Contemporary ocean warming and freshwater conditions are related to later sea age at maturity in Atlantic salmon spawning in Norwegian rivers

Atlantic salmon populations are reported to be declining throughout its range, raising major management concerns. Variation in adult fish abundance may be due to variation in survival, growth, and timing of life history decisions. Given the complex life history, utilizing highly divergent habitats, the reasons for declines may be multiple and difficult to disentangle. Using recreational angling data of two sea age groups, one‐sea‐winter (1SW) and two‐sea‐winter (2SW) fish originated from the same smolt year class, we show that sea age at maturity of the returns has increased in 59 Norwegian rivers over the cohorts 1991–2005. By means of linear mixed‐effects models we found that the proportion of 1SW fish spawning in Norway has decreased concomitant with the increasing sea surface temperature experienced by the fish in autumn during their first year at sea. Furthermore, the decrease in the proportion of 1SW fish was influenced by freshwater conditions as measured by water discharge during summer months 1 year ahead of seaward migration. These results suggest that part of the variability in age at maturity can be explained by the large‐scale changes occurring in the north‐eastern Atlantic pelagic food web affecting postsmolt growth, and by differences in river conditions influencing presmolt growth rate and later upstream migration.     

Sea ice predicts long‐term trends in Adélie penguin population growth,but not annual fluctuations: Results from a range‐wide multiscale analysis

Understanding the scales at which environmental variability affects populations is critical for projecting population dynamics and species distributions in rapidly changing environments. Here we used a multilevel Bayesian analysis of range‐wide survey data for Adélie penguins to characterize multidecadal and annual effects of sea ice on population growth. We found that mean sea ice concentration at breeding colonies (i.e., “prevailing” environmental conditions) had robust nonlinear effects on multidecadal population trends and explained over 85% of the variance in mean population growth rates among sites. In contrast, despite considerable year‐to‐year fluctuations in abundance at most breeding colonies, annual sea ice fluctuations often explained less than 10% of the temporal variance in population growth rates. Our study provides an understanding of the spatially and temporally dynamic environmental factors that define the range limits of Adélie penguins, further establishing this iconic marine predator as a true sea ice obligate and providing a firm basis for projection under scenarios of future climate change. Yet, given the weak effects of annual sea ice relative to the large unexplained variance in year‐to‐year growth rates, the ability to generate useful short‐term forecasts of Adélie penguin breeding abundance will be extremely limited. Our approach provides a powerful framework for linking short‐ and longer term population processes to environmental conditions that can be applied to any species, facilitating a richer understanding of ecological predictability and sensitivity to global change.     

湖北钉螺种群内螺壳形态形状变异分析

在中国大陆血吸虫病流行的7个省中,采集不同环境类型的21个湖北钉螺(Oncomelania hupensis)种群,每个种群各测量60只湖北钉螺的11个形态性状。采用形态性状的变异系数、种群内个体间的欧氏距离与多样性指数及主成分分析3种方法,分析不同湖北钉螺种群内形态性状的变异程度。结果表明,在种群内个体间的欧氏距离和形态性状多样性方面,都以江西都昌的变异最大,平均欧氏距离为2.88,方差为2.33,极差为9.05,多样性指数为1.56,个体间平均距离以四川西昌湖北钉螺种群的最小,仅为1.37,而多样性指数以四川丹棱湖北钉螺种群的最小,为0.91。在不同光壳湖北钉螺种群中,以云南大理湖北钉螺个体间的平均距离最大,为1.90,但方差和极差以江苏宜兴的最大,分别为0.55和4.46。不同湖北钉螺种群内形态性状变异程度存在较大的差异,肋壳湖北钉螺种群内的形态性状变异程度普遍高于光壳湖北钉螺种群内的变异程度。     

Genetic variability of plant characters in the partial inbreeder Collinsia heterophylla (Scrophulariaceae)

Quantitative genetic variability for six characters was estimated in four populations of the annual plant, Collinsia heterophylla, with estimated selling rates ranging from 0.36 to 0.68. Based on large samples of parental plants, all four populations showed significant genetic variation for two or more characters, and there was no sign that the more selfing populations had lower amounts of genetic variance or lower heritability values. Autogamous fruit set rates in the absence of pollinators also showed significant heritability in one population.     

