Climatic Tolerances Research Articles

Vertebrate responses to human land use are influenced by their proximity to climatic tolerance limits

AbstractAimLand‐use change leads to local climatic changes, which can induce shifts in community composition. Indeed, human‐altered land uses favour species able to tolerate greater temperature and precipitation extremes. However, environmental changes do not impact species uniformly across their distributions, and most research exploring the impacts of climatic changes driven by land use has not considered potential within‐range variation. We explored whether a population's climatic position (the difference between species' thermal and precipitation tolerance limits and the environmental conditions a population experiences) influences their relative abundance across land‐use types.LocationGlobal.MethodsUsing a global dataset of terrestrial vertebrate species and estimating their realized climatic tolerance limits, we analysed how the abundance of species within human‐altered habitats relative to that in natural habitats varied across different climatic positions (controlling for proximity to geographic range edge).ResultsA population's thermal position strongly influenced abundance within human‐altered land uses (e.g. agriculture). Where temperature extremes were closer to species' thermal limits, population abundances were lower in human‐altered land uses (relative to natural habitat) compared to areas further from these limits. These effects were generally stronger at tropical compared to temperate latitudes. In contrast, the influences of precipitation position were more complex and often differed between land uses and geographic zones. Mapping the outcome of models revealed strong spatial variation in the potential severity of decline for vertebrate populations following conversion from natural habitat to cropland or pasture, due to their climatic position.Main conclusionsWe highlight within‐range variation in species' responses to land use, driven (at least partly), by differences in climatic position. Accounting for spatial variation in responses to environmental changes is critical when predicting population vulnerability, producing successful conservation plans, and exploring how biodiversity may be impacted by future land‐use and climate change interactions.

Is whitebark pine less sensitive to climate warming when climate tolerances of juveniles are considered?

Whitebark pine (Pinus albicaulis) (PIAL) is a proposed threatened species that plays a keystone ecological role in the Greater Yellowstone Ecosystem (GYE). Its population response to climate change is of high interest to managers because climate-induced declines may adversely affect critical ecosystem services that this species provides. While previous studies of reproductive size classes of the species have projected dramatic reductions in area of suitable habitat under climate warming scenarios, it has been suggested that the species can tolerate warmer and drier conditions if seedlings and saplings are not competitively excluded by other conifer species. Thus, we asked if juvenile-sized PIAL are found in warmer and drier locations than larger individuals, under the assumption that competitive exclusion would require several years to decades to influence the distribution of regenerating PIAL. We used a new genetic technique to distinguish non-cone bearing PIAL from the more warm-dry tolerant limber pine (P. flexilis) among samples collected along transects extending from lower treeline to the subalpine around the GYE. Predictor data on climate and water balance were obtained from a 250-m spatially explicit data product. We used a stochastic gradient boosting model to predict probability of presence of PIAL < 1 cm dbh (diameter at breast height) and >=1 cm dbh as a function of these predictors. We discovered that smaller diameter PIAL were not proportionally more abundant at lower elevations, suggesting that competitive exclusion may not be the primary mechanism limiting this species' low elevation distribution. In contrast, the small size class PIAL were slightly less warm-dry tolerant than larger individuals. This suggests that the zone of regeneration of PIAL has shifted upwards in elevation in recent decades, perhaps associated with the observed warming in the GYE. In comparison to a previous study of reproductive-sized trees (>20 cm dbh) from a coarser (1.6 km) sampling frame, however, the predicted zone of suitable habitat of PIAL (<1 cm dbh) was 122 m lower in elevation. We conclude that consideration of the fine-scale distribution of PIAL near lower treeline suggests that the tree species is slightly less sensitive to climate warming than found by previous studies of reproductive-sized trees, but, nonetheless, large range contractions of PIAL in GYE are likely under projected future climates.

