Global Ecology and Biogeography

Ecological networks are increasingly studied at large spatial scales, expanding their focus from a conceptual tool for community ecology into one that also adresses questions in biogeography and macroecology. This effort is supported by increased access to standardized information on ecological networks, in the form of openly accessible databases. Yet, there has been no systematic evaluation of the fitness for purpose of these data to explore synthesis questions at very large spatial scales. In particular, because the sampling of ecological networks is a difficult task, they are likely to not have a good representation of the diversity of Earths bioclimatic conditions, likely to be spatially aggregated, and therefore unlikely to achieve broad representativeness. In this paper, we analyze over 1300 ecological networks in the mangal.io database, and discuss their coverage of biomes, and the geographic areas in which there is a deficit of data on ecological networks. Taken together, our results suggest that while some information about the global structure of ecological networks is available, it remains fragmented over space, with further differences by types of eco-logical interactions. This causes great concerns both for our ability to transfer knowledge from one region to the next, but also to forecast the structural change in networks under climate change.

Shifts between biomes, the broad types of ecosystems, are far less understood than other ecological transitions. In this study, we aimed at identifying a possible and preliminary lineage between terrestrial biomes on Earth by using up-to-date phylogenetic methods. Although a deep statistical power was lacking, we built on expert knowledge a double-entry table filled by a variety of traits characterizing all the 14 terrestrial biomes on Earth. As a central result, the biome phylogeny computed here is a clear approximation of the dominant biome successions observed on Earth. Latitudes (i.e., locations), not included into the trait table, may first explain the computed phylogeny. In particular, tropical biomes appeared well related and exhibited a possible common ancestor (higher than 50% confidence level). We discussed this possible history of terrestrial biome on Earth, along to the involved processes over the long term. This helped explaining how biomes differ from purely biological materials and partly why ecosystems are not evolving as life does.

AimWe examined the patterns and processes of taxonomic and functional dissimilarities for two disparate organismal groups (ectothermic hawkmoths and endothermic birds) across a broad tropical elevational gradient. LocationEaglenest Wildlife Sanctuary (northeast India), eastern Himalayan global biodiversity hotspot. Taxon4,731 hawkmoths; 15,387 birds MethodsTurnover and nestedness components for taxonomic and functional dissimilarities were obtained using the methods developed by Baselga (2013) and Leprieur et al., 2012. We used Generalized Dissimilarity Modeling (GDM) with geographic distance, contemporary and historic climatic variables to assess the relative importance of dispersal and environmental processes in determining the beta diversity. Functional redundancy (FRed) was calculated for both organismal groups using the Simpsons diversity indices. Null modeling was used to determine randomness in species and trait distributions. ResultsTurnover dominated taxonomic and functional dissimilarities, however the contribution of nestedness was considerably higher to the latter. Overall, the rate of dissimilarity with distance, for both facets of diversity, was significantly higher for birds, with stronger contributions of geographic distance and historic climate; whereas the hawkmoth dissimilarities were strongly correlated with only contemporary climate. Taxonomic dissimilarities deviated significantly from null, whereas functional dissimilarities exhibited high redundancy and randomness. Main ConclusionsOverall, our results suggest that while the drivers of beta-diversity exhibit idiosyncrasy and taxon-specificity; for a given taxa, they are consistent across the two facets of dissimilarity. More importantly, regardless of the principal predictor, the net result was that of high taxonomic turnover, which is de-coupled to a high degree from functional turnover in these tropical ecosystems. The large redundancy in trait values, despite high species turnover, indicates functional resilience of these tropical communities. The consistency of this pattern, across two disparate organismal groups, is suggestive of a key mechanism in which tropical communities may retain functionality of ecosystems in a changing environment.

