall condition of individuals. We demonstrated that changes in Insulin Signaling (which modulates the developmental mechanisms influencing how an organism senses its nutritional conditions and uses this to mediate growth) influence the development of these sexually dimorphic traits. In particular showing that the highly exaggerated traits (such as the beetle horns) that differ across the sexes are also the most sensitive to nutritional signaling (in an Insulin dependent manner).

Yet despite this, many aspects of the differences between the sexes in the expression of genes still differ. In particular the vast majority of genes that are modulated in a nutrition dependent VS sex dependent manner are not the same.

Thus our results suggest only a partial coupling of the mechanisms governing the growth of nutritionally sensitive morphology and for exaggerated sexually dimorphic traits.

Last Modified: 04/11/2017
Modified by: Ian M Dworkin

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