Shifting latitudinal clines in avian body size correlate with global warming in Australian passerines

Intraspecific latitudinal clines in the body size of terrestrial vertebrates, where members of the same species are larger at higher latitudes, are widely interpreted as evidence for natural selection and adaptation to local climate. These clines are predicted to shift in response to climate change. We used museum specimens to measure changes in the body size of eight passerine bird species from south-eastern Australia over approximately the last 100 years. Four species showed significant decreases in body size (1.8–3.6% of wing length) and a shift in latitudinal cline over that period, and a meta-analysis demonstrated a consistent trend across all eight species. Southern high-latitude populations now display the body sizes typical of more northern populations pre-1950, equivalent to a 7° shift in latitude. Using ptilochronology, we found no evidence that these morphological changes were a plastic response to changes in nutrition, a likely non-genetic mechanism for the pattern observed. Our results demonstrate a generalized response by eight avian species to some major environmental change over the last 100 years or so, probably global warming.     

Shared morphological consequences of global warming in North American migratory birds

Increasing temperatures associated with climate change are predicted to cause reductions in body size, a key determinant of animal physiology and ecology. Using a four‐decade specimen series of 70 716 individuals of 52 North American migratory bird species, we demonstrate that increasing annual summer temperature over the 40‐year period predicts consistent reductions in body size across these diverse taxa. Concurrently, wing length – an index of body shape that impacts numerous aspects of avian ecology and behaviour – has consistently increased across species. Our findings suggest that warming‐induced body size reduction is a general response to climate change, and reveal a similarly consistent and unexpected shift in body shape. We hypothesise that increasing wing length represents a compensatory adaptation to maintain migration as reductions in body size have increased the metabolic cost of flight. An improved understanding of warming‐induced morphological changes is important for predicting biotic responses to global change.     

Geographic signatures in species turnover: decoupling colonization and extinction across a latitudinal gradient

High latitude communities have low species richness and are rapidly warming with climate change. Thus, temporal changes in community composition are expected to be greatest at high latitudes. However, at the same time traits such as body size can also change with latitude, potentially offsetting or increasing changes to community composition over time. We tested how zooplankton communities (copepods and cladocerans) have changed over a 25–75 year time span by assessing colonization and extinction rates from lakes across an 1800 km latitudinal gradient, and further tested whether species traits predict rates of community change over time. Lake‐level dissimilarity, measured with Sorenson distance, decreased at higher latitudes. This decrease was due to higher colonization rates of cladocerans in lower latitude lakes and consistent extinction rates across the latitudinal gradient. At the species level, colonization increased with regional occupancy, and tended to be higher for smaller bodied, locally abundant, species. Local extinction rates were negatively correlated with local abundance and regional occupancy, but were not influenced by body size. None of these species‐specific characteristics changed predictably with latitude. Contrary to our expectations, low‐latitude zooplankton communities changed more rapidly than high‐latitude communities by becoming more species rich, not by losing species that were historically present. Moreover, colonization and extinction trends suggest that lakes have become increasingly dominated by species with smaller body sizes and that are already common locally and regionally. Together, these findings indicate that rates of species turnover in freshwater lakes across a latitudinal gradient are not predicted by rates of temperature change, but that turnover is nonetheless resulting in trait‐shifts that favour small, generalist species.     

The complex drivers of thermal acclimation and breadth in ectotherms

Thermal acclimation capacity, the degree to which organisms can alter their optimal performance temperature and critical thermal limits with changing temperatures, reflects their ability to respond to temperature variability and thus might be important for coping with global climate change. Here, we combine simulation modelling with analysis of published data on thermal acclimation and breadth (range of temperatures over which organisms perform well) to develop a framework for predicting thermal plasticity across taxa, latitudes, body sizes, traits, habitats and methodological factors. Our synthesis includes > 2000 measures of acclimation capacities from > 500 species of ectotherms spanning fungi, invertebrates, and vertebrates from freshwater, marine and terrestrial habitats. We find that body size, latitude, and methodological factors often interact to shape acclimation responses and that acclimation rate scales negatively with body size, contributing to a general negative association between body size and thermal breadth across species. Additionally, we reveal that acclimation capacity increases with body size, increases with latitude (to mid‐latitudinal zones) and seasonality for smaller but not larger organisms, decreases with thermal safety margin (upper lethal temperature minus maximum environmental temperatures), and is regularly underestimated because of experimental artefacts. We then demonstrate that our framework can predict the contribution of acclimation plasticity to the IUCN threat status of amphibians globally, suggesting that phenotypic plasticity is already buffering some species from climate change.     