AimTo examine the support of two ecological diversity theories- The Ecological Limits Hypothesis (ELH) and the Niche Conservatism Hypothesis (NCH) - in explaining patterns of global shark diversity. LocationGlobal scale and two ecological realms: the Tropical Atlantic and the Central Indo-Pacific. Time PeriodPast 100 years Major Taxa StudiedWe examined 534 species of sharks and chimaeras, and we performed two subclade analyses on 272 species of ground sharks and 15 species of mackerel sharks. MethodsWe compared the species richness, mean root distance (MRD), and tree imbalance patterns to those simulated under the ELH and NCH with temperate and tropical centers of origin. We used sea temperature as a proxy for energy availability. We examined the importance of biogeographic history by comparing the model fits between two taxonomic groups, ground and mackerel sharks, and two geographic regions, the Tropical Atlantic realm and Central Indo-Pacific realm. ResultsThe ELH, temperate-origin model had the best fit to the global dataset and the sub-analyses on ground sharks, mackerel sharks, and the Tropical Atlantic. The NCH temperate-origin model provided the best fit for the Central Indo-Pacific. The {beta} metric of tree symmetry showed the best potential for differentiating between the ELH and NCH models, and the correlation coefficient for temperature vs MRD performed the best at differentiating between temperate and tropical origin of ancestors. Main ConclusionsThe global and subclade analyses indicate the ELH provides the best explanation for global scale shark diversity gradients even in clades with varying ecology. However, at the realm scale, biogeographic history has an impact on richness patterns. Comparing multiple metrics in relation to a simulation model provides a more rigorous comparison of these models than simple regression fits.

AimThe effects of equilibrium and nonequilibrium processes are generally investigated using species richness on a single biological group. However, little is known about how these two classes of processes also affect trait diversity, considering multiple taxa within the same geographical template. Here, we evaluated which variables representing equilibrium (topography, climate, and primary productivity) and nonequilibrium (diversification rate and evolutionary time) processes best explain species richness and trait diversity of four clades of vertebrates within the same global hotspot. We also investigated how trait disparity has accumulated over time and whether there are congruent spatial patterns between groups. LocationAtlantic Rainforest Time periodContemporary. Major taxa studiedTerrestrial vertebrates. MethodsWe tested whether the spatial pattern of Functional Dispersion (FDis), richness, diversification rate, and evolutionary time of each group are correlated. We used a spatially explicit structural equation model to test how species richness and functional dispersion are influenced by variables representing equilibrium and nonequilibrium mechanisms. Additionally, we explored how trait disparity accumulated over time in the four groups. ResultsWe found that non-equilibrium proxies, evolutionary time and diversification rate, played a primary role in driving species richness and trait diversity, with elevation and climate variables having only an indirect effect species and trait diversity via diversification rate and evolutionary time. We found a congruent pattern of species richness among all groups, except among ectotherms. In contrast, the spatial distribution of evolutionary time was distinct for each group. Main conclusionsDespite nonequilibrium processes were more important for generating large-scale diversity patterns within the same geographical template, the interplay between evolutionary time and dispersal ability have disparately determined the assembly of communities.

AimQuantifying the phylogenetic diversity of temperate trees is essential for understanding what processes are implicated in shaping the modern distribution of temperate broadleaf forest and other major forest biomes. Here we focus on Fagales, an iconic member of forests worldwide, to uncover global diversity and endemism patterns and investigate potential drivers responsible for the spatial distribution of fagalean forest communities. LocationGlobal. TaxonFagales. MethodsWe combined phylogenetic data covering 60.2% of living species, fine-scale distribution models covering 90% of species, and nodulation data covering all species to investigate the distribution of species richness at fine spatial scales and compare this to relative phylogenetic diversity (RPD) and phylogenetic endemism. Further, we quantify phylogenetic betadiversity and bioregionalization of Fagales and determine hotspots of Fagales species engaging in root nodule symbiosis (RNS) with nitrogen-fixing actinomycetes. ResultsWe find the highest richness in temperate east Asia, eastern North America, and equatorial montane regions of Asia and Central America. By contrast, RPD is highest at higher latitudes, where RNS also predominates. We found a strong spatial structuring of regionalizations of Fagales floras as defined by phylogeny and traits related to RNS, reflecting distinct Northern and Southern Hemisphere floras (with the exception of a unique Afro-Boreal region) and highly distinct tropical montane communities. Main conclusionsSpecies richness and phylogenetic regionalization accord well with traditional biogeographic concepts for temperate forests, but RPD does not. This may reflect ecological filtering specific to Fagales, as RNS strategies are almost universal in the highest RPD regions. Our results highlight the importance of global-scale, clade-specific spatial phylogenetics and its utility for understanding the history behind temperate forest diversity.

