Biology subjects

Rees-Baylis, E.

Publications and source records attributed to Rees-Baylis, E..

4 recordsLinked to original sources

bioRxiv2026

Generation time is not a universal constraint on adaptive evolution

Conventional wisdom suggests that adaptive evolution proceeds more slowly in long-lived organisms than in short-lived ones due to longer generation times. As a result, long-lived organisms are often viewed as less capable of responding to rapid environmental change. However, empirical evidence challenges this view. Using mathematical models and demographic data from 322 wild animal populations, we show that long generation times slow adaptive evolution only under limited conditions, notably when selection acts on fecundity. When selection targets early survival, intermediate and long generation times can instead accelerate adaptive evolution. Remarkably, short-lived species tend to occupy demographic regimes in which fecundity is the dominant fitness component, whereas long-lived species occupy regimes in which early survival dominates. Therefore, both short- and long-lived species can potentially adapt rapidly, calling into question the widespread use of generation time as a general predictor of adaptive capacity to current environmental change.

evolutionary biology↗

bioRxiv2025

Asymmetric life-history trade-offs shape sex-biased longevity patterns

Sex differences in ageing and lifespan are widespread across taxa, yet their evolutionary causes remain debated. A leading hypothesis suggests these differences are adaptive and driven by sex-specific life-history trade-offs, but formal theoretical support is lacking. To address this, we developed a mathematical model to investigate how such trade-offs shape lifespan evolution in a monogamous mating system. In the model, individuals evolve to optimise a trade-off between reproduction and survival - mediated by mating opportunities in males and offspring production in females. By systematically varying trade-off strengths, we show that either sex can evolve greater longevity, but male-biased longevity evolves under a broader set of conditions - consistent with patterns in monogamous species. This asymmetry arises because female longevity is more constrained: the trade-off between offspring production and survival directly affects the fertility of both sexes. In contrast, the male trade-off for mating opportunities has a weaker indirect effect on female fertility, allowing selection to more readily favour longer male lifespans. We also show that extrinsic density-dependent mortality can disproportionately affect the intrinsically longer-living sex, and obscure the magnitude of this evolved difference. Together, our results provide new theoretical insights into the adaptive bases of sex-biased longevity and highlight the importance of life-history trade-offs in shaping lifespan evolution.

evolutionary biology↗

bioRxiv2024

Inbreeding and demography interact to impact population recovery from bottlenecks

Biodiversity loss driven by climate change and human activities poses a critical global challenge. Population restoration and reintroduction programs are essential for mitigating this threat, yet their outcomes are often unpredictable due to poorly understood success factors. The conservation program of the crested ibis (Nipponia nippon) marks a successful example where the population rose from seven survivors to over 9,000 in the past four decades. To learn whether this successful restoration was due to chance or largely repeatable, we developed an individual-based model that simulates the restoration process by incorporating life-history parameters from empirical data. Our simulation results closely mirror empirical findings, including the time taken to reach the current population size and population-level inbreeding coefficients. We further analyzed the model to compare the effectiveness of two reintroduction strategies and analyzed how inbreeding depression interacts with demography to influence the chance of recovery from bottlenecks. The reintroduction simulations reveal that the firework approach (one-source translocations) outperforms the stepping-stone (serial translocations) approach in restoration effectiveness. Our simulations over broad demographic parameters demonstrate that the net effect of inbreeding varies with species-specific demography, and highlight the importance of considering this interaction when interpreting conservation outcomes and designing future reintroduction programs.

ecology↗

bioRxiv2024

Maternal manipulation of offspring size can trigger the evolution of eusociality in promiscuous species

Eusocial organisms typically live in colonies with one reproductive queen supported by thousands of sterile workers. It is widely believed that monogamous mating is a precondition for the evolution of eusociality. Here, we present a theoretical model that simulates a realistic scenario for the evolution of eusociality. In the model, mothers can evolve control over resource allocation to offspring, affecting offspring body size. The offspring can evolve body-size-dependent dispersal, by which they disperse to breed or stay at the nest as helpers. We demonstrate that eusociality evolves, even if mothers are not strictly monogamous, if mothers can constrain their offsprings reproduction by manipulation. We also observe the evolution of social polymorphism with small individuals that help and larger individuals that disperse to breed. Our model unifies the traditional kin selection and maternal manipulation explanations for the evolution of eusociality and demonstrates that - contrary to current consensus belief - eusociality can evolve despite highly promiscuous mating.

evolutionary biology↗