Annual survival of adult Atlantic Puffins Fratercula arctica is positively correlated with Herring Clupea harengus availability

Atlantic Herring is a keystone species in several marine ecosystems, supporting intensive fisheries as well as many predators including seabirds. Biomass of this stock in eastern North America has declined considerably in recent years, potentially putting at risk populations of its predators. Although adult survival in seabirds is considered robust to moderate changes in food availability, it is also the life‐history component most critical to sustaining populations of long‐lived birds. To investigate the possibility that Atlantic Puffin survival has been affected by reduced abundance of its main prey, we analysed the encounter histories of 2999 Atlantic Puffins ringed on Machias Seal Island to estimate annual adult survival for the years 1999–2011 and assess trends in survival and the effects of several biological and environmental covariates. Features of Puffin biology and resighting procedures likely to introduce heterogeneity into our resighting probabilities were accounted for and models of survival were assessed using standard methods. We used the variance components procedure in Program MARK and survival estimates from a time‐varying model to estimate the process variance (biological variation in survival) accounted for by suspected covariates of survival. Two proxies of food availability each explained more than half of the variation in annual survival: fishery landings of Atlantic Herring (52%) and per cent (by mass) of 1‐group Herring in the diet of Puffin chicks (51%). In addition to these proxies, May sea‐surface temperature accounted for 37% of variance in survival, but winter values of North Atlantic Oscillation showed no effect. Of those parameters of Puffin biology examined, chick growth rate explained 19% of the process variance in annual survival; laying date, fledging condition and fledging date all explained no variance. A decline in fishery landings of Herring since the early 1990s, and a concurrent decline in adult Puffin survival, reinforces concern for the health of the population of Herring, a keystone forage fish in this region, and of the community of marine predators in the Gulf of Maine that rely on Herring for their survival and reproduction.     

Population stability over a ten-year period in the short-lived fish Liparis liparis (L.)

A ten-year study of the population dynamics of the sea-snail, Liparis lipuris , in the Bristol Channel, England is reported. This small fish which only lives for 1 year undertakes a regular seasonal migration from birth in marine waters into the estuary from which it retreats during the winter to return to the spawning grounds by early spring. At Hinkley Point, Somerset (salinity 22–3O%), abundance has been shown to be negatively correlated with water temperature presumably because of the avoidance of warmer inshore waters during mild winters. When the temperature effect is removed from the data the peak winter abundance of the population was found to have a coefficient of variation of only 27%. For a population which only comprises of age group individuals, this shows a remarkable stability. No statistically significant relationship was found between the abundance of sea-snail and either their predators or prey. However, there were indications of a negative relationship with the abundance of whiting, Merlangius merlangus , which was the most abundant predator. We conclude that the population of a short-lived marine fish living within a physically variable marine environment can be constrained within tight limits. Further. sea-snail reproductive success has been independent of variation in local physical conditions.     

Effects of range position,inter-annual variation and density on demographic transition rates of <Emphasis Type="Italic">Hornungia petraea</Emphasis> populations

The central-marginal model assumes unfavourable and more variable environmental conditions at the periphery of a species’ distribution range to negatively affect demographic transition rates, finally resulting in reduced population sizes and densities. Previous studies on density-dependence as a crucial factor regulating plant population growth have mainly focussed on fecundity and survival. Our objective is to analyse density-dependence in combination with the effect of inter-annual variation and range position on all life stages of an annual plant species, Hornungia petraea, including germination and seed incorporation into the seed bank. As previous studies on H. petraea had revealed a pattern opposite to existing theory with lower population densities at the distribution centre in Italy than at the periphery in Germany, we hypothesised that (1) demographic transition rates are lower, (2) the inter-annual variation in demographic transition rates is higher and (3) the intensity of density-dependence is weaker in Italy than in Germany. To analyse demographic transition rates, we used an autoregressive covariance strategy for repeated measures including density and inter-annual variation. All the three hypotheses were confirmed, but the impact of range position, density-dependence and inter-annual variation differed among the transition steps. All transition rates except fecundity were higher in the German populations than in the Italian populations. Germination rate and incorporation rate into the seed bank were strongly density-dependent. Central populations showed a larger inter-annual variation in fecundity and winter survival rate. Winter survival rate was the only transition step with a stronger density-dependence in peripheral populations. In most cases, these differences between distribution centre and periphery would not have emerged without taking density-dependence and inter-annual variation into account. We conclude that including range position, inter-annual variation and density-dependence in one single statistical model is an important tool for the interpretation of demographic patterns regarding the central-marginal model. Electronic Supplementary Material Supplementary material is available for this article at     

