Assessing the climatic niche changes and global invasion risk of Solanum elaeagnifolium in relation to human activities.

As an invasive plant, Solanum elaeagnifolium has posed a serious threat to agriculture and natural ecosystems worldwide. In order to better manage and limit its spread, we established niche models by combining distribution information and climate data from the native and invasive ranges of S. elaeagnifolium to analyze its niche changes during its colonization. Additionally, we evaluated its global invasion risk. Our results showed that the distribution of S. elaeagnifolium is affected by temperature, precipitation, altitude, and human activities. Solanum elaeagnifolium exhibits different degrees of niche conservatism and niche shift in different invasion ranges. During the global invasion of S. elaeagnifolium, both the niche shift and conservatism were observed, however, niche shift was particularly significant due to the presence of unoccupied niches (niche unfilling). Solanum elaeagnifolium generally occupied a relatively stable niche. However, a notable expansion was observed primarily in Europe and China. In Australia and Africa, its niche largely remains a subset of its native niche. Compared to the niche observed in its native range, its realized niche in China and Europe has shifted toward lower temperature and higher precipitation levels. Conversely, in Africa, the niche has shifted toward lower precipitation levels, while in Australia, it has shifted toward higher temperature. Our model predicted that S. elaeagnifolium has high invasion potential in many countries and regions. The populations of S. elaeagnifolium in China and Africa have reached the adapted stage, while the populations in Australia and Europe are currently in the stabilization stage. In addition, our research suggests that the potential distribution of S. elaeagnifolium will expand further in the future as the climate warms. All in all, our study suggests that S. elaeagnifolium has high potential to invade globally. Due to its high invasive potential, global surveillance and preventive measures are necessary to address its spread.

Offspring may succeed well next to their relatives, but it needs particular traits.

BACKGROUND AND AIMS: There is ongoing debate about whether offspring perform best next to phylogenetically distantly related adult neighbours (due to the scarcity of enemies and competitors) or next to closely related adults (due to the abundance of mutualists). Here we hypothesise that relatedness of adult neighbours affects which traits confer performance rather than performance itself. METHODS: We studied seed removal, seed germination and sapling growth in Sessile Oaks (Quercus petraea and hybrids), and how they depend on size, shape and other traits, under both closely and distantly related canopies, manipulating offspring-density, presence of insects, and fungi, and spatial proximity to oaks. KEY RESULTS: We found that phylogenetic distance of adult neighbours affects only little performance of offspring but strongly which traits confer performance to offspring, in particular the size and shape of seeds and saplings. Differences in trait-performance relationships mostly disappear once insects or conspecific competitors are excluded (albeit exclusion of fungi reinforced these differences). Effects of phylogenetic distance of neighbours were not replaceable by the percentage of the gymnosperms among neighbours, nor the environmental conditions considered. CONCLUSIONS: We suggest that by responding to a biotic micro-mosaic of selection pressures, Sessile Oak flexibly succeeds in diverse neighbourhoods. Sessile Oak might maintain the potential for both, convergence with and divergence from phylogenetically distantly related species, thereby reinforcing or eroding phylogenetic signal of niches.

Freshwater Habitats Promote Rapid Rates of Phenotypic Evolution in Sculpin Fishes (Perciformes: Cottoidea).

AbstractInvasions of freshwater habitats by marine fishes provide exceptional cases of habitat-driven biological diversification. Freshwater habitats make up less than 1% of aquatic habitats but contain ∼50% of fish species. However, while the dominant group of freshwater fishes (Otophysi) is older than that of most marine fishes (Percomorphaceae), it is less morphologically diverse. Classically, scientists have invoked differences in the tempo and/or mode of evolution to explain such cases of unequal morphological diversification. We tested for evidence of these phenomena in the superfamily Cottoidea (sculpins), which contains substantial radiations of marine and freshwater fishes. We find that the morphology of freshwater sculpins evolves faster but under higher constraint than that of marine sculpins, causing widespread convergence in freshwater sculpins and more morphological disparity in marine sculpins. The endemic freshwater sculpins of Lake Baikal, Siberia, are exceptions that demonstrate elevated novelty akin to that of marine sculpins. Several tantalizing factors may explain these findings, such as differences in habitat stability and/or habitat connectivity between marine and freshwater systems.