ClimPlant: Realized climatic niches of vascular plants in European forest understoreys

AbstractMotivationDetailed knowledge on the climatic tolerances of species is crucial to understand, quantify and predict the impact of climate change on biodiversity and ecosystem functions. However, quantitative data are limited; often, only expert‐based qualitative estimates are available. With the ClimPlant database, we capitalize on the link between species distribution ranges and macroclimate to infer the realized climatic niches of 968 European forest plant species.Main types of variables containedThe ClimPlant database contains information on the distribution of monthly, growing‐season and annual mean, minimum and maximum temperature and total precipitation within the distribution range of 968 European forest plants.Spatial location and grainEurope in 10 arc‐min grid cells; the study area has been cropped rectangularly at 15° W (Atlantic Ocean), 60° E (Ural Mountains), 25° N (Sahara) and 75° N (Arctic Ocean).Time period and grainThe distribution ranges of forest plant species are based on two renowned distribution atlases. The monthly mean, minimum and maximum temperature and precipitation between 1970 and 2000 were extracted from WorldClim v.2.Major taxa and level of measurementNine hundred and sixty‐eight vascular plant species of European forests, with taxonomy following the Euro+Med PlantBase nomenclature .Software formatData in 56 CSV files, with 1,000 values for monthly, growing season and annual observations of mean, minimum and maximum temperature and precipitation in the distribution range for every species. One summary CSV file with summary statistics (mean, median, fifth and 95th percentile), for every species, of each climatic variable, together with seven key geographical descriptors: area of the distribution range, latitude and longitude of the centroid, and northern, eastern, western and southern range limits within the study area.

Variation in climatic tolerance, but not stomatal traits, partially explains Pooideae grass species distributions.

Grasses in subfamily Pooideae live in some of the world's harshest terrestrial environments, from frigid boreal zones to the arid windswept steppe. It is hypothesized that the climate distribution of species within this group is driven by differences in climatic tolerance, and that tolerance can be partially explained by variation in stomatal traits. We determined the aridity index (AI) and minimum temperature of the coldest month (MTCM) for 22 diverse Pooideae accessions and one outgroup, and used comparative methods to assess predicted relationships for climate traits versus fitness traits, stomatal diffusive conductance to water (gw) and speed of stomatal closure following drought and/or cold. Results demonstrate that AI and MTCM predict variation in survival/regreening following drought/cold, and gw under drought/cold is positively correlated with δ 13C-measured water use efficiency (WUE). However, the relationship between climate traits and fitness under drought/cold was not explained by gw or speed of stomatal closure. These findings suggest that Pooideae distributions are at least partly determined by tolerance to aridity and above-freezing cold, but that variation in tolerance is not uniformly explained by variation in stomatal traits.

The relationship between niche breadth and range size of beech (Fagus) species worldwide

AbstractAimThis work explores whether the commonly observed positive range size–niche breadth relationship exists for Fagus, one of the most dominant and widespread broad‐leaved deciduous tree genera in temperate forests of the Northern Hemisphere. Additionally, we ask whether the 10 extant Fagus species’ niche breadths and climatic tolerances are under phylogenetic control.LocationNorthern Hemisphere temperate forests.TaxonFagus L.MethodsCombining the global vegetation database sPlot with Chinese vegetation data, we extracted 107,758 relevés containing Fagus species. We estimated biotic and climatic niche breadths per species using plot‐based co‐occurrence data and a resource‐based approach, respectively. We examined the relationships of these estimates with range size and tested for their phylogenetic signal, prior to which a Random Forest (RF) analysis was applied to test which climatic properties are most conserved across the Fagus species.ResultsNeither biotic niche breadth nor climatic niche breadth was correlated with range size, and the two niche breadths were incongruent as well. Notably, the widespread North American F. grandifolia had a distinctly smaller biotic niche breadth than the Chinese Fagus species (F. engleriana, F. hayatae, F. longipetiolata and F. lucida) with restricted distributions in isolated mountains. The RF analysis revealed that cold tolerance did not differ among the 10 species, and thus may represent an ancestral, fixed trait. In addition, neither biotic nor climatic niche breadths are under phylogenetic control.Main ConclusionsWe interpret the lack of a general positive range size–niche breadth relationship within the genus Fagus as a result of the widespread distribution, high among‐region variation in available niche space, landscape heterogeneity and Quaternary history. The results hold when estimating niche sizes either by fine‐scale co‐occurrence data or coarse‐scale climate data, suggesting a mechanistic link between factors operating across spatial scales. Besides, there was no evidence for diverging ecological specialization within the genus Fagus.

