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Tropical forests play a critical role in the hydrological cycle and can influence local and regional precipitation 1 . Previous work has assessed the impacts of tropical deforestation on precipitation, but these efforts have been largely limited to case studies 2 . A wider analysis of interactions between deforestation and precipitation—and especially how any such interactions might vary across spatial scales—is lacking. Here we show reduced precipitation over deforested regions across the tropics. Our results arise from a pan-tropical assessment of the impacts of 2003–2017 forest loss on precipitation using satellite, station-based and reanalysis datasets. The effect of deforestation on precipitation increased at larger scales, with satellite datasets showing that forest loss caused robust reductions in precipitation at scales greater than 50 km. The greatest declines in precipitation occurred at 200 km, the largest scale we explored, for which 1 percentage point of forest loss reduced precipitation by 0.25 ± 0.1 mm per month. Reanalysis and station-based products disagree on the direction of precipitation responses to forest loss, which we attribute to sparse in situ tropical measurements. We estimate that future deforestation in the Congo will reduce local precipitation by 8–10% in 2100. Our findings provide a compelling argument for tropical forest conservation to support regional climate resilience. A pan-tropical analysis using satellite, station-based and reanalysis datasets shows that deforestation causes reduced precipitation, and demonstrates that the effect increases with spatial scale.

Comparative analysis of the expanding genomic resources for scleractinian corals may provide insights into the evolution of these organisms, with implications for their continued persistence under global climate change. Here, we sequenced and annotated the genome of Pocillopora damicornis , one of the most abundant and widespread corals in the world. We compared this genome, based on protein-coding gene orthology, with other publicly available coral genomes (Cnidaria, Anthozoa, Scleractinia), as well as genomes from other anthozoan groups (Actiniaria, Corallimorpharia), and two basal metazoan outgroup phlya (Porifera, Ctenophora). We found that 46.6% of P. damicornis genes had orthologs in all other scleractinians, defining a coral ‘core’ genome enriched in basic housekeeping functions. Of these core genes, 3.7% were unique to scleractinians and were enriched in immune functionality, suggesting an important role of the immune system in coral evolution. Genes occurring only in P. damicornis were enriched in cellular signaling and stress response pathways, and we found similar immune-related gene family expansions in each coral species, indicating that immune system diversification may be a prominent feature of scleractinian coral evolution at multiple taxonomic levels. Diversification of the immune gene repertoire may underlie scleractinian adaptations to symbiosis, pathogen interactions, and environmental stress.

Water recycled through transpiring forests influences the spatial distribution of precipitation in the Amazon and has been shown to play a role in the initiation of the wet season. However, due to the challenges and costs associated with measuring evapotranspiration (ET) directly and high uncertainty in remote-sensing ET retrievals, the spatial and temporal patterns in Amazon ET remain poorly understood. In this study, we estimated ET over the Amazon and 10 sub-basins using a catchment-balance approach, whereby ET is calculated directly as the balance between precipitation, runoff, and change in groundwater storage. We compared our results with ET from remote-sensing datasets, reanalysis, models from Phase 5 and Phase 6 of the Coupled Model Intercomparison Projects (CMIP5 and CMIP6 respectively), and in situ flux tower measurements to provide a comprehensive overview of current understanding. Catchment-balance analysis revealed a gradient in ET from east to west/southwest across the Amazon Basin, a strong seasonal cycle in basin-mean ET primarily controlled by net incoming radiation, and no trend in ET over the past 2 decades. This approach has a degree of uncertainty, due to errors in each of the terms of the water budget; therefore, we conducted an error analysis to identify the range of likely values. Satellite datasets, reanalysis, and climate models all tended to overestimate the magnitude of ET relative to catchment-balance estimates, underestimate seasonal and interannual variability, and show conflicting positive and negative trends. Only two out of six satellite and model datasets analysed reproduced spatial and seasonal variation in Amazon ET, and captured the same controls on ET as indicated by catchment-balance analysis. CMIP5 and CMIP6 ET was inconsistent with catchment-balance estimates over all scales analysed. Overall, the discrepancies between data products and models revealed by our analysis demonstrate a need for more ground-based ET measurements in the Amazon as well as a need to substantially improve model representation of this fundamental component of the Amazon hydrological cycle.