Climatic niche shifts and ecological sky-island dynamics in Mesoamerican montane birds.

An ongoing challenge in evolutionary and ecological research focuses on testing biogeographic hypotheses for the understanding of both species' distributional patterns and of the factors influencing range limits. In this study, we described the climatic niches of Neotropical humid montane forest birds through the analysis of factors driving their evolution at inter- and intraspecific levels; and tested for differences among allopatric lineages within Aulacorhynchus, Chlorospingus, Cardellina, and Eupherusa. We employed ecological niche models (ENMs) along with an ordination approach with kernel smoothing to perform niche overlap analyses and test hypotheses of niche equivalence/similarity among lineages. In addition, we described the potential distributions of each lineage during the Late Pleistocene climate fluctuations, identifying historical range expansions, connectivity, and stability. Overall, we observed differences in environmental variables influencing climatic requirements and distributional patterns for our selected species. We detected the highest values of niche overlap mainly between Eupherusa and some Chlorospingus lineages. At both interspecific and intraspecific levels, sister lineages showed non-identical environmental niches. Our results offer weak support to a moist forest model, in which populations followed the expansion and contraction cycles of montane forests, leading to a lack of niche conservatism among lineages (they tend to occupy not identical climatic environments) throughout Mesoamerica. Therefore, historical climatic conditions may act as ecological barriers determining the distributional ranges of these species.

Morphological evolution and niche conservatism across a continental radiation of Australian blindsnakes.

Understanding how continental radiations are assembled across space and time is a major question in macroevolutionary biology. Here, we use a phylogenomic-scale phylogeny, a comprehensive morphological dataset and environmental niche models to evaluate the relationship between trait and environment, and assess the role of geography and niche conservatism in the continental radiation of Australian blindsnakes. This fossorial snake group comprises 47 described species and is widespread across various biomes on continental Australia. Although we expected blindsnakes to be morphologically conserved, we found considerable interspecific variation in all morphological traits we measured. Absolute body length is negatively correlated with mean annual temperature and body shape ratios are negatively correlated with soil compactness. We found that morphologically similar species are likely not a result of ecological convergence. Age-overlap correlation tests revealed niche similarity decreased with relative age of speciation events. We also found low geographical overlap across the phylogeny suggesting speciation is largely allopatric with low rates of secondary range overlap. Our study offers insights into the eco-morphological evolution of blindsnakes, and the potential for phylogenetic niche conservatism to influence continental scale radiations.

Woody plant taxonomic, functional, and phylogenetic diversity decrease along elevational gradients in Andean tropical montane forests: Environmental filtering and arrival of temperate taxa.

Mountains are paramount for exploring biodiversity patterns due to the mosaic of topographies and climates encompassed over short distances. Biodiversity research has traditionally focused on taxonomic diversity when investigating changes along elevational gradients, but other facets should be considered. For first time, we simultaneously assessed elevational trends in taxonomic, functional, and phylogenetic diversity of woody plants in Andean tropical montane forests and explored their underlying ecological and evolutionary causes. This investigation covered four transects (traversing ca. 2200 m a.s.l.) encompassing 114 plots of 0.1 ha across a broad latitudinal range (ca. 10°). Using Hill numbers to quantify abundance-based diversity among 37,869 individuals we observed a consistent decrease in taxonomic, functional, and phylogenetic diversity as elevation increased, although the decrease was less pronounced for higher Hill orders. The exception was a slight increase in phylogenetic diversity when dominant species were over-weighted. The decrease in taxonomic and functional diversity might be attributed to an environmental filtering process towards highlands, where the increasingly harsher conditions exclude species and functional strategies. Besides, the differences in steepness decrease between Hill orders suggest that rare species disproportionately contribute to functional diversity. For phylogenetic diversity the shifting elevational trend between Hill orders indicates a greater than previously considered influence in central Andean highlands of tropical lowlands originated species with strong niche conservatism relative to distantly related temperate lineages. This could be explained by a decreasing presence and abundance of temperate, extratropical taxa towards the central Andes relative to northern or southern Andes, where they are more prevalent.