Climate as a driver of population variability in breeding Gentoo Penguins Pygoscelis papua at the Falkland Islands

Detecting and predicting how populations respond to environmental variability are eminent challenges in conservation research and management. This is particularly true for wildlife populations at high latitudes, many of which demonstrate changes in population dynamics associated with global warming. The Falkland Islands (Southwest Atlantic) hold one of the largest Gentoo Penguin Pygoscelis papua populations in the world, representing c. 34% of the global population. The numbers of breeding Gentoo Penguins at the Falkland Islands have shown a high degree of inter‐annual variability since monitoring commenced in 1990. However, proximate causes of annual variability in breeding numbers have not been explored. Here we examine 21 years of Gentoo Penguin breeding surveys from the Falkland Islands and assess whether inter‐annual variability in the number of breeding pairs were correlated with proxies of environmental variability. There was a positive correlation between the number of breeding pairs and a broad‐scale climatic variation index, the Southern Oscillation Index (SOI). In turn, the SOI was significantly correlated with spring sea surface temperature anomalies, indicating a more immediate atmospherically forced response to El Niño Southern Oscillation variability in the Southwest Atlantic than previously reported. However, we also describe a non‐linear response to environmental variability that may highlight foraging plasticity and/or the complexity of regional ecosystem interactions that operate across a range of different scales.     

Variability in the distribution and abundance of stream salmonids, and the associated use of habitat models

The effective management of salmonid fisheries requires that the factors influencing variation in the abundance of stream populations are understood. The use of habitat models to explain the spatial component of population variance offers potential for management, but has not previously been set in the context of long term variation in population abundance because of the lack of suitable data sets. This paper examines contributions of spatial and temporal factors lo fish density variance using a 10-year data set from five tributaries of the River Conwy, North Wales. Recently developed habitat models were applied to the data to test their ability to explain nominal spatial variance. Spatial variance accounted for between 21 and 62% of the overall variance of salmonid abundance, and habitat models explained up to 95% of the spatial variance component. Synchrony in population variation amongst sites within and between tributaries is described, and some of the factors that may influence this are discussed.     

Loss of genetic diversity in sea otters (Enhydra lutris) associated with the fur trade of the 18th and 19th centuries

Sea otter (Enhydra lutris) populations experienced widespread reduction and extirpation due to the fur trade of the 18th and 19th centuries. We examined genetic variation within four microsatellite markers and the mitochondrial DNA (mtDNA) d-loop in one prefur trade population and compared it to five modern populations to determine potential losses in genetic variation. While mtDNA sequence variability was low within both modern and extinct populations, analysis of microsatellite allelic data revealed that the prefur trade population had significantly more variation than all the extant sea otter populations. Reduced genetic variation may lead to inbreeding depression and we believe sea otter populations should be closely monitored for potential associated negative effects.     

Variability of Black and Caspian Sea sprat <Emphasis Type="Italic">Clupeonella cultriventris</Emphasis> (Clupeidae) growth in the contemporary range

The size and age composition of the population of Black and Caspian Sea sprat Clupeonella cultriventris, as well as the variation of the growth of fish in the reservoirs of the upper reaches of the Volga, are reported and a comparative analysis of group and individual variability of fish growth within the native (Caspian, Azov, and Black seas) and contemporary (formed due to invasion) ranges is presented. The degree of variability and the asymmetry of sprat body length distribution have been shown to increase under the conditions of large population sizes, deficit of food, and slow growth. Variability was also elevated near the borders of the range of the species, notwithstanding the abundance of food. It is shown that invasion of sea walnut comb jelly Mnemiopsis leydi into the Azov and Caspian Seas had so undermined feed base of sprat, that it is not only decreased its abundance and fecundity but also slowed growth of the fish.     

