Biology Letters最新文献

Across diverse species with sexual reproduction, typically the more male-biased the adult sex ratio (ASR), the greater the investments by the more populous males in the rarer females who hold greater bargaining power in a mating context. Relatively few studies have examined this effect in humans however, and almost none involve observations of actual male investment in a potential mating context. Here, we present one of the first studies to observe investments of men in a potential mating context under differing ASRs. Across 163 mixed-sex groups from three taverns on 7 days of observation, we measured both a group's ASR and each group's leading man's latency to position himself at the tavern's bar to order and pay for beverages. The higher the proportion of men in a group (ASR) and the fewer the absolute number of women in a group, the faster the leading man in the group travelled to reach the bar to order and pay for beverages. Results are consistent with the hypothesis that similar to males in many species, men tactically regulate their investments to adapt to the fluctuation in the ASR in order to maximize their probabilities of attracting a mate.

Much of our view on Mesozoic dinosaur diversity is obscured by biases in the fossil record. In particular, spatiotemporal sampling heterogeneity affects identification of the timing and geographical location of radiations, the recognition of the latitudinal diversity gradient, as well as interpretation of purported extinctions, faunal turnovers and their drivers, including the Early Jurassic Jenkyns Event and across the Jurassic/Cretaceous boundary. The current distribution of sampling means it is impossible to robustly determine whether these 'events' were globally synchronous and geologically instantaneous or spatiotemporally staggered. Accounting for sampling heterogeneity is also paramount to reconciling notable differences in results based on sampling-standardized dinosaur species richness versus reconstructions of diversification rates, particularly with regards to the lead-up to the Cretaceous/Paleogene mass extinction. Incorporation of a greater proportion of stratigraphically well-resolved dinosaurs into analyses is also imperative and must include the substantial Mesozoic radiation of birds. Given the relative rarity of temporally successive, well-sampled spatial windows, it remains possible that dinosaur species richness and diversification rate showed little change after the clade's initial radiation until the Cretaceous/Paleogene boundary. However, better understanding of underlying sampling, combined with a holistic approach to reconstructing dinosaur diversity and diversification, is an important step in testing this hypothesis.

Talitrid amphipods are an extensively studied system for navigation due to their robust ability to navigate back to the optimal burrowing zone after foraging and could be a model system in which to study the impacts of collective behaviour on short-distance navigation and orientation. We investigated whether talitrid amphipods (Megalorchestia pugettensis) differ in their orientation abilities when released individually versus in a group. When released individually, the amphipods took longer to start moving (p < 0.001), travelled longer paths (p = 0.003), moved faster (p = 0.016), had a different initial bearing (p = 0.003) and exhibited more spread in their initial bearing (p = 0.009) than when released in groups. There was no difference between individuals and groups in terms of their trial time nor in the direction or spread of their final orientation. This study introduces a tractable, invertebrate species in which to study the impacts of collective movement and reveals previously unexamined differences in orientation abilities for talitrid amphipods released independently versus in a group that have implications for experimental design in this system.

Behavioural predictability describes the behavioural variability of an individual. Unpredictability can arise from many sources including non-adaptive passive plasticity in which an environmental factor acts directly on the individual to create non-adaptive phenotypic variation. In this study, I use radiotelemetry to field test the hypothesis that Cook Strait giant weta Deinacrida rugosa (Orthoptera: Anostostomatidae) exhibit a sex difference in the predictability of their nightly travel distance due to passive behavioural plasticity. As predicted, I found that male mobility (i.e. nightly travel distance) was less predictable than female mobility. Females travel short and predictable distances each night for food and refuges that are close by and readily available. In contrast, male travel is less predictable because they search for female mates that are stochastically dispersed across the landscape. Therefore, their travel distance can vary considerably across nights.

The widespread distribution of microplastics (MPs) in the environment has motivated research on the ecological significance and fate of these pervasive particles. Recent studies have demonstrated that MPs may not always have negative effects, and in contrast, several species of Tenebrionidae beetles utilized plastic as a food source in controlled laboratory experiments. However, most studies of plastic-eating insects have not been ecologically realistic, and thus it is unclear whether results from these experiments apply more broadly. Here, we quantified the ability of mealworms (Coleoptera: Tenebrionidae) to consume MPs derived from polypropylene and polylactic acid face masks; these are two of the most commonly used conventional and plant-based plastics. To simulate foraging in nature, we mixed MPs with wheat bran to create an environment where beetles were exposed to multiple food types. Mealworms consumed approximately 50% of the MPs, egested a small fraction, and consumption did not affect survival. This study adds to our limited knowledge of the ability of insects to consume MPs. Understory or ground-dwelling insects may hold the key to sustainable plastic disposal strategies, but we caution that research in this field needs to proceed concomitantly with reductions in plastic manufacturing.

