Macronutrient balance mediates the growth of sexually selected weapons but not genitalia in male broad-horned beetles

Clarissa M. House, Kim Jensen, James Rapkin, Sarah Lane, Kensuke Okada, David J. Hosken, John Hunt

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


Condition is defined as the pool of resources available to an individual that can be allocated to fitness-enhancing traits. Consequently, condition could influence developmental trade-offs if any occur. Although many studies have manipulated diet to demonstrate condition-dependent trait expression, few studies have determined the contribution of specific nutrients to condition or trade-offs. We used nutritional geometry to quantify the effects of dietary protein and carbohydrate content on larval performance and the development of adult morphology including body size as well as a primary and secondary sexually selected trait in male broad-horned beetles, Gnatocerus cornutus. We found that offspring survival, development rate and morphological traits were highly affected by dietary carbohydrate content and to a lesser extent by protein content and that all traits were maximized at a protein-to-carbohydrate ratio around 1:2. The absolute size of a secondary sexual character, the mandibles, had a heightened response to the increased availability and ratio of both macronutrients. Male genitalia, in contrast, were relatively insensitive to the increased availability of macronutrients. Overall, while nutrition influenced trait expression, the nutritional requirements of development rate and morphological traits were largely the same and resource acquisition seems to implement only weak trade-offs in this species. This finding contrasts with some resource constraint predictions, as beetles seem able to simultaneously meet the nutritional requirements of most traits.

Original languageEnglish
Pages (from-to)769-779
Number of pages11
JournalFunctional Ecology
Issue number5
Publication statusPublished - May 1 2016


  • Condition dependence
  • Genitalia
  • Larval diet
  • Nutritional geometry
  • Sexual selection and weapons

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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