AimRapoports rule posits that species range size increases with distance from benign conditions along environmental gradients. We asked whether, and along which axis, marine species obey Rapoports rule when ranges are quantified in three dimensions. LocationGlobal ocean. Taxon> 20,000 marine species spanning pelagic and benthic habitats across major animal phyla and fishes. MethodsWe combined AquaMaps 2.0 / AquaX modelled distributions with independently curated depth limits from FishBase and SeaLifeBase to estimate latitudinal and vertical (bathymetric) ranges for each species. We quantified latitudinal range versus absolute mid-latitude and depth range versus mid-depth, and repeated analyses by habitat and taxonomic group. We used linear and polynomial regressions and Gaussian mixture models in range-gradient space to identify and compare alternative Rapoport regimes. ResultsMarine biodiversity exhibits a classic latitudinal diversity gradient and strong concentration of richness in the upper ocean, with broader ranges at higher latitudes and greater depths. Support for Rapoports rule is weak and inconsistent for latitudinal ranges, but strong and pervasive with depth, with correlations between vertical range and mid-depth frequently exceeding 0.8 across habitats and taxa. Latitudinal and vertical ranges are positively, but only moderately, coupled, with a small subset of "3-D generalists" spanning both large latitudinal and depth extents. Main conclusionsThe marine realm appears to obey Rapoports rule primarily along the vertical, rather than latitudinal, axis. Depth-structured environmental tolerance thus emerges as a dominant constraint on marine range limits and three-dimensional biodiversity gradients.

The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in areas with high gamma-diversity to have inflated measures of beta-diversity. Here, we provide here a novel analytical test, using beta-diversity metrics that correct the gamma-diversity and sampling biases, to compare beta-diversity and species packing across a latitudinal gradient in tree species richness of 21 large forest plots along a large environmental gradient in East Asia. We demonstrate that after accounting for topography and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate analogs. This suggests that beta-diversity contributes to the latitudinal species richness gradient as a component of gamma-diversity. Moreover, both niche specialization and niche marginality (a measure of niche spacing along an environmental gradient) also increase towards the equator, after controlling for the effect of topographic heterogeneity. This supports the joint importance of tighter species packing and larger niche space in tropical forests while also demonstrating the importance of local processes in controlling beta-diversity.

O_LIUnderstanding the long-term impact of projected climate change on tropical rainforests is critical given their central role in the Earths system. Palaeoecological records can provide a valuable perspective on this problem. Here we examine for the first time the effects of past climatic changes on the dominant forest type of Southeast Asia - Dipterocarp forest. C_LIO_LIWe use a range of proxies extracted from a 1,400-year-old lacustrine sedimentary sequence from north-eastern Philippines to model long-term vegetation responses of Dipterocarp forest, including its dominant tree group Dipterocarps, to changes in precipitation, fire and nutrient availability over time. C_LIO_LIOur results show a positive relationship between Dipterocarps pollen accumulation rates (PARs) and leaf wax hydrogen isotope values, which suggests a negative effect of drier conditions on Dipterocarp tree abundance. Furthermore, we find a positive relationship between Dipterocarp PARs and the proxy for phosphorus availability, which suggests phosphorus controls the productivity of these keystone trees on longer time scales. Other plant taxa show widely varying relationships with the abiotic factors, demonstrating a high diversity of functional responses. C_LIO_LIOur findings provide novel insights into Dipterocarp forest responses to changing climatic conditions in the past, and highlight potential impacts of future climate change on this globally important ecosystem. C_LI

