Genetic background and thermal regime influence adaptation to novel environment in the seed beetle, Callosobruchus maculatus.

Climate change is associated with the increase in both the mean and variability of thermal conditions. Therefore, the use of more realistic fluctuating thermal regimes is the most appropriate laboratory method for predicting population responses to thermal heterogeneity. However, the long- and short-term implications of evolving under such conditions are not well understood. Here, we examined differences in key life-history traits among populations of seed beetles (Callosobruchus maculatus) that evolved under either constant control conditions or in an environment with fluctuating daily temperatures. Specifically, individuals from two distinct genetic backgrounds were kept for 19 generations at one of two temperatures, a constant temperature (T = 29 °C) or a fluctuating daily cycle (Tmean = 33 °C, Tmax = 40 °C, and Tmin = 26 °C), and were assayed either in their evolved environment or in the other environment. We found that beetles that evolved in fluctuating environments but were then switched to constant 29 °C conditions had far greater lifetime reproductive success compared with beetles that were kept in their evolved environments. This increase in reproductive success suggests that beetles raised in fluctuating environments may have evolved greater thermal breadth than control condition beetles. In addition, the degree of sexual dimorphism in body size and development varied as a function of genetic background, evolved thermal environment, and current temperature conditions. These results not only highlight the value of incorporating diel fluctuations into climate research but also suggest that populations that experience variability in temperature may be better able to respond to both short- and long-term changes in environmental conditions.

Fasting increases investment in soma upon refeeding at the cost of gamete quality in zebrafish.

Fasting increases lifespan in invertebrates, improves biomarkers of health in vertebrates and is increasingly proposed as a promising route to improve human health. Nevertheless, little is known about how fasted animals use resources upon refeeding, and how such decisions affect putative trade-offs between somatic growth and repair, reproduction and gamete quality. Such fasting-induced trade-offs are based on strong theoretical foundations and have been recently discovered in invertebrates, but the data on vertebrates are lacking. Here, we report that fasted female zebrafish, Danio rerio, increase investment in soma upon refeeding, but it comes at a cost of egg quality. Specifically, an increase in fin regrowth was accompanied by a reduction in 24 h post-fertilization offspring survival. Refed males showed a reduction in sperm velocity and impaired 24 h post-fertilization offspring survival. These findings underscore the necessity of considering the impact on reproduction when assessing evolutionary and biomedical implications of lifespan-extending treatments in females and males and call for careful evaluation of the effects of intermittent fasting on fertilization.

Implementing code review in the scientific workflow: Insights from ecology and evolutionary biology.

Code review increases reliability and improves reproducibility of research. As such, code review is an inevitable step in software development and is common in fields such as computer science. However, despite its importance, code review is noticeably lacking in ecology and evolutionary biology. This is problematic as it facilitates the propagation of coding errors and a reduction in reproducibility and reliability of published results. To address this, we provide a detailed commentary on how to effectively review code, how to set up your project to enable this form of review and detail its possible implementation at several stages throughout the research process. This guide serves as a primer for code review, and adoption of the principles and advice here will go a long way in promoting more open, reliable, and transparent ecology and evolutionary biology.

Fitness benefits of dietary restriction.

Dietary restriction (DR) improves survival across a wide range of taxa yet remains poorly understood. The key unresolved question is whether this evolutionarily conserved response to temporary lack of food is adaptive. Recent work suggests that early-life DR reduces survival and reproduction when nutrients subsequently become plentiful, thereby challenging adaptive explanations. A new hypothesis maintains that increased survival under DR results from reduced costs of overfeeding. We tested the adaptive value of DR response in an outbred population of Drosophila melanogaster fruit flies. We found that DR females did not suffer from reduced survival upon subsequent re-feeding and had increased reproduction and mating success compared to their continuously fully fed (FF) counterparts. The increase in post-DR reproductive performance was of sufficient magnitude that females experiencing early-life DR had the same total fecundity as continuously FF individuals. Our results suggest that the DR response is adaptive and increases fitness when temporary food shortages cease.

Transgenerational fitness effects of lifespan extension by dietary restriction in Caenorhabditis elegans.

Dietary restriction (DR) increases lifespan in a broad variety of organisms and improves health in humans. However, long-term transgenerational consequences of dietary interventions are poorly understood. Here, we investigated the effect of DR by temporary fasting (TF) on mortality risk, age-specific reproduction and fitness across three generations of descendants in Caenorhabditis elegans. We show that while TF robustly reduces mortality risk and improves late-life reproduction of the individuals subject to TF (P0), it has a wide range of both positive and negative effects on their descendants (F1-F3). Remarkably, great-grandparental exposure to TF in early life reduces fitness and increases mortality risk of F3 descendants to such an extent that TF no longer promotes a lifespan extension. These findings reveal that transgenerational trade-offs accompany the instant benefits of DR, underscoring the need to consider fitness of future generations in pursuit of healthy ageing.