G-space versus E-space: Are hornets (Hymenoptera: Vespidae) at equilibrium with honeybees in Asia?

This study delves into the concept of niche conservatism (NC) and its implications for how hornets (Hymenoptera: Vespidae) and honeybees respond to climate change. Our primary objectives are threefold: firstly, to assess whether distinct environmental niche spaces (E-space) exist between 12 hornets and honeybees like Apis cerana and Apis mellifera in Asia; Secondly, to explore the degree to which Asian hornets have attained geographic equilibrium alongside honeybee species. Lastly, is to investigate how the geographic niche overlap (G-space) between hornets and honeybees could potentially change under climate change scenarios. To accomplish these goals, we employed ordination and ecological niche modeling techniques to analyze 91 pairs of hornets and honeybees in both geographic (G-space) and environmental (E-space) contexts. Then, we projected the potential impacts of climate change on the future geographic overlap between hornets and honeybees, specifically under the SSP585 climate scenario for the year 2070. Our results demonstrated that the environmental niches (E-space) of hornets and honeybees can be treated as interchangeable, indicating they have similar environmental preferences despite being unrelated taxa. We found that Vespa velutina currently exhibits a moderate geographic niche overlap (G-space) of 0.63 with both honeybee species. Meanwhile, Vespa mandarinia demonstrates an overlap of 0.46 with Apis cerana and 0.63 with Apis mellifera. The overlap of Vespa velutina with Apis cerana might potentially decrease to 0.51 and 0.56 with Apis mellifera. For Vespa mandarinia, the overlap could reach 0.41 with Apis cerana and 0.6 with Apis mellifera under a climate change scenario. This study indicates that the limited spatial overlap between honeybees and hornets across certain areas in Asia is more likely influenced by geographical barriers rather than solely environmental unsuitability for hornets. In this study, we delve into the concept of niche conservatism (NC) and its implications for how hornets (Hymenoptera: Vespidae) and honeybees respond to climate change.

Pleistocene climate oscillations have shaped the expansion and contraction speciation model of the globose Eriosyce sect. Neoporteria cacti in Central Chile.

BACKGROUND AND AIMS: Pleistocene climatic oscillations, characterized by arid (interglacial) and pluvial (glacial) phases, have profoundly impacted the floras of Mediterranean climates. Our study investigates the hypothesis that these climatic extremes have promoted phases of range expansion and contraction in the Eriosyce sect. Neoporteria, resulting in pronounced genetic structuring and restricted gene flow. METHODS: Utilizing nuclear microsatellite markers, we genotyped 251 individuals across 18 populations, encompassing all 14 species and one subspecies within the Eriosyce sect. Neoporteria. Additionally, Species Distribution Models (SDMs) were employed to reconstruct past (Last Interglacial, Last Glacial Maximum, Mid-Holocene) and current potential distribution patterns, aiming to delineate the climatic influences on species' range dynamics. KEY RESULTS: The gene flow analysis disclosed disparate levels of genetic interchange among species, with marked restrictions observed between entities that are geographically or ecologically separated. Notably, E. subgibbosa from Hualpen emerged as genetically distinct, warranting its exclusion for clearer genetic clustering into north, central, and south clusters. The SDMs corroborated these findings, showing marked range expansions during warmer periods and contractions during colder times, indicating significant shifts in distribution patterns in response to climatic changes. CONCLUSIONS: Our findings emphasize the critical role of Pleistocene climatic fluctuations in driving the dynamic patterns of range expansions and contractions that have led to geographic isolation and speciation within the Eriosyce sect. Neoporteria. Even in the face of ongoing gene flow, these climate-driven processes have played a pivotal role in sculpting the species' genetic architecture and diversity. This study elucidates the complex interplay between climatic variability and evolutionary dynamics among Mediterranean cacti in central Chile, highlighting the necessity of considering historical climatic millenial oscillations in conservation and evolutionary biology studies.

Spatial patterns and climatic drivers of phylogenetic structure of regional liverwort assemblages in China.

