Global Change Biology最新文献

Climate change is increasing the risk of emerging parasites. However, whether more virulent variants will spread during climate-driven outbreaks remains unclear. Here, we aimed to explore the short-term trajectory of parasite evolution—at the phenotypic and genomic scales—across environmentally relevant temperatures in a thermally mismatched host–parasite interaction. We experimentally evolved a wild parasitic bacterium (Leucobacter musarum), across the thermal range (20°C–30°C) and extremes (35°C) of Cabo Verde—the site of field collection—in a Caenorhabditis elegans host strain. Starting from a single bacterial isolate, we then tracked phenotypic and de novo genomic changes that arose across replicate populations following ten passages of experimental evolution. We found that at 25°C, warm for the host but an average temperature for the parasite, host-mediated selection favoured higher virulence and genomic diversification by the end of the experiment. At hot temperatures, towards the limit of host survival, virulence was maintained across all parasite populations. Parasites evolved at hot temperatures also displayed a latent virulence boost, deadlier once hosts experienced a heatwave. Patterns of molecular evolution were constrained to parallel changes in fewer loci at extreme temperatures. Our findings suggest that shifting environmental temperatures will leave phenotypic and genomic signatures on evolving parasites.

With their location at the land-sea edge, coastal marine invertebrates withstand marked changes in water and air temperatures and abrupt salinity changes through tidal cycles. In a climate-changing world, these stressors are being magnified by the increased intensity and emergence of extreme climatic events (ECEs). Diverse habitat-dependent communities on rocky shores, mudflats, mangroves and saltmarsh are at the forefront of ECEs, which can co-occur and interact with other anthropogenic stressors. This review synthesises information on the vulnerabilities of coastal marine invertebrates living at the interface between marine and terrestrial environments to marine and atmospheric heatwaves, fire, flooding, hyposalinity and changes in intertidal ice cover. The impacts of ECEs on bivalves are investigated as these are ecologically and economically important keystone species. We synthesise impacts of extreme heat stress on these molluscs as a case study. Temperature and salinity extremes are particularly damaging to coastal invertebrate communities if they coincide with low tide cycles. As adaptation to environmental variability is an inherent feature of the evolution in the intertidal, it will be important to understand tolerance levels with respect to ECEs, as this varies between species and across tidal cycles. It is also important to understand the capacity to build climate resilience through acclimatisation, adaptation, plasticity and the presence of refuge habitats, as well as identify the potential for species' redundancy with respect to the provision of key ecosystem services.

Accounting for spatial structure within populations is critical for defining appropriate scales of management, particularly in the Arctic, where habitats of ice-dependent species such as the polar bear (Ursus maritimus) are being transformed at an accelerated rate. We examined broad-scale patterns of space use and finer-scale habitat selection by adult female polar bears in James Bay, located at the southernmost extent of the species' global range. Using satellite telemetry data collected during the annual on-ice period from 2012 to 2017, we estimated individual- and population-level utilization distributions (UDs) and applied hierarchical clustering to assess whether individuals formed distinct spatial groups based on the degree of UD overlap. We also fit step-selection functions (SSFs) to evaluate selection for sea-ice concentration, ocean depth, and distance to coast. Fifteen bears with data spanning at least one complete on-ice period had individual 95% UDs averaging 74,770 km² (SE = 11,663). Results of hierarchical clustering identified two distinct spatial groups: three “resident” bears remained within southern James Bay, whereas 12 “non-resident” bears had larger UDs extending into Hudson Bay. Overlap between groups remained near zero throughout winter, including during the breeding season. Step-selection analyses, which included an additional four bears (n_total = 19), indicated consistent positive selection for high sea-ice concentration, with individual variation in selection strength. For non-resident bears, selection for distance to coast and ocean depth varied seasonally, with bears selecting areas farther from the Ontario coast during freeze-up, closer to the coast during April–May, and deeper offshore areas during breakup. Together with previous genetic evidence, our results suggest resident southern James Bay bears represent a spatially structured component of the broader subpopulation that warrants continued monitoring and explicit consideration in future harvest-risk assessments and conservation planning, particularly as sea-ice loss continues to alter habitat availability.

