Ecography最新文献

Amphibians balance their thermal and water budgets depending on their physiological state and the physical environment, with both factors capable of constraining activity. Most mechanistic assessments emphasize thermal over water constraints, potentially missing important aspects of amphibian ecophysiological patterns. Here, we evaluate the potential role of thermal and hydric constraints on the activity time of three Neotropical frogs (Leptodactylus fuscus, L. mystacinus, and L. macrosternum) across their geographic distribution. We inferred environmental suitability based on heat and mass transfer principles through a mechanistic modeling procedure anchored to empirically obtained laboratory and field data. We integrated species-specific thermal, hydric, and performance attributes with their immediate physical environment (ground-level microclimate) under nocturnal conditions, while allowing for the interactive response of retreating into shelter when facing physiological heat or water stress. Our results demonstrate the desiccation-prone role of smaller body sizes in increasing hydric restrictions and inhibiting activity, even under thermally adequate conditions, as well as the role of shelters as thermal and hydric refugia. More strikingly, thermal-induced restrictions in activity were linked to low temperatures rather than warmer conditions, indicating that their engagement in activity is mostly driven by the lower thermal bounds of their functional organismal performance. These findings provide a broader picture of climatic constraints on anuran activity and distribution, as well as insights into how species may respond to changing climatic conditions.

Understanding species distributions across Antarctica is crucial for biodiversity conservation under climate change, but continental-scale analyses of key terrestrial species remain scarce. Here, we modelled distributions of 28 moss species across Antarctica using log-Gaussian Cox process models and environmental covariates including topographic wetness index, distance to seabird colonies, and temperature. Broad-scale distributions were primarily driven by proximity to seabird colonies, while species exhibited distinct responses to water availability and temperature. Species exclusive to maritime Antarctica showed negative relationships with a topographic wetness index, whereas continent-wide species responded positively to water accumulation potential, reflecting regional differences in water availability and habitat preferences. Bias-corrected predictions revealed highest moss diversity in coastal regions, with inland areas supporting ecologically distinct assemblages. Our Bayesian modelling approach provides a foundation for forecasting biodiversity responses to environmental change in data-poor systems, offering critical insights for evidence-based conservation planning under increasing anthropogenic pressures.

Arctic marine ecosystems are rapidly transforming due to climate change. Warming temperatures and shrinking sea ice are enabling boreal fish to expand northward, possibly disturbing cold-adapted Arctic species assemblages. Species range shifts have been documented in the Bering and Barents Seas, raising concerns about ecosystem restructuring. Range shifts are especially difficult to detect in the Arctic due to sparse and inconsistent data. Here, we studied fish composition from eDNA water samples taken in East Greenland, Svalbard, the Barents Sea, and the Kara Sea during the TOPtoTOP and Arctic Century expeditions. We examined the environmental drivers of fish community structure using global dissimilarity models. We calculated the decadal rate of temperature change to identify the fastest-changing areas. We compared fish detections from eDNA with published historical records for the Kara Sea to assess possible range expansions. We found that temperature was the main factor influencing the taxa turnover of fish communities, with Gadidae and Liparis sp. driving the greatest compositional differences. Over the past 30 years, temperatures increased by 0.2 to 0.6°C per decade at our study sites, with the highest increases in western Svalbard and the lowest in the eastern Kara Sea. Despite the apparent dependence on temperature, we identified only one species detected outside its known latitudinal range, and five species in the Kara Sea with recent occurrences or representing an extended distribution. Our study suggests that temperature, the main driver of fish community assembly, is increasing rapidly in the Arctic, and a few species have likely already shifted recently, or at least their detections are new in some areas. While these detections cannot be definitively linked to range shifts, our results highlight the need to improve monitoring of high-latitude fish communities to detect and predict future ecosystem changes.

Human activities exert numerous, simultaneous pressures on biodiversity. In particular, land cover and climate change are major contributors to biodiversity change, and these pressures can vary spatiotemporally and interact in complex ways. Adding to this complexity is the necessity to evaluate a suite of biodiversity metrics in concert, given that single-metric assessments have proven insufficient for a comprehensive understanding of community dynamics. We examined the effects of interactions between climate and land-cover change on bird communities across the continental United States over nearly three decades. We analyzed temperature and precipitation data alongside data on tree canopy, cropland, urban, and surface-water cover to understand how climate/land-cover change interactions influence observed richness, rarefied richness, and community abundance. Temporal trends in species richness and abundance were both associated with temporal trends in climate and land cover; however, richness responses were variable, while abundances tended to decline across the entire range of climate and land-cover change predictors. These concurrent biodiversity responses suggest that communities lost individuals from more common species, and consequently increased in evenness. Critically, we found that these community changes were jointly shaped by climate and land-cover change in 18 out of 24 biodiversity/climate/land-cover combinations, while climate-change impacts were dominant relative to land-cover change in the remaining six combinations. These results highlight the potential for both positive and negative synergies between climate change and land-cover change.

