Biology subjects

von Schmalensee, L.

Publications and source records attributed to von Schmalensee, L..

3 recordsLinked to original sources

bioRxiv2026

Pest evolution amplifies projected crop losses under climate change

Climate change influences the physiology and population dynamics of ectothermic pests, with major repercussions for global crop production. Yet, how evolution modulates these outcomes remains unclear. We exposed the widespread beetle pest Callosobruchus maculatus to 10 years of experimental evolution at different temperatures and quantified thermal responses of life-history traits. Hot- and cold-adapted populations evolved differences in thermal sensitivity, but these were modest relative to evolved differences in trait averages. By leveraging high-resolution temperature time-series we show that the observed evolution translates into cold-adapted genotypes having highest fitness in cold climates and hot-adapted genotypes in warm climates. Hot-adapted beetles maximize fitness in warm climates by increased larval growth, resulting in larger body sizes and higher fecundity. This evolutionary strategy compounds projected crop losses under warming by increasing both intrinsic population growth and per-capita host consumption rates. By year 2100 under intermediate-to-high warming (SSP3-7.0), pest evolution is projected to increase global crop damage potential by +113% from present--twice that expected from warming alone (not accounting for evolution). In major crop-producing areas, where temperatures and the beetles host consumption rates are already high, warming increases average crop damage potential by +29%, but evolution amplifies this three-fold to +87%. Evolution also expands C. maculatus projected colonizable range and in some regions even flips forecasted crop damage reductions into increases. These results identify climate-driven evolution of pest life-histories as an amplifier of agricultural losses and suggest that current projections may significantly understate the threat warming poses to future food security.

ecology↗

bioRxiv2026

The flaws of fitness functions in changing environments

When predicting species responses to changing environments, one can use mathematical functions that describe how individual fitness components depend on the environment, or a single "composite" function that directly links fitness to the environmental state. The former approach is a cornerstone of process-based modelling, but the latter remains standard for developing fundamental theory and making ecological predictions. Yet, fitness is not a single instantaneous trait, but an integrated outcome of multiple underlying processes accruing throughout an organisms life. We show that by ignoring the distinct environmental dependence of the underlying processes, predictions from composite fitness functions become inherently flawed in variable environments. We explore the magnitude of this error by leveraging empirical thermal reaction norms for four important life-history processes in an insect pest, the seed beetle Callosobruchus maculatus. We parameterize two fitness functions: one explicitly modelling the temperature-dependence of the four life-history traits independently (the "ground truth") and one composite function, which treats fitness as a single, instantaneous outcome of the environment. By combining these two functions with hourly temperature data, we projected demographic responses under different warming scenarios across 300 sites over three beetle population origins (California, USA; Yemen; Brazil). We show that the composite function over- or underestimates fitness depending on subtle climatic differences and whether fitness is assumed to accumulate additively or multiplicatively, highlighting the problems of applying composite fitness functions to variable conditions. We conclude that explicitly modeling trait-specific processes will become increasingly important for accurate eco-evolutionary forecasting under future environmental change.

ecology↗

bioRxiv2025

Environmental predictability favours adaptive behavioural plasticity and relaxes selection against deleterious alleles

Behavioural plasticity can play a key role in evolution by either facilitating or impeding genetic adaptation. The latter occurs when behaviours mitigate selection pressures that otherwise would target associated traits. Therefore, environments that facilitate adaptive behavioural plasticity could relax the strength of natural selection, but experimental evidence for this prediction remains scarce. Here, we first demonstrate that maternal care in the beetle Callosobruchus maculatus is dependent on environmental cues that allow females to reduce larval competition via learning and informed oviposition choices. We show that this facilitation of maternal care relaxes selection against deleterious alleles in offspring. We further find that mothers of low genetic quality generally provide poorer care. However, when receiving environmental cues providing accurate information about future host-quality, the increased opportunity for adaptive behavioural plasticity reduced genetic differences in maternal care, further relaxing selection against deleterious alleles. We use our data to illustrate how the identified link between adaptive behavioural plasticity in maternal care and the strength of natural selection can impact indirect genetic effects between mothers and offspring and the accumulation of cryptic genetic loads in populations inhabiting environments that differ in their predictability.

animal behavior and cognition↗