Temperature Niche Research Articles

Lineage‐specific climatic niche drives the tempo of vicariance in the Rand Flora

AbstractAimThe disjunct distribution patterns of sister taxa can arise when previously continuous distribution ranges are fragmented by environmental changes such as major climatic events. Populations become isolated on either side of the newly established environmental barrier, and absence of gene flow promotes allopatric speciation, in a process that is known as ecological vicariance. If climate change altered the ancestral range gradually, such as along temporal temperature or moisture gradients, the age of divergence of disjunct species should be related to the lineage tolerance to climatic conditions. Here, we investigate this hypothesis using as a study model the African Rand Flora, a continental‐scale floristic pattern that relates sister taxa distributed on either side of the Saharan Desert.LocationAfrica, Macaronesia, Mediterranean Basin and the Middle East.MethodsWe estimated the extant climatic tolerances of 14 Rand Flora lineages based on present occurrence data, and correlated the phylogenetic age of divergence between vicariant clades. We tested whether the tempo of the vicariance in the Rand Flora lineages was associated with the average values of their climatic niches in agreement with niche‐driven divergence. We hindcasted species ranges using species distribution models combined with palaeoclimate simulations to infer the potential distribution of each lineage's ancestors.ResultsWe found a positive relationship between the lineage temperature niche and the age of the Rand Flora disjunction: lineages with subtropical affinities diverged first, whereas those with a higher tolerance to drier conditions (temperate or sub‐xeric adaptations) exhibited younger disjunctions. The range reconstructions showed the existence of climatic corridors south of the Sahara in the wetter Late Miocene, which became interrupted during the mid‐Pliocene warming event.Main conclusionsOur results suggest that climate change leading to the formation of the Sahara Desert drove Rand Flora lineages divergences along a temporal sequence that matched the climatic niche of species.

Erratum to: Aedes albopictus and Aedes japonicus - two invasive mosquito species with different temperature niches in Europe.

Aedes albopictus and Ae. japonicus are two of the most widespread invasive mosquito species that have recently become established in western Europe. Both species are associated with the transmission of a number of serious diseases and are projected to continue their spread in Europe. In the present study, we modelled the habitat suitability for both species under current and future climatic conditions by means of an Ensemble forecasting approach. We additionally compared the modelled MAXENT niches of Ae. albopictus and Ae. japonicus regarding temperature and precipitation requirements. Both species were modelled to find suitable habitat conditions in distinct areas within Europe: Ae. albopictus within the Mediterranean regions in southern Europe, Ae. japonicus within the more temperate regions of central Europe. Only in few regions, suitable habitat conditions were projected to overlap for both species. Whereas Ae. albopictus is projected to be generally promoted by climate change in Europe, the area modelled to be climatically suitable for Ae. japonicus is projected to decrease under climate change. This projection of range reduction under climate change relies on the assumption that Ae. japonicus is not able to adapt to warmer climatic conditions. The modelled MAXENT temperature niches of Ae. japonicus were found to be narrower with an optimum at lower temperatures compared to the niches of Ae. albopictus. Species distribution models identifying areas with high habitat suitability can help improving monitoring programmes for invasive species currently in place. However, as mosquito species are known to be able to adapt to new environmental conditions within the invasion range quickly, niche evolution of invasive mosquito species should be closely followed upon in future studies.

Climate change is not a major driver of shifts in the geographical distributions of North American birds

