Macronutrients and micronutrients drive trade‐offs between male pre‐ and postmating sexual traits

Abstract

Nutrition fundamentally affects life span and reproduction, and identifying how nutrient intakes are linked to the expression of these life‐history traits can advance understanding of the mechanisms underlying life‐history trade‐offs. Males are thought to face trade‐offs between the allocation of resources to premating secondary sexual traits for gaining access to females and allocation to postmating traits such as ejaculate quality that affects their fertility. We used the Geometric Framework for nutrition to examine the effects of macronutrient and micronutrient consumption on life span and the expression of pre‐ and postmating sexual traits in male field crickets Teleogryllus oceanicus. We found that life span was maximized on diets with a low protein‐to‐carbohydrate (P:C) ratio, whereas premating sexual traits (courtship song and cuticular hydrocarbons) were maximized on high P:C ratios. In contrast, sperm viability, a postmating trait, was lowest on high‐P:C‐ratio diets. Higher consumption of micronutrients (minerals and vitamins) was associated with decreased life span and lower relative abundances of longer chained CHCs, but improved the performance of sperm viability and courtship song. We show that different macronutrients are not simply calories to be allocated to different traits, but directly determine the expression of different life‐history traits and mediate their trade‐offs. In this study, we also provide evidence that micronutrients influenced the expression of life‐history traits, emphasizing the value of including micronutrients in experiments using nutritional geometry. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13190/suppinfo is available for this article.

Sex differences in nutrient intake can reduce the potential for sexual conflict over fitness maximization by female and male crickets

“…Crickets have emerged as a model animal for studying the effects of nutrients on life‐history traits and their trade‐offs, as males and females possess multiple distinct traits that are maximized by different types of nutrients (Archer et al., ; Harrison et al., ; Maklakov et al., ; Rapkin, Jensen, House, Wilson, & Hunt, ; Rapkin, Jensen, et al., ). We have previously demonstrated a trade‐off between pre‐ and post‐mating sexual traits driven by nutritional intake in male Teleogryllus oceanicus (Ng et al., ). Male fertility was found to be maximized by low‐protein diets (Ng et al., ).…”

“…The Geometric Framework for nutrition has been used to integrate the intake of specific nutrients with the expression of various life‐history traits; specifically, axes assigned to relevant nutrients define a nutrient space where the dietary intakes and the trait performance superimpose, providing a graphical representation of nutritional causes and consequences for biological systems (Simpson & Raubenheimer, ). The Framework has been utilized successfully to disentangle the effects of specific macronutrients and caloric content, and demonstrate how macronutrients influence life‐history trade‐offs (Maklakov et al., ; Ng, Simpson, & Simmons, ; Rapkin, Jensen, Archer, et al., ). For example, in many species, lifespan is shown to be maximized on high intake of low‐protein:carbohydrate (P:C) diets, which indicates that the ratio of macronutrients in the diet plays a more crucial role in extending lifespan under ad libitum feeding conditions than caloric restriction (Fanson, Weldon, Perez‐Staples, Simpson, & Taylor, ; Le Couteur et al., ; Lee et al., ; Solon‐Biet et al., ).…”

“…For example, female reproduction is often maximized on higher protein diets required for egg production, whereas males perform better on high‐carbohydrate diets (e.g. required for calling effort in male crickets; Maklakov et al., ; Rapkin, Archer, et al., ; Ng et al., ). Moreover, recent studies suggest that each sex can seek its own optimal target of nutrient intake (Harrison, Raubenheimer, Simpson, Godin, & Bertram, ; Rapkin, Archer, et al., ; Rho & Lee, ).…”

A costly chemical trait: phenotypic condition dependence of cuticular hydrocarbons in a dung beetle

“…Despite the attention CHCs have received in studies of sexual selection, manipulative experiments testing for condition dependence are more limited. CHCs respond to manipulations of diet composition (Liang & Silverman, ; Otte et al ., ; Rapkin et al ., ; Ng et al ., ) including diets of varying quality that presumably alter condition (Delcourt & Rundle, ; Gosden & Chenoweth, ; Weddle et al ., ). The response of CHCs to diets of different composition/quality can potentially reflect condition‐dependent responses, and effects that are independent of condition.…”

“…To isolate changes in CHCs that reflect variation in condition therefore requires a diet restriction or dilution treatment, which directly manipulates the pool of resources available to an individual. This protocol has revealed condition dependence of male CHCs in the fruit fly Drosophila melanogaster (Bonduriansky et al, 2015), the decorated cricket Gryllodes sigillatus and the Australian field cricket, Teleogryllus oceanicus (Ng et al, 2018). It remains an open question as to whether CHCs are condition-dependent across a broader range of taxa.…”