The distribution of the Lansing Effect across animal species.

Maternal senescence is the reduction in individual performance associated with increased maternal age at conception. When manifested on adult lifespan, this phenomenon is known as the "Lansing Effect." Single-species studies report both maternal age-related increases and decreases in adult lifespan, but no comprehensive review of the literature has yet been undertaken to determine if the Lansing Effect is a widespread phenomenon. To address this knowledge gap, we performed a meta-analysis of maternal aging rates taken from all available published studies. We recovered 78 estimates from 22 studies representing 15 species. All studies taken together suggest a propensity for a Lansing Effect, with an estimated average effect of maternal age on offspring's adult lifespan of between -17% and -22%, depending upon our specific choice of model. We failed to find a significant effect of animal class or insect order but given the oversampling of insect species in the published literature and the paucity of vertebrate studies, we infer that only rotifers and insects yet demonstrate a tendency toward expressing the phenomenon.

Technology-enhanced simulation for healthcare professionals: A meta-analysis.

Aim: There have been substantial changes in the simulation technology landscape, in particular virtual reality (VR), during the past decade, which have resulted in increased abundance and decreased cost. We therefore updated a previous meta-analysis conducted in 2011, aiming to quantify the impact of digital technology-enhanced simulation (T-ES) compared with traditional teaching in physicians, physicians-in-training, nurses, and nursing students. Design: We conducted a meta-analysis consisting of randomized controlled trials published in English between January 2011 and December 2021 in peer-reviewed journals indexed in seven databases. Moderators for study duration, instruction, type of healthcare worker, type of simulation, outcome measure, and study quality rated by Medical Education Research Study Quality Instrument (MERSQI) score were included in our model and used to calculate estimated marginal means (EMMs). Results: The overall effect of T-ES was positive across the 59 studies included in the analysis compared with traditional teaching [overall effect size 0.80 (95% CI 0.60, 1.00)]. This indicates that T-ES is effective in improving outcomes across a wide variety of settings and participants. The impact of T-ES was found to be greatest for expert-rated product metrics such as procedural success, and process metrics such as efficiency, compared with knowledge and procedure time metrics. Conclusions: The impacts of T-ES training on the outcome measures included in our study were greatest in nurses, nursing students and resident physicians. T-ES was strongest in studies featuring physical high-fidelity mannequins or centers, compared with VR sensory environment T-ES, though there was considerable uncertainty in all statistical analyses. Further high-quality studies are required to assess direct effects of simulation training on patient and public health outcomes.

Advice for improving the reproducibility of data extraction in meta-analysis.

Extracting data from studies is the norm in meta-analyses, enabling researchers to generate effect sizes when raw data are otherwise not available. While there has been a general push for increased reproducibility in meta-analysis, the transparency and reproducibility of the data extraction phase is still lagging behind. Unfortunately, there is little guidance of how to make this process more transparent and shareable. To address this, we provide several steps to help increase the reproducibility of data extraction in meta-analysis. We also provide suggestions of R software that can further help with reproducible data policies: the shinyDigitise and juicr packages. Adopting the guiding principles listed here and using the appropriate software will provide a more transparent form of data extraction in meta-analyses.

Triparental ageing in a laboratory population of an insect with maternal care.

Parental age at reproduction influences offspring size and survival by affecting prenatal and postnatal conditions in a wide variety of species, including humans. However, most investigations into this manifestation of ageing focus upon maternal age effects; the effects of paternal age and interactions between maternal and paternal age are often neglected. Furthermore, even when maternal age effects are studied, pre- and post-natal effects are often confounded. Using a cross-fostered experimental design, we investigated the joint effects of pre-natal paternal and maternal and post-natal maternal ages on five traits related to offspring outcomes in a laboratory population of a species of burying beetle, Nicrophorus vespilloides. We found a significant positive effect of the age of the egg producer on larval survival to dispersal. We found more statistical evidence for interaction effects, which acted on larval survival and egg length. Both interaction effects were negative and involved the age of the egg-producer, indicating that age-related pre-natal maternal improvements were mitigated by increasing age in fathers and foster mothers. These results agree with an early study that found little evidence for maternal senescence, but it emphasizes that parental age interactions may be an important contributor to ageing patterns. We discuss how the peculiar life history of this species may promote selection to resist the evolution of parental age effects, and how this might have influenced our ability to detect senescence.