Anthropogenic habitat transformation has led to population declines and increasing isolation of populations of many species, particularly top predators, where small and fragmented populations often experience limited dispersal and reduced genetic diversity. Jaguars (Panthera onca), for example, have lost half of their historical range and most populations outside the Amazon biome are small, isolated and highly threatened. Here, we assess jaguar population connectivity across the species' range by identifying and ranking core areas and dispersal corridors, including linkages among Protected Areas and Indigenous Lands (hereafter, PAs). We used cumulative resistant kernels and factorial Least-Cost Paths (fLCP) in two complementary approaches: core area-based and PA-based connectivity. We identified 307 core areas for jaguar movement, covering ~7.75 million km² (55% of the current range), of which approximately half lies within PAs. The largest and highest-ranked core area spans ~6.5 million km² across four biomes (Amazon, Llanos, Chaco and Pantanal). We identified 176 dispersal corridors connecting core areas, although connectivity was not continuous across the entire range. Northern populations (Mexico and Central America) showed several connectivity gaps, whereas South America displayed a large, highly interconnected network linking the Amazon, Llanos, Chaco, Pantanal, Cerrado, Caatinga, Iberá and the Atlantic Forest's Green Corridor. In contrast, coastal Atlantic Forest patches appeared largely isolated. The PA-based analysis predicted 507 potential corridors connecting 905 PAs, including potential links absent from the core area model, particularly across Central America and between the Darién Gap, Amazon and coastal Atlantic Forest. The core-area approach provides a more biologically realistic representation of current connectivity, while the PA-based approach complements it by identifying pragmatic opportunities for long-term connectivity conservation. Together, these approaches identify priority areas and regions of uncertainty, providing a spatial framework to guide jaguar conservation and connectivity planning under accelerating global change.

Tropical wetlands have historically been resilient to fire, but ongoing climate and hydrological changes are undermining this stability. Here, we provide robust multi-decadal evidence (1985–2024) of structural changes in the contemporary fire regime of the Pantanal, the world's largest wetland, associated with hydroclimatic disruption. We investigated changes in burned area, mean fire size, and fire seasonality using hydrological, climatic, and fuel-condition predictors. To identify the major drivers of fire dynamics, we applied trend analyses and Elastic Net models across multiple temporal and spatial scales. Although no significant monotonic trend was detected for annual burned area across the entire time series, change point analysis identified 2014 as the onset of a significant upward trend. Mean fire size exhibited a significant long-term upward trend across the full period, which intensified after 2018, suggesting larger fire sizes in recent years. Across models, reduced precipitation, shorter seasonal wetland flood pulses, and higher atmospheric and fuel dryness emerged as the strongest predictors of burned area and fire size. These changes have expanded the duration of the fire season, particularly in the northern and central Pantanal, by delaying the onset of rains and shortening the flood pulse period. Our findings suggest a weakening of the hydroclimatic coupling that has regulated ignition and fuel availability in the Pantanal. Broader environmental changes in the upper basin and regional climate may be reinforcing this transition. These results highlight the Pantanal's increasing vulnerability to drought-driven fires and underscore the urgent need for integrated water and fire management strategies to preserve the resilience of the Pantanal and other tropical wetlands under intensifying global change pressures.

Global change is increasing river drying and transforming surrounding landscapes through human land use, with important consequences for freshwater biodiversity. Yet how river drying and land use jointly influence biodiversity across spatial scales remains poorly understood. Using macroinvertebrate data from 49 riverine metacommunities in southeastern France, we examined how river drying and land use affect biodiversity across spatial scales and the metacommunity properties underlying these patterns. We estimated species-area relationship (SAR), with intercept and slope of SAR curve representing patterns analogous to alpha- and beta-diversity, respectively, and fitted structural equation models to assess how flow intermittence, land use (% of non-natural surface), and network size affected the metacommunity properties underlying these patterns, including intraspecific aggregation, species abundance distribution, total abundance, and regional species pool. Flow intermittence increased intraspecific aggregation and reduced evenness, leading to a lower SAR intercept and a steeper slope, reflecting lower local diversity but greater compositional differentiation among non-perennial rivers, and revealing strong scale-dependent responses of biodiversity to drying. Trait analyses further showed that flow intermittence favored aerial passive dispersers while reducing the relative abundance of aquatic active dispersers, suggesting that altered dispersal dynamics in non-perennial river networks contribute to biodiversity organization. In addition, land use primarily influenced biodiversity through nonlinear effects on the metacommunity species pool, with intermediate levels of land use associated with the highest regional diversity. Moreover, land use weakened the positive effect of flow intermittence on aggregation, indicating that anthropogenic pressures can homogenize metacommunities in drying regimes. Our findings demonstrate that flow intermittence strongly influences biodiversity across spatial scales through different mechanisms rather than uniformly reducing it. As climate change is forecast to increase the proportion of non-perennial rivers worldwide, our results highlight the importance of incorporating metacommunity processes and multi-scale diversity patterns into the conservation and management of these ecosystems.