BACKGROUND AND AIMS: Latitudinal diversity gradients have been intimately linked to the tropical niche conservatism hypothesis, which posits that there has been a strong filter due to the challenges faced by ancestral tropical lineages to adapt to low temperatures and colonize extra-tropical regions. In liverworts, species richness is higher towards the tropics, but the centres of diversity of the basal lineages are distributed across extra-tropical regions, pointing to the colonization of tropical regions by phylogenetically clustered assemblages of species of temperate origin. Here, we test this hypothesis through analyses of the relationship between macroclimatic variation and phylogenetic diversity in Chinese liverworts. METHODS: Phylogenetic diversity metrics and their standardized effect sizes for liverworts in each of the 28 regional floras at the province level in China were related to latitude and six climate variables using regression analysis. We conducted variation partitioning analyses to determine the relative importance of each group of climatic variables. KEY RESULTS: We find that the number of species decreases with latitude, whereas phylogenetic diversity shows the reverse pattern, and that phylogenetic diversity is more strongly correlated with temperature-related variables compared with precipitation-related variables. CONCLUSIONS: We interpret the opposite patterns observed in phylogenetic diversity and species richness in terms of a more recent origin of tropical diversity coupled with higher extinctions in temperate regions.

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.

Ecological niche divergence or ecological niche partitioning in a widespread Neotropical bird lineage.

Ecological niche divergence is generally considered to be a facet of evolution that may accompany geographic isolation and diversification in allopatry, contributing to species' evolutionary distinctiveness through time. The null expectation for any two diverging species in geographic isolation is that of niche conservatism, wherein populations do not rapidly shift to or adapt to novel environments. Here, I test ecological niche divergence for a widespread, pan-American lineage, the avian genus of martins (Progne). The genus Progne includes migrant and resident species, as well as geographically restricted taxa and widespread, intercontinentally distributed taxa, thus providing an ideal group in which to study the nature of niche divergence within a broad geographic mosaic. I obtained distributional information for the genus from publicly available databases and created ecological niche models for each species to create pairwise comparisons of environmental space. I combined these data with the most up-to-date phylogeny of Progne currently available to examine the patterns of niche evolution within the genus. I found limited evidence for niche divergence across the breeding distributions of Progne, and much stronger support for niche conservatism with patterns of niche partitioning. The ancestral Progne had a relatively broad ecological niche, like extant basal Progne lineages, and several geographically localized descendant species occupy only portions of this larger ancestral niche. I recovered strong evidence of breeding niche divergence for four of 36 taxon pairs but only one of these divergent pairs involved two widespread species (Southern Martin P. elegans vs. Gray-breasted Martin P. chalybea). Potential niche expansion from the ancestral species was observed in the most wide-ranging present-day species, namely the North American Purple Martin P. subis and P. chalybea. I analyzed populations of P. subis separately, as a microcosm of Progne evolution, and again found only limited evidence of niche divergence. This study adds to the mounting evidence for niche conservatism as a dominant feature of diversifying lineages, and sheds light on the ways in which apparently divergent niches may arise through allopatry while not involving any true niche shifts through evolutionary time. Even taxa that appear unique in terms of habitat or behavior may not be diversifying with respect to their ecological niches, but merely partitioning ancestral niches among descendant taxa.

Radiating diversification and niche conservatism jointly shape the inverse latitudinal diversity gradient of Potentilla L. (Rosaceae).

BACKGROUND: The latitudinal diversity gradient (LDG), characterized by an increase in species richness from the poles to the equator, is one of the most pervasive biological patterns. However, inverse LDGs, in which species richness peaks in extratropical regions, are also found in some lineages and their causes remain unclear. Here, we test the roles of evolutionary time, diversification rates, and niche conservatism in explaining the inverse LDG of Potentilla (ca. 500 species). We compiled the global distributions of ~ 90% of Potentilla species, and reconstructed a robust phylogenetic framework based on whole-plastome sequences. Next, we analyzed the divergence time, ancestral area, diversification rate, and ancestral niche to investigate the macroevolutionary history of Potentilla. RESULTS: The genus originated in the Qinghai-Tibet Plateau during the late Eocene and gradually spread to other regions of the Northern Hemisphere posterior to the late Miocene. Rapid cooling after the late Pliocene promoted the radiating diversification of Potentilla. The polyploidization, as well as some cold-adaptive morphological innovations, enhanced the adaptation of Potentilla species to the cold environment. Ancestral niche reconstruction suggests that Potentilla likely originated in a relatively cool environment. The species richness peaks at approximately 45 °N, a region characterized by high diversification rates, and the environmental conditions are similar to the ancestral climate niche. Evolutionary time was not significantly correlated with species richness in the latitudinal gradient. CONCLUSIONS: Our results suggest that the elevated diversification rates in middle latitude regions and the conservatism in thermal niches jointly determined the inverse LDG in Potentilla. This study highlights the importance of integrating evolutionary and ecological approaches to explain the diversity pattern of biological groups on a global scale.