AbstractAimMany studies postulate that physiological tolerance of climatic variables imposes the primary limit on species geographical distributions, that tolerances are constant through time, that climate has warmed and that geographical distributions shift to maintain species in their thermal niches when climate changes. However, recent studies present evidence that is inconsistent with each of these propositions. Here we ask: how strongly did avian species entire geographical distributions (as opposed to their latitudinal extremes) in North America track temperature changes between 1979 and 2010?LocationThe continental United States (excluding Alaska) and southern Canada.MethodsWe examined changes from 1979 to 2010 in the geographical distributions, and the realized temperature niches, of 21 species of passerine birds whose entire breeding ranges fall within the area well sampled by the North American Breeding Bird Survey. We related changes in breeding distributions to the concomitant changes in breeding season temperature.ResultsThe median temperature increased within the breeding ranges of most, but not all, species. Temperature on the coolest 2.5% of routes increased significantly for only 8 of 21 species. Most species' distributions shifted geographically, but the most frequent shift was westward, not northward. Most species' realized temperature niches changed detectably through time, mainly as a result of changing temperature (versus geographical shifts). Where shifts in geographical distribution occurred, in most cases they did not result in smaller changes in species realized temperature niche than species would have experienced by not moving at all. There is little suggestion of a lagged response to climate change.Main conclusionsWe find only slight evidence that the geographical distributions of North American passeriform birds, considered in their entirety (as opposed to their latitudinal extremes), tracked temperature change. Of the factors that have driven recent shifts in the geographical distributions of North American avian species temperature change is probably only a minor one.

Aedes albopictus and Aedes japonicus - two invasive mosquito species with different temperature niches in Europe.

Background Aedes albopictus and Ae. japonicus are two of the most widespread invasive mosquito species that have recently become established in western Europe. Both species are associated with the transmission of a number of serious diseases and are projected to continue their spread in Europe.MethodsIn the present study, we modelled the habitat suitability for both species under current and future climatic conditions by means of an Ensemble forecasting approach. We additionally compared the modelled MAXENT niches of Ae. albopictus and Ae. japonicus regarding temperature and precipitation requirements.ResultsBoth species were modelled to find suitable habitat conditions in distinct areas within Europe: Ae. albopictus within the Mediterranean regions in southern Europe, Ae. japonicus within the more temperate regions of central Europe. Only in few regions, suitable habitat conditions were projected to overlap for both species. Whereas Ae. albopictus is projected to be generally promoted by climate change in Europe, the area modelled to be climatically suitable for Ae. japonicus is projected to decrease under climate change. This projection of range reduction under climate change relies on the assumption that Ae. japonicus is not able to adapt to warmer climatic conditions. The modelled MAXENT temperature niches of Ae. japonicus were found to be narrower with an optimum at lower temperatures compared to the niches of Ae. albopictus. ConclusionsSpecies distribution models identifying areas with high habitat suitability can help improving monitoring programmes for invasive species currently in place. However, as mosquito species are known to be able to adapt to new environmental conditions within the invasion range quickly, niche evolution of invasive mosquito species should be closely followed upon in future studies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1853-2) contains supplementary material, which is available to authorized users.

Comparing macroecological patterns across continents: evolution of climatic niche breadth in varanid lizards

Macroecological analyses often test hypotheses at the global scale, or among more closely related species in a single region (e.g. continent). Here, we test several hypotheses about climatic niche widths among relatively closely related species that occur across multiple continents, and compare patterns within and across continents to see if they differ. We focus on the lizard genus Varanus (monitor lizards), which occurs in diverse environments in Africa, Asia, and Australia. We address three main questions. 1) How do climatic niche breadths of species on a given niche axis change based on the position of species along that niche axis? (E.g. are species that occur in more extreme environments more narrowly specialized for those conditions?) 2) Are there trade‐offs in niche breadths on temperature and precipitation axes among species, or are niche widths on different axes positively related? 3) Is variation in niche breadths among species explained primarily by within‐locality seasonal variation, or by differences in climatic conditions among localities across the species range? We generate a new time‐calibrated phylogeny for Varanus and test these hypotheses within and between continents using climatic data and phylogenetic methods. Our results show that patterns on each continent often parallel each other and global patterns. However, in many other cases, the strength of relationships can change dramatically among closely related species on different continents. Overall, we found that: 1) species in warmer environments have narrower temperature niche breadths, but there is no relationship between precipitation niche breadth and niche position; 2) temperature and precipitation niche breadths tend to be positively related among species, rather than showing trade‐offs; and 3) within‐locality seasonal variation explains most variation in climatic niche breadths. Some of these results are concordant with previous studies (in amphibians and North American lizards), and might represent general macroecological patterns.

