Biological Reviews最新文献

The environment experienced by a mother influences offspring phenotype through maternal effects, which can have significant adaptive benefits for both the mother and the offspring. However, the ways in which maternal environments influence offspring development are extremely diverse, and empirical studies using an outcome-based approach often fail to support different maternal effect hypotheses. We argue that this is in part because such studies overlook the ontogeny of the maternal phenotype. Here, we review how the environments experienced by a mother across different life stages influence the development of the maternal phenotype. Then, we propose a new framework that differentiates between two main processes of maternal effects according to the life stage at which a specific maternal trait is developed and how long its effect persists during the mother's reproductive life. The “consistent” maternal phenotype is developed mainly during a mother's early life and consistently affects the phenotype of all offspring produced during her lifetime, whereas the “flexible” maternal phenotype changes in response to environmental conditions experienced during her adult life and affects the phenotype of her subsequent offspring. We review how consistent and flexible maternal effects can contribute to different maternal effect processes, such as condition-transfer effects, cascading effects, intergenerational plasticity and developmental programming. We also provide empiricists with a quantitative genetic method, which integrates the ontogenetic scope into maternal effect testing, to determine how the early or late environments shape the maternal phenotype across ontogeny and then examine how this maternal phenotype affects offspring phenotype. We highlight that this conceptual and methodological framework of disassembling the multiple processes by which genes and environments interactively influence the maternal and offspring phenotypes will help us to explain the astonishing variation in maternal strategies and life-history trade-off patterns.

Multiple hypotheses have been suggested to explain why the three zebra species (Equus quagga, E. grevyi and E. zebra) are striped. We review how well these theories explain the nature (rather than simply the existence) of the stripes. Specifically, we explore how well different theories explain (i) the form of zebra stripes (especially on different body parts), (ii) stripe variation between zebra populations and among species, and (iii) the lack of striping in other equids or other large mammalian herbivores. The main hypotheses discussed during the last decade are the deterrence of biting flies, thermoregulation through stripe-generated air movement, and three anti-predation hypotheses: crypsis to avoid detection; dazzle colouration to confuse pursuers; and interspecies signalling to encourage protective mixed-species herding. Our evaluation suggests that these theories struggle to explain all aspects of variation in striping. For each theory we identify where through logical reasoning or empirical data, the theory is unable to account for an aspect of variation, or whether information is currently lacking. In the latter case we offer concrete suggestions for the types of empirical study that would be most useful. Deterrence of biting flies is the theory that currently has strongest empirical support, but this theory alone struggles to explain why striping occurs so strongly in zebra but not in other African mammals, and the distribution of stripes across the body. These aspects can be explained by the interspecies signalling theory, but this theory has not been empirically evaluated. We suggest how future studies could best utilise our framework to close the most pressing knowledge gaps in our understanding of this iconic example of animal colouration.

Identifying the role of marine and estuarine habitats in supporting fish and invertebrate populations during vulnerable juvenile life stages is essential to achieve effective conservation and fisheries management. There remains general agreement that: (i) the quality of juvenile habitat is best measured as the contribution of juveniles to adult populations (here “juvenile–adult contribution”) and (ii) this contribution may be measured directly or inferred from habitat-specific abundance, growth and survival. Obtaining effective estimates of juvenile habitat quality using these four metrics, however, is challenging. Through a systematic review of approaches to measure juvenile habitat quality, we critically evaluate current abilities to identify key habitats and provide recommendations for future work. We found that research in this area remains dominated by measurements of abundance (85% of studies) and, to a lesser extent growth (51% of studies), with limitations in the spatiotemporal resolution and extent of sampling. Relatively few approaches are available to measure survival and juvenile–adult contribution. Knowledge of juvenile habitat quality is further limited by restricted coverage of geographic areas, taxonomic groups and habitats. Based on our analysis of 874 studies over the past ca. 50 years, we provide five recommendations for enabling juvenile habitat research to support fisheries and conservation management better in future.

