Climatic Niche Models Research Articles

Population structure and hybridization under contemporary and future climates in a heteroploid foundational shrub species (Artemisia tridentata).

Current and past climatic changes can shift plant climatic niches, which may cause spatial overlap or separation between related taxa. The former often leads to hybridization and introgression, which may generate novel variation and influence the adaptive capacity of plants. An additional mechanism facilitating adaptations to novel environments and an important evolutionary driver in plants is polyploidy as the result of whole genome duplication. Artemisia tridentata (big sagebrush) is a landscape-dominating foundational shrub in the western United States which occupies distinct ecological niches, exhibiting diploid and tetraploid cytotypes. Tetraploids have a large impact on the species' landscape dominance as they occupy a preponderance of the arid spectrum of A. tridentata range. Three distinct subspecies are recognized, which co-occur in ecotones - the transition zone between two or more distinct ecological niches - allowing for hybridization and introgression. Here we assess the genomic distinctiveness and extent of hybridization among subspecies at different ploidies under both contemporary and predicted future climates. We sampled five transects throughout the western United States where a subspecies overlap was predicted using subspecies-specific climate niche models. Along each transect, we sampled multiple plots representing the parental and the potential hybrid habitats. We performed reduced representation sequencing and processed the data using a ploidy-informed genotyping approach. Population genomic analyses revealed distinct diploid subspecies and at least two distinct tetraploid gene pools, indicating independent origins of the tetraploid populations. We detected low levels of hybridization (2.5%) between the diploid subspecies, while we found evidence for increased admixture between ploidy levels (18%), indicating hybridization has an important role in the formation of tetraploids. Our analyses highlight the importance of subspecies co-occurrence within these ecotones to maintain gene exchange and potential formation of tetraploid populations. Genomic confirmations of subspecies in the ecotones support the subspecies overlap predicted by the contemporary climate niche models. However, future mid-century projections of subspecies niches predict a substantial loss in range and subspecies overlap. Thus, reductions in hybridization potential could affect new recruitment of genetically variable tetraploids that are vital to this species' ecological role. Our results underscore the importance of ecotone conservation and restoration.

Environment as a limiting factor of the historical global spread of mungbean.

While the domestication process has been investigated in many crops, the detailed route of cultivation range expansion and factors governing this process received relatively little attention. Here using mungbean (Vigna radiata var. radiata) as a test case, we investigated the genomes of more than one thousand accessions to illustrate climatic adaptation's role in dictating the unique routes of cultivation range expansion. Despite the geographical proximity between South and Central Asia, genetic evidence suggests mungbean cultivation first spread from South Asia to Southeast, East, and finally reached Central Asia. Combining evidence from demographic inference, climatic niche modeling, plant morphology, and records from ancient Chinese sources, we showed that the specific route was shaped by the unique combinations of climatic constraints and farmer practices across Asia, which imposed divergent selection favoring higher yield in the south but short-season and more drought-tolerant accessions in the north. Our results suggest that mungbean did not radiate from the domestication center as expected purely under human activity, but instead the spread of mungbean cultivation is highly constrained by climatic adaptation, echoing the idea that human commensals are more difficult to spread through the south-north axis of continents.

A new species and a new record for Cedrela (Meliaceae, Sapindales) in Ecuador: morphological, molecular, and distribution evidence

A new Cedrela (Meliaceae) species, Cedrela angusticarpa, is described through a combination of taxonomic, morphological, and molecular analyses. Cedrela kuelapensis, originally described as an endemic species of northern Peru, is also reported here as a new record for Ecuador. Cedrela angusticarpa has oblong or oblong-lanceolate glabrous leaflets, rounded at the base. Inflorescences are up to 70 cm long, and flowers present a cupuliform calyx with five regular teeth. Fruits are narrowly obovoid capsules. Through molecular analyses using nine microsatellite loci, it is evident that samples from C. angusticarpa form their own genetic cluster when compared to the most morphologically similar species, C. odorata, suggesting that they belong to a new separate species. Additionally, here we report that C. angusticarpa has a very narrow geographic range, recorded between 550 and 1300 m in elevation, and restricted to the relatively small areas of northwestern Ecuador. Climatic niche modelling techniques were used as a proxy for assessing potential distributions and habitat loss percentages for both C. angusticarpa and C. kuelapensis. Finally, IUCN Red List categories and criteria were applied to assess the conservation status of both Cedrela species analyzed here.

