Biological Reviews最新文献

Human childbirth is widely presumed to be uniquely difficult and dangerous compared to birth in other mammals. Tight fetopelvic proportions can result in obstructed labour and contribute to high rates of maternal and neonatal mortality. Ideas summarised under the ‘obstetrical dilemma’ have contributed to this assumption by explaining difficult childbirth as the outcome of a unique evolutionary history of bipedalism and encephalisation. However, a comprehensive review of the literature and an analysis of collated data demonstrate that human birth is not truly exceptional in its risk. Dystocia (birth difficulties) occurs across a phylogenetically wide range of placental mammals, including wild populations where natural selection would be expected to minimise its occurrence. Various species show similar or higher dystocia prevalence compared to humans, and fetopelvic disproportion is particularly common in species with precocial, large-bodied offspring. The underlying causes and risk factors are also highly comparable. Contrary to long-standing assumptions, natural selection has not eliminated dystocia in natural mammal populations, suggesting that parturition in placentals may be characterised by a persistent baseline risk of complications. This persistent risk likely reflects a life history trade-off between the improved survival of large offspring and the occasional costs of birth complications. A cliff-edge model of selection can explain the evolutionary dynamics underlying this trade-off and the persistent fraction of fetopelvic disproportion and related forms of obstructive dystocia. An additional trade-off involving litter size is evident in litter-bearing, often altricial species, where both small and large litters increase the risk of dystocia. Phenotypic plasticity further maintains dystocia in populations despite selection, while also contributing to variation in birth difficulty within and among species. These findings reposition human birth difficulties within a broader mammalian pattern rather than as a uniquely human phenomenon requiring exceptional explanations. Reframing human childbirth in this broader context challenges entrenched assumptions and highlights the value of a comparative evolutionary perspective.

A review of behavioural studies using home-cage monitoring (HCM) systems revealed that over 61% of studies used only male subjects, with only 24% including both sexes, despite evidence of substantial behavioural differences between male and female animals. This bias could influence the outcomes of biomedical research. This preference for male subjects has introduced a significant bias in preclinical animal studies, compromising the generalisability of research findings and potentially overlooking important sex differences in disease manifestation and response to therapies. This review highlights such sex differences in laboratory rodent behaviour, as observed through HCM systems. HCM provides an automated method for observing the behaviour of undisturbed animals in a familiar environment, offering valuable insights into sex-specific differences in behaviour and disease progression. In particular, we emphasise how this technology revealed sex differences in spontaneous activity and behaviour in models of neurodegenerative diseases, while demonstrating that, contrary to common belief, female rodents are not more variable than males in their behaviour. We further discuss the reasons underlying the prevalent sex bias in research and advocate for the inclusion of both sexes in neuroscience and behavioural studies, to enhance the generalisability and informative value of preclinical research, avoid unethical waste of animals and resources, and thereby support the Three Rs principles (Replacement, Reduction, and Refinement of animal use).

The irreversibility of complex trait loss has long been a tenet of evolutionary biology. However, this idea is increasingly at odds with the numerous documented exceptions across the Tree of Life. We synthesise this growing body of evidence across a diverse array of taxa and traits, exploring the evolutionary conditions that enable evolutionary reversal. By integrating macroevolutionary, genetic, and developmental information, we argue that trait reversal is commonly fostered by some form of persistence in the generative developmental pathway of the lost trait. We identify three overarching modes of trait reversal and support them with multiple case studies: by pleiotropy (the involvement of the same generative components in other traits and/or functions), by plasticity (environment-dependent expression of the trait) and by hemiplasy (persistence in another lineage, followed by reticulate evolution). We also examine important affinities between trait reversal and evolutionary novelties, undermining a neat distinction between what is old and what is new in evolution. This survey may provide a useful framework for future explorations of the developmental mechanisms underlying these still overlooked macroevolutionary dynamics.

Recent methodological development in phylogenetic inference has focused predominantly on molecular data. However, renewed interest in other data types, particularly morphological data, has followed from the increased recognition of the power of total evidence and tip-dating approaches, including fossil data, for inference of time-scaled trees and rates of evolution. However, attention has largely focused on the improvement of models of morphological evolution and other analytical tools with much less discussion about data acquisition itself. Here we review past and current practice for describing and collecting morphological data for phylogenetic inference. We present a systematic review of 164 phylogenetic analyses conducted over the last 35 years and focused on a diverse group of extinct arthropods: trilobites. Trends in increasing matrix size, data type, and coding strategy are evident. Where present, polymorphic characters have been predominantly derived from discretized continuous characters, although increasingly practitioners are utilizing alternative approaches for the treatment of quantitative characters. Not surprisingly, traditional indices that describe character consistency are highly correlated with matrix size but show surprising variation at different taxonomic scales. More recent attempts to describe data quality using information theory imply that characters can have high information content even if data are missing for many tips, providing support against the exclusion of characters because of missing data. In consideration of this, as well as advances in the study of developmental biology and variational complexity, we identify several avenues for increasing the quality and quantity of morphological data going forward.