Effects of the Climate Change on Peripheral Populations of Hydrophytes: A Sensitivity Analysis for European Plant Species Based on Climate Preferences

Biogeographical theory suggests that widespread retractions of species’ rear edges are expected due to anthropogenic climate change, affecting in a particularly intense way those linked to fragile habitats, such as species’ rear edges closely dependent on specific water conditions. In this way, this paper studies the potential effects of anthropogenic climate change on distribution patterns of threatened rear edge populations of five European hydrophyte plants distributed in the Iberian Peninsula. We explored (i) whether these populations occur at the limit of the species’ climatic tolerance, (ii) we quantified their geographic patterns of vulnerability to climate change, and in addition, (iii) we identified in a spatially explicit way whether these threatened populations occur in vulnerable environments to climate change. To do this, we simulated the climatic niche of five hydrophyte species using an ecological modelling approach based on occurrences and a set of readily available climatic data. Our results show that the Iberian populations studied tended to occur in less suitable environments relative to each of the species’ optimal climates. This result suggests a plausible explanation for the current degree of stagnancy or regression experienced by these populations which showed high sensitivity and thus vulnerability to thermal extremes and high seasonality of wet and temperature. Climatic predictions for 2050 displayed that most of the examined populations will tend to occur in situations of environmental risk in the Iberian Peninsula. This result suggests that the actions aimed at the conservation of these populations should be prioritized in the geographic locations in which vulnerability is greatest.

Searching for synthetic mechanisms on how biological traits mediate species responses to climate change

Abstract: Climate change will likely be the most significant challenge faced by species in this century, and species’ ability to cope with climate change depends on their life history and ecological and evolutionary traits. Understanding how these traits mediate species’ responses is beneficial for identifying more vulnerable species or prone to extinction risk. Here, we carried out a literature review describing how four traits commonly used in vulnerability assessments (i.e. clutch size, diet breadth, dispersal ability, and climatic tolerance) may determine species vulnerability. We also portray the possible mechanisms that explain how these traits govern species responses to climate change. The literature suggests different mechanisms operating for the evaluated traits. The mechanism of response to climate change differs between species inhabiting tropical and temperate regions: while species from the temperate areas may respond positively to temperature rise, tropical species may be severely affected. Since ectotherms depend on environment temperature, they are more sensitive and present different response mechanisms from endotherms.

Changes in the pasting properties of millet grains due to different processing methods using rapid Visco analyzer

Millets are considered as under-utilized crops compared with other cereal grains but the year 2018 has been declared as the year of millets after understanding their importance as they are crops that has tendency to fulfill the requirements if the future generations. It possesses unique inherent characteristics of adaptation that makes them sustain harsh climatic changes tolerance which includes resistance to drought, high temperatures, low soil fertility and diseases or pests or for making special foods or beverages because of which they are gaining more attention in the recent years as an alternative to the cereal grains. Millets possess phytochemicals that has capacity to prevent or reduce several diseases thereby imparting several health benefits upon consumption; helps in delaying occurrence of non-communicable diseases. So facing the climatic changes along with maintaining or improving the health of its nation is the major concern which can be counteracted with the help of “nutri-cereals” which possess unique characteristics with which it can sustain the dramatic climatic changes that is happening or will happen in the future where other fine cereals like paddy and wheat would fail to survive. The present work analyses the effect on pasting properties of millet grains which has given different hydrothermal treatments.

An improved statistical approach for reconstructing past climates from biotic assemblages.

