The geometry of nutrient space–based life-history trade-offs: Sex-specific effects of macronutrient intake on the trade-off between encapsulation ability and reproductive effort in decorated crickets

James Rapkin, Kim Jensen, C. Ruth Archer, Clarissa M. House, Scott K. Sakaluk, Enrique Del Castillo, John Hunt

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Life-history theory assumes that traits compete for limited resources, resulting in trade-offs. The most commonly manipulated resource in empirical studies is the quantity or quality of diet. Recent studies using the geometric framework for nutrition, however, suggest that trade-offs are often regulated by the intake of specific nutrients, but a formal approach to identify and quantify the strength of such trade-offs is lacking. We posit that trade-offs occur whenever life-history traits are maximized in different regions of nutrient space, as evidenced by nonoverlapping 95% confidence regions of the global maximum for each trait and large angles (θ) between linear nutritional vectors and Euclidean distances (d) between global maxima. We then examined the effects of protein and carbohydrate intake on the trade-off between reproduction and aspects of immune function in male and female Gryllodes sigillatus. Female encapsulation ability and egg production increased with the intake of both nutrients, whereas male encapsulation ability increased with protein intake but calling effort increased with carbohydrate intake. The trade-offs between traits was therefore larger in males than in females, as demonstrated by significant negative correlations between the traits in males, nonoverlapping 95% confidence regions, and larger estimates of θ and d. Under dietary choice, the sexes had similar regulated intakes, but neither optimally regulated nutrient intake for maximal trait expression. We highlight the fact that greater consideration of specific nutrient intake is needed when examining nutrient space–based trade-offs.

Original languageEnglish (US)
Pages (from-to)452-474
Number of pages23
JournalAmerican Naturalist
Volume191
Issue number4
DOIs
StatePublished - Apr 2018

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics

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