Eco-evolutionary evidence for the global diversity pattern of Cycas (Cycadaceae).

The evolution of the latitudinal diversity gradient (LDG), characterized by a peak in diversity toward the tropics, has captured significant attention in evolutionary biology and ecology. However, the inverse LDG (i-LDG) mechanism, wherein species richness increases toward the poles, remains inadequately explored. Cycads are among one of the oldest lineages of extant seed plants and have undergone extensive diversification in the tropics. Intriguingly, the extant cycad abundance exhibits an i-LDG pattern, and the underlying causes for this phenomenon remain largely elusive. Here, using 1,843 nuclear genes from a nearly complete sampling, we conducted comprehensive phylogenomic analyses to establish a robust species-level phylogeny for Cycas, the largest genus within cycads. We then reconstructed the spatial-temporal dynamics and integrated global environmental data to evaluate the roles of species ages, diversification rates, contemporary environment, and conservatism to ancestral niches in shaping the i-LDG pattern. We found Cycas experienced decreased diversification rates, coupled with the cooling temperature since its origin in the Eocene from continental Asia. Different regions have distinctively contributed to the formation of i-LDG for Cycas, with the northern hemisphere acting as evolutionary museums and the southern hemisphere serving as cradles. Moreover, water-related climate variables, specifically precipitation seasonality and potential evapotranspiration, were identified as paramount factors constraining Cycas species richness in the rainforest biome near the equator. Notably, the adherence to ancestral monsoonal climates emerges as a critical factor in sustaining the diversity pattern. This study underscores the imperative of integrating both evolutionary and ecological approaches to comprehensively unravel the mechanisms underpinning global biodiversity patterns.

Ecological niche divergence or ecological niche partitioning in a widespread Neotropical bird lineage.

Ecological niche divergence is generally considered to be a facet of evolution that may accompany geographic isolation and diversification in allopatry, contributing to species' evolutionary distinctiveness through time. The null expectation for any two diverging species in geographic isolation is that of niche conservatism, wherein populations do not rapidly shift to or adapt to novel environments. Here, I test ecological niche divergence for a widespread, pan-American lineage, the avian genus of martins (Progne). Despite containing species with distributions that go from continent-spanning to locally endemic, I found limited evidence for niche divergence across the breeding distributions of Progne, and much stronger support for niche conservatism with patterns of niche partitioning. The ancestral Progne had a relatively broad ecological niche, similar to extant basal Progne lineages, and several geographically localized descendant species occupy only portions of the larger ancestral Progne niche. I recovered strong evidence of breeding niche divergence for four of 36 taxon pairs but only one of these divergent pairs involved two widespread, continental species (Southern Martin P. elegans vs. Gray-breasted Martin P. chalybea). Potential niche expansion from the ancestral species was observed in the most wide-ranging present-day species, namely the North American Purple Martin P. subis and P. chalybea. I analyzed populations of P. subis separately, as a microcosm of Progne evolution, and again found only limited evidence of niche divergence. This study adds to the mounting evidence for niche conservatism as a dominant feature of diversifying lineages. Even taxa that appear unique in terms of habitat or behavior may still not be diversifying with respect to their ecological niches, but merely partitioning ancestral niches among descendant taxa.

Exploring the Climatic Niche Evolution of the Genus Falco (Aves: Falconidae) in Europe.