The comparative study of communicative behaviour in non-human animals, especially primates, has yielded crucial insights into the evolution of human language. This research, mostly focused on the species and population level, has improved our understanding of the various socio-ecological factors that shape communication systems. However, despite the inherent flexibility of human communication, the impact of individual variation on non-human communication systems has often been overlooked, along with its potential to shed light on the roots of human language. While the eco-evolutionary relevance of genetic and phenotypic differences between individuals is well established, animal communication studies have traditionally focused on group averages and treated outliers as noise. In this review, we address this gap by providing a comprehensive overview of the sources of individual variation in animal communicative behaviour (e.g. physiological, sociodemographic, or personality traits), across parameters such as signal forms, repertoires, and usage strategies. In particular, recent evidence from comparative work underscores the potential evolutionary significance of individual plasticity in communicative behaviour. We argue for an explicit focus on within-individual variation and propose advancing the study of animal communication through multi-level approaches that integrate intrinsic and environmental factors, as well as between- and within-individual variation. Such approaches not only refine our view of complexity in animal communication systems and their implications for social evolution, but also help trace the evolutionary trajectory of human language through comparative studies.

Inhibitory control, the ability to control impulsive or pre-learned behaviour in order to reach a more rewarding goal, is essential in many aspects of normal life. In non-human animals, better inhibitory control performances have been associated with a larger brain, better problem-solving skills, and fitness benefits. This crucial cognitive ability has been studied in a wide range of fields (psychology, neurosciences, animal cognition) and has been tested in several animal classes from insects to mammals. Unfortunately, unlike in human test psychology, the common paradigms designed to measure inhibitory control in non-human animals often suffer from a lack of validity and reliability and have yielded mixed results. Therefore, the nature of inhibitory control, either defined as a common ability or a suite of distinct processes, is still debated. Besides, the evolutionary processes shaping the variation in inhibitory control, often tested using a single task, are still poorly understood and the relative influences of ecological, anatomical or social factors as evolutionary drivers of this ability remain unclear. Finally, it is only recently that researchers have focused efforts on the factors necessary for the evolution of inhibitory control, that is individual variation in inhibitory control performance, heritability of this trait and fitness benefits. Hence, our main objective herein is to conduct a review of the existing literature to discuss conceptual and methodological challenges faced by researchers wanting to study inhibitory control in animals. We then suggest tools to tackle these challenges and propose a framework to build a valid and reliable measure of inhibitory processes. Next, we describe the requirements to study the selective pressures involved in this cognitive process in order to have a better understanding of its evolutionary underpinnings. We finally consider the future of interspecies comparative studies of inhibitory control.

Animal medical systems encompass a wide range of behaviours aimed at maintaining or improving health. It has become clear that these behaviours are not limited to animals treating themselves (self-medication) but also include the treatment of group members, resulting in the adoption of the more inclusive term “animal medication”. Behaviour with the intent to avoid, reduce the impact, or otherwise treat disease transmission, rather than the use of medicinal substances, can be described as medical behaviours. However, most behaviours described here involve the ingestion or application of items with medicinal properties to oneself or the application of items to others or their temporary or permanent communal living spaces like nests or burrows, hereto named medicinal or medication behaviours. This review begins with a historical overview of the field, showcasing an increasing awareness of the wide diversity of taxa exhibiting animal medication and elucidating the development of criteria used to define and categorise such behaviours across the animal kingdom. A thorough synthesis of recent research is presented, by providing critical reflection that challenges conventional notions and emphasises the significance of sociality and ecological context. To this end, medical systems are explored by using numerous examples, thus highlighting the diverse strategies animals employ to maintain health and improve fitness, ranging from honey bees foraging on antimicrobial resin to control hive disease to apes ingesting small amounts of toxic secondary compounds to control parasite infection. The understanding of how animals maintain their health through medical strategies offers valuable insights into the evolutionary origin and complexity of the drivers behind these behaviours. Evidence suggests that advanced cognition is not necessarily a prerequisite because innate mechanisms are likely involved in the expression of these behaviours across the animal kingdom. By highlighting the importance of life-history traits and ecological context in predicting animal medical systems, we reassess the presumed primary drivers of these adaptations. Finally, this review raises important questions about animal medical systems, including the universality of the mechanisms involved, the evolutionary significance of parasite pressure, and the ecological implications of this suite of behaviours. By addressing these complexities, this review provides a nuanced understanding of animal medical systems and highlights avenues for future research in this field.

