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Spatio-temporal assessment of phylogenetic diversity gradients during the Holocene (past 12,000 years) provides an opportunity for a deeper understanding of the dynamics of species co-occurrence patterns under environmental fluctuations. Using two robust metrics of phylogenetic dispersion (PD) and 99 fossil pollen sequences containing 6557 samples/assemblages, we analyse spatio-temporal variation in PD of angiosperms and its relationship with Holocene climate in central Asia. Overall, PD throughout the Holocene decreases linearly with increasing latitude, except for a rise in mean nearest taxon distance from ca. 25 to 35° N. This indicates that phylogenetically divergent taxa decrease progressively with increasing latitude, leaving more phylogenetically closely related taxa in the assemblages, thereby increasing phylogenetic relatedness among the co-occurring taxa. The latitudinal gradient of PD has not been consistent during the Holocene, and this temporal variation is concordant with the Holocene climate dynamics. In general, profound temporal changes in the latitudinal PD toward higher latitudes implies that the major environmental changes during the Holocene have driven considerable spatio-temporal changes in the phylogenetic assembly of high-latitude angiosperm assemblages. Our results suggest that environmental filtering and the tendency of taxa and lineages to retain ancestral ecological features and geographic distributions (phylogenetic niche conservatism) are the main mechanisms underlying the phylogenetic assembly of angiosperms along the climate-latitudinal gradient. Ongoing environmental changes may pose future profound phylogenetic changes in high-latitude plant assemblages, which are adapted to harsh environmental conditions, and therefore are phylogenetically less dispersed (more conservative or clustered)., (© 2024. The Author(s).)

The high proportion of woody plant species on oceanic islands has hitherto been explained mainly by gradual adaptation to climatic conditions. Here, we present a novel hypothesis that such woodiness is adaptative to volcanic ash (tephra) deposition. Oceanic islands are subject to frequent eruptions with substantial and widespread ash deposition on evolutionary time scales. We postulate that this selects for woodiness through an increased ability to avoid burial of plant organs by ash, and to re-emerge above the new land surface. We sense-checked using observations of plant occurrences and distributions on La Palma (Canary Islands) in April 2022, 4 months after the end of the eruptions of the Tajogaite volcano (Cumbre Vieja ridge). In contrast to herbs and grasses, most woody plants persisted and were already in full flower in areas with 10+ cm ash deposition. Remarkably, these persisting woody plants were almost exclusively endemics., (© 2023. The Author(s).)

There is a consensus that climate factors strongly influence species richness along elevation gradients, but which factors are crucial and how they operate are still elusive. Here, we assess the relative importance of temperature-related versus precipitation-related variables and the relative importance of extreme climate versus climate seasonality in driving pteridophyte species richness. We used correlation and regression analyses to relate species richness of pteridophytes, and their two major groups (lycophytes, ferns), in fifty 100-m vertical bands to climatic factors representing different aspects of climatic conditions (general climate, stressful climate, and climate seasonality). Variation partitioning analysis was used to determine the relative importance of each group of climatic factors on species richness. Across the entire elevational gradient, species richness had a parabolic response to mean annual temperature (adjusted R 2  = .87-.91), and a linear response to annual precipitation (adjusted R 2  = .82). Mean annual temperature and annual precipitation in the second-order polynomial model together explained 96.3%-98.7% of the variation in species richness. The variation in species richness uniquely explained by minimum temperature of the coldest month was much greater than that uniquely explained by temperature seasonality, but the variation in species richness uniquely explained by precipitation during the driest month was much smaller than that uniquely explained by precipitation seasonality. Overall, extreme climate variables explained slightly more variation than did climate seasonality. Our study suggests that pteridophyte richness along the elevational gradient is largely driven by a combination of both temperature- and precipitation-related parameters, although precipitation-related variables play a slightly stronger role, and that extreme low temperature events (at high elevations) and seasonal precipitation variability (at low elevations) are the strongest determinants of pteridophyte species richness., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Habitat richness, that is, the diversity of ecosystem types, is a complex, spatially explicit aspect of biodiversity, which is affected by bioclimatic, geographic, and anthropogenic variables. The distribution of habitat types is a key component for understanding broad-scale biodiversity and for developing conservation strategies. We used data on the distribution of European Union (EU) habitats to answer the following questions: (i) how do bioclimatic, geographic, and anthropogenic variables affect habitat richness? (ii) Which of those factors is the most important? (iii) How do interactions among these variables influence habitat richness and which combinations produce the strongest interactions? The distribution maps of 222 terrestrial habitat types as defined by the Natura 2000 network were used to calculate habitat richness for the 10 km × 10 km EU grid map. We then investigated how environmental variables affect habitat richness, using generalized linear models, generalized additive models, and boosted regression trees. The main factors associated with habitat richness were geographic variables, with negative relationships observed for both latitude and longitude, and a positive relationship for terrain ruggedness. Bioclimatic variables played a secondary role, with habitat richness increasing slightly with annual mean temperature and overall annual precipitation. We also found an interaction between anthropogenic variables, with the combination of increased landscape fragmentation and increased population density strongly decreasing habitat richness. This is the first attempt to disentangle spatial patterns of habitat richness at the continental scale, as a key tool for protecting biodiversity. The number of European habitats is related to geography more than climate and human pressure, reflecting a major component of biogeographical patterns similar to the drivers observed at the species level. The interaction between anthropogenic variables highlights the need for coordinated, continental-scale management plans for biodiversity conservation., Competing Interests: No conflict of interest., (© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Background: Biogeographical units are widely adopted in ecological research and nature conservation management, even though biogeographical regionalisation is still under scientific debate. The European Environment Agency provided an official map of the European Biogeographical Regions (EBRs), which contains the official boundaries used in the Habitats and Birds Directives. However, these boundaries bisect cells in the official EU 10 km × 10 km grid used for many purposes, including reporting species and habitat data, meaning that 6881 cells overlap two or more regions. Therefore, superimposing the EBRs vector map over the grid creates ambiguities in associating some cells with European Biogeographical Regions., New Information: To provide an operational tool to unambiguously define the boundaries of the eleven European Biogeographical Regions, we provide a specifically developed raster map of Grid-Based European Biogeographical Regions (GB-EBRs). In this new map, the borders of the EBRs are reshaped to coherently match the standard European 10 km × 10 km grid imposed for reporting tasks by Article 17 of the Habitats Directive and used for many other datasets. We assign each cell to the EBR with the largest area within the cell.