Assessment of the impact of climate change on endangered conifer tree species by considering climate and soil dual suitability and interspecific competition

Climate change results in the habitat loss of many conifer tree species and jeopardizes species biodiversity and forest ecological functions. Delineating suitable habitats for tree species via climate niche model (CNM) is widely used to predict the impact of climate change and develop conservation and management strategies. However, the robustness of CNM is broadly debated as it usually does not consider soil and competition factors. Here we developed a new approach to combine soil variables with CNM and evaluate interspecific competition potential in the niche overlapping areas. We used an endangered conifer species - Chamaecyparis formosensis (red cypress) - as a case study to predict the impact of climate change. We developed a novel approach to integrate the climate niche model and soil niche model predictions and considered interspecific competition to predict the impacts of climate change on tree species. Our results show that the suitable habitat for red cypress would decrease significantly in the future with an additional threat from the competition of an oak tree species. Our approach and results may represent significant implications in making conservation strategies and evaluating the impacts of climate change, and providing the direction of the refinement of the ecological niche model.

Predicting fundamental climate niches of forest trees based on species occurrence data

Species climate niche models (CNMs) have been widely used for assessing climate change impact, developing conservation strategies and guiding assisted migration for adaptation to future climates. However, the CNMs built based on species occurrence data only reflect the species’ realized niche, which can overestimate the potential loss of suitable habitat of existing forests and underestimate the potential of assisted migration to mitigate climate change. In this study, we explored building a fundamental climate niche model using widely available species occurrence data with two important forest tree species, lodgepole pine (Pinus contorta Dougl. ex Loud.) and Douglas-fir (Pseudotsuga menziesii Franco.), which were introduced to many countries worldwide. We first compared and optimized three individual modeling techniques and their ensemble by adjusting the ratio of presence to absence (p/a) observations using an innovative approach to predict the realized climate niche of the two species. We then extended the realized climate niches to their fundamental niches by determining a new cut-off threshold based on species occurrence data beyond the native distributions. We found that the ensemble model comprising Random Forest and Maxent had the best performance and identified a common cut-off threshold of 0.3 for predicting the fundamental climate niches of the two species, which is likely applicable to other species. We then predicted the fundamental climate niches of the two species under current and future climate conditions. Our study demonstrated a novel approach for predicting species’ fundamental climate niche with high accuracy using only species occurrence data, including both presence and absence data points. It provided a new tool for assessing climate change impact on the future loss of existing forests and implementing assisted migration for better adapting to future climates.

Historical demography and climatic niches of the Natal multimammate mouse (Mastomys natalensis) in the Zambezian region

The Natal multimammate mouse (Mastomys natalensis) is the most widespread rodent species in sub-Saharan Africa, often studied as an agricultural pest and reservoir of viruses. Its mitochondrial (Mt) phylogeny revealed six major lineages parapatrically distributed across open habitats of sub-Saharan Africa. In this study we used 1949 sequences of the mitochondrial cytochrome b gene to elaborate on distribution and evolutionary history of three Mt lineages inhabiting the open habitats of the Zambezian region (corresponding roughly to the African savannas south of the Equator). We describe in more detail contact zones between the lineages—their location and extent of co-occurrence within localities—and infer past population trends. The estimates are interpreted in the light of climatic niche models. The lineages underwent reduction in effective population size during the last glacial, but they spread widely after that: two of them after the last glacial maximum and the last one in mid-Holocene. The centers of expansion, i.e., possible long-term savanna refugia, were estimated to lie close to the Eastern Arc Mountains and lakes of the Great African Rift, geomorphological structures likely to have had long-term influence on geographical distribution of the lineages. Environmental niche modeling shows climate could also affect the broad scale distribution of the lineages but is unlikely to explain the narrow width of the contact zones. The intraspecific Mt differentiation of M. natalensis echoes phylogeographic patterns observed in multiple co-distributed mammal species, which suggests the mammal communities in the region are shaped by the same long-term processes.