Quo vadis amphibia? Global warming and breeding phenology in frogs,toads and salamanders

As the earth is getting warmer, many animals and plants have shifted their timing of breeding towards earlier dates. However, there is substantial variation between populations in phenological shifts that typically goes unexplained. Identification of the different location and species characteristics that drive such variable responses to global warming is crucial if we are to make predictions for how projected climate change scenarios will play out on local and global scales. Here we conducted a phylogenetically controlled meta‐analysis of breeding phenology across frogs, toads and salamanders to examine the extent of variation in amphibian breeding phenology in response to global climate change. We show that there is strong geographic variation in response to global climate change, with species at higher latitudes exhibiting a more pronounced shift to earlier breeding than those at lower latitudes. Our analyses suggest that this latitude effect is a result of both the increased temperature (but not precipitation) at higher latitudes as well as a greater responsiveness by northern populations of amphibians to this change in temperature. We suggest that these effects should reinforce any direct effect of increasing warming at higher latitudes on breeding phenology. In contrast, we found very little contribution from other location factors or species traits. There was no evidence for a phylogenetic signal on advancing breeding phenology or responsiveness to temperature, suggesting that the amphibians that have been studied to date respond similarly to global warming.     

Failure to migrate: lack of tree range expansion in response to climate change

Tree species are expected to track warming climate by shifting their ranges to higher latitudes or elevations, but current evidence of latitudinal range shifts for suites of species is largely indirect. In response to global warming, offspring of trees are predicted to have ranges extend beyond adults at leading edges and the opposite relationship at trailing edges. Large‐scale forest inventory data provide an opportunity to compare present latitudes of seedlings and adult trees at their range limits. Using the USDA Forest Service's Forest Inventory and Analysis data, we directly compared seedling and tree 5th and 95th percentile latitudes for 92 species in 30 longitudinal bands for 43 334 plots across the eastern United States. We further compared these latitudes with 20th century temperature and precipitation change and functional traits, including seed size and seed spread rate. Results suggest that 58.7% of the tree species examined show the pattern expected for a population undergoing range contraction, rather than expansion, at both northern and southern boundaries. Fewer species show a pattern consistent with a northward shift (20.7%) and fewer still with a southward shift (16.3%). Only 4.3% are consistent with expansion at both range limits. When compared with the 20th century climate changes that have occurred at the range boundaries themselves, there is no consistent evidence that population spread is greatest in areas where climate has changed most; nor are patterns related to seed size or dispersal characteristics. The fact that the majority of seedling extreme latitudes are less than those for adult trees may emphasize the lack of evidence for climate‐mediated migration, and should increase concerns for the risks posed by climate change.     

Predicting woodrat (Neotoma) responses to anthropogenic warming from studies of the palaeomidden record

Aim The influence of anthropogenic climate change on organisms is an area of great scientific concern. Increasingly there is recognition that abrupt climate transitions have occurred over the late Quaternary; studies of these shifts may yield insights into likely biotic responses to contemporary warming. Here, we review research undertaken over the past decade investigating the response of Neotoma (woodrats) body size and distribution to climate change over the late Quaternary (the last 40,000 years). By integrating information from woodrat palaeomiddens, historical museum specimens and field studies of modern populations, we identify potential evolutionary responses to climate change occurring over a variety of temporal and spatial scales. Specifically, we characterize climatic thresholds in the past that led to local species extirpation and/or range alterations rather than in situ adaptation, and apply them to anticipate potential biotic responses to anthropogenic climate change. Location Middens were collected at about 55 sites scattered across the western United States, ranging from about 34 to 46° N and about 104 to 116° W, respectively. Data for modern populations were drawn from studies conducted in Death Valley, California, Missoula, Montana and the Sevilleta LTER site in central New Mexico. Methods We analysed faecal pellets from midden series collected at numerous cave sites across the western United States. From these we estimated body mass using techniques validated in earlier studies. We compared body size fluctuations at different elevations in different regions and integrated these results with studies investigating temperature–body size tradeoffs in modern animals. We also quantify the rapidity of the size changes over the late Quaternary to estimate the evolutionary capacity of woodrats to deal with predicted rates of anthropogenic climate change over the next century. Results We find remarkable similarities across the geographical range to late Quaternary climate change. In the middle of the geographical range woodrats respond in accordance to Bergmann's rule: colder climatic conditions select for larger body size and warmer conditions select for smaller body size. Patterns are more complicated at range boundaries, and local environmental conditions influence the observed response. In general, woodrat body size fluctuates with approximately the same amplitude and frequency as climate; there is a significant and positive correlation between woodrat body size and generalized climate proxies (such as ice core records). Woodrats have achieved evolutionary rates of change equal to or greater than those needed to adapt in situ to anthropogenic climate change. Main conclusions In situ body size evolution is a likely outcome of climate change, and such shifts are part of a normal spectrum of adaptation. Woodrats appear to be subject to ongoing body size selection in response to fluctuating environmental conditions. Allometric considerations suggest that these shifts in body size lead to substantial changes in the physiology, life history and ecology of woodrats, and on their direct and indirect interactions with other organisms in the ecosystem. Our work highlights the importance of a finely resolved and long‐term record in understanding biotic responses to climatic shifts.     