Temperature is better than precipitation as a predictor of plant community assembly across a dryland region

AbstractQuestionHow closely do plant communities track climate? Research suggests that plant species converge toward similar environmental tolerances relative to the environments that they experience. Whether these patterns apply to severe environments or scale up to plant community‐level patterns of relative climatic tolerances is poorly understood. Using estimates of species' climatic tolerances acquired from occurrence records, we determined the contributions of individual species' climatic niche breadths and environmental filtering to the relationships between community‐average climatic tolerances and the local climates experienced by those communities.LocationSouthwestern United States drylands.MethodsInterspecific variation in niche breadth was assessed as a function of species' climatic optima (median climatic niche value). The relationships between climatic optima and tolerances were used as null expectations for the relationship between abundance‐weighted mean climatic tolerances of communities and the local climate of that community. Deviations from this null expectation indicate that species with greater or lesser climatic tolerances are favoured relative to co‐occurring species. The intensity of environmental filtering was estimated by comparing the range of climatic tolerances within each community to a null distribution generated from a random assembly algorithm.ResultsThe temperature niches of species were consistently symmetrical and of similar breadths, regardless of their temperature optima. In contrast, precipitation niches were skewed toward wetter conditions, and niche breadth increased with increasing precipitation optima. At the community level, relationships with climate were much stronger for temperature than for precipitation. Furthermore, cold and heat were stronger assembly filters than drought or precipitation, with the intensity of environmental filtering increasing at both ends of climatic gradients. Community‐average climatic tolerances did deviate significantly from null expectations, indicating that species with higher or lower relative climatic tolerances were favoured under certain conditions.ConclusionsDespite strong water limitation of plant performance in dryland ecosystems, communities tracked variation in temperature much more closely, intimating strong responses to anticipated temperature increases. Furthermore, abundance distributions were biased toward species with higher or lower relative climatic tolerances under different climatic conditions, but predictably so, indicating the need for assembly models that include processes other than simple environmental filtering.

Scale dependence of temperature as an abiotic driver of species' distributions

AbstractAim Scale dependence of patterns and processes remains one of the major unresolved problems in ecology. The responses of ecosystems to environmental stressors are reported to be strongly scale dependent, but projections of the effects of climate change on species' distributions are still restricted to particular scales and knowledge about scale dependence is lacking. Here we propose that the scale dependence of those species' niche dimensions related to climate change is strongly related to the strength of climatic cross‐scale links. More specifically, we hypothesize that the strong cross‐scale links between micro‐ and macroclimatic conditions are related to high cross‐scale similarity (low scale dependence) of species' realized temperature niches and, thus, species' spatial distributions.Location This study covers seven orders of magnitude of spatial scale, ranging from local‐scale (below a metre) and regional‐scale (kilometre) investigations in central European wetland ecosystems to continental‐scale (thousands of kilometres) studies of species' distributions.Methods We combined data on the spatial occurrence of species (vegetation records at local and regional scales, digitized distribution maps at the continental scale) with information about the corresponding temperature regime of vascular plant species occurring in environmentally stable wetland ecosystems characterized by strong cross‐scale links between micro‐ and macroclimatic conditions.Results We observed high cross‐scale similarity of the characteristics of species temperature niches across seven orders of magnitude of spatial scale. However, the importance of temperature as an abiotic driver decreased nonlinearly with decreasing scale, suggesting greater importance of additional (biotic) drivers of species' occurrence at small spatial scales.Main conclusions We report high cross‐scale similarity of realized temperature niches for species inhabiting ecosystems where small‐scale environmental noise is low and cross‐scale links between micro‐ and macroclimatic conditions are strong. By highlighting a strong relationship between abiotic and biotic cross‐scale similarity, our results will help to improve niche‐based species distribution modelling, one of the major assessment tools for determining the ecological effects of climate change.

