Fire regimes are shifting worldwide, yet no common framework describes their direction, rate, or ecological effects. We introduce fire-regime velocity, the rate and direction of movement through a multidimensional fire-regime state space. By linking velocity to adaptive responses, the framework can help predict the consequences of fire-regime shifts for population persistence.
Succession is a fundamental concept in ecology because it provides perspectives on how ecosystems change over time and respond following disturbance. It is also a useful concept for conservation and restoration because human activity has increased the frequency and magnitude of disturbances globally. Ecosystem ecology offers a unique perspective on succession because it views dynamics through the lens of process-based currencies-such as net ecosystem production-that subsume multiple simultaneous properties of energy and nutrient flow, thereby providing a useful measure with which to monitor and anticipate net change. Studying succession through these perspectives reveals fundamental patterns that unify central principles of ecosystem ecology and provide a predictive model on which to base conservation and restoration efforts.
Rare events are low-frequency environmental events whose magnitude and ecological consequences can vary across ecosystems. In this review, we clarify the terminology used to describe these anomalies and propose a statistical definition that disentangles environmental rarity and magnitude from ecological impact. Rare events generate a wide range of responses, from population declines and ecosystem reorganisation to neutral or even positive demographic outcomes. Exceptionally intense perturbations potentially dominate ecological outcomes regardless of their rarity. More commonly, however, their influence on long-term dynamics emerges from the joint effects of magnitude and return interval, such that less extreme but more frequent perturbations could contribute more consistently to population trajectories than rarer events. Long-term demographic studies are essential to identify how rare events shape ecological dynamics.
Collective behaviour is widespread in the animal kingdom and can enhance individual fitness. Yet not all collective behaviours are adaptations. Instead, some may be nonadaptive or 'evolutionary spandrels'-traits that originated as by-products in the sense proposed by Stephen Jay Gould and Richard Lewontin. Here, we argue that self-organising processes provide a route through which evolutionary spandrels in collective animal behaviour can occur, and we provide three examples: spatial organisation in primate groups, division of labour in ants, and insect chorusing. We then consider how such outcomes may be co-opted into adaptive roles through exaptation and conclude by outlining the challenges associated with testing adaptive and nonadaptive hypotheses in collective behaviour research using individual-based studies, phylogenetic comparative analyses, and agent-based models.
Phytoplankton fix half of global CO2 annually and drive key global nutrient cycles. They depend on interactions with bacteria, viruses, and protists. Yet our understanding of these interactions remains fragmented. We introduce symbiotic capacity—an organism’s ability to initiate, maintain, and modulate partnerships—as a quantifiable trait fundamental to phytoplankton ecology and resilience in changing oceans. By adapting Tinbergen’s four questions from ethology, we reveal critical gaps in our knowledge regarding phytoplankton symbiotic capacity. While functional benefits, molecular mechanisms, and evolutionary origins of phytoplankton symbioses are increasingly documented, their developmental dynamics remain almost entirely unexplored. Bridging molecular mechanisms to planetary-scale biogeochemical processes requires a fifth question and suitable model systems, such as Chaetoceros diatoms, that integrate laboratory tractability with ecological relevance.
Droughts are intensifying worldwide, reorganizing ecosystems and threatening biodiversity and human health. Yet their effects on infectious diseases are poorly understood and sometimes paradoxical, with water limitation often amplifying water-associated infections. This complexity arises because drought not only reduces water availability but also restructures the host-pathogen interactions that govern transmission. Synthesizing theory and empirical evidence from water-associated diseases, we identify three ecological mechanisms through which drought modifies infection dynamics: concentrating organisms into shrinking refugia, selectively favoring drought-tolerant hosts, vectors, and pathogens, and amplifying transmission heterogeneity across landscapes. By linking hydrological change to core epidemiological and ecological processes, this framework highlights parasite traits and strategies likely to be favored during drought while providing a foundation for forecasting infections in a water-limited world.
Darwin's Naturalization Conundrum asks whether invaders succeed by resembling or differing from native species. Ramirez-Parada et al. demonstrate that climate plays a crucial role in determining both outcomes: invaders resemble natives in cold or dry regions but diverge in warm, humid ones, thereby reframing the conundrum as an environmental continuum.
Fungi are widely recognized as phenotypically plastic, a characteristic often invoked to explain the persistence of ecosystem functions under disturbance. How plasticity varies across taxa remains a key question. Emerging evidence implies species-specific, phylogenetically structured responses, with the strongest divergence under environmental extremes, making fungal community composition essential to ecosystem functioning.