Both historical and contemporary environmental conditions determine present biodiversity patterns, but their relative importance is not well understood. One way to disentangle their relative effects is to assess how different dimensions of beta-diversity relate to past climatic changes, i.e., taxonomic, phylogenetic and functional compositional dissimilarity, and their components generated by replacement of species, lineages and traits (turnover) and richness changes (nestedness). Here, we quantify global patterns of each of these aspects of beta-diversity among neighboring sites for angiosperm trees using the most extensive global database of tree species-distributions (43,635 species). We found that temperature change since the Last Glacial Maximum (LGM) was the major influence on both turnover and nestedness components of beta-diversity, with a negative correlation to turnover and a positive correlation to nestedness. Moreover, phylogenetic and functional nestedness was higher than expected from taxonomic beta-diversity in regions that experienced large temperature changes since the LGM. This pattern reflects relatively greater losses of phylogenetic and functional diversity in species-poor assemblages, possibly caused by phylogenetically and functionally selective species extinction and recolonization during glacial-interglacial oscillations. Our results send a strong warning that rapid anthropogenic climate change is likely to result in a long-lasting phylogenetic and functional compositional simplification, potentially impairing forest ecosystem functioning.

AimEurope should be considered as a diversity hotspot for diurnal raptors, but just during the breeding season, as it holds the higher proportion of transcontinental migratory species of any landmass, and the area becomes depleted during the winter period. This study will test the hypothesis that the high diversification of the raptor assemblage in Europe is a recent event, occurring mainly during the Quaternary, and that closely related species sharing the same trophic niches can only coexist in sympatry during the breeding period, when food availability is higher. LocationContinental Europe. TaxonDiurnal birds of prey (Accipitriformes and Falconiformes). MethodsA consensus molecular phylogeny for the 38 regular breeding species of raptors in Europe was obtained from BirdTree. For the same species, a trophic niche cluster dendrogram was constructed. Size and migratory strategy were introduced in the resulting phylogeny, where trophic groups were also identified. ResultsA total of 16 trophic groups were identified. Multispecific trophic groups tended to be composed of reciprocal sister species, while monospecific groups (only three) were composed of highly specialized species. According to time calibrated phylogenies, the speciation events took place during the glacial cycles of the Quaternary period in a majority of cases. During the non-breeding season, the smaller species in every trophic group migrate to sub-Saharan Africa, whereas larger species are either non-migratory or perform shorter migrations within Europe and/or northern Africa. Main conclusionsThis investigation illustrates how the rich assemblage of diurnal birds of prey in Europe, more diverse and more migratory than the North American assemblage at equivalent latitudes, has emerged recently due to the multiplication of look-alike species with similar trophic ecologies, mainly in climate refugia during cold periods. In the non-breeding season, when shared food resources are limited, smaller species migrate to Africa and alleviate competition.