Predicting the global fundamental climate niche of lodgepole pine for climate change adaptation

The widely used species-occurrence-based models that predict the realized climate niche of plants can be too restrictive and do not reflect among-population variation in assessing climate change impact and guiding assisted migration for adaptation to future climates. To mitigate this deficiency, this study built a fundamental climate niche model for lodgepole pine (Pinus contortaDougl. ex Loud.) based on 20-year tree height from wide-ranging provenance trials as a case study. The model was built through comparisons and optimizations of two candidate models, universal response function (URF) and universal transfer function (UTF), with linear and linear mixed-effect forms, against varying sample sizes based on the comprehensive provenance trials. We found that URF and UTF models had similar performances, while URF models were more straightforward in identifying optimal provenances for planting sites. Linear mixed-effect models did not show clear advantages over linear models in our case but prevented including additional predictors, which are often critical. We selected the linear model of URF and predicted the fundamental climate niche of lodgepole pine on a global scale and revealed a great potential of using this species for climate change adaptation beyond its native distribution, representing a significant step in forest genecology. Our study presented a new approach for assisted migration at the species and the population levels to optimize adaptation and productivity under a changing climate.

Widespread and ongoing invasion by the ant Technomyrmex brunneus Forel in eastern Asia as elucidated by molecular data

AbstractAnts are among the most pervasive and impactful invasive species. While some characteristics of invasive ants have been linked to establishment success and competitive dominance, these traits are not universal to all successful invaders and much crucial information on the biology of both well‐known and lesser‐known invasive ants remains lacking. In this study, we address this knowledge gap using a molecular approach to define the ongoing invasion by the white‐footed ant, Technomyrmex brunneus, in eastern Asia. This species is native to eastern and south‐eastern Asia but has become a problematic invader in Japan where significant expansions in range have been documented in recent decades. Its status in eastern Asia is complicated by taxonomic confusion and misidentifications, creating significant hurdles to threat assessment, management, and the establishment of fundamental information such as the delineation of the native and invasive range. We combine mitochondrial DNA sequences with genome‐wide single‐nucleotide polymorphisms to elucidate relationships between populations from Vietnam to Japan. Our data reveal very limited genetic differentiation among populations despite their broad geographic spread. This can most parsimoniously be explained as a recent and ongoing invasion, likely facilitated by human dispersal. The one exception to this pattern was strong genetic distinction between two regions in China indicated by mitochondrial DNA. We speculate that this may indicate a boundary between a native population and more recent wave of invasion. Finally, we present the results of climate niche modeling indicating that extensive additional areas remain suitable for this species, suggesting this invasion is far from complete.

Challenges for incorporating long‐term baselines into biodiversity restoration: A case study of the Dalmatian Pelican (Pelecanus crispus) in Britain

Species reintroductions are a core component of conservation but require critical assessment of past baselines. The Dalmatian Pelican Pelecanus crispus formerly occurred in Britain during the Holocene and there is interest in its possible reintroduction, but its regional extinction dynamics remain poorly understood. Pelican bones are known from subfossil and zooarchaeological contexts at 11 British Holocene sites in three regions (East Anglian Fens, Somerset Levels and Moors, Humber Valley). Dalmatian Pelican is positively identified from four of these sites, with other specimens only identified to genus level. Pelican populations were probably only present periodically in Britain during intervals of suitable climate and available habitat: there is little evidence for pelicans before the Bronze Age, and most sites are known or inferred to be Iron Age. There is a suggested Medieval specimen but no secure evidence of pelican presence after the Roman period. However, no specimens are directly dated, with age estimation reliant upon indirect dates or inference. Climatic niche modelling indicates that southern Britain was the northwestern limit of pelican climate tolerance under postglacial conditions, and pelicans may have been unable to persist regionally until the mid‐ or late Holocene. Considerable pelican breeding and foraging habitat might have existed until the Medieval period, but availability of suitable habitat fluctuated throughout the Holocene. Probabilistic analysis suggests possible mean extinction date estimates between ad 589 and ad 1587, highlighting uncertainty associated with indirect data, and hindering our ability to correlate pelican disappearance with putative extinction drivers (overexploitation, human modification of wetlands, or non‐anthropogenic environmental changes). Improving our understanding of conditions associated with past pelican occurrence is essential for potential reintroduction decision‐making, and direct dating of bones from all sites is needed to establish a secure chronological framework for correlating pelican presence and disappearance with regional landscape change. This review provides a robust framework for how to integrate past environmental baselines into conservation decision‐making and reintroduction feasibility assessments.