Shifts in frog size and phenology: Testing predictions of climate change on a widespread anuran using data from prior to rapid climate warming

Changes in body size and breeding phenology have been identified as two major ecological consequences of climate change, yet it remains unclear whether climate acts directly or indirectly on these variables. To better understand the relationship between climate and ecological changes, it is necessary to determine environmental predictors of both size and phenology using data from prior to the onset of rapid climate warming, and then to examine spatially explicit changes in climate, size, and phenology, not just general spatial and temporal trends. We used 100 years of natural history collection data for the wood frog, Lithobates sylvaticus with a range >9 million km², and spatially explicit environmental data to determine the best predictors of size and phenology prior to rapid climate warming (1901–1960). We then tested how closely size and phenology changes predicted by those environmental variables reflected actual changes from 1961 to 2000. Size, phenology, and climate all changed as expected (smaller, earlier, and warmer, respectively) at broad spatial scales across the entire study range. However, while spatially explicit changes in climate variables accurately predicted changes in phenology, they did not accurately predict size changes during recent climate change (1961–2000), contrary to expectations from numerous recent studies. Our results suggest that changes in climate are directly linked to observed phenological shifts. However, the mechanisms driving observed body size changes are yet to be determined, given the less straightforward relationship between size and climate factors examined in this study. We recommend that caution be used in “space‐for‐time” studies where measures of a species’ traits at lower latitudes or elevations are considered representative of those under future projected climate conditions. Future studies should aim to determine mechanisms driving trends in phenology and body size, as well as the impact of climate on population density, which may influence body size.     

Diversity and assemblage structure of phytophagous Hemiptera along a latitudinal gradient: predicting the potential impacts of climate change

Aims The aims were (1) to assess the species richness and structure of phytophagous Hemiptera communities along a latitudinal gradient, (2) to identify the importance of rare species in structuring these patterns, and (3) to hypothesize about how phytophagous Hemiptera communities may respond to future climate change. Location East coast of Australia. Methods Four latitudes within the 1150 km coastal distribution of Acacia falcata were selected. The insect assemblage on the host plant Acacia falcata was sampled seasonally over two years. Congeneric plant species were also sampled at the sites. Results Ninety‐eight species of phytophagous Hemiptera were collected from A. falcata. Total species richness was significantly lower at the most temperate latitude compared to the three more tropical latitudes. We classified species into four climate change response groups depending on their latitudinal range and apparent host specificity. Pairwise comparisons between groups showed that the cosmopolitan, generalist feeders and specialists had a similar community structure to each other, but the climate generalists had a significantly different structure. Fifty‐seven species were identified as rare. Most of these rare species were phloem hoppers and their removal from the dataset led to changes in the proportional representation of all guilds in two groups: the specialist and generalist feeders. Main conclusions We found no directional increase in phytophagous Hemiptera species richness. This indicates that, at least in the short term, species richness patterns of these communities may be similar to that found today. As the climate continues to change, however, we might expect some increases in species richness at the more temperate latitudes as species migrate in response to shifting climate zones. In the longer term, more substantial changes in community composition will be expected because the rare species, which comprise a large fraction of these communities, will be vulnerable to both direct climatic changes, and indirect effects via changes to their host's distribution.     