Surviving north of the natural range: the importance of density independence in determining population size

The relative importance of density-dependent and -independent processes in determining population density has been predicted to vary according to whether the population concerned is located near the centre or the periphery of the species' range. Thus, density-independent processes should be more pronounced near the periphery. The long-tailed wood mouse Apodemus sylvaticus in Iceland is at the northern and western edge of its geographical range. We estimated the autumn population density in an open habitat in south-western Iceland in 9 years out of 10 during 1996–2005 in order to monitor the annual maximum population size. Furthermore, we estimated population density and survival at c . 5-week intervals from September 2001 to October 2003 and from September 2004 to November 2005 in order to reveal the causes of variation in maximum population size. The estimated autumn population density was low, ranging from 2.7 to 8.9 mice ha⁻¹ while spring densities ranged from 0.4 to 0.8 mice ha⁻¹. Apparent monthly survival probabilities ranged from 0.4 to 0.7 per month in autumn and 0.7 to 0.9 in winter. Our results suggest that low temperature in early winter (October–December) is the major determinant of population density in the following autumn, explaining 74% of the variation in autumn population density. No significant correlation was found between either the NAO index or the NAO winter index and variation in wood mouse population density in autumn. Differential mortality in early winter results in variation in spring population size. This study shows clear evidence of density-independent control of a mammal population at the edge of its geographical range as opposed to the mostly density-dependent control previously recorded near its centre of distribution.     

Reduced variability in range‐edge butterfly populations over three decades of climate warming

Populations at the high latitude edge of species’ geographical ranges are thought to show larger interannual population fluctuations, with subsequent higher local extinction risk, than those within the ‘core’ climatic range. As climate envelopes shift northward under climate warming, however, we would expect populations to show dampened variability. We test this hypothesis using annual abundance indices from 19 butterfly species across 79 British monitoring sites between 1976 and 2009, a period of climatic warming. We found that populations in the latter (warmer) half of the recording period show reduced interannual population variability. Species with more southerly European distributions showed the greatest dampening in population variability over time. Our results suggest that increases in population variability occur towards climatic range boundaries. British sites, previously existing at the margins of suitable climate space, now appear to fall closer to the core climatic range for many butterfly species.     

Detecting the impact of oceano-climatic changes on marine ecosystems using a multivariate index: The case of the Bay of Biscay (North Atlantic-European Ocean)

Large‐scale univariate climate indices (such as NAO) are thought to outperform local weather variables in the explanation of trends in animal numbers but are not always suitable to describe regional scale patterns. We advocate the use of a Multivariate Oceanic and Climatic index (MOCI), derived from ‘synthetic’ and independent variables from a linear combination of the total initial variables objectively obtained from Principal Component Analysis. We test the efficacy of the index using long‐term data from marine animal populations. The study area is the southern half of the Bay of Biscay (43°–47°N; western Europe). Between 1974 and 2000 we monitored cetaceans and seabirds along 131000 standardized line transects from ships. Fish abundance was derived from commercial fishery landings. We used 44 initial variables describing the oceanic and atmospheric conditions and characterizing the four annual seasons in the Bay of Biscay. The first principal component of our MOCI is called the South Biscay Climate (SBC) index. The winter NAO index was correlated to this SBC index. Inter‐annual fluctuations for most seabird, cetacean and fish populations were significant. Boreal species (e.g. gadiformes fish species, European storm petrel and Razorbill …) with affinities to cold temperate waters declined significantly over time while two (Puffin and Killer Whale) totally disappeared from the area during the study period. Meridional species with affinities to hotter waters increased in population size. Those medium‐term demographic trends may reveal a regime shift for this part of the Atlantic Ocean. Most of the specific observed trends were highly correlated to the SBC index and not to the NAO. Between 40% and 60% of temporal variations in species abundance were explained by the multivariate SBC index suggesting that the whole marine ecosystem is strongly affected by a limited number of physical parameters revealed by the multivariate SBC index. Aside the statistical error of the field measurements, the remaining variation unexplained by the physical characteristics of the environment correspond to the impact of anthropogenic activities such overfishing and oil‐spills.     