Quantitative reconstructions of past climates are an important resource for evaluating how well climate models reproduce climate changes. One widely used statistical approach for making such reconstructions from fossil biotic assemblages is weighted averaging partial least-squares regression (WA-PLS). There is however a known tendency for WA-PLS to yield reconstructions compressed towards the centre of the climate range used for calibration, potentially biasing the reconstructed past climates. We present an improvement of WA-PLS by assuming that: (i)the theoretical abundance of each taxon is unimodal with respect to the climate variable considered; (ii)observed taxon abundances follow a multinomial distribution in which the total abundance of a sample is climatically uninformative; and (iii) the estimate of the climate value at a given site and time makes the observation most probable, i.e. it maximizes the log-likelihood function. This climate estimate is approximated by weighting taxon abundances in WA-PLS by the inverse square of their climate tolerances. We further improve the approach by considering the frequency ( fx) of the climate variable in the training dataset. Tolerance-weighted WA-PLS with fx correction greatly reduces the compression bias, compared with WA-PLS, and improves model performance in reconstructions based on an extensive modern pollen dataset.

A Major Change in Rate of Climate Niche Envelope Evolution during Hominid History.

SummaryHomo sapiens is the only species alive able to take advantage of its cognitive abilities to inhabit almost all environments on Earth. Humans are able to culturally construct, rather than biologically inherit, their occupied climatic niche to a degree unparalleled within the animal kingdom. Precisely, when hominins acquired such an ability remains unknown, and scholars disagree on the extent to which our ancestors shared this same ability. Here, we settle this issue using fine-grained paleoclimatic data, extensive archaeological data, and phylogenetic comparative methods. Our results indicate that whereas early hominins were forced to live under physiologically suitable climatic conditions, with the emergence of H. heidelbergensis, the Homo climatic niche expanded beyond its natural limits, despite progressive harshening in global climates. This indicates that technological innovations providing effective exploitation of cold and seasonal habitats predated the emergence of Homo sapiens.

Vicariance in a generalist fish parasite driven by climate and salinity tolerance of hosts.

Acanthocephalans are parasites with complex lifecycles that are important components of aquatic systems and are often model species for parasite-mediated host manipulation. Genetic characterization has recently resurrected Pomphorhynchus tereticollis as a distinct species from Pomphorhynchus laevis, with potential implications for fisheries management and host manipulation research. Morphological and molecular examinations of parasites from 7 English rivers across 9 fish species revealed that P. tereticollis was the only Pomphorhynchus parasite present in Britain, rather than P. laevis as previously recorded. Molecular analyses included two non-overlapping regions of the mitochondrial gene - cytochrome oxidase and generated 62 sequences for the shorter fragment (295 bp) and 74 for the larger fragment (583 bp). These were combined with 61 and 13 sequences respectively, from Genbank. A phylogenetic analysis using the two genetic regions and all the DNA sequences available for P. tereticollis identified two distinct genetic lineages in Britain. One lineage, possibly associated with cold water tolerant fish, potentially spread to the northern parts of Britain from the Baltic region via a northern route across the estuarine area of what is now the North Sea during the last Glaciation. The other lineage, associated with temperate freshwater fish, may have arrived later via the Rhine/Thames fluvial connection during the last glaciation or early Holocene when sea levels were low. These results raise important questions on this generalist parasite and its variously environmentally adapted hosts, and especially in relation to the consequences for parasite vicariance.

Latitudinal gradient of termite diversity indicates higher diversification and narrower thermal niches in the tropics

AbstractAimTo investigate the contributions of ecosystem productivity, temperature‐dependent metabolism and climatic tolerances to the latitudinal gradient in species richness and changes in species composition in tropical and subtropical regions.LocationGlobal.Time periodContemporary.Major taxa studiedTermites.MethodsWe compiled termite occurrence data from papers using the standardized sampling protocol proposed 20 years ago by Jones and Eggleton. Three continents, 28 countries and 494 sampling plots were included in our database. We used structural equation models to determine the direct and indirect effects of productivity, and the average and extreme values of temperature and precipitation on termite species richness. We also compared the observed association between diversity and temperature with predictions from the metabolic theory of ecology and compared how the similarity in species composition relates to geographic distance and environmental differences in tropical versus subtropical regions.ResultsTermite species richness was, directly and indirectly, related to average and extreme temperatures, but not to productivity. However, the association of species richness and temperature was much stronger than predicted by the metabolic theory of ecology. Moreover, species composition changed more rapidly with geographic distance and temperature differences between plots in the tropics than in the subtropics.Main conclusionsThese results suggest that the increase of species richness toward the equator cannot be explained by productivity gradients. Instead, the increase in the speciation rates and the narrow species niches along the temperature gradient in tropical regions likely determine the distribution of termites at broad spatial scales.