Regulating partner abundance may allow symbiotic organisms to mediate interaction outcomes, facilitating adaptive responses to environmental change. To explore the capacity for adaptive regulation in an ecologically important endosymbiosis, we studied the population dynamics of symbiotic algae in reef-building corals under different abiotic contexts. We found high natural variability in symbiont abundance in corals across reefs, but this variability converged to different symbiont-specific abundances when colonies were maintained under constant conditions. When conditions changed seasonally, symbiont abundance readjusted to new equilibria. We explain these patterns using an a priori model of symbiotic costs and benefits to the coral host, which shows that the observed changes in symbiont abundance are consistent with the maximization of interaction benefit under different environmental conditions. These results indicate that, while regulating symbiont abundance helps hosts sustain maximum benefit in a dynamic environment, spatiotemporal variation in abiotic factors creates a broad range of symbiont abundances (and interaction outcomes) among corals that may account for observed natural variability in performance (e.g., growth rate) and stress tolerance (e.g., bleaching susceptibility). This cost or benefit framework provides a new perspective on the dynamic regulation of reef coral symbioses and illustrates that the dependence of interaction outcomes on biotic and abiotic contexts may be important in understanding how diverse mutualisms respond to environmental change.

Tropical forests have an important regulating influence on local and regional climate, through modulating the exchange of moisture and energy between the land and the atmosphere. Deforestation disrupts this exchange, though the climatic consequences of progressive, patch-scale deforestation of formerly intact forested landscapes have not previously been assessed. Remote sensing datasets of land surface and atmospheric variables were used to compare the climate responses of Amazon forests that lost their intact status between 2000 and 2013. Clear gradients in environmental change with increasing disturbance were observed. Leaf area index (LAI) showed progressively stronger reductions as forest loss increased, with evapotranspiration (ET) showing a comparative decline. These changes in LAI and ET were related to changes in temperature (T), with increased warming as deforestation increased. Severe deforestation of intact Amazon forest, defined as areas where canopy cover was reduced below 70%, was shown to have increased daytime land surface T by 0.44°C over the study period. Differences between intact and disturbed forests were most pronounced during the dry season, with severely deforested areas warming as much as 1.5°C. Maintenance of canopy cover was identified as an important factor in minimizing the impacts of disturbance. Overall, the results highlight the climate benefits provided by intact tropical forests, providing further evidence that protecting intact forests is of utmost importance.

The stability of Amazonian vegetation is strongly influenced by land–atmosphere feedbacks. It has been hypothesized that deforestation‐induced precipitation decline may lead to widespread forest decline across the entire basin. Using a moisture‐tracking model, we quantify how deforestation across South America alters downwind rainfall and affects forest stability. We find widespread forest collapse will not result from deforestation‐induced precipitation changes alone. However, we identify key hotspots of vulnerability, including forests in southwestern Amazonia which could transition to non‐forest ecosystems in response to upwind deforestation (affecting 81% of the Rondônia state). Western Amazonia and the eastern Amazonia‐Cerrado transition zone emerge as key conservation hotspots, where forest loss produces the strongest downwind impacts on vegetation stability. Conversely, restoration in northeast Amazonia could enhance regional rainfall and improve ecosystem stability. Overall, our findings underscore the importance of preserving Amazonia's continental‐scale moisture connectivity to safeguard both local ecosystem and broader hydroclimatic stability.

Corals in the genus Pocillopora are the primary framework builders of eastern tropical Pacific (ETP) reefs. These corals typically associate with algal symbionts (genus Symbiodinium ) in clade C and/or D, with clade D associations having greater thermal tolerance and resistance to bleaching. Recently, cryptic \"species\" delineations within both Pocillopora and Symbiodinium have been suggested, with host–symbiont specificity used as a supporting taxonomic character in both genera. In particular, it has been suggested that three lineages of Pocillopora (types 1–3) exist in the ETP, of which type 1 is the exclusive host of heat-tolerant Symbiodinium D1. This host specificity has been used to support the species name \" Symbiodinium glynni \" for this symbiont. To validate these host–symbiont relationships and their taxonomic utility, we identified Pocillopora types and their associated Symbiodinium at three sites in the ETP. We found greater flexibility in host–symbiont combinations than previously reported, with both Pocillopora types 1 and 3 able to host and be dominated by Symbiodinium in clade C or D. The prevalence of certain combinations did vary among sites, showing that a gradient of specificity exists which may be mediated by evolutionary relationships and environmental disturbance history. However, these results limit the utility of apparent host–symbiont specificity (which may have been a result of undersampling) in defining species boundaries in either corals or Symbiodinium . They also suggest that a greater diversity of corals may benefit from the thermal tolerance of clade D symbionts, affirming the need to conserve Pocillopora across its entire geographic and environmental range.