Environmental variation and cohort effects in an Antarctic predator

Understanding the potential influence of environmental variation experienced by animals during early stages of development on their subsequent demographic performance can contribute to our understanding of population processes and aid in predicting impacts of global climate change on ecosystem functioning. Using data from 4178 tagged female Weddell seal pups born into 20 different cohorts, and 30 years of observations of the tagged seals, we evaluated the hypothesis that environmental conditions experienced by young seals, either indirectly through maternal effects and/or directly during the initial period of juvenile nutritional independence, have long‐term effects on individual demographic performance. We documented an approximately three‐fold difference in the proportion of each cohort that returned to the pupping colonies and produced a pup within the first 10 years after birth. We found only weak evidence for a correlation between annual environmental conditions during the juvenile‐independence period and cohort recruitment probability. Instead, the data strongly supported an association between cohort recruitment probability and the regional extent of sea ice experienced by the mother during the winter the pup was in utero. We suggest that inter‐annual variation in winter sea‐ice extent influences the foraging success of pregnant seals by moderating the regional abundance of competing predators that cannot occupy areas of consolidated sea ice, and by directly influencing the abundance of mid‐trophic prey species that are sea‐ice obligates. We hypothesize that this environmentally‐induced variation in maternal nutrition dictates the extent of maternal energetic investment in offspring, resulting in cohort variation in mean size of pups at weaning which, in turn, contributes to an individual's phenotype and its ultimate fitness. These linkages between sea ice and trophic dynamics, combined with demonstrated and predicted changes in the duration and extent of sea ice associated with climate change, suggest significant alterations in Antarctic marine ecosystems in the future.     

Breeding system and demography shape population genetic structure across ecological and climatic zones in the African freshwater snail, Bulinus forskalii (Gastropoda, Pulmonata), intermediate host for schistosomes

The role of breeding system and population bottlenecks in shaping the distribution of neutral genetic variation among populations inhabiting patchily distributed, ephemeral water bodies was examined for the hermaphroditic freshwater snail Bulinus forskalii, intermediate host for the medically important trematode Schistosoma guineensis. Levels of genetic variation at 11 microsatellite loci were assessed for 600 individuals sampled from 19 populations that span three ecological and climatic zones (ecozones) in Cameroon, West Africa. Significant heterozygote deficiencies and linkage disequilibria indicated very high selfing rates in these populations. Despite this and the large genetic differentiation detected between populations, high levels of genetic variation were harboured within these populations. The high level of gene flow inferred from assignment tests may be responsible for this pattern. Indeed, metapopulation dynamics, including high levels of gene flow as well as extinction/contraction and recolonization events, are invoked to account for the observed population structuring, which was not a consequence of isolation-by-distance. Because B. forskalii populations inhabiting the northern, Sahelian area are subject to more pronounced annual cycles of drought and flood than the southern equatorial ones, they were expected to be subject to population bottlenecks of increased frequency and severity and, therefore, show reduced genetic variability and elevated population differentiation. Contrary to predictions, the populations inhabiting the most northerly ecozone exhibited higher genetic diversity and lower genetic differentiation than those in the most southerly one, suggesting that elevated gene flow in this region is counteracting genetic drift.     

Spatial and temporal operation of the Scotia Sea ecosystem: a review of large-scale links in a krill centred food web

The Scotia Sea ecosystem is a major component of the circumpolar Southern Ocean system, where productivity and predator demand for prey are high. The eastward-flowing Antarctic Circumpolar Current (ACC) and waters from the Weddell-Scotia Confluence dominate the physics of the Scotia Sea, leading to a strong advective flow, intense eddy activity and mixing. There is also strong seasonality, manifest by the changing irradiance and sea ice cover, which leads to shorter summers in the south. Summer phytoplankton blooms, which at times can cover an area of more than 0.5 million km2, probably result from the mixing of micronutrients into surface waters through the flow of the ACC over the Scotia Arc. This production is consumed by a range of species including Antarctic krill, which are the major prey item of large seabird and marine mammal populations. The flow of the ACC is steered north by the Scotia Arc, pushing polar water to lower latitudes, carrying with it krill during spring and summer, which subsidize food webs around South Georgia and the northern Scotia Arc. There is also marked interannual variability in winter sea ice distribution and sea surface temperatures that is linked to southern hemisphere-scale climate processes such as the El Ni?o-Southern Oscillation. This variation affects regional primary and secondary production and influences biogeochemical cycles. It also affects krill population dynamics and dispersal, which in turn impacts higher trophic level predator foraging, breeding performance and population dynamics. The ecosystem has also been highly perturbed as a result of harvesting over the last two centuries and significant ecological changes have also occurred in response to rapid regional warming during the second half of the twentieth century. This combination of historical perturbation and rapid regional change highlights that the Scotia Sea ecosystem is likely to show significant change over the next two to three decades, which may result in major ecological shifts.     

Variation of distal genitalia in the simultaneously hermaphroditic land snail Arianta arbustorum (Pulmonata,Stylommatophora) caused by sexual selection?