Coprolites-fossil material extruded from an animal's digestive system-represent a rare insight into trophic interactions in deep time. However, while the first animals appeared about 600 million years ago, the first coprolites are only observed in the earliest Cambrian. Conversely, in modern oceans, fecal pellets are an important part of the particulate organic carbon in the water column and the global flux of organic carbon to deep water. In this review, we analyze the impact of the advent of fecal matter on the Cambrian Radiation by examining coprolites, analyzing animal biology, and contextualizing this through the role of fecal pellets in the oceanic nutrient cycle. We illustrate the central position of coprolites in driving the Cambrian Radiation.
In cooperatively breeding species, reproductively capable individuals often forgo breeding to assist others. This socially induced infertility is typically viewed as a consequence of cooperative breeding, yet the remarkable diversity of its mechanisms remains unexplained. We propose that cooperative living inevitably increases opportunities for reproduction among relatives, selecting for reproductive suppression to regulate the costs of inbreeding and reproductive conflict. Species-specific variation in inbreeding tolerance subsequently determines how suppression evolves. Where inbreeding tolerance is high, increased intragroup reproductive conflict favours strong physiological suppression of the hypothalamic-pituitary-gonadal axis to maintain social cohesion. Where inbreeding tolerance is low, behavioural mechanisms regulate reproduction while preserving reproductive competence. This framework explains mechanistic diversity and generates testable predictions across cooperative vertebrates.
Animals in dryland systems often aggregate around water, concentrating trophic pressure, transporting resources, and modifying habitat. These effects have been described as piospheres of degraded soils and vegetation; however, we argue that this framing is incomplete. We propose that animal aggregations around surface water generate a ripple effect: cross-scale, reciprocal impacts on both terrestrial and aquatic ecosystems that vary with water availability. As surface water becomes increasingly scarce under global change, management and conservation approaches should prioritize the restoration of spatiotemporal variability in surface waters. An integrated approach that bridges linked terrestrial and aquatic ecosystems and combines community and ecosystem ecology is necessary to identify emergent ecosystem properties, predict landscape-scale impacts of altered surface water availability, and inform adaptive management.
Fisheries-induced evolution (FIE) is typically framed in terms of genetic change, yet epigenetic processes linking environmental variation to phenotype remain overlooked. We propose that selective harvesting, by restructuring demographic and ecological conditions, can shape epigenetically mediated phenotypic responses in exploited populations, with important implications for FIE research and fisheries management.
In natural chemical mixtures, a few molecules matter far more than their abundance suggests. Two recent studies identify defensive polyketides in estuarine mudflats and root exudate metabolites in a nitrogen-limited rhizosphere as compounds that restructure communities at trace concentrations, providing convergent evidence for candidate keystone molecules at the molecular scale.
Whole-genome resequencing data, associated metrics, and their trends over time can be used to inform extinction threat rankings rendered by conservation agencies around the world. Surveys of individual genome sequences can critically address risks to population sustainability by means of key metrics such as heterozygosity. Genomic metrics have yet-unrealized potential to help authorities determine how a given population or species of conservation concern should be formally categorized (e.g., 'listed' or 'delisted') with respect to discrete threat categories. To stimulate productive discourse, we provide a general heuristic framework for how genomic metrics could be used to refine conservation threat assessments (e.g., to help determine whether species should be listed or not).
Intergroup conflict is a powerful selective force throughout the animal kingdom. While research has traditionally focused on actions during and after contests, animals also exhibit behavioural flexibility in anticipation of potential intergroup encounters. Synthesising findings from diverse taxa, we describe how social species adjust pre-emptive information gathering, resource use, cohesion, synchrony, and intragroup interactions across a heterogeneous 'landscape of intergroup conflict'. We show how variation in threat level, driven by spatial context, rival characteristics, and individual motivation, affects these behaviours, and how balancing sensed information and memories of past interactions underlies associated decision-making. Testing the consequences of intergroup pre-emptive behaviour using experimental, technological, and analytical advances will develop understanding of its role in socio-cognitive evolution, population dynamics, and community structure.
Species range contractions are a defining feature of the Anthropocene. Given their prevalence, a key question arises: do range contractions follow consistent patterns? Empirical studies have produced mixed results, revealing some emergent patterns, but also considerable variation among taxa. Here, we present a framework that seeks to explain this variation, conceptualising range contractions as the outcome of the interplay between species' intrinsic population growth rates and the impact of threats across environmental gradients. Our framework shows how four primary patterns of range contraction arise, with a fifth emerging under incomplete threat spread. By describing when, where, and why particular patterns of decline occur, our framework advances understanding of species' responses to global change and provides a basis for more generalisable conservation strategies.
Anthropogenic food subsidies often elevate wildlife populations. Reducing these subsidies may alter behavior more rapidly than population size, creating a transient period of heightened human-wildlife conflict. Recognizing these transitional dynamics can improve conflict mitigation and conservation outcomes while enhancing public safety for communities living alongside dangerous species.
