Climatic Niche Models Research Articles

Acacia dealbata invasion in Chile: Surprises from climatic niche and species distribution models.

AimTree invasions are a threat to biodiversity conservation, and although it is hard to predict the future spread of invasive tree species, there are tools available which could allow some estimations. The magnitude of spatial spread (a proxy of invasiveness) can be predicted from species climatic requirement (climatic niche) and can be represented by species distribution models (SDMs). We aimed to assess whether Acacia dealbata conserves its niche in the new environment of south‐central Chile, and also, to estimate the invasive stage of the species.LocationSouth‐central area of Chile, between the O'Higgins (34°0″0′S) and Aysen Regions (47°0″0′S).MethodsWe used a combination of global, native, and regional data to improve the estimation of the potential distribution of A. dealbata, which has been considered one of the most invasive species of the genus, being registered in at least 34 countries in all the Continents.ResultsOur results show that A. dealbata does not conserve its niche in the study area, invading areas with climatic conditions different from those of the native range. It is also not at equilibrium with the environment. According to the global versus regional SDM comparisons, populations present in south‐central Chile present different invasion stages. There are some stable populations, but there are other populations colonizing new areas, occupying unsuitable habitats and some of them are adapting to new climatic conditions. Climatic factors, such as precipitation seasonality, could be acting behind the expansion to new environments, and biotic factors or dispersal limitations could be preventing the species to colonize suitable areas.Main conclusionsThe invasion process of A. dealbata is far from stabilizing, and management options should focus on prevention, avoiding, for example, the introduction of the species to Patagonia where the species has not spread yet. More research is needed to complement our results and enhance the development of effective management strategies.

Phylogeography and ecological niche modeling unravel the evolutionary history of the Yarkand hare, Lepus yarkandensis (Mammalia: Leporidae), through the Quaternary

BackgroundThe Taklimakan Desert in China is characterized by unique geological and historical dynamics and endemic flora and fauna, but the influence of historical climate oscillations on the evolutionary history of endemic animals is poorly understood. Lepus yarkandensis is an oases-dependent Near Threatened species that lives in fragmented oasis habitats in the Taklimakan Desert, China. We investigated the geological and climatic impacts on its geographical differentiation, demographic history and influence of Pleistocene glacial-interglacial cycles on the evolutionary history of L. yarkandensis. Further, studied the impact of climatic oscillation based modification on phylogeography, distribution and diversification pattern of Yarkand hare by using Cytb (1140 bp), MGF (592 bp) and SPTBN1 (619 bp) markers. Ecological niche modeling (ENM) revealed the evolutionary history of this species in response to climate change during the Quaternary. Paleodistribution modeling was used to identify putative refugia and estimate their historical distributions.ResultsBoth historical demographic analyses and climatic niche modeling revealed strong effects of glacial climate changes, suggesting recurrent range contractions and expansions. The EBSP results indicated clear population expansion of L. yarkandensis since the Pleistocene. In the “early Pleistocene”, the demographic expansion continued from 0.83 MYA to the last glacial period. The ENM analysis supported a wide distribution of Lepus yarkandensis at high altitudes during the last interglacial (LIG) period. During the last glacial maximum (LGM), the suitable climate was reduced and restricted to the western part of the Taklimakan Desert.ConclusionsInland aridification, oasis evolution and river flow played major roles in the population differentiation and demographic history of Yarkand hares. Historically, the large, continuous oases in the Taklimakan Desert contained a viable and unique population of L. yarkandensis. The fragmented desert environment might have caused low gene flow between individuals or groups, thus leading to predominant genetic differentiation. The Pleistocene climatic cycles triggered the diversification and expansion of this species during cold and warm periods, respectively, leading to multiple colonization events within the Taklimakan Desert. These events might be due to the expansion of the Taklimakan Desert during the Middle Pleistocene. Yarkand hare previously occupied vast areas at low and intermediate altitudes in Xinjiang, Gansu, Shanxi, Henan and Shaanxi Provinces in China. The past aridification, climate change-induced oasis modifications, changes in river volumes and flow directions, and human activities all affected the population demography and phylogeography of the Yarkand hare.

