Stable isotope tracers reveal a trade‐off between reproduction and immunity in a reptile with competing needs

Abstract

Trade‐offs between the reproductive and immune systems are predicted when resources are limited, but are difficult to measure. We used 15N‐labelled amino acids to directly compare protein allocation by lizards to eggs and healing wounds. We showed that these two demands compete for the same resource, and that the ratio of protein allocation between them was related to body size, reproductive stage and plasma corticosterone levels. On average, rates of leucine deposition into eggs (0.022 μg/day) were an order of magnitude greater than those into scabs (0.002 μg/day), similar to leucine excretion rates (0.027 μg/day), and about half as large as leucine egestion rates (0.054 μg/day). We found that earlier reproductive stages and greater amounts of stored energy, but not manipulated food availability or the amount of food consumed, increased the absolute and relative allocation of protein to self‐maintenance. We provide direct evidence for amino acid trade‐offs between reproduction and wound healing. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13002/suppinfo is available for this article.

Investment of both essential fatty and amino acids to immunity varies depending on reproductive stage

“…However, we did observe increased fatty acid deposition in the eggs of animals that ingested more food, suggesting that these animals had overall higher lipid turnover rates. Finally, in absolute terms, our rate estimates were lower than those of Durso and French () and of Brace et al () for 13 C‐leucine to female Anolis sagrei gonads.…”

“…We calculated the amount of excess 15 N and 13 C in each tissue by subtracting the background abundance of these isotopes measured by Durso and French () and using additional unpublished data. We calculated the rate of deposition into each tissue following Stark ().…”

“…Using stable isotope tracers allows for a nonlethal comparison using common units to follow the “fates” of ingested nutrients and compare resource investment among fundamentally different sink pools within the bodies of living vertebrates (McCue, ). Nutrient use (Cherel, Hobson, & Hassani, ; Khalilieh, McCue, & Pinshow, ) and allocation of resources to reproduction (Hobson, ; O'Brien, Schrag, & del Rio, ) have been studied separately using stable isotope tracers in organisms as diverse as hawkmoths and birds, but few studies have compared rates of isotope deposition into tissues or organs that compete for common resources (Brace, Sheikali, & Martin, ; Durso & French, ), and no studies have attempted to use multiple tracers to simultaneously track the fates of different biomolecules.…”

A dynamic threshold model for terminal investment

“…An especially salient trade-off is between reproductive effort and somatic defense (i.e., immunity) (Reznick 1985; Lochmiller and Deerenberg 2000; Zera and Harshman 2001; Zuk and Stoehr 2002; Lawniczak et al 2007; Durso and French 2017). Investments in these traits can enhance fitness through their effects on reproduction and survival, but such investments inevitably entail evolutionary, maintenance, and deployment costs, which leads to an allocation trade-off between them (Schwenke et al 2016).…”

Dehydration enhances cellular and humoral immunity in a mesic snake community

“…Immune function competes with other physiological processes for energetic resources (Canale & Henry, 2011; Demas & Nelson, 2011; Lochmiller & Deerenberg, 2000), and, because of the high energetic requirements of reproduction (Angilletta & Sears, 2000; Nilsson & Råberg, 2001), immunocompetence is highly influenced by a tradeoff with reproduction (Adamo, Jensen, & Younger, 2001; Cox et al, 2010; Durso & French, 2018; French, DeNardo, & Moore, 2007; Knowles, Nakagawa, & Sheldon, 2009; Stahlschmidt et al, 2013). The energy demands of reproduction can lead to a seasonal suppression of the immune system in seasonally breeding animals (Martin, Weil, & Nelson, 2008; Walton et al, 2011).…”