Are sexually selected traits affected by a poor environment early in life?

Abstract

BackgroundChallenging conditions experienced early in life, such as a restricted diet, can detrimentally affect key life-history traits. Individuals can reduce these costs by delaying their sexual maturation, albeit at the price of the later onset of breeding, to eventually reach the same adult size as individuals that grow up in a benevolent environment. Delayed maturation can, however, still lead to other detrimental morphological and physiological changes that become apparent later in adulthood (e.g. shorter lifespan, faster senescence). In general, research focuses on the naturally selected costs of a poor early diet. In mosquitofish (Gambusia holbrooki), males with limited food intake early in life delay maturation to reach a similar adult body size to their well-fed counterparts (‘catch-up growth’). Here we tested whether a poor early diet is costly due to the reduced expression of sexually selected male characters, namely genital size and ejaculate traits.ResultsWe found that a male’s diet early in life significantly influenced his sperm reserves and sperm replenishment rate. Shortly after maturation males with a restricted early diet had significantly lower sperm reserves and slower replenishment rates than control diet males, but this dietary difference was no longer detectable in older males.ConclusionsAlthough delaying maturation to reach the same body size as well fed juveniles can ameliorate some costs of a poor start in life, our findings suggest that costs might still arise because of sexual selection against these males. It should be noted, however, that the observed effects are modest (Hedges’ g = 0.20–0.36), and the assumption that lower sperm production translates into a decline in fitness under sperm competition remains unconfirmed.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0838-2) contains supplementary material, which is available to authorized users.

Effects of early nutritional stress on physiology, life-histories and their trade-offs in a model ectothermic vertebrate

“…In our study, once nutritional stress was alleviated (all animals on normal-diet), we found that as animals increased their growth rates, there was no concomitant reduction in immunocompetence. This lack of a trade-off between investment in compensatory growth and investment into immune function is in contrast to results in damselflies (Stoks et al, 2006) and poultry (van der Most et al, 2011), but is in accordance with work conducted on zebra finches (Killpack et al, 2014). In garter snakes , measures of adaptive but not innate immune function have been shown to trade off with reproduction.…”

“…Animals deploy different strategies to mitigate early-life nutritional stress on growth and maturation (Auer, 2010;Mueller et al, 2012;Vega-Trejo et al, 2016). Growth rates are plastic, particularly in species with indeterminate growth, and are usually regulated at optimal rather than maximal rates (Arendt, 1997).…”

“…Compensatory growth has been reported across vertebrates: in mammals (Ryan, 1990), birds (Criscuolo et al, 2011), fish (Ali et al, 2003), amphibians (Hector et al, 2012) and reptiles (Radder et al, 2007). Compensatory growth is often achieved through a hyperphagic response to increases in resources (Ali et al, 2003;Gurney and Nisbet, 2004;Morgan and Metcalfe, 2001), but can also be achieved by allocating more energy into growth at the expense of other traits such as locomotor performance (Criscuolo et al, 2011;Lee et al, 2010), immune function (Norris and Evans, 2000), cognition (Fisher et al, 2006), maturation Hector et al, 2012;Vega-Trejo et al, 2016), adult body size (Auer, 2010), lifespan (Birkhead et al, 1999;Lee et al, 2013) and litter size .…”

Combined effects of rearing and testing temperatures on sperm traits

“…Initially, our models included 'days since maturity', as previous studies have shown that it can influence both sperm number and velocity (e.g. Vega-Trejo et al, 2016). However, we excluded this term from our final models as it had no effect.…”

Development time mediates the effect of larval diet on ageing and mating success of male antler flies in the wild

“…A high-quality developmental environment is generally predicted to confer lasting benefits on individual performance [3]; this is known as the "silver-spoon" effect [4]. For instance, high quality environments in early life can lead to increased survival [5,6], fecundity [7], mating success [8][9][10], sperm quality and quantity [8,11,12], and immune function [13,14] in adulthood, compared to individuals from poor environments.…”