Climatic niche comparison across a cryptic species complex.

According to current molecular evidence, the Chionaspis pinifoliae heterophyllae species complex has been recognized as 10 cryptic species. In this study, we construct potential distribution maps for seven cryptic species based on climatic variables. This was done to assess the main environmental factors that have contributed to the distribution map and test the degree of niche overlap across the seven cryptic species. We used MaxEnt to build the climatic niche models under climatic variables. For these models, the similarities and differences of the niches across the cryptic species were estimated. By comparing the potential distribution model of each cryptic species, our results suggested parapatric, sympatric and allopatry populations for this cryptic species complex. Our results showed high variability in niche overlap, and more often niche conservatism than niche divergence. The current species delimitation of the Chionaspis pinifoliae heterophyllae complex by molecular information and the hypothesis that the niche overlap in the sympatric population is higher than that of the allopatry population were supported based on the findings. This study will provide baseline data and a distribution range to facilitate the further control of these insects and formulate quarantine measures.

Mesoscale climatic impacts on the distribution ofHomarus americanusin the US inshore Gulf of Maine

American lobster (Homarus americanus) supports one of the most valuable fisheries in the United States. Spatial distributions of H. americanus are hypothesized to be influenced by climate-driven environmental factors, but such effects have not been quantified. We developed a Tweedie generalized additive model (GAM) to quantify environmental effects on season-, sex-, and size-specific distributions of H. americanus in the inshore Gulf of Maine. Tweedie GAMs were coupled with regional circulation model output to predict spatiotemporal changes in distribution of H. americanus due to mesoscale climate variability. GAM results indicated that bottom temperature and salinity impacts on H. americanus distribution were more pronounced during spring. The coupled climate–niche model predicted significantly higher H. americanus abundance under a warm climatology scenario. This study provides a predictive climate–niche modelling framework that may be useful for planning fishery investments and anticipating management challenges given ongoing climate-driven changes in the Northwest Atlantic.

Quaternary climatic fluctuations and resulting climatically suitable areas for Eurasian owlets.

AimThe nested pattern in the geographical distribution of three Indian owlets, resulting in a gradient of endemicity, is hypothesized to be an impact of historical climate change. In current time, the Forest Owlet Athene blewitti is endemic to central India, and its range is encompassed within the ranges of the Jungle Owlet Glaucidium radiatum (distributed through South Asia) and Spotted Owlet Athene brama (distributed through Iran, South and Southeast Asia). Another phylogenetically close species, Little Owl Athene noctua, which is largely Palearctic in distribution, is hypothesized to have undergone severe range reduction during the Last Glacial Maximum, showing a postglacial expansion. The present study tests hypotheses on the possible role of Quaternary climatic fluctuations in shaping geographical ranges of owlets.MethodsWe used primary field observations, open access data, and climatic niche modeling to construct climatic niches of four owlets for four periods, the Last Interglacial (~120–140 Ka), Last Glacial Maximum (~22 Ka), Mid‐Holocene (~6 Ka), and Current (1960–1990). We performed climatic niche extent, breadth, and overlap analyses and tested if climatically suitable areas for owlets are nested in a relatively stable climate.ResultsClimatically suitable areas for all owlets examined underwent cycles of expansion and reduction or a gradual expansion or reduction since the Last Interglacial. The Indian owlets show significant climatic niche overlap in the current period. Climatically suitable areas for Little Owl shifted southwards during the Last Glacial Maximum and expanded northwards in the postglaciation period. For each owlet, the modeled climatic niches were nested in climatically stable areas.Main ConclusionsThe study highlights the impact of Quaternary climate change in shaping the present distribution of owlets. This is relevant to the current scenario of climate change and global warming and can help inform conservation strategies, especially for the extremely range‐restricted Forest Owlet.