Wildfire severity and postfire salvage harvest effects on long‐term forest regeneration

AbstractFollowing a wildfire, regeneration to forest can take decades to centuries and is no longer assured in many western U.S. environments given escalating wildfire severity and warming trends. After large fire years, managers prioritize where to allocate scarce planting resources, often with limited information on the factors that drive successful forest establishment. Where occurring, long‐term effects of postfire salvage operations can increase uncertainty of establishment. Here, we collected field data on postfire regeneration patterns within 13‐ to 28‐yr‐old burned patches in eastern Washington State. Across 248 plots, we sampled tree stems &lt;4 m height using a factorial design that considered (1) fire severity, moderate vs. high severity; (2) salvage harvesting, salvaged vs. no management; and (3) potential vegetation type (PVT), sample resides in a dry, moist, or cold mixed‐conifer forest environment. We found that regeneration was abundant throughout the study region, with a median of 4414 (IQR 19,618) stems/ha across all plots. Only 15% of plots fell below minimum timber production stocking standards (350 trees/ha), and &lt;2% of plots were unstocked. Densities were generally highest in high‐severity patches and following salvage harvesting, although high variability among plots and across sites led to variable significance for these factors. Post hoc analyses suggested that mild postfire weather conditions may have reduced water stress on tree establishment and early growth, contributing to overall high stem densities. Douglas fir was the most abundant species, particularly in moderate‐severity patches, followed by ponderosa pine, lodgepole pine, western larch, and Engelmann spruce. Generalized additive models (GAMs) revealed species‐level climatic tolerances and seed dispersal limits that portend future challenges to regeneration with expected future climate warming and increased fire activity. Postfire regeneration will occur on sites with adequate seed sources within their climatic tolerances.

Geographic patterns and environmental correlates of taxonomic and phylogenetic beta diversity for large‐scale angiosperm assemblages in China

A full understanding of the origin and maintenance of β‐diversity patterns in a region requires exploring the relationships of both taxonomic and phylogenetic β‐diversity (TBD and PBD, respectively), and their respective turnover and nestedness components, with geographic and environmental distances. Here, we simultaneously investigated all these aspects of β‐diversity for angiosperms in China. Specifically, we evaluated the relative importance of environmental filtering vs dispersal limitation processes in shaping β‐diversity patterns. We found that TBD and PBD as quantified using a moving window approach decreased towards higher latitudes across the whole of China, and their turnover components were correlated with latitude more strongly than their nestedness components. When quantifying β‐diversity as pairwise distances, geographic and climatic distances across China together explained 60 and 53% of the variation in TBD and PBD, respectively. After the variation in β‐diversity explained by climatic distance was accounted for, geographic distance independently explained about 23 and 12% of the variation in TBD and PBD, respectively, across China. Overall, our results suggest that environmental filtering based on climatic tolerance conserved across lineages is the main force shaping β‐diversity patterns for angiosperms in China.

CLIMATIC AND ECOLOGICAL CONSTRAINTS IN THE DISTRIBUTION OF EUROPEAN BEECH (FAGUS SYLVATICA) AT THE EASTERN LIMIT (SCIENTIFIC RESERVE "PLAIUL FAGULUI")

For the Republic of Moldova, the European beech forests (Fagus sylvatica specie) represent their most eastern areal in the spatial distribution, in Europe. During the last century there have been unfavorable changes in the climate conditions for the development of beech forests in Moldova. The summer mean temperature has increased, while the annual rainfall showed a decreasing trend. Therefore, on the basis of the beech climate tolerance index (QBTI), it was determined that the limit of drought tolerance, in temporal and spatial aspect, clarify beech death phenomena. The data obtained were compared with the state of vitality of the beech crowns within "Plaiul Fagului Reserve", which in the last years is unsatisfactory, largely due to this phenomenon.

