Structural and Performance Costs of Reproduction in a Pure Capital Breeder, the Children’s PythonAntaresia childreni

Abstract

Females often manage the high energy demands associated with reproduction by accumulating and storing energy in the form of fat before initiating their reproductive effort. However, fat stores cannot satisfy all reproductive resource demands, which include considerable investment of amino acids (e.g., for the production of yolk proteins or gluconeogenesis). Because capital breeders generally do not eat during reproduction, these amino acids must come from internal resources, typically muscle proteins. Although the energetic costs of reproduction have been fairly well studied, there are limited data on structural and performance costs associated with the muscle degradation required to meet amino acid demands. Thus, we examined structural changes (epaxial muscle width) and performance costs (constriction and strength) over the course of reproduction in a pure capital breeder, the children's python (Antaresia childreni). We found that both egg production (i.e., direct resource allocation) and maternal care (egg brooding) induce muscle catabolism and affect performance of the female. Although epaxial muscle loss was minimal in nonreproductive females, it reached up to 22% (in females after oviposition) and 34% (in females after brooding) of initial muscle width. Interestingly, we found that individuals with higher initial muscular condition allocated more of their muscle into reproduction. The amount of muscle loss was significantly linked to clutch mass, underscoring the role of structural protein in egg production. Egg brooding significantly increased proteolysis and epaxial loss despite no direct allocation to the offspring. Muscle loss was linked to a significant reduction in performance in postreproductive females. Overall, these results demonstrate that capital-breeding females experience dramatic costs that consume structural resources and jeopardize performance.

Penny and penny laid up will be many: large Yellow anacondas do not disregard small prey

“…As diet divergence as a product of SSD has been demonstrated for a range of taxa (Weise, Harvey & Costa, ; for mammals; Natusch & Lyons, for reptiles; Cook et al ., for birds), this may be a secondary consequence of increases in fitness generated by larger body size in males and/or females. Although female anacondas prey is both larger and different from that of males, they feed more frequently, which may be related to fat accumulation associated with the higher costs of reproduction (Lourdais, Lorioux & DeNardo, ). This notion is supported by the fact that, while diverging in composition, males and females diet overlaps extensively, excluding the possibility of SSD being a way to reduce competition.…”

Capital Breeding in a Diapausing Copepod: A Transcriptomics Analysis

“…Proteins were the most important source of energy in these females as indicated by the upregulation of genes involved in proteolysis and ubiquitination, concurrent with low expression of genes encoding enzymes involved in the TCA cycle, glycolysis and lipid catabolism. During reproduction, protein catabolism is activated in order to produce amino acids which can be directly used to support embryo development (e.g., egg yolk) or can be converted to glucose via gluconeogenesis when other resources are insufficient (Lourdais et al, 2013;Brusch et al, 2018). Furthermore, activation of the ubiquitin-proteasome system is associated with decreases in muscle activity and muscle mass and is indicative of muscle loss (Lourdais et al, 2013).…”

Morphological and Physiological Changes during Reproduction and Their Relationships to Reproductive Performance in a Capital Breeder

“…Additionally, oxidative damage due to fasting and, thus, protein catabolism has been documented in birds (Poljicak-Milas et al 2007) and mammals (reviewed in Abdelmegeed et al 2009). Recent research indicates that fasted nonreproductive female A. childreni lose musculature and contractile strength at a much slower rate than their fasted reproductive counterparts (Lourdais et al 2013). Thus, if fasting alone cannot fully explain the effects of reproduction on morphology and performance, then shifts in self-maintenance (immune function and oxidative damage) during reproduction may similarly be due to more than fasting alone.…”

“…This species is also a capital breeder, with energy reserves driving reproductive decisions and supporting reproductive effort. Thus, the potential confounding effect of energy intake on reproduction-related trade-offs (e.g., van Noordwijk and de Jong 1986; Zera and Harshman 2001;King et al 2010) is eliminated because A. childreni does not eat during reproduction (Lourdais et al 2013). However, individuals enter the breeding season in varying body condition (a proxy for energy reserves), allowing for examination of the effect of interindividual variation in resource acquisition on reproductive effort.…”

“…An optimal design would have included a control group of females that were not allowed to breed but that were fasted similar to reproductive females. Although our sample size precluded this design, recent research in A. childreni used this approach and demonstrated that fasted nonreproductive females exhibit greater musculature and contractile strength than fasted reproductive females sampled at the same time (Lourdais et al 2013). Thus, we have confidence that any Figure 2.…”