Pleistocene range expansions might explain striking disjunctions between eastern Brazil, Andes and Mesoamerica inLeandras.str. (Melastomataceae)

AbstractLeandras.str. clade has around 200 species nearly restricted to eastern Brazil. Most species in this group are narrow endemics, but a few present striking disjunct distributions between eastern Brazil and Andes or Mesoamerica. Given the predominantly “montane” distribution observed in mostLeandras.str., we hypothesized that cyclical range expansions during colder Pleistocene periods, followed by local extinctions during warmer interglacial periods, could have shaped the distribution of the disjunct species in this clade. In order to gather support for this biogeographical scenario in a phylogenetic framework, the species that occur outside eastern Brazil were identified, ages of the dispersal events estimated, climatic niche models for the disjuncts were generated, and the climatic envelope of these species compared. Our results place all dispersal events from eastern Brazil to Andes or Mesoamerica during the Pleistocene. Climatic niche modeling indicates a potential range expansion during the Pleistocene colder times for the disjunct species. Although the surpassing of the “dry diagonal” could have been facilitated during glacial periods, this open corridor is an effective barrier forLeandra, given the reduced number of species that dispersed beyond an eastern Brazilian origin. Additionally, the disjunct species do not present significant differences in their climatic envelopes to the non‐disjunct species. Our results provide support to a short‐dispersion/stepping‐stone migration scenario to account for the observed disjunctions in this clade. Range expansions during Pleistocene colder periods followed by local extinctions during interglacial periods could have shaped the distribution ofLeandras.str.

CONTEMPORARY AND FUTURE POTENTIAL GEOGRAPHIC DISTRIBUTION OF Cedrela fissilis Vell. UNDER CLIMATE CHANGE SCENARIOS

ABSTRACT The objective of the present work was to model the climate niche of Cedrela fissilis Vell. and to project the contemporary and future potential spatial distribution considering different climate change scenarios. Species occurrence data were obtained from the SpeciesLink and Global Biodiversity Information Facility (GBIF) databases. Altitude data, and 19 climate variables for both present and future conditions were obtained from the WorldClim database. The spatial prediction for the year 2070, considering an optimistic scenario (RCP 4.5) and a pessimistic one (RCP 8.5), was defined by Intergovernmental Panel on Climate Change (IPCC) regarding the concentration of greenhouse gases. The climate niche modeling was performed using the Maximum Entropy algorithm (MaxEnt). The results showed that C. fissilis has a wide geographic distribution, occurring in most South American countries. Its distribution showed a high correlation associated with the isothermal and precipitation variables in the humid month. In future scenarios, impacts on the climatic suitability of the areas in which the species occur, will not be spatially homogeneous. Indeed, reductions of about 47% (RCP4.5) and 63% (RCP8.5) are expected. It is recommended the creation and expansion of Conservation Units (CU) in areas that will remain climatically suitable for this species. The areas that will not have a favorable climate in the future should be considered strategic for genetic rescue and establishment of germplasm banks. Areas changing into a favorable climate should be considered as new areas of ecological and forestry interest.

Anticipating the response of the Brazilian giant earthworm (Rhinodrilus alatus) to climate change: implications for its traditional use.

Our understanding of the impacts of ongoing global warming on terrestrial species has increased significantly during the last several years, but how climatic change has affected, and will affect, the distribution of earthworms remains largely unknown. We used climate niche modeling to model the current distribution of the giant earthworm Rhinodrilus alatus - an endemic species of the Cerrado Domain in Brazil, which is traditionally harvested and commercialized for fishing bait. R. alatus is sensitive to environmental changes because climate, in synergy with soil attributes, determine its annual reproductive cycle and distribution. The paleoclimatic reconstructions predict important geographical shifts from LGM (~21,000 yBp) to the present potential distribution of R. alatus: range expansion, fragmentation, and shrinkage of the current core area. Further, the 2070 scenarios predict substantial shrink and losses of stable areas. Our results indicate that climate change will not only affect the extent of the distribution, but will also promote significant fragmentation and a geographical shift to outside of the currently recognized geographical boundaries. In this context, populations of R. alatus would decline and traditional harvesting would collapse, requiring immediate implementation of management and conservation measures for the species and economically sustainable alternatives for the local community.