AbstractWater availability is widely recognized for its importance in shaping plant diversity gradients globally. However, even in arid ecosystems such as drylands, a remarkable diversity of plant species can persist. Yet, the environmental, topographic, and geographic drivers that have structured plant diversity gradients within drylands over evolutionary time, and their relative importance, are poorly understood, particularly for understudied ecosystems such as coastal lomas. Here, we evaluated the geographic distribution and drivers of taxonomic and phylogenetic diversity of plants across the coastal lomas of South America, which are isolated fog-fed vegetation oases within the Peruvian and Chilean coastal desert. We collated the most comprehensive data set to date of 72 coastal lomas, and used generalised linear models to assess latitudinal diversity gradients, and evaluated the relative importance of environmental, topographic, and geographic drivers of plant taxonomic and phylogenetic diversity. Notably, we found that both plant species richness and standardized mean nearest taxon distance (MNTD) decreased linearly towards the Equator, while standardized phylogenetic diversity (PD) and mean phylogenetic distance (MPD) exhibited non-linear relationships with latitude, peaking in the hyper-arid core of the Atacama Desert. Our results suggest that current climate, environmental heterogeneity, and geographical factors are the primary drivers of plant diversity. Plant species richness increased with cloud cover, slope, and area, and decreased with soil pH, while standardized PD increased with aridity, elevation, and the human footprint and decreased with distance to the coast. Standardized MNTD increased with elevation, and decreased with increasing area and temperature; standardized MPD increased with slope, and decreased with increasing aridity and distance to the coast. Our results suggest that environmental filtering is not the only macroecological process acting on plant diversity across coastal lomas, and has often been counterbalanced at different points in evolutionary time by factors associated with environmental heterogeneity, possibly reflecting the presence of climate refugia and diverse habitats that promote species coexistence. Also, our results offer empirical evidence supporting an inverse latitudinal gradient in plant diversity across coastal lomas, which emerges as a consequence of multiple factors that influence water availability, both directly and indirectly. Over evolutionary time, these factors may have significantly contributed to shaping the current structure and composition of coastal lomas.

AimThe modern latitudinal diversity gradient of planktonic foraminifera is bimodal with a distinct depression near the equator, surrounded by mid-latitude diversity peaks. This pattern emerged after the Last Glacial Maximum, but it is unclear how species spatial dynamics contributed to its formation. Here, we investigate how species range dynamics, i.e., trailing-edge contractions (extirpations) and leading-edge expansions (colonisations), shaped the modern bimodal pattern, and how global biodiversity patterns arise from local patterns. LocationGlobal open ocean, with basin-specific analyses in the Atlantic and Pacific Oceans. Time periodLast Glacial Maximum (19 - 23 ka) (LGM) and the Pre-Industrial (modern) Major taxa studiedPlanktonic foraminifera (unicellular eukaryotes) MethodsWe analysed taxonomically standardized LGM and modern foraminiferal assemblage datasets to characterize changes in species richness at multiple spatial scales: global ocean, basin-wide, and within basin. We quantified species range shifts by comparing their trailing- and leading-edge movements. We estimated temporal turnover locally, and the net imbalance between colonisations and extirpations (NICE) within sites, and tested whether species thermal preferences correlate with their extirpation risk. ResultsWe found no evidence of systematic trailing edge contractions, indicating that equatorial extirpations did not drive the bimodal LDG pattern. In the Atlantic, leading-edge expansions generated a coherent increase in species richness in the mid-latitudes, whereas the Pacific exhibited highly spatially heterogeneous responses, including extirpation hotspots in the western tropical Pacific and colonisation zones in the eastern and southern Pacific. Species thermal optima weakly predicted extirpations, with species adapted to lower temperatures more at risk of extirpation, consistent with the general warming trend since the last ice age. Main conclusionsThe modern bimodal LDG of planktonic foraminifera arises primarily from mid-latitude colonisations rather than equatorial extirpations. Colonisations were particularly frequent in the North Atlantic. Localized extirpations in the western Pacific highlight small-scale patches of vulnerability, that spatially aggregated richness metrics mask. Our results underscore the need to distinguish between trailing and leading processes in climate-induced range shifts, and to consider spatial variability in monitoring and protection of marine biodiversity.