Water temperature affects life-cycle duration of tadpoles of Natal cascade frog

Direct and indirect effects of climate change on amphibians include range shifts and changes in community structure. The Natal cascade frog Hadromophryne natalensis has an altitudinal range of some 2 400 m in KwaZulu-Natal, and presents an opportunity to assess how increased water temperatures may impact on widely distributed amphibians. We sampled populations of tadpoles at three sites near the upper and lower altitudinal extremes of their range, measuring total length, mass and habitat water temperatures. Except for the spring survey, frequency–size class data showed bimodal curves at the two high-altitude sites and unimodal curves at the low-altitude site, suggesting a two-year aquatic life cycle in the cooler, higher rivers and a one-year life cycle at the warmer site. These data were consistent with cumulative degree days, which doubled from the higher- to the lower-altitude sites. Tadpoles at the warmer, lower-altitude site were in worse condition than those at the cooler, higher-altitude sites. We hypothesise that, while thermal changes may not result in rapid, large range shifts for this species, there are a number of unknown variables that may result from potential reductions in life-cycle length, including changes in competitive behaviour and community structure linked to asynchronies between species.     

Phenological delay despite warming in wood frog Rana sylvatica reproductive timing: a 20-year study

Across all taxa, amphibians exhibit some of the strongest phenological shifts in response to climate change. As climates warm, amphibians and other animals are expected to breed earlier in response to temperature cues. However, if species use fixed cues such as daylight, their breeding timing might remain fixed, potentially creating disconnects between their life history and environmental conditions. Wood frogs Rana sylvatica are a cold-adapted species that reproduce in early spring, immediately after breeding ponds are free of ice. We used long-term surveys of wood frog oviposition timing in 64 breeding ponds over 20 yr to show that, despite experiencing a warming of 0.29°C per decade in annual temperature, wood frog breeding phenology has shifted later by 2.8 d since 2000 (1.4 d per decade; 4.8 d per °C). This counterintuitive pattern is likely the result of changes in the timing of snowpack accumulation and melting. Finally, we used relationships between climate and oviposition between 2000 and 2018 to hindcast oviposition dates from climate records to model longer-term trends since 1980. Our study indicates that species can respond to fine-grained seasonal climate heterogeneity within years that is not apparent or counterintuitive when related to annual trends across years.     

Temporal patterns of avian body size reflect linear size responses to broadscale environmental change over the last 50 years

Alongside well researched shifts in species' distributions and phenology, reduction in the body size of organisms has been suggested as a third universal response to contemporary climate change. Despite mounting evidence for declining body size, several recent reviews highlight studies reporting increases in body size or no change over time. This variability in response may derive from the geographic scale of contributing studies, masking species‐level responses to broad‐scale environmental change and instead reflecting local influences on single populations. Using museum specimens, we examine temporal patterns of body size of 24 Australian passerine species, sampling multiple populations across the geographic ranges of each species between 1960 and 2007. Generalised additive models indictated that the majority (67%) of species showed important inter‐annual body size variation, and there was striking cross‐species similarity in temporal size patterns. Most displayed near‐linear or linear, unidirectional size trends, suggesting a pervasive and directional change in environmental conditions, consistent with climate change. For species showing linear size responses, the absolute rate of size change ranged between 0.016 and 0.114% of body size (wing length) per year, consistent with studies on other continents. Overall, 38% (9/24) of species showed temporal declines in body size and 21% (5/24) showed increases, consistent with the variability and direction of size responses thus far documented among populations; declining body size is a pervasive response to climate change but it is not universal.     

Warming temperatures and smaller body sizes: synchronous changes in growth of North Sea fishes

Decreasing body size has been proposed as a universal response to increasing temperatures. The physiology behind the response is well established for ectotherms inhabiting aquatic environments: as higher temperatures decrease the aerobic capacity, individuals with smaller body sizes have a reduced risk of oxygen deprivation. However, empirical evidence of this response at the scale of communities and ecosystems is lacking for marine fish species. Here, we show that over a 40‐year period six of eight commercial fish species in the North Sea examined underwent concomitant reductions in asymptotic body size with the synchronous component of the total variability coinciding with a 1–2 °C increase in water temperature. Smaller body sizes decreased the yield‐per‐recruit of these stocks by an average of 23%. Although it is not possible to ascribe these phenotypic changes unequivocally to temperature, four aspects support this interpretation: (i) the synchronous trend was detected across species varying in their life history and life style; (ii) the decrease coincided with the period of increasing temperature; (iii) the direction of the phenotypic change is consistent with physiological knowledge; and (iv) no cross‐species synchrony was detected in other species‐specific factors potentially impacting growth. Our findings support a recent model‐derived prediction that fish size will shrink in response to climate‐induced changes in temperature and oxygen. The smaller body sizes being projected for the future are already detectable in the North Sea.     

