Maternal predator‐exposure affects offspring size at birth but not telomere length in a live‐bearing fish

Abstract

The perception of predation risk could affect prey phenotype both within and between generations (via parental effects). The response to predation risk could involve modifications in physiology, morphology, and behavior and can ultimately affect long‐term fitness. Among the possible modifications mediated by the exposure to predation risk, telomere length could be a proxy for investigating the response to predation risk both within and between generations, as telomeres can be significantly affected by environmental stress. Maternal exposure to the perception of predation risk can affect a variety of offspring traits but the effect on offspring telomere length has never been experimentally tested. Using a live‐bearing fish, the guppy (Poecilia reticulata), we tested if the perceived risk of predation could affect the telomere length of adult females directly and that of their offspring with a balanced experimental setup that allowed us to control for both maternal and paternal contribution. We exposed female guppies to the perception of predation risk during gestation using a combination of both visual and chemical cues and we then measured female telomere length after the exposure period. Maternal effects mediated by the exposure to predation risk were measured on offspring telomere length and body size at birth. Contrary to our predictions, we did not find a significant effect of predation‐exposure neither on female nor on offspring telomere length, but females exposed to predation risk produced smaller offspring at birth. We discuss the possible explanations for our findings and advocate for further research on telomere dynamics in ectotherms.

Imminent risk of predation reduces the relative strength of postcopulatory sexual selection in the guppy

“…We used a repeated-measures design because male mating, insemination and competitive fertilization success are significantly repeatable across females [58,59]. We simulated IPR using visual ( predator models consisting of a fish bait resembling a pike cichlid Crenicichla alta, 10.8-12.5 cm long) and olfactory stimuli (adult guppy skin extract mimicking a predation event), following an established procedure [55]. In the IPR group, a predator attack was simulated in the afternoon before each mating trial (both model and skin extract) and before the start of mating trials (skin extract only).…”

“…Adaptations to predation include plastic behavioural responses to predation risk cues, which are well documented in both the field and the laboratory [53], even in domestic guppies [54]. These allow for ecologically realistic manipulations of IPR under controlled conditions [55,56], and for separating the effects on sexual selection processes that are due to selective mortality from those associated with prey's antipredator responses. Finally, guppies show a very large phenotypic and genetic variance in sperm production, as estimated from the number of sperm stripped from rested males [14,57].…”

Transgenerational Plasticity in the Context of Predator-Prey Interactions

“…Some of these more general responses may nevertheless contribute to anti-predator strategy, such as larger eggs (McGhee et al, 2012) or higher size at birth of offspring prey (Donelan and Trussell, 2018b), which allow to faster reach a refuge-size. In other cases, the responses are more likely to be by-products of carry-over effects of parental exposure to predator-cues (stress-based responses, e.g., smaller egg size: McGhee et al, 2012; smaller size at birth: Monteforte et al, 2020) or reflect trade-offs between anti-predator defenses and other functions in offspring (e.g., induction of morphological defenses at the expense of growth rate or investment in reproduction: DeWitt et al, 1998). For example, two studies (Stein and Bell, 2014;Stein et al, 2018) showed that stickleback offspring produced by fathers exposed to predation risk were lighter and smaller.…”

Prenatal Visual Exposure to a Predator Influences Lateralization in Goldbelly Topminnows

“…When reared in the presence of a caged larvivorous-fish (Gambusia affinis), mosquito larvae (Culex pipiens) reduce their development time and increase their body size [56]. On the contrary, Monteforte and colleagues [42] showed that in guppies, maternal exposure to predation risk did not affect significantly telomere (nucleoprotein complexes susceptible to stress exposure) length in both adult females and in their offspring. However, subjects exposed to predation risk produced smaller offspring at birth.…”

“…There are several possible interpretations of this finding. Simulated predators, usually fish lures, proved to be valid [39,40,42] in several fish studies, while here we used a modified net already adopted in a previous study but for a different purpose. One of the weaknesses of this study is that we cannot exclude that in this context this particular version was not effective.…”