Macroclimate is a key driver of biodiversity, but habitat conditions can modulate the local microclimate by amplifying or buffering macroclimatic temperatures. The interplay between microclimatic modulation and macroclimatic temperature is crucial for shaping local biodiversity in a warming world, but remains poorly understood across life forms. We examined how macroclimate and microclimatic modulation jointly shape alpha diversity across eight taxonomic groups. We surveyed multi-taxon biodiversity along gradients of macroclimate (elevation) and microclimatic modulation (habitat structure), focusing on soil bacteria, soil fungi, understory plants, ground-dwelling arthropods, moths, flying insects, bats, and birds. We hypothesized that alpha diversity would increase with temperature at both macro- and microclimatic scales, with the strongest effects for immobile and ectothermic taxa, and that microclimatic effects would be more pronounced in thermally constrained (cold) macroclimates. Contrary to our expectations, micro- and macroclimatic effects were weakest for soil bacteria, soil fungi, and vascular plants, which responded more strongly to edaphic factors. Alpha diversity increased with macroclimatic temperature for arthropods, but not for the other groups. Effects of microclimatic amplification varied across taxa, with positive effects for flying insects and bats, but negative effects for soil bacteria and fungi. Interactive effects of microclimatic modulation and macroclimatic temperature on understory plants, ground-dwelling arthropods, moths, and birds indicated that microclimate influenced diversity differently in warm versus cold macroclimates. However, we found both stronger (ground-dwelling arthropods and moths) and weaker (understory plants and birds) positive effects of microclimatic amplification under cold compared to warm macroclimates. Our findings demonstrate that effects of microclimatic modulation on biodiversity depend on macroclimatic context and differ between taxa, and thus, both have to be considered when predicting climate-change impacts on biodiversity. Conservation planning should account for potentially changing effects of microclimatic modulation under climate warming that might affect the role of climatic microrefugia within the landscape.

Whether the limits of species' ranges and their seasonal activity reflect physiological tolerance of climatic extremes is a long-standing question in ecology and has implications for species' responses to recent climate change. We explored these associations in butterflies, using thermal tolerance traits and traits describing geographic distribution across 119 butterfly species, as well as adult flight season phenological traits across 87 species, accompanied by nearly 30 years of temporal population abundance trends. Butterflies with more poleward cold range edges and those that emerged earlier in the season were better able to tolerate low temperatures. By contrast, heat tolerance was unrelated to the equatorward warm range edge position and the timing of peak abundance across the flight season. Nevertheless, the difference between heat tolerance and high-temperature extremes (warming tolerance) revealed differences in vulnerability of butterflies across large spatial extents from the tropics to the subarctic. Warming tolerances in the tropics approached zero or were in deficit for many species, whereas warming tolerances at higher latitudes were consistently large. Yet, even among butterflies at higher latitudes, there was substantial interspecific variation in warming tolerance. This variation in warming tolerance, including its components and correlates, had complex relationships with multi-decadal population abundance trends. In some cases, our results directly implicated climate as a factor associated with population trends, as range-wide coldadapted species had larger declines than more warm-adapted species. In other cases, our results implicated indirect effects of ecological and demographic consequences of climate adaptation to seasonal variation in temperature, as species with earlier emergence and longer flight seasons (traits associated with better cold tolerance and worse heat tolerance) had smaller population declines than species with later emergence and shorter flight seasons. These results suggest caution when using physiological trait-based analyses to forecast vulnerability without an explicit consideration of mechanism.

Copious questions in global change biology require estimates of climatic suitability for species in the past or future, often via transfers of ecological niche models (ENMs) using outputs from global circulation models (GCMs). However, available GCMs differ markedly, affecting hindcasts and forecasts of species potential distributions. We propose using demographic inferences based on genetic data (indicative of either population-level continuous occupation or postglacial colonization) to test which GCM leads to a better match with reality for ENM hindcasting. We implement an intuitive worked example for four isolated focal populations of a montane shrew Cryptotis mexicanus in central-eastern Mexico, by comparing suitability maps at the Last Glacial Maximum (LGM) and today. We built an optimized Maxent niche model and transferred it to the LGM based on four GCMs (CCSM4, IPSL-CM5A-LR, MIROC-ESM, MPI-ESM-P), followed by phylogeographic analyses to test hypotheses of changes in distribution according to each GCM. CCSM4 and IPSL-CM5A-LR indicated an LGM suitability area for C. mexicanus mainly in the southern portion of its range, suggesting that extant focal populations to the north result from postglacial colonization. In contrast, MIROC-ESM and MPI-ESM-P indicated LGM suitability for three or all the populations, respectively. Genetic results for the four focal populations showed high genetic diversity and signals of constant population size. Because only the hindcast based on MPI-ESM-P generated the prediction of stable occupation for all four sites, we interpret that its estimate (a cold and wet LGM climate) best approximates reality for this system. Future studies can apply this framework using more extensive genetic or genomic data and finer temporal resolutions, also exploring differences in the assumptions and methodologies underlying the various GCMs.