Between the Cape Fold Mountains and the deep blue sea: Comparative phylogeography of selected codistributed ectotherms reveals asynchronous cladogenesis.

We compare the phylogeographic structure of 13 codistributed ectotherms including four reptiles (a snake, a legless skink and two tortoise species) and nine invertebrates (six freshwater crabs and three velvet worm species) to test the presence of congruent evolutionary histories. Phylogenies were estimated and dated using maximum likelihood and Bayesian methods with combined mitochondrial and nuclear DNA sequence datasets. All taxa demonstrated a marked east/west phylogeographic division, separated by the Cape Fold Mountain range. Phylogeographic concordance factors were calculated to assess the degree of evolutionary congruence among the study species and generally supported a shared pattern of diversification along the east/west longitudinal axis. Testing simultaneous divergence between the eastern and western phylogeographic regions indicated pseudocongruent evolutionary histories among the study taxa, with at least three separate divergence events throughout the Mio/Plio/Pleistocene epochs. Climatic refugia were identified for each species using climatic niche modelling, demonstrating taxon-specific responses to climatic fluctuations. Climate and the Cape Fold Mountain barrier explained the highest proportion of genetic diversity in all taxa, while climate was the most significant individual abiotic variable. This study highlights the complex interactions between the evolutionary history of fauna, the Cape Fold Mountains and past climatic oscillations during the Mio/Plio/Pleistocene. The congruent east/west phylogeographic division observed in all taxa lends support to the conclusion that the longitudinal climatic gradient within the Greater Cape Floristic Region, mediated in part by the barrier to dispersal posed by the Cape Fold Mountains, plays a major role in lineage diversification and population differentiation.

Cerrado native vegetation is a refuge for birds under the current climate change trajectory

AbstractClimate change is already seen as one of the biggest threats to biodiversity in the 21st century. Not many studies direct attention to its effects on whole communities of threatened hotspots. In this work, we combine climate niche modelling (ENM) with a future climate scenario of greenhouse gases emissions to study the future changes in alpha and beta diversity of birds of the Brazilian Cerrado biome, a hot spot of biodiversity with high velocity of climate change and agricultural expansion. We expected Southern Cerrado (highly modified) to present most negative changes. In general, we found heterogeneous results for changes in species richness, spatial and temporal taxonomic and functional beta diversity, and mean ecological distinctiveness. We analysed 1301 birds, 1115 Least Concern, 83 Near Threatened, 63 Vulnerable, 33 Endangered, five Critically Endangered and two Extinct in the Wild. Contrary to a previous study on Cerrado mammals, species richness is expected to increase in Northern Cerrado, where homogenization of communities (decreasing spatial turnover) is also expected to occur especially through local invasions. We show that biotic homogenization increasing (similarity among communities) will occur in two biological groups but through different subprocesses: local extinctions for mammals and local invasions for birds. Distinct conservation management actions should be directed depending on the outcomes of analyses of alpha and spatial and temporal beta diversity, for example controlling species invasions in Northern Cerrado. We also show species‐level priorities for Cerrado birds. Conservation studies should continue evaluating Cerrado in Brazil even under covid pandemic, as environmental situation in the country is not good and incentives for scientific studies are almost nonexistent. We also consider that Northern Cerrado could be seen as a potential refuge for other organismal groups (bats, butterflies, frogs, etc). Therefore, ambitious conservation actions by decision‐makers are now crucial.