AimBiodiversity is distributed unevenly among lineages and regions, and understanding the processes generating these global patterns is a central goal in evolutionary research, particularly in light of the current biodiversity crisis. Here, we integrate phylogenetic relatedness with species diversity patterns in four major clades of living tetrapods (amphibians, squamates, birds, and mammals) to approach this challenge. LocationGlobal. Time period300 million years ago - Present. Major taxa studiedTetrapods. MethodsWe studied geographic patterns of richness-corrected phylogenetic diversity (residual PD), identifying regions where species are phylogenetically more closely or distantly related than expected by richness. We explored the effect of different factors in residual PD: recent speciation rates, temporal trends of lineage accumulation, and environmental variables. Specifically, we searched for evolutionary and ecological differences between regions of high and low residual PD. ResultsOur results show heterogeneous spatial patterns of diversity dynamics across tetrapods. They reveal an overall negative relationship between recent speciation rates and residual PD, underscoring the role of recent speciation events in structuring current biogeographic patterns. Furthermore, we found differences between endothermic and ectothermic tetrapods in response to temperature and precipitation, highlighting the pivotal role of thermal physiology in shaping diversity dynamics. Main conclusionsGeographic patterns of diversity dynamics are heterogeneous across tetrapod clades and help us disentangle the evolutionary and ecological processes underlying them. By illuminating the multifaceted factors underpinning global diversity patterns, our study represents a significant advancement towards better understanding of how the present-day diversity of tetrapods was formed and how speciation rates influenced their species and phylogenetic diversity across clades and regions.

The drivers of biodiversity in mountain ecosystems have long been a central focus in ecologists. Increasing evidence suggests that energy is a key determinant of mountain species diversity; however, whether this pattern holds universally across different mountain ecosystems remains unclear, especially as there may be differences between different plant taxa. To address this knowledge gap, we selected mountain endemic plant genera from global biodiversity hotspots to explore the main drivers of diversity of different taxa in the mountains. Our results indicate that energy is the key driver of endemic plant richness in mountain regions worldwide, particularly for endemic tree and shrub taxa, while endemic herb richness is shaped by both energy and environmental heterogeneity. Regional studies have shown that energy availability drives total endemic plant groups in 70% of mountain regions. Specifically, energy is the dominant driver for 86% of endemic tree groups and 67% of endemic shrub groups, whereas endemic herb groups are the least influenced by energy, with only 50% of mountain regions showing energy as the primary driver. Our findings indicate that energy availability is the predominant factor shaping the diversity of endemic plant groups in mountain ecosystems worldwide. Therefore, mountain ecological conservation efforts should focus extensively on energy input aspects. HighlightsO_LIClimate energy is the main driver of the richness of montane endemic plant taxa, especially for tree and shrub, whereas herb richness is determined by a combination of energy and environmental heterogeneity. C_LIO_LIEnvironmental heterogeneity predominantly drives endemic taxa richness in the Cape of Good Hope, whereas both climatic energy and environmental heterogeneity jointly influence endemic taxa richness in the Andes and Japan. In all other mountain ranges, climatic energy is the primary determinant. C_LIO_LIEndemic tree taxa have the highest number of mountains dominated by climatic energy, followed by endemic shrub taxa, and endemic herb taxa are more affected by environmental heterogeneity. C_LI

The scale at which diversity is observed shapes the patterns we find. While spatial scale is known to influence biodiversity patterns, the effects of temporal scale, namely the average duration of sampling (known as temporal span), have been mostly overlooked. Here, we investigate how temporal span affects species richness patterns, their environmental drivers, and species richness hotspots. We used species richness data from several large bird datasets from Czechia, with over 7000 observations, a spatial grain ranging from 0.03 to 100 km2, and a temporal span ranging from 1 to 36 years (1985-2017). Using Random Forests, we modelled species richness as a response to temporal span, while also including area, geographic location, time, and environmental and land-cover predictors. We found that the temporal span is consistently among the most important predictors of bird species richness. Moreover, temporal span interacts with key environmental conditions, particularly precipitation and water bodies, modulating their effects on species richness and revealing processes that differ from those traditionally attributed solely to spatial grain. We also found that using different time spans can shift the predicted locations of biodiversity hotspots. Our results provide empirical evidence that temporal span should be included in studies about biodiversity and conservation planning, given the urgent challenges arising from ongoing biodiversity change and the complexity of its drivers.

