Document Type

Article

Publication Title

Ecology and Evolution

Publication Date

Summer 6-23-2020

Keywords

cricket, diet, immunity, life history theory, reproductive effort, terminal investment

Abstract

Nutritional geometry has advanced our understanding of how macronutrients (e.g.,proteins and carbohydrates) influence the expression of life history traits and theircorresponding trade-offs. For example, recent work has revealed that reproduc-tion and immune function in male decorated crickets are optimized at very differentprotein:carbohydrate (P:C) dietary ratios. However, it is unclear how an individual'smacronutrient intake interacts with its perceived infection status to determine in-vestment in reproduction or other key life history traits. Here, we employed a fullyfactorial design in which calling effort and immune function were quantified formale crickets fed either diets previously demonstrated to maximize calling effort(P:C = 1:8) or immune function (P:C = 5:1), and then administered a treatment froma spectrum of increasing infection cue intensity using heat-killed bacteria. Both dietand a simulated infection threat independently influenced the survival, immunity,and reproductive effort of males. If they called, males increased calling effort at thelow infection cue dose, consistent with the terminal investment hypothesis, but in-terpretation of responses at the higher threat levels was hampered by the differen-tial mortality of males across infection cue and diet treatments. A high protein, lowcarbohydrate diet severely reduced the health, survival, and overall fitness of malecrickets. There was, however, no evidence of an interaction between diet and infec-tion cue dose on calling effort, suggesting that the threshold for terminal investmentwas not contingent on diet as investigated here.

Funding Source

This research was funded by a grant from the National Science Foundation to S.K.S., B.M.S., and J.H. [IOS 16-54028], grants from the Sigma Xi Research Honor Society, the Beta Lambda Chapter of the Phi Sigma Biological Honor Society, a Godfrey Hewitt Mobility Award from the European Society for Evolutionary Biology, and Graduate Student Association of Illinois State University to K.R.D., a grant from the Australian Research Council to J.H. [DP180101708], and a grant from the National Institutes of Health to B.M.S.

Comments

First published in Ecology and Evolution (2020): https://doi.org/10.1002/ece3.6813

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

DOI

10.1002/ece3.6813

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