The right tree in the right place? A major economic tree species poses major ecological threats

Tree species in the Pinaceae are some of the most widely introduced non-native tree species globally, especially in the southern hemisphere. In New Zealand, plantations of radiata pine (Pinus radiata D. Don) occupy c. 1.6 million ha and form 90% of planted forests. Although radiata pine has naturalized since 1904, there is a general view in New Zealand that this species has not invaded widely. We comprehensively review where radiata pine has invaded throughout New Zealand. We used a combination of observational data and climate niche modelling to reveal that invasion has occurred nationally. Climate niche modelling demonstrates that while current occurrences are patchy, up to 76% of the land area (i.e. 211,388 km2) is climatically capable of supporting populations. Radiata pine has mainly invaded grasslands and shrublands, but also some forests. Notably, it has invaded lower-statured vegetation, including three classes of naturally uncommon ecosystems, primary successions and secondary successions. Overall, our findings demonstrate pervasive and ongoing invasion of radiata pine outside plantations. The relatively high growth rates and per individual effects of radiata pine may result in strong effects on naturally uncommon ecosystems and may alter successional trajectories. Local and central government currently manage radiata pine invasions while propagule pressure from existing and new plantations grows, hence greater emphasis is warranted both on managing current invasions and proactively preventing future radiata pine invasions. We therefore recommend a levy on new non-native conifer plantations to offset costs of managing invasions, and stricter regulations to protect vulnerable ecosystems. A levy on economic uses of invasive species to offset costs of managing invasions alongside stricter regulations to protect vulnerable ecosystems could be a widely adopted measure to avert future negative impacts.

Trees planted under a global restoration pledge have mixed futures under climate change

Nations worldwide have committed to restoring millions of hectares of forest as a strategy to mitigate climate change with many other co‐benefits. Paradoxically, the suitability of climatic conditions for the trees being planted at the restoration sites is changing, which may reduce the long‐term viability of these projects. We assessed the potential future viability of trees planted as part of Ecuador's National Reforestation Plan from 2014 to 2017, committed under the global Bonn Challenge. We selected the 10 most frequently planted tree species (all native) in 1237 restoration sites in northwest Ecuador. We modeled the species' climatic suitability at the restoration sites under Representative Concentration Pathways (RCP) 4.5 and 8.5 using 14 individual general circulation models for the 2030s, 2050s, and 2070s. We combined the 14 suitability models to create continuous climatic suitability models for each species. We then assessed the species suitability against three modeling thresholds simultaneously. Seven of the species showed high and medium climatic viability, all of these species were native to the region of planting. Three species showed low climatic viability; two of these are native to the country but not to the region being restored. Our results also show how using continuous rather than discrete modeling can affect viability assessments. Our study suggests the importance of including climate niche modeling in restoration projects; however, choosing to plant species that are within their native distribution range may be a good strategy in tropical regions if climate niche projections are not available.

From the Balkan towards Western Europe: Range expansion of the golden jackal (Canis aureus)-A climatic niche modeling approach.

In recent decades, a rapid range expansion of the golden jackal (Canis aureus) towards Northern and Western Europe has been observed. The golden jackal is a medium‐sized canid, with a broad and flexible diet. Almost 200 different parasite species have been reported worldwide from C. aureus, including many parasites that are shared with dogs and cats and parasite species of public health concern. As parasites may follow the range shifts of their host, the range expansion of the golden jackal could be accompanied by changes in the parasite fauna in the new ecosystems. In the new distribution area, the golden jackal could affect ecosystem equilibrium, e.g., through changed competition situations or predation pressure. In a niche modeling approach, we project the future climatic habitat suitability of the golden jackal in Europe in the context of whether climatic changes promote range expansion. We use an ensemble forecast based on six presence‐absence algorithms to estimate the climatic suitability of C. aureus for different time periods up to the year 2100 considering different IPCC scenarios on future development. As predictor variables, we used six bioclimatic variables provided by worldclim. Our results clearly indicate that areas with climatic conditions analogous to those of the current core distribution area of the golden jackal in Europe will strongly expand towards the north and the west in future decades. Thus, the observed range expansion may be favored by climate change. The occurrence of stable populations can be expected in Central Europe. With regard to biodiversity and public health concerns, the population and range dynamics of the golden jackal should be surveyed. Correlative niche models provide a useful and frequently applied tool for this purpose. The results can help to make monitoring more efficient by identifying areas with suitable habitat and thus a higher probability of occurrence.