Earths ecosystems are characterized by numerous gradients related to the distribution of environmental conditions and resources. Niche theory predicts that animals will evolve traits to exploit changing resource availability and environmental conditions across these gradients. Much work has been done examining how animal traits like body mass and diet change across gradients from regional to global scales. Environmental and resource gradients in the vertical dimension tend to exhibit strong changes over relatively short distances due to the influence of elevation and vegetation. Vegetation structure may be an especially important vertical axis as it contributes to strong gradients in micro- climate, food resources, and predation risk. To investigate interrelationships between the vertical niche and its presumed drivers, we use functional traits, phylogenies, and predation risk to predict the vertical foraging niche for 4,828 mammals and 9,437 birds globally. To provide biogeographic context to the predictive analysis, we use species ranges to map geographic distributions of the vertical foraging niche and relationships between the niche and its presumed drivers. Linking trait databases with species range maps revealed distinct global distributions of vertical foraging niches for mammals and birds. The most important predictors of these niches varied by taxon but there were several systematic relationships. Diet, body mass, and phylogeny were strong predictors of vertical foraging niche across mammal and bird species. Percent fruit in diet exhibited progressively more positive relationships with higher canopy foraging positions. Predation pressure was relatively unimportant in predicting most vertical foraging niches for birds and mammals but displayed a positive trend with arboreal foraging. Geographic hotspots for the importance of fruit in both mammal and bird diets included the Andes-Amazon transition zone, the Amazon Basin, and New Guinea. Our results provide support for the theory of resource driven vertical niche partitioning but also reveal that vertical niches are strongly associated with phylogeny, suggesting niche conservatism in numerous mammal and bird families. Geographic patterns in variable importance values suggest multiple mechanisms behind spatial structure in eco- evolutionary relationships, including latitudinal gradients in vegetation structure and composition, historical patterns of island isolation (in Southeast Asia), and the influence of habitat heterogeneity driven by tectonic processes (in South America).

AimCommunity phylogenetics provides important information about the evolutionary and ecological factors help structure regional species assemblages. Here, we analyze phylogenetic diversity (phylodiversity) patterns among fish species in 97 sub-drainages of the Amazon basin, to evaluate the roles of historical and contemporary processes in generating and maintaining the exceptional richness and endemism of Amazonian fish species assemblages. LocationAmazon River basin TaxonFreshwater fishes MethodsUsing a large comprehensive database of freshwater fish species distributions, and a well-sampled molecular phylogeny of ray-finned (actinopterygian) fishes, we develop of multivariate statistical model to correlate estimated historical and contemporary environmental parameters with sub-drainage phylodiversity patterns. The model employs three phylogenetic metrics: i.e.: phylogenetic diversity (PD) sensu stricto, mean pairwise phylogenetic distance (MPD) between species capturing phylodiversity variation at older evolutionary timescales), and mean nearest taxon distance (MNTD) capturing variation in phylodiversity at younger evolutionary timescales. ResultsThe model recovered significant effects of elevation gradients, contemporary climate, habitat fragmentation, water types, and past marine incursions on assemblage phylodiversity patterns. The model also found significantly negative relationships among the three phylogenetic metrics, and between these metrics and distance to mouth of the Amazon, representing a West-East longitudinal gradient. Main conclusionsOur study revealed a highly non-random spatial and environmental distribution of our three phylogenetic diversity metrics across the 97 sub-drainages of the Amazon basin. Beyond significant regional effects of several environmental and historical drivers, we also found a significant West-East gradient of increasing phylogenetic diversity and phylogenetic relatedness, both patterns suggesting deeper evolutionary divergences among taxa located to the east, and more diverse, more recent radiations in the western sub-drainages. We conclude that western Amazonia can be seen as an evolutionary "cradle" of biodiversity for freshwater fishes in the Amazon basin as a whole. Significance StatementThis manuscript reveals spatial patterns of freshwater fish phylogenetic diversity and relatedness and explains its major contemporary and historical drivers in the Amazon basin. Amazon basin contains the highest freshwater biodiversity on Earth, as so investigate phylogenetic dimension of diversity is extremally relevant from the perspective of understanding the information on the evolutionary processes that had shaped Amazonian contemporary fish assemblages.