Current and future distributions of Espeletiinae (Asteraceae) in the Venezuelan Andes based on statistical downscaling of climatic variables and niche modelling

ABSTRACTBackground: Páramos are the high-elevation ecosystems of the humid tropical Andes, characterised by the presence of giant rosettes of the Espeletiinae subtribe (Asteraceae). Forecasted climate change is likely to reduce the extent of the area climatically suitable/occupied currently by Espeletiinae and their elevation distribution patterns.Aims: The aim of this study was to estimate the potential impacts of forecasted climate change on the geographic distribution (extent of area and elevation distribution patterns) of 28 species of Espeletiinae that have been recorded in the Cordillera de Mérida, Venezuela.Methods: Six bioclimatic variables, downscaled to a 90 m × 90 m cell size, were used to construct species distribution models (SDM) for the 28 species to model their current and likely future distribution (2070) by using two general circulation models and four representative concentration pathways (RCP).Results: Nine species were estimated to have potential distribution over less than 1000 km2 and five over less than 500 km2, in current climatic conditions. Fifteen and eight species had elevation spans narrower than 1000 m and 500 m, respectively. No significant differences in modelled areas or spans were detected between north, central and south sections of the Cordillera de Mérida. Mean ± SE future reduction in the extent of area climatically suitable were estimated between 51.3% ± 6.3% (RCP2.6) and 78.1% ± 5.3% (RCP8.5), coupled with upward range retreat of between 277.8 m ± 27.4 m (RCP2.6) and 762.5 m ± 59.8 m (RCP8.5).Conclusions: Our study predicts large reductions in modelled area and important upward shifts in the distribution of Venezuelan Espeletiinae by 2070 compared to their current distribution.

Naturalized distributions show that climatic disequilibrium is structured by niche size in pines (PinusL.)

AbstractAimThe assumption that the native distributions of species are in equilibrium with climate has been shown to be frequently violated, despite its centrality to many niche model applications. We currently lack a framework that predicts these violations. Here, we examine whether variation in climatic disequilibrium is structured by properties of species’ native distributions and climatic niches.LocationGlobal.MethodsWe built climatic niche models for 106 pine (PinusL.) species, including 25 that have naturalized outside their native range. We measured the extent of climate space occupied exclusively by naturalized populations and considered what fraction of this space was available within the native continent and near the native range. We examined the consequences of disequilibrium for estimates of potential range filling and sister species niche conservatism.ResultsMost species (23 of 25) have naturalized in climate conditions outside the native niche, leading to increases in the total known suitable climate space. Increases in niche size were negatively related to native niche size. Increases were often large; one species expanded its niche by almost 10% of the global climate space. These increases were associated primarily with cooler, wetter and less seasonal climates. Increases in known niche size lowered potential range filling estimates within species’ native continent and ecoregion. Naturalized data did not strengthen support for niche conservatism among sister species.Main conclusionsAmong pines, climatic disequilibrium is the norm and not the exception. The magnitude of this disequilibrium can be vast, such that the native range greatly under‐represents the true climatic tolerances of some species. Fortunately, this disequilibrium can be predicted largely by the size of a species’ native niche. Accounting for this disequilibrium can improve our ability to characterize ecological phenomena, including potential range filling. This is an essential step towards improving the conservation value of ecological niche models.

Climatic Niche Model for Overwintering Monarch Butterflies in a Topographically Complex Region of California.

We use climatic conditions that are associated with known monarch butterfly overwintering groves in California to build a Maxent model, and focus on the fine scale probability of overwintering grove occurrence in a topographically complex region of the state (Santa Barbara County). Grove locations are known from recent and historical surveys and a long-term citizen science database. The climatic niche model performs well, predicting that overwintering habitat is most likely to occur along the coast and at low elevations, as shown by empirical data. We then use climatic variables in conjunction with climate change scenarios to model the future location of overwintering habitat, and find a substantial shift in the predicted distribution. Under a plausible scenario, the probability of occurrence of overwintering habitat directly reflects elevation, with coastal regions having a reduced probability relative to today, and higher elevation sites increasing in probability. Under a more extreme scenario, high probability sites are only located along ridgelines and in mountaintop regions of the county. This predicted shift in distribution is likely to have management implications, as sites that currently lack monarchs may become critical to conservation in the future. Our results suggest that estimating the size of the western overwintering population in the future will be problematic, unless annual counts compensate for a shift in the distribution and a potential change in the number and location of occupied sites.

