We address a critical gap in the elevational community ecology of tropical non-volant mammals in the Australian and Oceanian zoogeographic realms. Specifically, we document alpha and beta diversity, environmental predictors and community composition of individual clades in relation to their ecology and evolutionary history along an extensive elevational gradient, for the first time in this region.
Complete rainforest elevational gradient and subalpine zone of Mount Wilhelm (45–3700 masl), Papua New Guinea.
We conducted extensive sampling using traps (> 21,800 trap-nights) and collaboration with indigenous hunters across nine localities at 500 m intervals along the gradient, from lowland rainforest to subalpine grassland. The marsupial and rodent species were identified using morphological and genetic data. The community variables were correlated with key environmental variables.
In total, we recorded 61 marsupial and rodent species. We reveal an unusual pattern for tropical mammals: species richness increased linearly with elevation within continuous forest, then declined sharply in the open subalpine habitat. This contrasts with the mid-elevation richness peak, evident in regional mammal fauna and also common along elevation gradients globally. Community composition was primarily associated with temperature, with a sharp faunal turnover at 1200 masl dividing the assemblages into distinct lowland and highland communities.
The novel elevational pattern challenges prevailing models and underscores the importance of integrating multiple sampling techniques including collaboration with indigenous hunters, where possible, to accurately capture the full extent of community composition. We highlight the ecological and conservation values of examining complete elevational gradients in tropical ecosystems, as a single Mt. Wilhelm transect encompasses 80% of the regional diversity of non-volant mammals. We suggest that any long rainforest elevational gradient is likely a high conservation priority.
Globally, about 850 bird species depend on surface water habitats either year-round or during migration. However, large-scale analyses examining how different groups of waterbirds are associated with surface water across various regions and during different seasons are lacking. This study analyzes this relationship using high-resolution satellite imagery to determine when and where surface water and associated resources might be improved.
Western Palearctic (Europe, Middle East, Northern Africa).
We correlated monthly counts of 40 waterbird species with surface water availability in the Western Palearctic at a 100 × 100 km grid cell resolution. We then identified where and when surface water or associated resources might be limiting for waterbird numbers, using waterbird count data and the most recent release of high-resolution satellite imagery from the Copernicus project.
Surface water availability was higher in the East-Atlantic flyway than in the Black Sea–Mediterranean flyway, but differences were small, while bird abundances (after correction for observation effort) were comparable. The relationship between surface water and waterbird abundances was typically positive and slightly stronger in the East-Atlantic flyway. However, it was negative during summer in the northern regions, where many waterbirds breed. Correlations were stronger for ducks and other strictly wetland-dependent birds, reflecting their more exclusively aquatic feeding behaviour. Crowdedness, calculated as the number of birds per surface water area, was higher in autumn compared to spring migration.
Our results confirm that the importance of surface water availability for waterbirds varies seasonally and geographically. In addition, our maps integrating bird counts and surface water help to strategically prioritise regions where water availability could be limiting and high crowdedness implies a vulnerability for waterbirds, for example, in terms of resource competition or disease transmission. These include parts of the Iberian Peninsula, the UK, northern-central Europe, the Levant and Northern Africa.
Quantifying the speed of invasive species range expansion and the mechanisms behind it is a key management goal that also informs ecological theories of spread. Byers et al. found that time since first global introduction (TSI) was the strongest predictor of non-native range size of coastal marine invertebrates relative to environmental and species traits, and species were predicted to expand on average 400 km/decade along coastlines. Here, one decade later using the same 138 marine invertebrates, we repeat that analysis and test the prediction that the average invader expansion speed was 400 km from 2014 to 2024.
Using the Global Biodiversity Information Facility (GBIF), we downloaded species occurrences to estimate the non-native range size of each invader along coastlines in the northern and southern hemispheres. We calculated expansion speed as the difference between each species' 2024 range size and its 2014 range size estimated by Byers et al. We tested (Hypothesis 1) TSI is still the most important variable for explaining global invasive range size; (Hypothesis 2) Mean expansion speed is 400 km/decade; (Hypothesis 3) Expansion speed is best predicted by distributional characteristics of a species' non-native range (i.e., initial range size, initial number of coastlines occupied); and (Hypothesis 4) Expansion speeds vary across taxonomic groups.
TSI was still the best predictor of non-native range size (RVI = 1, β: 0.39–0.42). However, average range expansion speed since 2014 was 3000 km/decade, ~8× the previous prediction. Species that started with large ranges and distributions across multiple coastlines exhibited the fastest expansion speeds (R2 = 0.4), but there were no taxonomic patterns in expansion.
Ranges of non-native species are not at equilibrium and are still spreading rapidly, posing a challenge for coastal ecosystem management.
Using a widely distributed and frequently hybridising fish (genus Rutilus) in the Palearctic as a model system, we re-evaluated a series of hypotheses on phylogeny, taxonomy, phylogeography and the role of hybridization in evolutionary history based on the first large-scale analyses of nuclear SNPs together with mtDNA data obtained from all Rutilus species.
Water systems in Northern Eurasia.
Based on nuclear (ddRADseq) data, we applied phylogenomic, population genomic and introgression analyses to assess the diversity of lineages, their distribution and hybridization in the context of the hypotheses tested.
We identified 22 lineages in three major clades—Rutilus s. str., Leucos and Pararutilus. High diversity of lineages was discovered, with three revived species and three novel lineages of undescribed species in Europe. Evidence for extensive mito-nuclear discordance and ongoing and past inter- and intrageneric introgressive hybridization was found in many lineages. A Caucasian relic lineage and the endangered narrow endemic species ‘Rutilus’ atropatenus were found to represent an independent lineage (Orthroleucos) with a high level of past introgression with Rutilus.