Coexistence and emergent neutrality generate synchrony among competitors in fluctuating environments

Many competitive communities exhibit a puzzling amount of species diversity. In this study, we model a community of symmetric competitors in a fluctuating environment. We use biologically realistic temperature-dependent growth curves with a widely hypothesized trade-off between maximum growth and nice breadth to control the shapes of the curves of different species. We perform three analyses of the community dynamics to investigate the role of environmental fluctuations in community composition and species diversity. We initiate communities with equal abundances of all species and randomize the temperature fluctuations so that there is no correlation between species responses, only noise. We initiate single populations and allow other species to randomly invade the community. We also knock out extant species one by one from an established community and allow them to reinvade after the remaining species have adjusted. We find that competitors with sufficiently different temperature niches coexist via temporal niche differentiation. We also find long-term persistence of species that are very similar to a dominant competitor. This creates communities with species clumped along a temperature niche axis, with stable coexistence between groups and near neutrality within groups. The near neutrality results in interspecific synchrony within the groups, providing an explanation for the maintenance of high diversity in competitive communities where synchrony is commonly observed.

Evolutionarily divergent thermal sensitivity of germline development and fertility in hermaphroditic Caenorhabditis nematodes.

Thermal developmental plasticity represents a key organismal adaptation to maintain reproductive capacity in contrasting and fluctuating temperature niches. Although extensively studied, research on thermal plasticity has mainly focused on phenotypic outcomes, such as adult life history, rather than directly measuring plasticity of underlying developmental processes. How thermal plasticity of developmental phenotypes maps into plasticity of resulting final phenotypes, and how such mapping relationships evolve, thus remain poorly understood. Here we address these questions by quantifying thermal plasticity of Caenorhabditis hermaphrodite germline development. We integrate measurements of germline development and fertility at the upper thermal range in isolates of C. briggsae, C. elegans, and C. tropicalis. First, we compare intra- and interspecific variation in thermal germline plasticity with plasticity in reproductive output. Second, we ask whether the developmental errors leading to fertility break-down at upper thermal limits are evolutionarily conserved. We find that temperature variation modulates spermatogenesis, oogenesis and germ cell progenitor pools, yet the thermal sensitivity of these processes varies among isolates and species, consistent with evolutionary variation in upper thermal limits of hermaphrodite fertility. Although defective sperm function is a major contributor to heat-induced fertility break-down, high temperature also significantly perturbs oogenesis, germline integrity, and mitosis-meiosis progression. Remarkably, the occurrence and frequency of specific errors are strongly species- and genotype-dependent, indicative of evolutionary divergence in thermal sensitivity of distinct processes in germline development. Therefore, the Caenorhabditis reproductive system displays complex genotype-by-temperature interactions at the developmental level, which may remain masked when studying thermal plasticity exclusively at the life history level.

Temperature niche conservatism and strong genetic structure are involved in the trans-Panamanian colonization of Matudaea (Hamamelidaceae) to Andean forests

Matudaea is the only genus of the Hamamelidaceae found in South America. The genus is composed by two extant species, M. trinervia, from Mexico and Costa Rica, and Matudaea colombiana, from the Colombian Andes; additional fossil records are present in Central Europe. Population genetics, molecular phylogenetics and niche modelling approaches were applied to explain processes related with the trans-Panamanian M. trinervia/M. colombiana split and the putative colonization of the latter to the northern Andes. The split between the two Matudaea species was estimated during Middle Miocene. The colonization of Matudaea into South America could have been facilitated by the closure of the Isthmus of Panama and the global decreasing of temperature during Miocene. Five haplotypes of M. colombiana were identified, which show an eastwards decline of genetic diversity and suggest a founder effect in the colonization of Eastern cordillera of the Colombian Andes. We detected a niche conservatism signal between the two Matudaea species related with Temperature of Coldest Month and Mean Temperature of Driest Quarter bioclimatic variables; this signal might be related to the narrow altitudinal range occupied by the two species.