Latitudinal pattern in body size in a cockroach,Eupolyphaga sinensis

Body size of insects with flexible life cycles is expected to conform to the saw‐tooth model, a model in which the relationship between size and developmental time depends on length of the growing season. In species with high variability in terms of voltinism, however, more complex patterns can be expected. Few empirical studies have demonstrated the existence of such relationships, or whether climatic factors contribute to these relationships. In this study, we investigated the geographic variation in body size of the Chinese cockroach, Eupolyphaga sinensis Walker (Blattaria: Polyphagidae), which has a variable life cycle length. The sizes of adults – collected from 14 localities ranging from temperate to subtropical zones in China – were measured, using body length, body width, and pronotum width as parameters. The relationship between size, latitude, and climate factors (encompassing 10 variables) was then investigated. We found that the body size of E. sinensis varied considerably with latitude: cockroaches were larger at low and high latitudes, but smaller at intermediate latitudes. Thus, the relationship between climate and body size conformed to a saw‐tooth pattern. Results indicate that two factors were significantly associated with body size clines: season length and variability in life cycle length. Our results also demonstrated that climatic factors contribute to latitudinal clines in body size, which has important ecological and evolutionary implications. It can be expected that global climate change may alter latitudinal clines in body size of E. sinensis.     

Persistence and diversification of the Holarctic shrew,Sorex tundrensis (Family Soricidae), in response to climate change

Environmental processes govern demography, species movements, community turnover and diversification and yet in many respects these dynamics are still poorly understood at high latitudes. We investigate the combined effects of climate change and geography through time for a widespread Holarctic shrew, Sorex tundrensis. We include a comprehensive suite of closely related outgroup taxa and three independent loci to explore phylogeographic structure and historical demography. We then explore the implications of these findings for other members of boreal communities. The tundra shrew and its sister species, the Tien Shan shrew (Sorex asper), exhibit strong geographic population structure across Siberia and into Beringia illustrating local centres of endemism that correspond to Late Pleistocene refugia. Ecological niche predictions for both current and historical distributions indicate a model of persistence through time despite dramatic climate change. Species tree estimation under a coalescent process suggests that isolation between populations has been maintained across timeframes deeper than the periodicity of Pleistocene glacial cycling. That some species such as the tundra shrew have a history of persistence largely independent of changing climate, whereas other boreal species shifted their ranges in response to climate change, highlights the dynamic processes of community assembly at high latitudes.     

Effects of climate change on different geographical populations of the cotton bollworm Helicoverpa armigera (Lepidoptera,Noctuidae)

The effects of climate change on pest phenology and population size are highly variable. Understanding the impacts of localized climate change on pest distribution and phenology is helpful for improving integrated pest management strategies. Here, the population dynamics of cotton bollworms (Helicoverpa armigera) from Maigaiti County, south Xinjiang, and Shawan County, north Xinjiang, China, were analyzed using a 29‐year dataset at lower latitudes and a 23‐year dataset at higher latitudes to determine the effects of climate change on the population dynamics of H. armigera. The results showed that all generations of H. armigera at both sites showed increasing trends in population size with climate warming. Abrupt changes in phenology and population number occurred after abrupt temperature changes. Climate change had a greater effect on the phenology of H. armigera at higher latitudes than at lower latitudes and led to a greater increase in population size at lower latitudes than at higher latitudes; the temperature increase at higher latitudes will cause a greater increase in the adult moth population size in the future compared to that at lower latitudes; and abrupt changes in the phenology, temperature increase, and population size at lower latitudes occurred earlier than those at higher latitudes. Thus, it is necessary to develop sustainable management strategies for Helicoverpa armigera at an early stage.     

