Mismatch between dietary requirements for lipid by a predator and availability of lipid in prey

Abstract

Growth is an important factor in predicting an organism's overall success as an adult. Understanding how abiotic and biotic factors influence body size is key to predicting how environmental changes will impact organisms and predicting optimal behaviors under varying conditions. Food items can vary widely in nutrient content and this variation can affect growth. We tested how the quantity and macronutrient content of live prey affected the growth of juvenile jumping spiders, Phiddipus audax, using 420 spiderlings raised on one of 21 diets. In addition, we measured the nutrient content of prey from the field and compared average prey nutrient content with the diet at which spiders maximized growth. Our results show that the quantity and nutrient content of prey have significant and interacting effects on the growth of an actively hunting predator. In particular, spiders grew larger in body size (tibia/patella length and posterior lateral eye width) and were heavier on diets with higher lipid content. Yet, data on the nutrient content of prey from the field shows that most potential prey have high protein and low lipid content in their bodies. This apparent mismatch between spider nutritional requirements and prey nutrient availability likely presents a challenge to spiders seeking to maximize growth in the field. Several hypotheses for how these predators overcome this challenge to reach the large body sizes observed in the field are discussed.

Geometric Stoichiometry: Unifying Concepts of Animal Nutrition to Understand How Protein-Rich Diets Can Be “Too Much of a Good Thing”

“…In such circumstances, fitness and growth may be directly impacted by a deficit of carbohydrates and fats, as well as metabolic penalties associated with the energetic and toxicity costs of metabolizing amino acids (Solon-Biet et al, 2014;Piper et al, 2017;Raubenheimer and Simpson, 2019). Such dietary imbalance is frequently encountered in the wild, not only by herbivores (e.g., Rothman et al, 2011;Cui et al, 2018) and omnivores (Remonti et al, 2016), including humans (Speth and Spielmann, 1983), but also carnivores (Wilder et al, 2013;Jensen et al, 2014;Kohl et al, 2015;Wiggins and Wilder, 2018).…”

“…Protein is essential to animal nutrition, providing the building blocks for new tissue, enzymes, etc., and it is therefore unsurprising that animals in their natural environment commonly favor N-rich diets (Mattson, 1980). In many cases, however, consumers may be constrained to diets that are richer in protein relative to carbohydrate and lipid than is optimal (Rothman et al, 2011;Jensen et al, 2014;Nyffeler et al, 2016;Remonti et al, 2016;Wiggins and Wilder, 2018). Animals must then use protein as a source of energy, potentially leading to the onset of toxicity via deamination and release of ammonia and incurring various energetic and other costs associated with metabolic transformations, synthesis of reduced forms of N and excretion (Bender, 2012;Piper et al, 2017;Reed et al, 2017;Jennings et al, 2018).…”

Caught in the web: Spider web architecture affects prey specialization and spider–prey stoichiometric relationships

“…The observation that tangle‐web spiders have higher C content than their prey provides support to the hypothesis that predators may suffer from C (i.e., energy) limitation (Wilder et al., 2013). Recent empirical research suggests that energy limitation may be common for some predatory species such as ants, beetles, and spiders (Grover, Kay, Monson, Marsh, & Holway, 2007; Kohl, Coogan, & Raubenheimer, 2015; Noreika, Madsen, Jensen, & Toft, 2016; Wilder et al., 2013; Wiggins & Wilder, 2018). …”

Influence of maternal diet on offspring survivorship, growth, and reproduction in a sheetweb spider

“…In Jensen et al (2011), prey containing high levels of protein shortened juvenile development time and increased body size in the wolf spider Pardosa amentata although the juveniles were observed for only a few instars. In the jumping spider Phidippus audax, however, Wiggins and Wilder (2018) found that high-lipid prey was associated with larger body size (tibia/patella length and posterior-lateral eye width) and heavier weight. In our experiments, the positive effects of mother diet on juvenile growth were mediated by some substances in midges after a single feeding.…”