Climatic niche comparison among ploidal levels in the classic autopolyploid system, Galax urceolata.

Autopolyploidy, or whole-genome duplication within a species, leads to closely related cytotypes in one geographic location. One hypothesized mechanism by which autopolyploids become established is climatic niche divergence from their diploid progenitor. Here we tested this hypothesis in diploid, triploid, and tetraploid Galax urceolata (Diapensiaceae) and predicted the effects of climate change on the relative distributions of these cytotypes. We investigated whether climatic niche divergence has shaped the current distributions of Galax urceolata cytotypes in eastern North America using climatic niche modeling, multivariate analyses of environmental space, and geographic range analyses. We then projected the models of the three cytotypes onto an ensemble of future climate maps to determine how the distributions might be altered over time. All cytotypes are geographically sympatric; however, climatic niche contraction and a slight niche shift of the tetraploids was observed relative to that of the diploids. Climate projections for all diploid and tetraploid cytotypes showed substantial range contraction without much, or any, range shift, suggesting that Galax urceolata will likely go extinct in nature as mountain refugia become warmer. Galax urceolata tetraploids occupy a slightly wetter habitat than that of their diploid progenitors. While we cannot take into account future adaptation, our models suggest extensive decreases in range distributions for both diploid and tetraploid G. urceolata based on climate change projections. Galax urceolata may therefore be under extreme threat due to loss of suitable habitat, and conservation efforts will be needed.

Combined Effects of Global Climate Suitability and Regional Environmental Variables on the Distribution of an Invasive Marsh Species Spartina alterniflora

Invasion by Spartina alterniflora seriously threatens native ecosystem along Chinese coast. Determining the main influential factors and their relationships with the distribution of S. alterniflora is thus crucial for invasion control. However, the distribution is influenced by environmental variables at different scales and the relative importance of cross-scale variables is unclear. Based on the MaxEnt modelling technique, a combined regional environmental niche (CREN) model was built by integrating the global climate niche (GCN) model into the regional environment niche (REN) model to study the combined effects of global climate suitability and regional environmental variables on species distribution. The CREN model performed much better than the GCN model with AUC, TSS, specificity and sensitivity values increasing by 0.12, 0.04, 0.05 and 0.45, whereas it performed as well as the REN model, but reduced the overfitting. When considering the combined effects, the predicted suitable area decreased from 66.90% at the global scale to 18.53% at the regional scale. Global sensitivity analysis showed there were strong interactions among different variables, especially for elevation and global climate suitability, the most influential variables. Interactions reduced the importance of soil salinity, but enhanced that of soil percentage sand. The presence probability increased with increasing of global climate suitability and soil salinity, while decreased with increasing of elevation, soil organic carbon and percentage sand. The presence probability was the highest in moderately well drained and lowest in poorly drained soil. Ignoring the combined effects of cross-scale variables will prevent comprehensive elucidation of their relationship with species distribution, which should be considered to take effective measures against biological invasion.

El nicho ecológico como herramienta para predecir áreas potenciales de dos especies de pino

Modelar el nicho ecológico óptimo para determinar la distribución potencial de las especies es una opción viable en la ubicación de las mejores áreas para establecer Unidades Productoras de Germoplasma Forestal (UPGF). El objetivo del presente estudio fue modelar la distribución potencial de Pinus pseudostrobus y P. oocarpa en Chiapas, México, mediante el procesamiento cartográfico de variables topográficas, climáticas, edáficas, ecológicas y modelos de nicho ecológico (MaxEnt). Se utilizaron 220 datos de presencia de P. oocarpa y 52 para P. pseudostrobus obtenidos de la Red Mundial de Información sobre Biodiversidad, Global Biodiversity Information Facility, del Missouri Botanical Garden y del Herbario Nacional de México (MEXU). La distribución potencial de la especie fue modelada con 500 y 1 000 iteraciones a través de las regresiones de tipo Logistic, Cumulative y Cloglog. La validación estadística se realizó con 28 % de los datos para cada taxón con las técnicas Crossvalidate y Bootstrap. El modelo que mejor se ajustó fue el logístico con método de remuestreo crossvalidate. Los valores del Área Bajo la Curva (AUC) para los datos estimados y validados fueron de 0.882 para P. oocarpa y 0.947 en P. pseudostrobus. La variable que más influyó en la presencia o ausencia de las especies fue la altitud con 84.5 y 97.3 % para P. oocarpa y P. pseudostrobus, respectivamente. Los resultados del modelo permitieron ubicar áreas óptimas para el establecimiento de UPGF.

