The impact of human activities on the planet is unprecedented in its various aspects: climate change, the destruction of natural habitats, pollution (especially by pesticides), and the overexploitation of natural resources. These pressures have cumulative, even synergistic, effects on all living systems at all scales. They result in the rapid loss of biodiversity and disruptions in the functioning of ecosystems. The term ‘Anthropocene’ is now used by some to describe this new era shaped by human activities. Although the causes and effects of climate change are beginning to be relatively well quantified, the impacts of human activities on biodiversity and ecosystems remain more difficult to study because of the complexity of ecological and evolutionary systems, which involve numerous interactions, feedback loops, and complex dynamics.

The contributions collected in this thematic issue illustrate this complexity by addressing the effects of global changes on biodiversity at different organisational scales, from genes and populations to ecosystems and socio-ecological systems. These articles can also be viewed as significant contributions to fundamental research in ecology, given their focus on mechanisms, at a time when human activities constitute an unprecedented quasi-experiment.

Several articles (Lavelle, 2025; Martin, 2025) highlight the central role of soils as a source of agricultural production, a reservoir of biodiversity and a regulator of major biogeochemical cycles. Soil management techniques are essential for preserving the essential ecosystem services they provide, from soil fertility to climate regulation. Soil macroinvertebrate communities are proposed as indicators of these ecosystem services, offering a low-cost operational measure to inform public policies promoting sustainable agricultural production methods.

The analysis of the dynamics of the various components of biodiversity using long-term monitoring schemes is the focus of several articles, which highlight their importance in assessing biodiversity trends. Vimont et al. demonstrate how citizen science enables the detection of trends in the population dynamics of bird and plant species in France, providing key indicators for biodiversity monitoring and public policy (Vimont et al., 2025). The article on the ORCHAMP network (Thuiller et al., 2024) illustrates the interest of monitoring biodiversity and ecosystem functioning in mountain environments, combining environmental gradients, in situ measurements, remote sensing and new methodologies such as environmental DNA analysis.

Several contributions (Thuiller et al., 2024; Chave, 2024, and the companion article by Sandra Lavorel published in Comptes Rendus Géoscience, Lavorel, 2025) document the links between biodiversity, ecosystem functioning and climate change, drawing on concepts from complex systems theory. These articles highlight how extreme weather events, combined with other disruptive factors, can trigger profound transformations in ecosystems, involving non-linear responses and tipping points. Such dynamics can disrupt the ecosystem services that human societies depend on, especially the role that healthy ecosystems play in mitigating climate change as part of nature-based solutions.

Other articles (Cheptou, 2024; Thomas et al., 2024; Debat et al., 2025) adopt an eco-evolutionary perspective. They point out that the current biodiversity crisis is not limited to species extinction, but also affects genetic diversity, which is crucial for a population’s adaptability. Global changes alter selection pressures and can trigger rapid evolutionary responses, sometimes within just a few dozen generations. This convergence of evolutionary and ecological timescales is one of the major scientific discoveries of recent decades. The evolution of plant reproductive systems in response to the decimation of pollinators illustrates the magnitude of changes in ecological and evolutionary relationships. It demonstrates how the disruption of species interactions can lead to rapid evolutionary changes, which, in turn, have significant ecological consequences. Another example of the connections between evolutionary processes and ecosystem functioning is provided by the study of interactions between species in Morpho butterflies. Adaptive convergences in colouration combined with behavioural divergences allow for sympatric coexistence and probably even speciation.

The evolutionary perspective is also essential for understanding current societal issues related to diseases, such as the origin of SARS-CoV-2 (Débarre and Hensel, 2025). By placing certain characteristics of the virus within the broader context of evolutionary mechanisms, this research demonstrates how natural evolution can produce signatures that some interpret as artificial. This highlights the importance of a rigorous public debate grounded in evolutionary biology. Emerging diseases are another aspect of the global changes taking place today, driven by human activities, which threaten biodiversity and human health. The article by Thomas et al. introduces a fresh perspective by positioning oncogenic processes within an evolutionary ecological framework. It demonstrates that cancer – a field long absent from the ecological domain – can now be studied within the context of species’ evolutionary trajectories and the functioning of ecosystems (Thomas et al., 2024).

This issue also addresses important conceptual and epistemological questions, particularly regarding the very definition of biodiversity (Jarne, 2025 ; Lecointre, 2024). Clarifying these concepts appears essential, both for research and for public policy, to better understand what constitutes the characterisation of biodiversity per se and what concerns interactions between species. Several contributions (Frascaria-Lacoste et al., 2025; Vimont et al., 2025; Mathevet and Mounet, 2026) also examine the methods for restoring anthropised ecosystems and the conditions for implementing nature-based solutions. The concept of socio-ecological restoration is proposed as a framework for integrating ecological, social, and cultural objectives, specifically in urban areas, with concrete examples of projects involving human communities.

Finally, agricultural and food dynamics are examined using the example of traditional mixed-cropping systems (Vazeux-Blumental et al., 2024). In particular, the milpa system is used to demonstrate how positive interactions between species can improve the resilience, productivity and sustainability of agroecosystems. This type of research shows that the agroecological transition does not need to wait for technical innovations. Instead, but can be based on the rediscovery and adaptation of ancient systems while taking into account current constraints, especially crop variety selection and mechanisation.

Taken together, the articles in this thematic issue highlight that the biodiversity and climate crises are closely intertwined, and that understanding the causes and impacts of biodiversity collapse requires approaches that combine ecology, evolution and the social sciences. This issue complements another thematic issue of Comptes Rendus Biologies, more specifically dedicated to evolution, by demonstrating that evolutionary processes are not a distant backdrop, but a central driver of living organisms’ responses to current upheavals. All these studies contribute to a better understanding of the effects of global changes on biodiversity and ecosystems, providing a scientific foundation for identifying transition pathways capable of preserving both biodiversity and the well-being of human societies.

The studies presented here do not claim to be exhaustive, but they do demonstrate the dynamism and excellence of French research in ecology and evolutionary biology, which is internationally recognised for its ability to combine fundamental approaches, methodological innovations and responses to current challenges. They form part of a strong French scientific tradition, combining long-term field observations, experimentation, theoretical modelling and genomic analyses. From a detailed understanding of soil functioning and ecosystem services to the study of eco-evolutionary dynamics in the face of global change, these studies demonstrate the ability of French teams to develop new conceptual frameworks, such as approaches to ecosystem services, integrated eco-evolutionary perspectives, and the application of complex systems theory to biodiversity. Finally, they demonstrate the strong engagement of the French scientific community in societal debates, such as agroecological transition, nature-based solutions, the socio-ecological restoration of urban environments, or inferences regarding the origins and evolution of emerging pathogens. Through the integration of scientific excellence, cross-disciplinary approaches, and dialogue with public stakeholders and citizens, French research thus affirms its leading role in the production of robust knowledge that is useful for decision-making and that can bring about lasting transformations.

Tatiana Giraud et Jean-Dominique Lebreton

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Also available is an article on the role of biodiversity in ecosystem resilience published in CR Géoscience:

Ecosystem transformation by climate change and its consequences for human
Sandra Lavorel