Climatic stability drives latitudinal trends in range size and richness of woody plants in the Western Ghats, India.

Understanding the determinants of range location and size is fundamental to our understanding of spatial patterns in species richness. Here, we aimed to test the role of ‘climatic stability’ in determining latitudinal trends in range size and as a consequence on species richness of tropical woody plants. Using primary data from 156 (0.06 ha) plots comprising 20,400 occurrences of more than 400 species of tropical woody plants, we built a biome-wide species database that covers the entire latitudinal extent of the wet-evergreen forests of the Western Ghats (8o to 20o N), India. We consolidated this database using secondary data from other published species inventories. We then calculated the range sizes and climatic niche width of woody plants to test the predictions of the climatic stability hypothesis and examined the relationship between range position and climatic tolerance of species. Our results show a significant latitudinal gradient in species richness and turnover where local and regional species richness increase monotonically from higher latitudes to lower latitudes of the Western Ghats. We found strong support for Rapoport’s Rule with an increase in range size from lower to higher latitudes; our results are consistent with the predictions of the climatic stability hypothesis, where species at higher latitudes exhibited greater tolerance to temperature and rainfall seasonality. Contrary to earlier work, our findings suggest that Rapoport’s Rule and the climatic stability hypothesis can operate over regional scales, and even at lower latitudes. We suggest that latitude associated climatic seasonality through its influence on species ranges, can influence latitudinal patterns in species turnover as well as species richness.

MORADA-CICA: Variedad de papa resistente a Phytophthora infestans (Mont.) De Bary

El Centro de Investigación en Cultivos Andinos (CICA), de la Universidad Nacional de San Antonio de Abad de Cusco (UNSAAC), cuenta con el Programa de Investigación en Papa, siendo sus objetivos principales la conservación de una colección superior de germoplasma y el mejoramiento genético de cultivares nativos. Mediante el Proyecto: “Conservación ex situ de papa nativa y la liberación de variedades para la agricultura regional” financiado con fondos provenientes de Canon de Gas de Camisea, se logró liberar la nueva variedad de papa MORADA CICA. La variedad MORADA-CICA, es un genotipo tetraploide de progenitores andígena. Esta condición genética le otorga amplio límite de tolerancia climática en los diferentes valles interandinos y zonas altas de la Región Cusco y otras regiones del país. Sus rendimientos son superiores a 35 toneladas de tubérculo por hectárea, de alta calidad culinaria, con materia seca superior a 23% y carne amarilla. Tiene alta resistencia a Phytophthora infestans y otras enfermedades, así como poca preferencia al daño de insectos. Es una variedad muy vigorosa que le permite el efecto de escape y soportabilidad a los efectos de sus enemigos bióticos y abióticos. &#x0D; &#x0D; Palabras Clave: Progenitor, nativas, rendimiento, enfermedades, tetraploide.

Multiple invasions of a generalist herbivore-Secondary contact between two divergent lineages of Nezara viridula Linnaeus in Australia.

The presence of distinct evolutionary lineages within herbivorous pest insect taxa requires close attention. Scientific understanding, biosecurity planning and practice, and pest management decision‐making each suffer when such situations remain poorly understood. The pest bug Nezara viridula Linnaeus has been recorded from numerous host plants and has two globally distributed mitochondrial (mtDNA) lineages. These mtDNA lineages co‐occur in few locations globally, and the consequences of their divergence and recent secondary contact have not been assessed. We present evidence that both mtDNA lineages of N. viridula are present in Australia and their haplotype groups have a mostly separate distribution from one another. The north‐western population has only Asian mtDNA haplotypes, and the population with an eastern distribution is characterized mostly by European mtDNA haplotypes. Haplotypes of both lineages were detected together at only one site in the north of eastern Australia, and microsatellite data indicate that this secondary contact has resulted in mating across the lineages. Admixture and the movement of mtDNA haplotypes outside of this limited area of overlap has not, however, been extensive. Some degree of mating incompatibility or differences in the climatic requirements and tolerances of the two lineages, and perhaps a combination of these influences, might limit introgression and the movement of individuals, but this needs to be tested. This work provides the foundation for further ecological investigation of the lineages of N. viridula, particularly the consequences of admixture on the ecology of this widespread pest. We propose that for now, the Asian and European lineages of N. viridula would best be investigated as subspecies, so that “pure” and admixed populations of this bug can each be considered directly with respect to management and research priorities.