Disequilibrium and relaxation times for species responses to climate change

Climate change is widely expected to pose a threat to many of Earth’s plant and animal species. Based on climate models, a multitude of studies project that certain species will not be able to migrate fast enough to keep up with changing environmental conditions, presenting a greater risk of their possible extinction. However, many of these studies are based on correlative climate niche models that represent the current living conditions of species and may not consider their ability to tolerate projected changes in future climate, including the stimulative effects of rising CO2 for plant growth and drought tolerance. SDMs also are not usually run with sufficiently detailed spatial data to account for refugia. These and other aspects of model-based niche studies can potentially combine to mischaracterize the risk to species due to climate change. Even a SDM that perfectly predicts future equilibrium geographic range following climate change, however, does not yield a direct estimate of extinction risk. The key question is “What is the transient response to a climate disequilibrium situation?” The concept of relaxation is introduced to evaluate time-scales for responses at the trailing edge of species’ ranges. Simulation of relaxation at a forest ecotone shows the relaxation response in some cases can be hundreds of years. A classification of relaxation responses based on tolerance and dispersal ability is proposed as a second stage analysis for SDM studies.

Out of Africa: demographic and colonization history of the Algerian mouse (Mus spretus Lataste).

North Africa is now recognized as a major area for the emergence and dispersal of anatomically modern humans from at least 315 kya. The Mediterranean Basin is thus particularly suited to study the role of climate versus human-mediated changes on the evolutionary history of species. The Algerian mouse (Mus spretus Lataste) is an endemic species from this basin, with its distribution restricted to North Africa (from Libya to Morocco), Iberian Peninsula and South of France. A rich paleontological record of M. spretus exists in North Africa, suggesting hypotheses concerning colonization pathways, and the demographic and morphologic history of this species. Here we combined genetic (3 mitochondrial DNA loci and 18 microsatellites) and climatic niche modeling data to infer the evolutionary history of the Algerian mouse. We collected 646 new individuals in 51 localities. Our results are consistent with an anthropogenic translocation of the Algerian mouse from North Africa to the Iberian Peninsula via Neolithic navigators, probably from the Tingitane Peninsula. Once arrived in Spain, suitable climatic conditions would then have favored the dispersion of the Algerian mice to France. The morphological differentiation observed between Spanish, French and North African populations could be explained by a founder effect and possibly local adaptation. This article helps to better understand the role of climate versus human-mediated changes on the evolutionary history of mammal species in the Mediterranean Basin.

Climatic Suitability Derived from Species Distribution Models Captures Community Responses to an Extreme Drought Episode

The differential responses of co-occurring species in rich communities to climate change—particularly to drought episodes—have been fairly unexplored. Species distribution models (SDMs) are used to assess changes in species suitability under environmental shifts, but whether they can portray population and community responses is largely undetermined, especially in relation to extreme events. Here we studied a shrubland community in SE Spain because this region constitutes an ecotone between the Mediterranean biome and subtropical arid areas, and it has recently suffered its driest hydrological year on record. We used four different modeling algorithms (Mahalanobis distance, GAM, BRT, and MAXENT) to estimate species’ climatic suitability before (1950–2000) and during the extreme drought. For each SDM, we related species’ climatic suitability with their remaining green canopy as a proxy for species resistance to drought. We consistently found a positive correlation between remaining green canopy and species’ climatic suitability before the event. This relationship supports the hypothesis of a higher vulnerability of populations living closer to their species’ limits of aridity tolerance. Contrastingly, climatic suitability during the drought did not correlate with remaining green canopy, likely because the exceptional episode led to almost zero suitability values. Overall, our approach highlights climatic niche modeling as a robust approach to standardizing and comparing the behavior of different co-occurring species facing strong climatic fluctuations. Although many processes contribute to resistance to climatic extremes, the results confirm the relevance of populations’ position in the species’ climatic niche for explaining sensitivity to climate change.