By integrating species distribution modeling techniques, phylogenetic comparative methods, and climatic data, we analyzed how European falcon climatic niches have changed over evolutionary time in order to understand their tempo and mode of evolution and gain phylogenetic insights related to the ecological context of falcon evolution. For this purpose, we tested the relative contributions of niche conservatism, convergent evolution, and divergent evolution in the evolutionary history of this group of species in Europe. The occupation of climatic niche spaces by falcon species in Europe was not similar, considering that their climatic niche evolution was characterized by heterotachy, especially after ca. 4 Mya. Our results indicate that convergent evolution and niche divergence played an important role in the evolutionary history of these species, with no significant evidence of closely related species retaining their fundamental niche over time (phylogenetic niche conservatism). In most analyses, less closely related falcon species occupied similar climatic environments. We found that speciation in the European genus Falco was influenced by climatic niche differentiation, more prevalent in the last 4 million years, with the main climatic niche shifts occurring between closely related falcon species.

Insights from the past: Invasion trajectory and niche trends of a global freshwater invader.

Freshwater ecosystems are invaded by a non-random selection of taxa, among which crayfish stand out with successful examples worldwide. Species distribution models (SDMs) have been used to detect suitable areas for invasive species and predict their potential distributions. However, these prediction exercises assume the stability of realized environmental niches, which is uncertain during invasion. Worldwide evaluations involving cosmopolitan invaders may be particularly useful but have seldom been considered. Focusing on the successful invasion history of the red swamp crayfish, Procambarus clarkii, we assessed its geographic expansion and niche trends over time. Based on global occurrences from 1854 to 2022, multiple sequential SDMs have been implemented based on a set of bioclimatic variables. The environmental suitability for each period was projected through to the next period(s) using an ensemble procedure of commonly used SDM algorithms. As the records of the species are known, it was possible to check whether the modelling projections were concordant with the observed expansion of red swamp crayfish at a global scale. This also permitted analysis of its realized niche, and its dynamics, during different expansion phases. SDM maps based on past species records showed concordance with the known crayfish distributions and yielded similar spatial patterns with outputs overperforming random combinations of cells in term of suitability. The results also reflect the stability of the species niche, which despite some expansions during the invasion process, changed little in terms of main position in functional space over time. SDMs developed in the early stages of invasion provide useful insights but also tend to underpredict the potential range compared to models that were built for later stages. Our approach can be easily transferable to other well-documented taxa and represents valuable evidence for validating the use of SDMs, considering a highly dynamic world where biogeographical barriers are often bypassed.

Tropical Origin, Global Diversification, and Dispersal in the Pond Damselflies (Coenagrionoidea) Revealed by a New Molecular Phylogeny.

The processes responsible for the formation of Earth's most conspicuous diversity pattern, the latitudinal diversity gradient (LDG), remain unexplored for many clades in the Tree of Life. Here, we present a densely sampled and dated molecular phylogeny for the most speciose clade of damselflies worldwide (Odonata: Coenagrionoidea) and investigate the role of time, macroevolutionary processes, and biome-shift dynamics in shaping the LDG in this ancient insect superfamily. We used process-based biogeographic models to jointly infer ancestral ranges and speciation times and to characterize within-biome dispersal and biome-shift dynamics across the cosmopolitan distribution of Coenagrionoidea. We also investigated temporal and biome-dependent variation in diversification rates. Our results uncover a tropical origin of pond damselflies and featherlegs ~105 Ma, while highlighting the uncertainty of ancestral ranges within the tropics in deep time. Even though diversification rates have declined since the origin of this clade, global climate change and biome-shifts have slowly increased diversity in warm- and cold-temperate areas, where lineage turnover rates have been relatively higher. This study underscores the importance of biogeographic origin and time to diversify as important drivers of the LDG in pond damselflies and their relatives, while diversification dynamics have instead resulted in the formation of ephemeral species in temperate regions. Biome-shifts, although limited by tropical niche conservatism, have been the main factor reducing the steepness of the LDG in the last 30 Myr. With ongoing climate change and increasing northward range expansions of many damselfly taxa, the LDG may become less pronounced. Our results support recent calls to unify biogeographic and macroevolutionary approaches to improve our understanding of how latitudinal diversity gradients are formed and why they vary across time and among taxa.