Phylogenetic niche conservatism implies that sister taxa will have similar niches, although the niches of disjunct subspecies may evolve differently. This study uses Macaca assamensis, subspecies assamensis and pelops, to investigate the similarities of realized climatic niches of two disjunct subspecies (separated by the Brahmaputra River) along with a similarity analysis of their respective regions' climate. Modeled distributions were used to quantify their potential distribution under current and future climate scenarios. The climatic similarity between regions of each subspecies was tested with principal component analysis (PCA), and the realized climatic niche overlap between two subspecies was tested with a multivariate analysis of variance (MANOVA) on a subset of the least correlated variables out of 24 publicly available topo-bioclimatic variables. Tukey's honest significance difference (HSD) was used to test the range differences (on all 24 variables) between subspecies. The potential distribution of both taxa in the current climate and projected future climate was model-predicted using MaxEnt and Random Forest. We found significantly different climatic ranges for 21 predictors (HSD; p  <   0.05) for the two subspecies, significantly different climatic conditions for their regions (using PCA; p  <   0.001), and significantly different realized climatic niches for the two subspecies (MANOVA; p  <   0.001). The distribution models generated a larger potential area than the currently known distributions. Although literature show that the Brahmaputra River is an effective dispersal barrier, we found some of the neighboring geographic range for both subspecies appears to be potentially suitable for the other taxon. The projected future potential areas indicate that some parts of the currently occupied geography, mostly southern parts, may become climatically unsuitable, whereas other new geographical areas may become suitable. Most of these new potential areas will be toward the north where higher and fragmented mountains, which has conservation implications.

Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: ( i ) Indo-Pacific, ( ii ) Subtropical, ( iii ) African, ( iv ) American, and ( v ) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests., Competing Interests: Conflict of interest statement: V.A.-R., K.B.-G., B.B., F.Q.B., N.F., M.K., W.F.L., S. G. Letcher, C.B.S., D.S., T. Stevart, and S. Wiser have coauthored papers with Jens-Christian Svenning in the past 48 months. A.M.L. and Jens-Christian Svenning are both affiliated with Aarhus University., (Copyright © 2018 the Author(s). Published by PNAS.)

We compare different null models for species richness patterns in the Nepalese Himalayas, the largest altitudinal gradient in the world. Species richness is estimated by interpolation of presences between the extreme recorded altitudinal ranges. The number of species in 100-m altitudinal bands increases steeply with altitude until 1,500 m above sea level. Between 1,500 and 2,500 m, little change in the number of species is observed, but above this altitude, a decrease in species richness is evident. We simulate different null models to investigate the effect of hard boundaries and an assumed linear relationship between species richness and altitude. We also stimulate the effect of interpolation when incomplete sampling is assumed. Some modifications on earlier simulations are presented. We demonstrate that all three factors in combination may explain the observed pattern in species richness. Estimating species richness by interpolating species presence between maximum and minimum altitudes creates an artificially steep decrease in species richness toward the ends of the gradient. The addition of hard boundaries and an underlying linear trend in species richness is needed to simulate the observed broad pattern in species richness along altitude in the Nepalese Himalayas.