Globally there is an urgent need to find sustainable solutions to balance energy production with the protection of vulnerable species and conservation of biodiversity. This is particularly critical for freshwater ecosystems, habitats, and species that may be impacted by hydropower development and operations needed to meet energy grid demands. Reliable and accurate environmental impact assessments (EIAs) that identify the biological, physical, or social impacts of hydropower are key to ensure biodiversity, ecosystem, and societal sustainability. The analysis of environmental DNA (eDNA) has the potential to transform hydropower EIAs, management and mitigation planning, and decision-making procedures. Further, the incorporation of eDNA surveys into EIAs during both hydropower planning and continued operations may streamline regulatory processes by improving our understanding of potentially impacted biota and habitats and evaluating environmental impacts mitigation. Here, we: (i) highlight current understanding and use of eDNA in freshwater environments; (ii) examine critical considerations for eDNA integration into hydropower EIAs and biological monitoring; (iii) identify knowledge gaps in eDNA analysis and applications unique to hydropower-regulated systems; and (iv) discuss future opportunities to bolster the incorporation of eDNA into hydropower research including regulatory acceptance and public engagement. While we acknowledge that there are several factors that may complicate the broad adoption of eDNA as a tool for assessing the impacts of hydropower, we anticipate that growing confidence in eDNA through hydropower-specific protocols, calibrations, and validations will overcome these inherent uncertainties.

We discuss the intricate relationship between the evolution of the concept of stress and the development of the concept of animal welfare. After a brief review of the main concepts of animal welfare, we analyse important steps in the evolution of the concept of stress, starting from the mechanistic approach of the General Adaptation Syndrome to the recent integrative allostatic theory. We show how, over time, each concept of stress has informed the development of the concept of animal welfare. We discuss the role of emotions and affective states in the response of animals to challenges and how psychological stress is integral to the welfare of animals. Lastly, we discuss briefly the potential role of the gut–brain axis in both the concept of stress and the concept of welfare.

The concept of flexibility in communication is central to reconstructing the evolutionary history of language, and grappling with “contextual flexibility” in particular is pivotal to address implications for pragmatics-first accounts of language evolution. Despite significant advances in the field, research is hindered by definitional inconsistencies and methodological gaps across modalities. We build on recent frameworks to propose further, detailed methods for studying contextual and functional variability, incorporating modality-agnostic and standardised terminology to facilitate cross-species comparisons. Our approach includes a detailed classification of communicative contexts and outcomes, offering practical methods to disentangle context from function and meaning. By integrating insights across behavioural ecology and comparative psychology, we aim to enhance the comparability of findings and provide a robust foundation for exploring the evolutionary trajectory of communicative flexibility and pragmatics.

Recent research has shown that climate change can both induce and modulate the expression of plastic traits but our understanding of the role of phenotypic plasticity as an adaptive response to climate change is limited. In this review, we dissect the mechanisms and impact of phenotypic plasticity as a response to accumulating climatic pressures on the individual, species and community levels. (i) We discuss how plasticity can affect individuals, populations and community dynamics and how climate change can alter the role of plasticity. We hypothesise that some pathways to phenotypic plasticity such as irreversible and anticipatory organismal responses will be reduced under increasing climate change. (ii) We then propose an integrated conceptual framework for studying phenotypic plasticity to advance our understanding of the feedbacks between the different levels of biological organisation. (iii) By formulating as yet unaddressed research questions within and across levels of biological organisation, we aim to instigate new research on phenotypic plasticity and its role in climate change responses.