Evolutionary models of quantitative traits often assume trade-offs between beneficial and detrimental traits, requiring modellers to specify a function linking trait values. The choice of trade-off function can be consequential; functions that assume diminishing returns (accelerating costs) typically lead to single equilibrium genotypes, while decelerating costs often lead to genetic polymorphisms. Despite their importance, our current theory has little to say on which trade-off functions are the most biologically plausible. To address this gap, we explored how the genetic determination of quantitative traits can lead to different trade-off functions, using resistance to infectious diseases as an example trait. We developed a model where alleles at separate loci pleiotropically increase resistance while decreasing fecundity. We then used this model to generate genotype landscapes and investigate how epistasis effects the trade-off function. Regardless of the strength of epistasis, our model consistently led to accelerating costs. We then incorporated our genotype model into an eco-evolutionary model of disease resistance. Unlike other models with accelerating costs, our approach often led to genetic polymorphisms. Our results suggest that accelerating costs are a strong null model for evolutionary trade-offs and that the eco-evolutionary conditions required for polymorphism may be more nuanced than previously thought.

Why should, and how can, the fields of climate science and geroscience (which studies the biology of ageing) facilitate the cross-disciplinary collaboration needed to ensure that human and planetary health are both promoted in the future of an older, and warmer, world? Appealing to the ideal of 'wisdom-oriented' science (Maxwell 1984 In From knowledge to wisdom: a revolution in the aims and methods of science), where scientists consider themselves to be artisans working for the public good, a number of the real-world epistemic constraints on the scientific enterprise are identified. These include communicative frames that stoke intergenerational conflict (rather than solidarity) and treat the ends of planetary and human health as independent 'sacred values' (Tetlock 2003 Trends Cogn. Sci. 7, 320-324) rather than as interdependent ends. To foster 'climate geroscience'-the field of knowledge and translational science at the intersection of climate science and geroscience-researchers in both fields are encouraged to think of novel ways they could make researchers from the other field 'conversationally' present when framing the aspirations of their respective fields, applying for grant funding and designing their conferences and managing their scientific journals.

The timing and amount of foraging in birds are shaped by many of the same extrinsic factors, including temperature and daylength, as well as intrinsic factors, such as sex and age. Here, we investigate co-variation between these traits. We observed a population of 143 individually marked black-capped chickadees (Poecile atricapillus) over a 90 day period during the winter. For each day, we recorded the time an individual began and ended feeder use relative to sunrise/sunset, and the total number of feeder visits. Within-individuals, both earlier first feeder visit and later last feeder visit were associated with higher total daily feeder visits but lower feeding rates. Individuals also differed consistently in the timing of first and last feeder visits, and individuals that consistently started feeder use earlier in the day ended feeder use later and had higher total daily feeder visits compared with those that started later, but had no difference in feeding rate. Our study demonstrates that variation in the timing of foraging can have important consequences for energy acquisition at both the within- and among-individual levels.

Our fascination with dinosaur brains and their capabilities essentially began with the first dinosaur discovery. The history of this study is a useful reflection of palaeoneurology as a whole and its relationship to a more inclusive evolutionary neuroscience. I argue that this relationship is imbued with high heuristic potential, but one whose realization requires overcoming certain constraints. These constraints include the need for a stable phylogenetic framework, methods for efficient and precise endocast construction, and fossil researchers who are steeped in a neuroscience perspective. The progress that has already been made in these areas sets the stage for a more mature palaeoneurology-not only one capable of being informed by neuroscience discoveries but one that drives such discoveries. I draw from work on the size, shape, behavioural correlates and developmental role of the dinosaur brain to outline current advances in dinosaur palaeoneurology. My examples largely are taken from theropods and centre on questions related to the origin of birds and their unique locomotory capabilities. The hope, however, is that these exemplify the potential for study in other dinosaur groups, and for utilizing the dinosaur-bird lineage as a parallel model on a par with mammals for studying encephalization.