Size‐dependent predation and correlated life history traits alter eco‐evolutionary dynamics and selection for faster individual growth

Abstract

Age at maturation is a key life history trait influencing individual fitness, population age structure, and ecological interactions. We investigated the evolution of age at maturity through changes in the von Bertalanffy growth constant for organisms with a simple juvenile‐adult life history. We used Gillespie eco‐evolutionary models to uncover the role of predation in driving the evolution of the growth constant when eco‐evolutionary dynamics are present. We incorporated both size‐independent and size‐dependent predation into our models to generate differences in selection and dynamics in the system. Our results generally support the idea that faster ontogenetic growth is beneficial when populations are growing but that predation tends to have little effect on age at maturity unless there are trade‐offs with other life history traits. In particular, if faster ontogenetic growth comes at the cost of fecundity, our results suggest that predation selects for intermediate levels of growth and fecundity. Eco‐evolutionary dynamics influenced the nature of selection only when growth was linked to fecundity. We also found that predators that increasingly consume larger prey tend to have higher population sizes due to the greater energy intake from larger prey, but the growth rate‐fecundity trade‐off reversed this pattern. Overall, our results suggest an important role for interactions between size‐dependent foraging and life‐history trade‐offs in generating varying selection on age at maturity through underlying growth traits.

Warming can destabilize predator–prey interactions by shifting the functional response from Type III to Type II

“…The conversion efficiency is usually assumed to be temperature‐independent in studies in which predator–prey systems are investigated under warming (Fussmann, Rosenbaum, Brose, & Rall, ; Uszko et al, ; Vasseur & McCann, ). However, the conversion efficiency naturally depends on the body sizes of the involved predator–prey pair and has, for instance, been calculated as c = GGE (size prey /size predator ) (e.g., DeLong & Luhring, , GGE stands for gross growth efficiency, that is the fraction of prey biomass consumed and converted to predator biomass). Consequently, the assumption of temperature‐invariant conversion efficiency might be inadequate if warming affects the predator size and prey size in a qualitatively or quantitatively different way.…”

Warming can destabilise predator-prey interactions by shifting the functional response from Type III to Type II

“…However, the conversion efficiency naturally depends on the body sizes of the involved predator-prey pair and has thus for instance been calculated as (e.g. DeLong & Luhring, 2018, GGE stands for gross growth efficiency, i.e. the fraction of prey biomass consumed and converted to predator biomass).…”

Ecological pleiotropy and indirect effects alter the potential for evolutionary rescue

“…We assigned traits to newly formed offspring in the GEMs by randomly drawing the trait from a distribution of potential traits that depend on the parent trait, the heritability of that trait, and the level of trait variation in the population. The distribution from which the trait is drawn has a mean of the expected value of the offspring trait that is determined by a parent–offspring regression, following the approach of DeLong and Luhring (). In short, the expected value of a particular offspring's trait ( o c ) is related to the parent trait through the equation of a parent–offspring regression: ,where h 2 is narrow‐sense heritability, is the mean of the parent population, and p c is the current parent trait.…”