From butterflies to lizards and from sharks to seabirds, wildlife exhibit tactics to survive the impacts of tropical cyclones, also known as hurricanes, cyclones, or typhoons depending on where they occur. Some species seek refuge during the storm by moving, some remain in place and ride it out, and others move longer distances, avoiding the main impacts of the storm altogether. Tropical cyclones can have direct impacts on wildlife (e.g. mortality) but can also have indirect effects by altering resources and habitat, with downstream impacts on abundance and recruitment. Using examples from across taxa and ecosystems, we explore the pathways by which tropical cyclones can influence wildlife populations and communities. We describe tactics demonstrated by wildlife that enable them to survive the immediate impacts of the storm, as well as the longer-term impacts after the storm. We give examples of tropical cyclones as a selective pressure and as a facilitator for the introduction of invasive species. We also describe how tropical cyclones may provide a net benefit to some native species. The ecological and evolutionary impacts of tropical cyclones on wildlife can be complex, as they are often intertwined with concurrent pressures from land-use change, human development, and climate change. As the frequency of intense tropical cyclones is predicted to increase globally, identifying the mechanisms by which wildlife cope with such disturbances can aid in understanding and mitigating the impacts of climate change on wildlife.

Language has long been considered uniquely complex in the animal kingdom; however, animal research over the last decade has begun to challenge some long-standing premises about exactly which language capacities are uniquely human. The task of resolving why and how complex communication systems evolve, particularly human language, has manifested in a rich multi-disciplinary field, which relies on accurate empirical and comparative assessment of natural animal communicative capacities. For example, comparative models of relevant gene and brain functions will remain limited without cracking the animal communication code. To achieve this, empirical research needs an updated, quantitative and comparative framework that distinguishes combinatorial systems from simpler ones. We offer such a framework by integrating new work, demonstrating diverse meaning-bearing combinatorial signalling strategies in natural animal communication, into cross-disciplinary theoretical frameworks. We detail four major mechanistic transitions which we argue offer both evolutionary and ontogenetic routes from non-combinatorial communicators, that mainly rely on single signal utterances, to generative combinatorial signal users, that mainly rely on combinatorial, meaning-based utterances. These transitions are measurable and predictable: (i) signal combination versatility; (ii) signal combination learning and conventionalization; (iii) message expansion through combinatorial mechanism diversity and versatility; and (iv) message expansion through syntax involving linear or hierarchical rules. We offer testable hypotheses for each transition and propose that species demonstrating combinatorial Transitions (i) and (ii) will be prime candidates for testing Transitions (iii) and (iv), where generativity can emerge. We also point to future methodological tools to assess the meaning of signals and their combinations in signal utterance-to-context mapping analyses. Critically, we argue that simply having research on different species is not enough – testing evolution of language theories requires comparative research across species and ontogeny, based on relatable, quantitative measures. To date, only humans demonstrate meaning-based, generative communication. However, recent discoveries, particularly of combinatorial versatility in chimpanzee (Pan troglodytes) and bonobo (Pan paniscus) vocal sequences, open the possibility of generative communication in other species. Whether such traits are human-unique can no longer be assumed but must be tested.

The evaluation of oocyte competence is a fundamental step in achieving successful outcomes following assisted reproduction techniques (ART). At present, however, conventional oocyte maturation assessment is carried out by morphological observation, which is a subjective method that does not consider molecular features. For this reason, many authors have proposed cumulus cells (CCs) as biomarkers for oocyte quality, mainly due to their role in the modulation of the physiology and competence of the female gamete. This review summarises our current understanding of the influence of CCs on oocyte physiology and also on the first stages of embryo development. Thus, it includes studies carried out in mammalian species evaluating DNA integrity, viability, gene expression, and profiles of the metabolome and proteome in CCs. While previous research has proposed different CC molecules and features as biomarkers of oocyte functionality and competence, data are, in some cases, inconsistent. For instance, contradictory data have been published regarding the impact of DNA fragmentation, mitochondrial DNA content, or apoptosis in CCs on oocyte maturation and embryo development. On the other hand, looking into gene expression profiles in CCs may reflect oocyte quality, as the expression of several transcripts has been positively associated with oocyte growth and embryo development. Finally, we also point out areas in which more research should be carried out, as is the case for proteomics, telomere length, and metabolomics. This review discusses the most relevant findings not only to better understand the existing relationship between cell types but also to pinpoint the most promising characteristics that could be used as biomarkers.

During their long evolutionary history, land plants have evolved a range of adaptations to different abiotic stressors. These help explain present-day diversity and distribution patterns, as well as the potential resilience of natural and agricultural systems to a changing climate. Most previous research has focused on adaptation to individual stressors and much less is known about how plants deal with exposure to multiple abiotic stressors. Consequently, the evolutionary processes leading to abiotic stress polyresistance (i.e. resistance to multiple abiotic stressors) remain poorly understood. Here, we showcase plants in hot and cold deserts as a compelling system for studying evolution of polyresistance. We focus on three abiotic stressors with substantial physiological overlap - drought, frost and salinity - and present six plant groups that occur in both hot and cold deserts, thus being exposed to these stressors in at least parts of their ranges: Gnetales, Amaranthaceae sensu lato, Nitrariaceae, Poaceae, Tamaricaceae-Frankeniaceae and Zygophyllaceae. We examine key questions regarding the sequence and mechanisms underlying abiotic stress polyresistance evolution and summarize the diverse adaptive strategies that allow persistence under multiple environmental pressures. In doing so, we highlight how trade-offs and facilitation among abiotic stress responses may have influenced the evolutionary pathways that lead to present-day polyresistance. Despite limited evidence, broad patterns emerge for the plant groups examined here, with facilitation appearing especially important, at least during early stages of polyresistance evolution. However, fundamental knowledge gaps remain. Macroevolutionary and macroecological approaches, coupled with historical biogeography and palaeoclimatic and palaeoecological reconstructions, can be used to advance understanding of abiotic stress polyresistance evolution in plants. This will pave the way for applied trait-based research to support climate change mitigation, conservation and sustainable crop improvement in a rapidly changing world.