The most likely explanation for genitalic extravagance may be sexual selection acting either before, during, or after copulation. In promiscuous species, the intensity of postulating sexual selection may be a function of population density. In this study we examined the variability of the distal genitalia involved in spcrmatophore production, reception and manipulation of 113 adult individuals of the simultaneously hermaphroditic land snail Arianta arbustorum (L.) from six natural populations in the Eastern Alps (Gesause, Austria). We investigated the hypothesis that these genitalia increase in relation to shell size with increasing population density (range: 0.9 to 39.8 individuals/m²) and expected a higher variance of the genitalia compared to shell dimensions due to sexual selection. Genitalic size was unexpectedly inversely related to population density, probably due to increased inhibitor)^- effects of snail mucus. Patterns of variation of female and male characters did not differ. Coefficients of variation of the genitalia were significantly higher than those of the shell dimensions as predicted. This was due to a higher dispersion around the regression lines rather than higher allometric values. However, the influence of sexual selection on genitalic size and variance cannot be unambiguously determined. We discuss different scenarios emphasizing the importance of sexual selection to differing degrees and conclude that sexual selection has probably played only a minor role.     

Spatio-temporal dynamics of alternative male phenotypes in coho salmon populations in response to ocean environment

1. The coexistence of alternative reproductive phenotypes will probably be shaped by spatial and temporal variability in the environment. However, the effects of such variability on coexistence and the scale at which it operates are seldom understood. 2. To quantify such effects, we examined spatial and temporal dynamics in the abundance and frequency of alternative phenotypes of male coho salmon, Oncorhynchus kisutch Walbaum, which mature as either large fighters (age-3 'hooknoses') or small sneakers (age-2 'jacks'). Using over 20 years of data on coded-wire tagged fish released from nine Oregon hatcheries, we tested for the effects of ocean environment independent of those due to freshwater rearing. 3. Annual fluctuations of the abundance of jack and hooknose males within populations were correlated strongly by brood year (cohort) but not by return year (breeding group). This occurred independently of significant effects of release practice (i.e. the number of fish released, body size at release and date of release), indicating that a synchronized fluctuation in mortality during the first year at sea was the predominant cause. As a result, the annual frequency of the alternative phenotypes at breeding varied considerably within populations. 4. Spatial patterns in the annual fluctuations of the two phenotypes were similar (i.e. synchronous among populations), except that jacks showed local spatial structure (decreased synchrony with distance) not evident among hooknoses. This suggests that oceanic processes affecting the two phenotypes operate at different spatial scales. Despite effects on salmon abundance, the ocean environment had little influence through its effects on salmon growth on the relative frequencies of the alternative phenotypes within and among populations. 5. The results provide insight into the evolutionary dynamics of alternative phenotypes, including an intragenerational time lag that increases annual variability in phenotype frequencies at breeding (return years) and the significance of local freshwater processes, rather than oceanic processes, on phenotype expression. Freshwater processes, such as juvenile growth, timing of migration and breeding competition, operating at evolutionary and intragenerational time-scales, are probably the predominant forces affecting phenotype frequency.     

Similar performance in central and range‐edge populations of a Eurasian steppe grass under different climate and soil pH regimes

The abundant centre hypothesis predicts that changing environmental conditions are detrimental to a species’ abundance and performance towards the periphery of its range. We tested these predictions for the perennial grass Stipa capillata, a species that is commonly found in steppes of Asia but is rare at its north‐western range edge, in central Europe. We compared 21 populations in dry grassland fragments in central Europe and 20 populations in steppe habitats of Kazakhstan. We studied 15 plant performance traits both in situ and under laboratory and common greenhouse conditions, including local density, plant size and biomass production, seed size, weight and viability. To assess environmental conditions, we assembled data on topography, soil properties and climatic parameters. Using variance components analysis and multivariate methods we analyzed whether plant performance and environmental attributes differed more, as predicted, between the core and peripheral regions or whether they differed more among their subregions or populations. Additionally, we tested whether performance was affected by the same set of environmental predictors in each region. Contrary to our expectations, plant performance traits were virtually unchanged between the range periphery and centre. As expected, macroclimatic conditions showed a significant difference between the two regions (annual mean temperature, annual precipitation). The only other measured environmental variable that differed significantly between the two regions was soil pH, which was lower in core‐range populations. Our findings thus do not support the notion of reduced performance at the range edge. Instead, our data lend support to earlier theories of relative habitat constancy, suggesting that peripheral populations can shift to other habitats through plasticity or adaptation.