Environment and evolutionary history determine the global biogeography of phytoplankton temperature traits

AbstractAimEcological and evolutionary forces shape the functional traits of species within and across environments, generating biogeographical patterns in traits. We aimed to: (1) determine the extent to which temperature traits of phytoplankton are adapted to their local environment, and (2) detect and explain differences in patterns of adaptation between functional groups (reflecting evolutionary history) and across ecosystems (freshwater versus marine).LocationWe used laboratory‐measured data on phytoplankton strains isolated from marine (76° N to 75° S) and freshwater ecosystems (80° N to 78° S).MethodsWe studied variation in five temperature traits: optimum temperature for growth (Topt), maximum and minimum persistence temperature (Tmax, Tmin), temperature niche width and maximum growth rate, estimated in 439 strains from over 200 species. We tested whether these traits change along environmental temperature gradients (across latitude and ecosystems) and also investigated differences in trait–environment relationships related to evolutionary history (functional group identity). We used mixed models to evaluate our hypotheses while accounting for intraspecific variation.ResultsWe identified three patterns caused by adaptation and community assembly: (1) Topt, Tmax and Tmin decline sharply with latitude; (2) Topt, Tmax and Tmin are similar across all functional groups at the equator, where temperature variation is low; and (3) Topt and Tmax are higher in freshwater locations than marine locations at similar latitudes. Additionally, evolutionary history explained substantial variation in all traits: functional groups differ strongly in their niche widths and maximum growth rates, as well as their Topt, Tmax, and Tmin relationships with latitude.Main conclusionsGlobally, phytoplankton temperature traits are well adapted to local conditions, changing across ecosystems and latitude. Functional groups differ strongly in their patterns of adaptation: traits are similar in hot tropical environments, but diverge at temperate latitudes. These differences reflect two possible evolutionary constraints: cyanobacterial inability to adapt to low temperatures and differences in nutrient requirements between groups.

Predicting consequences of climate change for ecosystem functioning: variation across trophic levels, species and individuals

AbstractAimMaintenance of ecosystem function under climate change may depend on variation in the way species within functional guilds and individuals within species respond to changes in temperature. What level of variation among and within species do we need to understand, and is it predictable from distribution and trait data?LocationNorthern California, USA.MethodsWe used a mesocosm experiment and a set of feeding trials to test the ability of a guild of marine invertebrate grazers to control benthic algal blooms along a local temperature gradient. We investigate links between the locally disjunct distributions of these species, their temperature tolerance traits and the temperature dependence of their population growth and grazing rates.ResultsWe found that the effect of increased temperature on population growth rates is independent of species interactions, but strongly species specific. This variation among herbivores is only partly predictable from differences in species distributions and traits, but translated into large differences in their ability to control macroalgae. Further, these species effects were amplified at warmer temperatures. Finally, we found evidence for a strong response to temperature in the feeding rates of the most important consumer over the course of the experiment, resulting in almost as much variation in grazing rates within one species as the average difference between species.Main conclusionsThese results illustrate the importance of understanding the variation in responses to temperature among species within a trophic level, among populations within key species and potentially within populations over time. However, this variation is not easily predicted. Further research is needed to uncover links between individuals' thermal optima and their current and future temperature niche.

Life history lability underlies rapid climate niche evolution in the angiosperm clade Montiaceae

Despite the recent focus on phylogenetic niche conservatism in macroevolutionary studies, many clades have diversified widely along multiple niche dimensions. The factors underlying lineage-specific niche lability are still not well understood. We examined morphological and climate niche evolution in Montiaceae (Caryophyllales), an ecologically variable plant lineage distributed primarily along the mountain chains of the western Americas. Montiaceae inhabit a broader range of temperatures than their relatives, with an increase in the evolutionary rate of temperature niche diversification at the node subtending this clade. Within Montiaceae, life history is highly labile and significantly correlated with temperature, with perennials consistently occurring in cooler environments. This elevated evolutionary lability facilitated repeated shifts between habitats as new environments were created by post-Eocene orogenic events and aridification in the western Americas. The shifts between annual and perennial forms are elaborations of an underlying rosette body plan in most cases, and may involve simple alterations in biomass allocation. Montiaceae stand as another clear counterexample to phylogenetic niche conservatism, and demonstrate a mechanism by which pronounced ecological shifts may occur frequently and rapidly among closely related species.