AimMutualism can shape biogeographic patterns at macroecological scales. Recently, Delavaux et al. (2024) found that plant mutualisms with mycorrhizae, nitrogen-fixing bacteria, and animal pollinators limit island colonization, weakening the latitudinal diversity gradient (LDG) on oceanic islands. Here, we revisit their analysis and examine whether ants and plants engaged in a common defensive mutualism mediated by extrafloral nectaries (EFN) are similarly under-represented on oceanic islands, and whether this defensive ant-plant mutualism also weakens the LDG on islands. LocationGlobal. Time periodPresent-day species distributions and traits. Major taxa studiedVascular plants and ants. MethodsWe used global trait and occurrence databases to compare ant and plant species richness between oceanic islands and their likely source mainlands for taxa that do and do not interact mutualistically via EFNs. When analyzing the factors that determine whether a plant species occurs on oceanic islands, we also included the mutualism types studied by Delavaux et al. (2024), namely biotic pollination, mycorrhizal fungi, and nitrogen-fixing bacteria, and added plant habit, life history, and phylogeny as covariates. ResultsBoth plants with EFNs and EFN-visiting ants are significantly over-represented on islands. The species richness of EFN-visiting ants and EFN-bearing plants also positively covary across islands. In ants, engaging in mutualisms mediated by EFNs significantly strengthens, rather than weakens, the LDG on islands, while for plants, EFNs have no effect or strengthen the LDG on islands, depending on data filtering. After accounting for plant habit, life history, and phylogeny, only biotic pollination significantly limits plant colonization of islands, whereas mycorrhizae and nitrogen-fixing bacteria now have positive or non-significant effects, respectively, on island colonization. Main conclusionsEFNs facilitate rather than limit plant and ant colonization on islands. Mutualism does not ubiquitously limit island colonization, and some mutualism types strengthen rather than dampen the LDG on islands.

AimTropical rainforests harbour the richest biodiversity among terrestrial ecosystems, but few studies have addressed underlying processes of species diversification in these ecosystems. We use the pantropical and early divergent flowering plant family Annonaceae as a model system to investigate how abiotic factors such as climate and biogeographic events contribute to the diversification process and lead to its high diversity across a long evolutionary history. LocationTropics and subtropics TaxonAnnonaceae MethodsA super-matrix was constructed for 835 taxa (34% of Annonaceae species), based on eight chloroplast regions. To understand the patterns of diversification, we reconstructed climatic niche evolution and historical biogeographical events, and tested their association with diversification rates. ResultsThe analysis of temperature-dependent models in Annonaceae lineages provides strong support for the significant influence of global temperature on net diversification and accumulation of species diversity. The pattern of lineage accumulation in the initial radiation is better aligned with the "museum model," followed by later accumulation consistent with the "recent cradle model" from the late Oligocene to the present. The increase in the diversification rate of the family (around 25 Ma) lags behind the accumulation of niche divergences (around 15 Ma). Biogeographic events are related to only two of the five diversification rate shifts detected. While no direct relationship to shifts in the diversification rate was uncovered, shifts in niche evolution appear to be associated with increasingly seasonal environments. Main ConclusionsGlobal temperature plays a crucial role in driving recent rapid diversification in the Annonaceae. Our study challenges the prevailing assumption of the "museum model" alone and proposes instead a transition from the "museum model" to the "recent cradle model" during the diversification history of the family. However, our findings do not support the direct correlation of any particular climatic niche shifts or historical biogeographical events with shifts in diversification rate. Instead, Annonaceae diversification can lead to later niche divergence as a result of increasing interspecific competition arising from species accumulation. The evolutionary direction of niche shifts furthermore provides insight into the future expansion of Annonaceae into temperate regions. Our results highlight the complexity of the diversification process in taxa with long evolutionary histories, indicating that identifying isolated driving factors is simplistic and inadequate for explaining the observed patterns. Further comprehensive analyses of range evolution are necessary to delve deeper into the interplay among key opportunities, key innovation, and species diversification.