Rapid in situ diversification rates in Rhamnaceae explain the parallel evolution of high diversity in temperate biomes from global to local scales.

The macroevolutionary processes that have shaped biodiversity across the temperate realm remain poorly understood and may have resulted from evolutionary dynamics related to diversification rates, dispersal rates, and colonization times, closely coupled with Cenozoic climate change. We integrated phylogenomic, environmental ordination, and macroevolutionary analyses for the cosmopolitan angiosperm family Rhamnaceae to disentangle the evolutionary processes that have contributed to high species diversity within and across temperate biomes. Our results show independent colonization of environmentally similar but geographically separated temperate regions mainly during the Oligocene, consistent with the global expansion of temperate biomes. High global, regional, and local temperate diversity was the result of high in situ diversification rates, rather than high immigration rates or accumulation time, except for Southern China, which was colonized much earlier than the other regions. The relatively common lineage dispersals out of temperate hotspots highlight strong source-sink dynamics across the cosmopolitan distribution of Rhamnaceae. The proliferation of temperate environments since the Oligocene may have provided the ecological opportunity for rapid in situ diversification of Rhamnaceae across the temperate realm. Our study illustrates the importance of high in situ diversification rates for the establishment of modern temperate biomes and biodiversity hotspots across spatial scales.

Genomic data and ecological niche modeling reveal an unusually slow rate of molecular evolution in the Cretaceous Eupteleaceae.

Living fossils are evidence of long-term sustained ecological success. However, whether living fossils have little molecular changes remains poorly known, particularly in plants. Here, we have introduced a novel method that integrates phylogenomic, comparative genomic, and ecological niche modeling analyses to investigate the rate of molecular evolution of Eupteleaceae, a Cretaceous relict angiosperm family endemic to East Asia. We assembled a high-quality chromosome-level nuclear genome, and the chloroplast and mitochondrial genomes of a member of Eupteleaceae (Euptelea pleiosperma). Our results show that Eupteleaceae is most basal in Ranunculales, the earliest-diverging order in eudicots, and shares an ancient whole-genome duplication event with the other Ranunculales. We document that Eupteleaceae has the slowest rate of molecular changes in the observed angiosperms. The unusually low rate of molecular evolution of Eupteleaceae across all three independent inherited genomes and genes within each of the three genomes is in association with its conserved genome architecture, ancestral woody habit, and conserved niche requirements. Our findings reveal the evolution and adaptation of living fossil plants through large-scale environmental change and also provide new insights into early eudicot diversification.

Historical Assembly of Andean Tree Communities.

Patterns of species diversity have been associated with changes in climate across latitude and elevation. However, the ecological and evolutionary mechanisms underlying these relationships are still actively debated. Here, we present a complementary view of the well-known tropical niche conservatism (TNC) hypothesis, termed the multiple zones of origin (MZO) hypothesis, to explore mechanisms underlying latitudinal and elevational gradients of phylogenetic diversity in tree communities. The TNC hypothesis posits that most lineages originate in warmer, wetter, and less seasonal environments in the tropics and rarely colonize colder, drier, and more seasonal environments outside of the tropical lowlands, leading to higher phylogenetic diversity at lower latitudes and elevations. In contrast, the MZO hypothesis posits that lineages also originate in temperate environments and readily colonize similar environments in the tropical highlands, leading to lower phylogenetic diversity at lower latitudes and elevations. We tested these phylogenetic predictions using a combination of computer simulations and empirical analyses of tree communities in 245 forest plots located in six countries across the tropical and subtropical Andes. We estimated the phylogenetic diversity for each plot and regressed it against elevation and latitude. Our simulated and empirical results provide strong support for the MZO hypothesis. Phylogenetic diversity among co-occurring tree species increased with both latitude and elevation, suggesting an important influence on the historical dispersal of lineages with temperate origins into the tropical highlands. The mixing of different floras was likely favored by the formation of climatically suitable corridors for plant migration due to the Andean uplift. Accounting for the evolutionary history of plant communities helps to advance our knowledge of the drivers of tree community assembly along complex climatic gradients, and thus their likely responses to modern anthropogenic climate change.