Some like it hot: Thermal tolerance and oxygen supply capacity in two eurythermal crustaceans.

Thermal sensitivity of the cardiorespiratory oxygen supply capacity has been proposed as the cardinal link underlying the upper boundary of the temperature niche in aquatic ectotherms. Here we examined the evidence for this link in two eurythermal decapods, the Giant tiger shrimp (Penaeus monodon) and the European crayfish (Astacus astacus). We found that both species have a temperature resistant cardiorespiratory system, capable of maintaining oxygen delivery up to their upper critical temperature (Tcrit). In neither species was Tcrit reduced in hypoxia (60% air saturation) and both species showed an exponential increase in heart and gill ventilation rates up to their Tcrit. Further, failure of action potential conduction in preparations of A. astacus motor neurons coincided with Tcrit, indicating that compromised nervous function may provide the underlying determinant for Tcrit rather than oxygen delivery. At high temperatures, absolute aerobic scope was maintained in P. monodon, but reduced in A. astacus. However, A. astacus also displayed reduced exercise intensity indicating that impaired muscle performance with resulting reduced tissue oxygen demand may explain the reduced scope rather than insufficient oxygen supply capacity. This interpretation agrees with early literature on aquatic ectotherms, correlating loss of nervous function with impaired locomotion as temperatures approach Tcrit.

Ant assemblages along the Baekdudaegan Mountain Range in South Korea: Human roads and temperature niche

The Baekdudaegan is a Korean main mountain range that passes through the Korean Peninsula, and Korean people consider it to be the main ecological axis of the Korean Peninsula. Many motor roads cross the Baekdudaegan, and the Baekdudaegan trail is popular among hikers. The present study investigated the ants of Baekdudaegan using pitfall traps in two separate surveys (2006–2008 and 2009) with different sampling designs at six uphill passes to identify the impacts of motor roads and trails. There was no influence from motor roads found (distance from the road and forest fragmentation by road). In the case of trails, however, the further the ants were located from the trails, the less population tended to be observed. The composition of ant species was determined by the temperature niche of ants. When the ants went further south, cold-adapted species declined, while warm-adapted species increased. In this study, a total of 28 species were collected, which is not higher compared with species richness in other areas.

A cross-taxon analysis of the impact of climate change on abundance trends in central Europe

Advances in phenology and pole- and up-ward shifts in geographic ranges are well-documented signs that species are responding to climate change. A deeper understanding of such responses across ecologically different species groups will help to assess future consequences for entire ecosystems. A less well-studied pattern linked with climate change is increases in abundances of warm-adapted species compared with cold-adapted species. To compare how recent climate change has affected the abundances of species across different taxonomic groups, we analyzed long-term local population trends and related them to the species temperature niche, as inferred from geographic distributions. We used population data sets collected in different regions of Central Europe, primarily Germany, for bats, birds, butterflies, ground beetles, springtails and dry grassland plants. We found that temperature niche was positively associated with long-term population trends in some of the taxonomic groups (birds, butterflies, ground beetles) but was less important in others (bats, springtails, and grassland plants). This variation in the importance of temperature niche suggested that some populations have been affected more than others by climate change, which may be explained by differences in species attributes, such as generation time and microhabitat preference. Our findings indicate that relating temperature niches of species to population trends is a useful method to quantify the impact of climate change on local population abundances. We show that this widely applicable approach is particularly suited for comparative cross-system analyses to identify which types of organisms, in which habitats, are responding the most to climate change.