The genetic structure of Rutilus revealed by nuclear SNPs contrasts markedly with that supported by mtDNA. Numerous mito-nuclear discordances are evidence of the past secondary contacts and highlight the weakness of taxonomy based on mtDNA alone. A super-lineage of mtDNA covering the range of many European, Siberian, Caucasian, and Central Asian Rutilus species (5000 km long) is a result of introgression of mtDNA from a widespread Ponto-Caspian lineage whose distribution likely pulsed with Pleistocene glaciation cycles. Anadromous life histories may have evolved in parallel in different clades and been facilitated by hybridization. The high plasticity, adaptiveness and species diversity of the genus Rutilus may be underlined by their heterogeneous genomes resulting from extensive interspecific hybridization. However, narrow-range endemic species may be threatened by introgressive hybridization.
For several decades, substantial efforts have monitored cetacean distribution and abundance in the western North Pacific. Large-scale visual-based line transect surveys have been conducted since the early 1980s, covering almost the entire western North Pacific. However, information on distribution patterns of cetacean species is concentrated in summer months when sighting conditions are preferred, while dolphin fisheries, one of the main threats to cetacean populations, are conducted mainly during winter months.
The western North Pacific.
To fill information gaps between these seasons and improve conservation and management measures, we compiled long-term sighting data. We constructed a simple species distribution model (SDM) to estimate the seasonal patterns for 14 delphinid and phocoenid species. Although the sighting data remained limited outside summer, the distribution probability was intra- and extrapolated to respective seasons using the constructed SDMs.
Model fitting tended to be better for the species inhabiting higher latitudes than for those in lower latitudes. In addition, seasonal patterns observed in our habitat prediction maps roughly corresponded to those patterns previously reported from coastal fishers' logbooks and satellite-tracking records. The model also estimated that some species distribution changes in response to long-term warming in water temperature over the past 30 years.
The study addresses the seasonal gaps in conservation and management measures and improves understanding of population structures of the species targeted by dolphin fisheries. Our approach to predicting distribution patterns spatiotemporally is widely applicable to conservation systems for marine animals inhabiting dynamic ocean environments.
Niche conservatism and niche shift, as two opposing ecological processes influencing invasive species spread, pose challenges for developing management strategies in China. However, how these mechanisms interact during invasion remains unclear. We propose that this uncertainty stems from species traits and invasion histories. Specifically, compared to weak invasive and non-invasive alien plants, we hypothesize that vigorous invasive plants in China are more likely to exhibit niche shifts.
China.
We quantified the niche dynamics of three categories of alien plant species in China using PCA and their driving factors, while simultaneously predicting their potential distributions with the MaxEnt model.
Annual mean temperature (Bio1), maximum temperature of the warmest month (Bio5), and precipitation of the driest month (Bio14) were identified as key environmental variables. Most alien plant species exhibited strong niche conservatism. Vigorous and weak invaders showed higher niche stability, lower unfilling, and lower pioneering, whereas non-invaders displayed higher niche expansion, unfilling, and pioneering. The niche centroids of most species shifted toward warmer, drier, and lower-elevation areas with more intensive human activity. Longer residence time was associated with lower niche unfilling across all three species categories. Propagule pressure promoted niche filling in vigorous and weak invaders. Species with broader native ranges exhibited higher niche stability. MaxEnt models indicated that vigorous and weak invaders had extensive potential distributions, while non-invaders were more restricted.
The invasion success of alien plants in China mainly depends on niche conservatism and effective niche filling rather than extensive niche expansion. Long-term residence and strong propagule pressure promote the occupation of potential habitats. Native niche breadth has a positive effect on niche conservatism. These findings provide a scientific basis for the monitoring, risk assessment, and management of alien plants.
Climate change is driving species to either shift their ranges or face extinction. While its effects on taxonomic diversity (TD) are relatively well understood, the impacts on functional diversity (FD) and phylogenetic diversity (PD) remain less explored. Among the biological metrics considered in protected area (PA) selection, TD is the most common, yet its effectiveness in also capturing high FD and PD under future climate scenarios is uncertain. Here, we assess the implications of future climate scenarios for the conservation of TD, FD and PD of forest birds.
Central Corridor of the Atlantic Forest (CCAF), Brazil.
We used ecological niche models to project the species distributions of 292 forest birds for baseline and future (2050 and 2070) scenarios. We generated binary maps of suitable areas for each species and calculated alpha and beta diversities for TD, FD and PD. We also evaluated spatial overlaps between highly diverse areas and the current PA network.
Most species are projected to experience range contractions, leading to declines in TD, FD, and PD. The western CCAF, a subregion with low diversity, is expected to face the greatest losses, while coastal areas show greater resilience with fewer declines. FD and PD exhibit distinct spatial patterns, including functional type replacements in the northwestern CCAF and variations in phylogenetic lineages in the central-eastern subregion. Northeastern PAs may retain higher diversity in the future, while the southern CCAF remains underrepresented in the current PA network. The eastern CCAF is identified as a subregion of community stability across TD, FD and PD.
Incorporating multiple facets of diversity offers a comprehensive framework for conservation strategies. Beta diversity highlights critical stable areas connecting highly diverse subregions of the CCAF. Therefore, a better understanding of these patterns can guide the preservation of species, their ecological roles and evolutionary heritage in a changing world.
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