Multi-Decadal Mapping and Climate Modelling Indicates Eastward Rubber Plantation Expansion in India

Automated long-term mapping and climate niche modeling are important for developing adaptation and management strategies for rubber plantations (RP). Landsat imageries at the defoliation and refoliation stages were employed for RP mapping in the Indian state of Tripura. A decision tree classifier was applied to Landsat image-derived vegetation indices (Normalized Difference Vegetation Index and Difference Vegetation Index) for mapping RPs at two-three years intervals from 1990 to 2017. A comparison with actual plantation data indicated more than 91% mapping accuracy, with most RPs able to be identified within six years of plantation, while several patches were detected after six years of plantations. The RP patches identified in 1990 and before 2000 were used for training the Maxent species distribution model, wherein bioclimatic variables for 1960–1990 and 1970–2000 were used as predictor variables, respectively. The model-estimated suitability maps were validated using the successive plantation sites. Moreover, the RPs identified before 2017 and the Shared Socioeconomic Pathways (SSP) climate projections (SSP126 and SSP245) were used to predict the habitat suitability for 2041–2060. The past climatic changes (decrease in temperature and a minor reduction in precipitation) and identified RP patches indicated an eastward expansion in the Indian state of Tripura. The projected increase in temperature and a minor reduction in the driest quarter precipitation will contribute to more energy and sufficient water availability, which may facilitate the further eastward expansion of RPs. Systematic multi-temporal stand age mapping would help to identify less productive RP patches, and accurate monitoring could help to develop improved management practices. In addition, the existing RP patches, their expansion, and the projected habitat suitability maps could benefit resource managers in adapting climate change measures and better landscape management.

Climate Niche Modelling for Mapping Potential Distributions of Four Framework Tree Species: Implications for Planning Forest Restoration in Tropical and Subtropical Asia

Selecting tree species to plant for forest ecosystem restoration is critical but problematic. Knowing tree species’ climatic niches can help, but such information is limited for most tropical tree species. Consequently, the research presented here explored the use of climate and species record location data, to map the potential distribution of four tree species across tropical and subtropical Asia based on their modelled climatic niches. All were framework species, of proven effectiveness for forest restoration: Choerospondias axillaris (Roxb.) B.L. Burtt and A.W. Hill, Ficus hispida L.f., Hovenia dulcis Thunb., and Prunus cerasoides Buch.-Ham. ex D. Don. Potential species distributions were projected onto maps of known climatic conditions using the maximum entropy algorithm in Maxent software to predict where the climate is conducive for including each species in forest restoration trials. The models predicted species location very well for F. hispida and H. dulcis and fairly well for P. cerasoides and C. axillaris. Climatically suitable areas for C. axillaris were located mostly north of the equator, whilst those of F. hispida, H. dulcis and P. cerasoides extended south of the equator. The importance of each climatic niche variable differed among species. Driest-month precipitation was critical for F. hispida, as well as mean dry-season temperature for C. axillaris and P. cerasoides and cold-season precipitation for H. dulcis. In addition to aiding species selection for forest restoration, potential distribution maps based on climatic niche models can indicate where novel species for tree plantations might be successful and where species might become invasive. Applying such techniques to a large number of species will be needed to significantly improve species selection for forest ecosystem restoration.

Sur la présence de Xylocopa (Koptortosoma) pubescens Spinola, 1838, en France métropolitaine (Hymenoptera, Apidae)

On the presence of Xylocopa (Koptortosoma) pubescens Spinola, 1838, in metropolitan France (Hymenoptera, Apidae). Xylocopa (Koptortosoma) pubescens Spinola, 1838, species native to Africa and the Middle East, is recorded for the first time in metropolitan France where it has been observed in an urban garden in Ronchin (Nord). To assess its ability to establish and expand, we developed a MAXENT climatic niche model. Ronchin is slightly above the threshold of suitability of X. pubescens. We assume that it should not expand in this unsuitable region. However, the species should be monitored.

Distribution Patterns of Invasive Buffelgrass (Cenchrus ciliaris) in Mexico Estimated with Climate Niche Models under the Current and Future Climate.