Modeling constraints on the spread of agriculture to Southwest China with thermal niche models

Understanding how, why and by what mechanisms agricultural practices, technologies and products spread out of their zones of original development is a central theme of archaeology. To date, very few studies have combined agro-ecological modeling with detailed analyses of archaeobotanical remains to outline the kinds of challenges that ancient humans faced as they moved crops into environments different from their original homeland of domestication. This paper employs ecological niche modeling to outline the constraints faced by ancient humans as they moved rice, millets and eventually wheat and barley into the mountainous region of Southwest China. In particular, we propose that moving rice into this region presented considerable challenges for its cultivators and we infer that its spread into this area was facilitated by breeding cold adapted varieties of rice or by combining its cultivation with that of millet. High altitude areas did not take up full-scale agriculture until the introduction of cold adapted western Eurasian domesticates such as wheat and barley. The temperature niche models reinforce the adoption of these regionally varied agricultural strategies and support the significance of domesticates other than rice for the spread of agriculture into Southwest China.

Climatic niche breadth and species richness in temperate treefrogs

AbstractAimPatterns of species richness are often closely linked with climate, but the specific mechanisms by which species' climatic niches underlie large‐scale richness patterns remain poorly understood. It has been hypothesized that reduced temperature seasonality in the tropics promotes the evolution of species with narrow temperature niche breadths, and that this hypothesis helps explain high tropical richness. However, the relationship between species' climatic niche breadths and species richness has yet to be tested. We have addressed this issue using treefrogs (Hylidae) in eastern North America.LocationEastern North America.MethodsWe characterized climatic niches and niche breadths for all 24 hylid species in eastern North America using temperature and precipitation variables. We then examined the relationships between species richness, climatic niche positions and climatic niche breadths using phylogenetic comparative methods.ResultsSpecies richness was negatively associated with mean climatic niche breadth, such that high‐richness climates had species with narrower climatic niches. Our results also supported the roles of niche conservatism and the time‐for‐speciation effect in generating the relationship between climate and species richness in the region (more species in warm, wet regions that have been inhabited longer). Importantly, we show that the invasion of low‐richness climates has occurred primarily through recent intraspecific niche expansion into these climates rather than evolution of species that are narrowly specialized for these conditions (although the two hylid clades studied showed somewhat different patterns).Main conclusionsWe found that climatic zones with high species richness contain more species with narrower climatic niche breadths. Our results suggest that this pattern arose because narrow climatic niche breadths restricted the dispersal of most hylid species out of the ancestral, warm, moist climatic zones, allowing more time for speciation to build up higher species richness in these zones.

Decoupled evolution of foliar freezing resistance, temperature niche and morphological leaf traits inChileanMyrceugenia

SummaryPhylogenetic conservatism of tolerance to freezing temperatures has been cited to explain the tendency of plant lineages to grow in similar climates. However, there is little information about whether or not freezing resistance is conserved across phylogenies, and whether conservatism of physiological traits could explain conservatism of realized climatic niches. Here, we compared the phylogenetical lability of realized climatic niche, foliar freezing resistance and four morphological leaf traits that are generally considered to be adaptations to frost resistance in the Chilean species ofMyrceugenia, which grows in a wide range of habitats.We estimated the predicted niche occupancy profiles with respect to minimum temperature (minT) of all species. We measured foliar freezing resistance (using chlorophyll fluorescence), leaf size, leaf mass per area (LMA), stomatal and trichome densities of 10 individuals per species. Finally, we estimated phylogenetic signal, and we performed independent contrast analyses among all variables.We found that both foliar freezing resistance and minT were subject to a significant phylogenetic signal, but the former had a stronger signal. We also detected a significant, but weak correlation between them (r = 0.49,Pone tail = 0.04). Morphological traits evolved independent of any phylogenetic effect.Synthesis. Our results show that freezing resistance evolved in association with temperature niche, but with some delay that could result from phylogenetic inertia. Our results also show that morphological leaf traits are more labile than realized climatic niche and frost tolerance and that the formers probably evolved in association with microhabitat preferences.

Plants, Birds and Butterflies: Short-Term Responses of Species Communities to Climate Warming Vary by Taxon and with Altitude

As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003–2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world.