Dynamic symbioses may critically mediate impacts of climate change on diverse organisms, with repercussions for ecosystem persistence in some cases. On coral reefs, increases in heat-tolerant symbionts after thermal bleaching can reduce coral susceptibility to future stress. However, the relevance of this adaptive response is equivocal owing to conflicting reports of symbiont stability and change. We help reconcile this conflict by showing that change in symbiont community composition (symbiont shuffling) in Orbicella faveolata depends on the disturbance severity and recovery environment. The proportion of heat-tolerant symbionts dramatically increased following severe experimental bleaching, especially in a warmer recovery environment, but tended to decrease if bleaching was less severe. These patterns can be explained by variation in symbiont performance in the changing microenvironments created by differentially bleached host tissues. Furthermore, higher proportions of heat-tolerant symbionts linearly increased bleaching resistance but reduced photochemical efficiency, suggesting that any change in community structure oppositely impacts performance and stress tolerance. Therefore, even minor symbiont shuffling can adaptively benefit corals, although fitness effects of resulting trade-offs are difficult to predict. This work helps elucidate causes and consequences of dynamism in symbiosis, which is critical to predicting responses of multi-partner symbioses such as O. faveolata to environmental change.

Land–atmosphere interactions have an important influence on Amazon precipitation (P), but evaluation of these processes in climate models has so far been limited. We analysed relationships between Amazon P and evapotranspiration (ET) in the 5th Coupled Model Intercomparison Project models to evaluate controls on surface moisture fluxes and assess the credibility of regional P projections. We found that only 13 out of 38 models captured an energy limitation on Amazon ET, in agreement with observations, while 20 models instead showed Amazon ET is limited by water availability. Models that misrepresented controls on ET over the historical period projected both large increases and decreases in Amazon P by 2100, likely amplified by unrealistic land–atmosphere interactions. In contrast, large future changes in annual and seasonal-scale Amazon P were suppressed in models that simulated realistic controls on ET, due to modulating land–atmosphere interactions. By discounting projections from models that simulated unrealistic ET controls, our analysis halved uncertainty in basin-wide future P change. The ensemble mean of plausible models showed a robust drying signal over the eastern Amazon and in the dry season, and P increases in the west. Finally, we showed that factors controlling Amazon ET evolve over time in realistic models, reducing climate stability and leaving the region vulnerable to further change.

This study describes the response of common coral taxa at 15 sites to a warm-water anomaly in Mauritius in March 2004. Sites circumscribed the island and differed in their water flow and thermal history as a result of variation in local current patterns. We observed 2 distinct positive responses of coral taxa to the anomaly that correlated with their local abundance, with a group of sparse (22 taxa covering <5 cm m–1) and abundant taxa (7 taxa covering >5 cm m–1). The 2 most dominant taxaAcroporaandMontiporawere among the most susceptible genera in the abundant group, whileSeriatoporaandAlveoporawere the most susceptible taxa in the sparse group. This suggests that a temperature anomaly that is sufficient to cause mortality will remove taxa from 2 positions in the community spectrum with consequences for both ecological functions and diversity. We found that bleaching intensity at the sites was positively associated with water flow, with the most intense bleaching and highest currents on the windward and offshore sites. The algal symbiont communities in nearly all of the corals sampled on both sides of the island and 2 depths were dominated by diverseSymbiodiniumin CladeC, indicating that the observed differences in response among coral taxa and sites were unlikely to be greatly affected by the types of symbionts they contained. We suggest that high water flow reduces background stress and acclimation, and results in corals that are less tolerant of rare temperature anomalies.