Mitochondrial phylogeography of the Iberian endemic frog Rana iberica, with implications for its conservation.

Genetic characterization of species using phylogeographic approaches represents a basic reference to understand their evolutionary history as well as to identify conservation priorities to protect areas of particular interest regarding evolutionary potential. Even in well-studied regions such information is lacking for the majority of species, including many endemic species with reduced distribution ranges. We investigate the phylogeographic pattern of the Iberian frog Rana iberica, an endemic amphibian restricted to Central and North-Western Iberian Peninsula. Using mitochondrial sequences, we reconstruct the phylogeographic history of the species to test the effect of Quaternary climate changes on the evolutionary diversification of lineages, that is, the differentiation of mitochondrial lineages and the formation of genetic diversity melting pots, and integrate phylogeographic evidence for future conservation planning. Our results indicate the existence of 3 main mitochondrial lineages differentiated during the Upper Pleistocene. Both historical demographic analyses and climatic niche modeling show a strong effect of glacial climate changes, suggesting recurrent range contractions and expansions. Under such circumstances, differentiation took place most likely by isolation in allopatric interglacial refugia. Secondary lineage admixture in northern Portugal generated a broad mixed zone with highest nucleotide diversity. Given its particular evolutionary potential, its reduced distribution and eventual threats under current climate change scenario, conservation priorities should focus on the isolated lineage from Sierra de Guadalupe.

Changes in future potential distributions of apex predator and mesopredator mammals in North America

Climate change has determined shifts in distributions of species and changing climates are likely to continue to affect species in the future. In this study, we used Maxent, an ecological niche modeling algorithm, to estimate the potential future distributions of apex predator and mesopredator mammals in boreal forest and tundra biomes of North America. We projected the climatic niche models of apex predators and mesopredators on future climate datasets based on three global circulation models (Beijing Climate Center Climate System Model, Hadley Global Environment Model, and Model for Interdisciplinary Research on Climate Earth System Model) and four greenhouse gas emission scenarios (RCP2.6, RCP4.5, RCP6, and RCP8.5). Under future climate projections, the potential distributions of most of the predators studied increased by 2050 and 2070. The potential distributions of two apex predators (brown bear, Ursus arctos, and polar bear, U. maritimus) and two mesopredator species (Canadian lynx, Lynx canadensis, and Arctic fox, Vulpes lagopus) were predicted to decline under all emission scenarios, by 2050 and 2070. The only apex predator that was predicted to increase its distribution under all greenhouse gas emission scenarios was U. americanus (American black bear). Similarly, distributions of mesopredators like Mephitis mephitis (striped skunk), and Procyon lotor (raccoon) were predicted to increase greatly under future climate conditions of all four emission scenarios. Predicted expansions of distribution ranges of most mesopredators and contractions of distribution ranges of apex predators included in this study may result in changes of species interactions in North American boreal forests and tundras in the future.

Predicting Future Seed Sourcing of Platycladus orientalis (L.) for Future Climates Using Climate Niche Models

Climate niche modeling has been widely used to assess the impact of climate change on forest trees at the species level. However, geographically divergent tree populations are expected to respond differently to climate change. Considering intraspecific local adaptation in modeling species responses to climate change will thus improve the credibility and usefulness of climate niche models, particularly for genetic resources management. In this study, we used five Platycladus orientalis (L.) seed zones (Northwestern; Northern; Central; Southern; and Subtropical) covering the entire species range in China. A climate niche model was developed and used to project the suitable climatic conditions for each of the five seed zones for current and various future climate scenarios (Representative Concentration Pathways: RCP2.6, RCP4.5, RCP6.0, and RCP8.5). Our results indicated that the Subtropical seed zone would show consistent reduction for all climate change scenarios. The remaining seed zones, however, would experience various degrees of expansion in suitable habitat relative to their current geographic distributions. Most of the seed zones would gain suitable habitats at their northern distribution margins and higher latitudes. Thus, we recommend adjusting the current forest management strategies to mitigate the negative impacts of climate change.