Disparity in elevational shifts of European trees in response to recent climate warming

Predicting climate‐driven changes in plant distribution is crucial for biodiversity conservation and management under recent climate change. Climate warming is expected to induce movement of species upslope and towards higher latitudes. However, the mechanisms and physiological processes behind the altitudinal and latitudinal distribution range of a tree species are complex and depend on each tree species features and vary over ontogenetic stages. We investigated the altitudinal distribution differences between juvenile and adult individuals of seven major European tree species along elevational transects covering a wide latitudinal range from southern Spain (37°N) to northern Sweden (67°N). By comparing juvenile and adult distributions (shifts on the optimum position and the range limits) we assessed the response of species to present climate conditions in relation to previous conditions that prevailed when adults were established. Mean temperature increased by 0.86 °C on average at our sites during the last decade compared with previous 30‐year period. Only one of the species studied, Abies alba, matched the expected predictions under the observed warming, with a maximum abundance of juveniles at higher altitudes than adults. Three species, Fagus sylvatica, Picea abies and Pinus sylvestris, showed an opposite pattern while for other three species, such as Quercus ilex, Acer pseudoplatanus and Q. petraea, we were no able to detect changes in distribution. These findings are in contrast with theoretical predictions and show that tree responses to climate change are complex and are obscured not only by other environmental factors but also by internal processes related to ontogeny and demography.     

Climate warming is associated with smaller body size and shorter lifespans in moose near their southern range limit

Despite the importance of body size for individual fitness, population dynamics and community dynamics, the influence of climate change on growth and body size is inadequately understood, particularly for long‐lived vertebrates. Although temporal trends in body size have been documented, it remains unclear whether these changes represent the adverse impact of climate change (environmental stress constraining phenotypes) or its mitigation (via phenotypic plasticity or evolution). Concerns have also been raised about whether climate change is indeed the causal agent of these phenotypic shifts, given the length of time‐series analysed and that studies often do not evaluate – and thereby sufficiently rule out – other potential causes. Here, we evaluate evidence for climate‐related changes in adult body size (indexed by skull size) over a 4–decade period for a population of moose (Alces alces) near the southern limit of their range whilst also considering changes in density, predation, and human activities. In particular, we document: (i) a trend of increasing winter temperatures and concurrent decline in skull size (decline of 19% for males and 13% for females) and (ii) evidence of a negative relationship between skull size and winter temperatures during the first year of life. These patterns could be plausibly interpreted as an adaptive phenotypic response to climate warming given that latitudinal/temperature clines are often accepted as evidence of adaptation to local climate. However, we also observed: (iii) that moose with smaller skulls had shorter lifespans, (iv) a reduction in lifespan over the 4‐decade study period, and (v) a negative relationship between lifespan and winter temperatures during the first year of life. Those observations indicate that this phenotypic change is not an adaptive response to climate change. However, this decline in lifespan was not accompanied by an obvious change in population dynamics, suggesting that climate change may affect population dynamics and life‐histories differently.     

Are long‐term widespread avian body size changes related to food availability? A test using contemporaneous changes in carotenoid‐based color

Recent changes in global climate have been linked with changes in animal body size. While declines in body size are commonly explained as an adaptive thermoregulatory response to climate warming, many species do not decline in size, and alternative explanations for size change exist. One possibility is that temporal changes in animal body size are driven by changes in environmental productivity and food availability. This hypothesis is difficult to test due to the lack of suitable estimates that go back in time. Here, we use an alternative, indirect, approach and assess whether continent‐wide changes over the previous 100 years in body size in 15 species of Australian birds are associated with changes in their yellow carotenoid‐based plumage coloration. This type of coloration is strongly affected by food availability because birds cannot synthesize carotenoids and need to ingest them, and because color expression depends on general body condition. We found significant continent‐wide intraspecific temporal changes in body size (wing length) and yellow carotenoid‐based color (plumage reflectance) for half the species. Direction and magnitude of changes were highly variable among species. Meta‐analysis indicated that neither body size nor yellow plumage color showed a consistent temporal trend and that changes in color were not correlated with changes in size over the past 100 years. We conclude that our data provide no evidence that broad‐scale variation in food availability is a general explanation for continent‐wide changes in body size in this group of species. The interspecific variability in temporal changes in size as well as color suggests that it might be unlikely that a single factor drives these changes, and more detailed studies of museum specimens and long‐term field studies are required to disentangle the processes involved.     

A northward shift of range margins in British Odonata

Many species are predicted to shift their ranges to higher latitudes and altitudes in response to climate warming. This study presents evidence for 37 species of nonmigratory British dragonflies and damselflies shifting northwards at their range margins over the past 40 years, seemingly as a result of climate change. This response by an exemplar group of insects associated with fresh water, parallels polewards range changes observed in terrestrial invertebrates and other taxa.