The phylogenetic distance among species in a community (community phylogenetic structure) has been used to infer deterministic and stochastic assembly processes, albeit with criticisms. The effect of phylogenetic scale (old versus young lineages) and spatial scale on measures of CPS are rarely tested simultaneously, especially in the boreal biome, yet are essential to unravel different assembly processes that might operate in a community. We examined lineage-specific phylogenetic structure for six vascular plant communities defined at the habitat scale (Arctic-alpine barren, bog, fen, Kalmia barren, limestone barren, and serpentine barren) on the island of Newfoundland, Canada, and the phylogenetic structure of plant communities defined at a plot scale (72 plots × 1 m²). Contrary to the expectation under the stress-dominance hypothesis of phylogenetic clustering in challenging boreal environments, the majority of clades across the six boreal habitats had random phylogenetic structure. However, we observed a shift from phylogenetic clustering at the deepest nodes of the angiosperms to no phylogenetic structure at shallower nodes (< 110 Mya), suggesting changes in assembly processes with phylogenetic scale within a habitat, and the potential role for deterministic processes at deep nodes. The random phylogenetic structure of 1 m² plots and our modeling effort to test the effect of an environmental stress gradient on community composition suggest that a complex set of stochastic and deterministic factors is responsible for species assembly at this fine spatial scale, not just abiotic filtering in hostile environments like the serpentine as predicted by the stress-dominance hypothesis. The interpretation of phylogenetic structure metrics did not change when considering species abundances or when polytomies were resolved. Taken together, inference of assembly processes must be lineage-, habitat-, and spatial scale-specific, supplemented with knowledge on trait role and evolution for which we outline future research hypotheses.

About 14% of all fern species have chlorophyllous spores, which lack dormancy, have thin walls, and have a shorter viability (only a few days in some species). These spores should have limited dispersal distances and be more susceptible to harsher climatic conditions, raising questions about the evolutionary and ecological significance of this trait. Here, we assemble the global distribution of chlorophyllous-spored ferns and assess the underlying environmental and evolutionary factors. We first evaluated the environmental predictors of the proportional representation of 1387 chlorophyllous-spored species (CSS) across 577 geographical regions using generalized linear mixed models. We then estimated the phylogenetic signal of spore type and assessed the relative importance of environmental factors in the phylogenetic structure of fern assemblages. Species richness of CSS peaked in the tropics, while their proportional representation was highest in temperate and island floras. The proportion of CSS was positively associated with water availability and less seasonal climates. Spore type was strongly conserved phylogenetically, and CSS assemblages were phylogenetically clustered towards higher latitudes. Our study provides strong evidence that chlorophyllous spores do not limit the geographical distribution of fern species and that their latitudinal distribution patterns can be explained by a combination of environmental and evolutionary factors.

In natural or human-disturbed ecosystems, ecological networks often comprise multiple interaction types, which have been increasingly represented by multipartite ecological networks. One important aspect of their network architecture is how different interaction types or subnetworks are interconnected by connector species, here defined as the interconnection structure. Previous studies have proposed various indices of connector species to characterize macro-scale interconnection patterns and micro-scale centrality, but the meso-scale interconnection structures (here defined as interconnection motifs) remain largely unexplored. Furthermore, there is no package available in the R programming language for conducting analyses of various interconnection structures.

Within a tripartite network with two interaction subnetworks, we define the forms of interconnection motifs and unique roles within these motifs. Then we introduce the R package ‘ILSM' for analyzing interconnection pattern, interconnection centrality, and interconnection motif for unweighted and weighted networks. Specifically, we derive mathematical expressions for the frequencies of interconnection motifs and species roles within motifs.

We describe the main functions in the package and demonstrate their uses with an example pollinator–plant–herbivore network. In addition, we show that interconnection motifs can reveal additional variation beyond interconnection patterns and centrality using empirical tripartite interaction networks.

‘ILSM' will help ecologists understand how different types of interactions are interconnected by shared species using interconnection pattern, centrality, and motif.