Can polyploidy confer invasive plants with a wider climatic tolerance? A test using Solidago canadensis.

Polyploidy can cause variation in plant functional traits and thereby generate individuals that can adapt to fluctuating environments and exploit new environments. However, few empirical studies have tested for an association between ploidy level and climatic tolerance of invasive cytotypes relative to conspecific native‐range cytotypes. Here, we used an invasive plant Solidago canadensis to test whether invasive populations had a higher proportion of polyploids, greater height and stem‐base diameter, and occupied a wider range of climatic conditions than conspecific native‐range populations. We also tested whether the invasive populations had overcome genetic founder effects. We sampled a total of 80 populations in parts of the invaded range in China and native range in North America for in situ measurements of plant height and stem‐base diameter in the field and for population genetic and cytotype analyses. To examine climatic correlates, we augmented our field‐sampled data with occurrence records obtained from Global Biodiversity Information Facility. All, except one, of the populations that we sampled in China occurred in a humid subtropical climate. In contrast, the North American populations occurred in humid continental, humid subtropical, and semi‐arid climatic zones. All populations of S. canadensis in China were purely hexaploid, while the North American populations were diploid, tetraploid, and hexaploid. The invasive hexaploids were significantly taller and had a larger stem‐base diameter than native hexaploids. Native hexaploids were significantly taller and had larger stem‐base diameter than native diploids. Climatic correlate assessment found that invasive and native populations occupied different climatic envelopes, with invasive populations occurring in warmer and less seasonal climates than native populations. However, there was no significant correlation between ploidy level and climatic envelope of S. canadensis. Molecular phylogeography data suggest reduced genetic founder effects in the invaded range. Overall, these results suggest that polyploidy does not influence S. canadensis climatic tolerance.

Great journey of Great Tits(Parus majorgroup): Origin, diversification and historical demographics of a broadly distributed bird lineage

AbstractAimThe Pleistocene glacial cycles play a prominent role in shaping phylogeographical patterns of organisms, while few studies have focused on the regional difference of glacial effects. By acquiring comprehensive knowledge of the origin, diversification and historical demography of an intensively studied passerine species complex, Great Tit, we aim to test the regional variation of the Late Pleistocene glaciation impacts on this widely distributed bird lineage.LocationEurasia and associated peninsulas and archipelagos.TaxaParus majorspecies complex.MethodsPhylogeny, divergence times and demographic dynamics were estimated with Bayesian methods. Population structure, genetic diversity and correlation between genetic and physical distances were estimated based on mtDNA variation. Glacial‐to‐present distributional changes were assessed via ecological niche modelling (ENM).ResultsFive major clades (Central Asia, Eastern Asia, Eastern Himalaya, Northern and Western Eurasia and Southern Asia) were detected, with divergence times ranging 1.57–0.50 million years ago. Genetic diversity values and Bayesian skyline plots suggest that the three eastern clades had a deeper population history. A more complex geographic structure was observed in East Asia. Demographic expansion during the last glacial cycle was indicated for all five clades. ENM results showed broad conservatism of traits related to climate tolerances, and generally broader and more continuous distributional patterns under glacial conditions.Main ConclusionsThe Great Tit complex probably originated in Southeast Asia. Geographic barriers, such as the deserts of Central Asia and the Qinghai–Tibet Plateau appear to be related to the lineage divergence. Late Pleistocene climate cycles influenced both demographic dynamics and divergence, especially in terms of east–west differences in relation to geographic complexity.