Modeled distribution shifts of North American birds over four decades based on suitable climate alone do not predict observed shifts

Environmental DNA reveals the spatiotemporal distribution and migration characteristics of the Yangtze finless porpoise, the sole aquatic mammal in the Yangtze River

The Yangtze Finless Porpoise (YFP) is one of the 13 global flagship species identified by the World Wildlife Fund and is classified as "Critically Endangered." It is also the only extant aquatic mammal in the Yangtze River. In this study, 44 sampling points were deployed across the middle and lower reaches of the Yangtze River, with vertical sampling sections established in four key areas. Using environmental DNA (eDNA) and species distribution model(SDM), we explored the spatiotemporal distribution of YFPs and predicted their potential suitable habitats. The results indicate that the YFP has a relatively wide distribution during the flood season but exhibits clustering behavior during the dry season, showing a patchy distribution and a migratory trend from the midstream to downstream of the main channel. Predictions using the MAXENT model reveal varying trends in suitable habitat under different scenarios. Overall, YFP's potential habitat is expected to expand by 2050, but due to rising temperatures, it will contract by 2070. Elevation (dem, 65.4%), human footprint index (hfp, 8.8%), and isothermality (bio3, 8%) are key factors influencing habitat suitability. These findings demonstrate that eDNA is an effective tool for monitoring large aquatic organisms and provide scientific evidence for the conservation of the YFP.

Population trends are more strongly linked to environmental change and species traits in birds than mammals

Changes in land use and climate directly impact species populations. Species with divergent characteristics may respond differently to these changes. Therefore, understanding species' responses to environmental changes is fundamental for alleviating biodiversity loss. However, the relationships between land use changes, climate changes, species' intrinsic traits and population changes at different spatial scales have not been tested. In this study, we analysed the effects of land use and climate changes from different time periods and species traits on the population change rates of 2195 bird and mammal populations in 577 species recorded in the Living Planet Database at global, tropical and temperate scales. We hypothesized that both bird and mammal populations will decline owing to climate and land use changes, especially phylogenetically young and small-bodied species. We found that bird population trends were more closely related to environmental changes and phylogenetic age than those of mammals at global and temperate scales. Mammal population trends were not significantly correlated with land use or climate changes but were with longevity at global and temperate scales. Given the divergent responses of bird and mammal populations to these explanatory variables, different conservation strategies should be considered for these taxa and for different regions.

Local climate change velocities and evolutionary history explain multidirectional range shifts in a North American butterfly assemblage

Species are often expected to shift their distributions either poleward or upslope to evade warming climates and colonise new suitable climatic niches. However, from 18-years of fixed transect monitoring data on 88 species of butterfly in the midwestern United States, we show that butterflies are shifting their centroids in all directions, except towards regions that are warming the fastest (southeast). Butterflies shifted their centroids at a mean rate of 4.87 km year-1. The rate of centroid shift was significantly associated with local climate change velocity (temperature by precipitation interaction), but not with mean climate change velocity throughout the species' ranges. Species tended to shift their centroids at a faster rate towards regions that are warming at slower velocities but increasing in precipitation velocity. Surprisingly, species' thermal niche breadth (range of climates butterflies experience throughout their distribution) and wingspan (often used as metric for dispersal capability) were not correlated with the rate at which species shifted their ranges. We observed high phylogenetic signal in the direction species shifted their centroids. However, we found no phylogenetic signal in the rate species shifted their centroids, suggesting less conserved processes determine the rate of range shift than the direction species shift their ranges. This research shows important signatures of multidirectional range shifts (latitudinal and longitudinal) and uniquely shows that local climate change velocities are more important in driving range shifts than the mean climate change velocity throughout a species' entire range.

Forecasting species' responses to climate change using space-for-time substitution

To anticipate species' responses to climate change, ecologists have largely relied on the space-for-time-substitution (SFTS) approach. However, the hypothesis and its underlying assumptions have been poorly tested. Here, we detail how the efficacy of using the SFTS approach to predict future locations will depend on species' traits, the ecological context, and whether the species is declining or introduced. We argue that the SFTS approach will be least predictive in the contexts where we most need it to be: forecasting the expansion of the range of introduced species and the recovery of threatened species. We highlight how evaluating the underlying assumptions, along with improved methods, will rapidly advance our understanding of the applicability of the SFTS approach, particularly in the context of modelling the distribution of species.

Range and climate niche shifts in European and North American breeding birds

Species respond dynamically to climate change and exhibit time lags. Consequently, species may not occupy their full climatic niche during range shifting. Here, we assessed climate niche tracking during recent range shifts of European and United States (US) birds. Using data from two European bird atlases and from the North American Breeding Bird Survey between the 1980s and 2010s, we analysed range overlap and climate niche overlap based on kernel density estimation. Phylogenetic multiple regression was used to assess the effect of species morphological, ecological and biogeographic traits on range and niche metrics. European birds shifted their ranges north and north-eastwards, US birds westwards. Range unfilling was lower than expected by null models, and niche expansion was more common than niche unfilling. Also, climate niche tracking was generally lower in US birds and poorly explained by species traits. Overall, our results suggest that dispersal limitations were minor in range shifting birds in Europe and the USA while delayed extinctions from unfavourable areas seem more important. Regional differences could be related to differences in land use history and monitoring schemes. Comparative analyses of range and niche shifts provide a useful screening approach for identifying the importance of transient dynamics and time-lagged responses to climate change. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

Local colonisations and extinctions of European birds are poorly explained by changes in climate suitability

Climate change has been associated with both latitudinal and elevational shifts in species' ranges. The extent, however, to which climate change has driven recent range shifts alongside other putative drivers remains uncertain. Here, we use the changing distributions of 378 European breeding bird species over 30 years to explore the putative drivers of recent range dynamics, considering the effects of climate, land cover, other environmental variables, and species' traits on the probability of local colonisation and extinction. On average, species shifted their ranges by 2.4 km/year. These shifts, however, were significantly different from expectations due to changing climate and land cover. We found that local colonisation and extinction events were influenced primarily by initial climate conditions and by species' range traits. By contrast, changes in climate suitability over the period were less important. This highlights the limitations of using only climate and land cover when projecting future changes in species' ranges and emphasises the need for integrative, multi-predictor approaches for more robust forecasting.