In Mexico, buffelgrass (Cenchrus ciliaris) was introduced in the middle of the 20th century. Currently, buffelgrass has become an invasive species and has colonized various ecosystems in the country. In addition to its invasive capacity, climate change is a factor that has to be taken into account when considering how to effectively manage and control this species. The climatic niche models (CNM) and their projections for climate change scenarios allow for estimating the extent of biological invasions. Our study aimed to calibrate a CNM for buffelgrass in Mexico under the current climatic conditions and to project the extent of its biological invasion under climate change scenarios. For that, we used MaxEnt to generate the current CNM and to detect if climate change could cause future changes, we then evaluated the distribution patterns over the periods of 2041–2060, 2061–2080, and 2081–2100 for all the shared socioeconomic pathways (SSPs). Linear regressions were used to compare the outputs between current and future scenarios. Under the current climate, the CNM estimated that 42.2% of the continental surface of Mexico is highly suitable for buffelgrass. The regression analyses indicated no effects from climate change on the distribution of buffelgrass. Moreover, when the projected period is further in the future, and when the SSPs intensify, the surface of suitable areas for the species increases. These analyses clearly suggest Mexico is facing a biological invasion from buffelgrass, which may represent a threat to native biodiversity.

A snapshot of progenitor-derivative speciation in Iberodes (Boraginaceae).

Traditional classification of speciation modes has focused on physical barriers to gene flow. Allopatric speciation with complete reproductive isolation is viewed as the most common mechanism of speciation. Parapatry and sympatry, by contrast, entail speciation in the face of ongoing gene flow, making them more difficult to detect. The genus Iberodes (Boraginaceae, NW Europe) comprises five species with contrasting morphological traits, habitats and species distributions. Based on the predominance of narrow and geographically distant endemic species, we hypothesized that geographical barriers were responsible for most speciation events in Iberodes. We undertook an integrative study including: (i) phylogenomics through restriction-site-associated DNA sequencing (RAD-seq), (ii) genetic structure analyses, (iii) demographic modelling, (iv) morphometrics, and (v) climatic niche modelling and niche overlap analysis. The results revealed a history of recurrent progenitor-derivative speciation manifested by a paraphyletic pattern of nested species differentiation. Budding speciation mediated by ecological differentiation is suggested for the coastal lineage, deriving from the inland widespread Iberodes linifolia during the Late Pliocene. Meanwhile, geographical isolation followed by niche shifts are suggested for the more recent differentiation of the coastland taxa. Our work provides a model for distinguishing speciation via ecological differentiation of peripheral, narrowly endemic I.kuzinskyanae and I.littoralis from a widespread extant ancestor, I.linifolia. Ultimately, our results illustrate a case of Pliocene speciation in the probable absence of geographical barriers and get away from the traditional cladistic perspective of speciation as producing two species from an extinct ancestor, thus reminding us that phylogenetic trees tell only part of the story.

Adaptation to climate change through seasonal migration revealed by climatic versus demographic niche models.

Predicting the geographic range of species and their response to climatic variation and change are entwined goals in conservation and evolutionary ecology. Species distribution models (SDMs) are foundational in this effort and used to visualize the geographic range of species as the spatial representation of its realized niche. SDMs are also used to forecast range shifts under climate change, but often in the absence of empirical evidence that climate limits population growth. We explored the influence of climate on demography, seasonal migration, and the extent of the geographic range in song sparrows (Melospiza melodia), a species thought to display marked local adaptation to regional climate. To do so, we developed SDMs to predict the demographic and climate niches of migratory and resident song sparrows across our study area in western North America from California to Alaska, using 48years of demographic data from a focal population in British Columbia and 1.2million continental-scale citizen science observations. Spatial agreement of our demographic and climate niche models in the region of our focal population was strong (76%), supporting the hypothesis that demographic performance and the occurrence of seasonal migration varied predictably with climatic conditions. In contrast, agreement at the northern (58%) and southern (40%) extents of our study area was lower, as expected if the factors limiting population growth vary regionally. Our results support the hypothesis that local climate drives spatial variation in the occurrence of seasonal migration in song sparrows by limiting the fitness of year-round residents, and suggest that climate warming has favored range expansions and facilitated an upward shift in elevational range song sparrows that forgo seasonal migration. Our work highlights the potential role of seasonal migration in climate adaptation and limits on the reliability of climate niche models not validated with demographic data.