Uphill shifts in the distribution of the white stork Ciconia ciconia in southern Poland: the importance of nest quality

The aim of this paper is to explain the altitudinal changes that have occurred during the 20th century to the white stork distribution in the Podhale region of the uplands of the Tatra mountains, southern Poland. We analysed both historical data from the white stork censuses and detailed yearly records from 1974 to 2003 on population size, distribution and breeding success. A white stork nest was first recorded at Podhale in 1931 and numbers increased to seven nests in 1933, all located below 650 m altitude. During the 30‐years, 1974–2003, both the maximum and upper‐quartile altitudes of nests increased significantly. In 1974 the highest nest was at an altitude of 770 m, and the maximum reached 890 m in 1999. In the same period, the breeding population increased significantly. The minimum and lower‐quartile altitudes of nests decreased significantly following initial occupation of suitable lower altitude sites before uphill expansion. We noted the positive association between nest occupancy over the study period and breeding performance. As a result, long‐occupied nests contributed most of the young produced in the population and chicks from these nests probably colonized new areas. We believe this is the first well‐documented evidence of, and mechanism for, a particular bird species to ascend to higher elevations and that the altitudinal shifts reported for butterflies, plants and whole biomes can be detected in birds as well.     

Disturbance from traditional fire management in subalpine heathlands increases Afro‐alpine plant resilience to climate change

Species are often controlled by biotic factors such as competition at the warm edge of their distribution range. Disturbances at the treeline, disrupting competitive dominance, may thus enable alpine species to utilize lower altitudes. We searched for evidence for range expansion in grazed, fire‐managed Ethiopian subalpine Erica heathlands across a 25‐year chronosequence. We examined vascular plant composition in 48 plots (5 × 5 m) across an altitudinal range of 3,465–3,711 m.a.s.l. and analyzed how community composition changed in relation to increasing competition over time (using a Shade index based on Erica shrub height and cover) and altitude. Species‘ habitats and altitudinal ranges were derived from literature. Time since fire explained more variation (r² = .41) in species composition than altitude did (r² = .32) in an NMDS analysis. Community‐weighted altitudinal optima for species in a plot decreased strongly with increasing shade (GLM, Standardized Regression Coefficient SRC = ?.41, p = .003), but increased only weakly with altitude (SRC = .26, p = .054). In other words, young stands were dominated by species with higher altitudinal optima than old stands. Forest species richness increased with Log Shade index (SRC = .12, p = .008), but was unaffected by altitude (SRC = ?.07, p = .13). However, richness of alpine and heathland species was not highest in plots with lowest Shade index, but displayed a unimodal pattern with an initial increase, followed by a decrease when shading increased (altitude was not significant). Our results indicate that disturbance from the traditional patch burning increases the available habitat for less competitive high‐altitude plants and prevents tree line ascent. Therefore, maintaining, but regulating, the traditional land use increases the Afro‐alpine flora's resilience to global warming. However, this system is threatened by a new REDD+ program attempting to increase carbon storage via fire suppression. This study highlights the importance of understanding traditional management regimes for biodiversity conservation in cultural landscapes in an era of global change.     

Nematode distributions as spatial null models for macroinvertebrate species richness across environmental gradients: A case from mountain lakes

Nematode species are widely tolerant of environmental conditions and disperse passively. Therefore, the species richness distribution in this group might largely depend on the topological distribution of the habitats and main aerial and aquatic dispersal pathways connecting them. If so, the nematode species richness distributions may serve as null models for evaluating that of other groups more affected by environmental gradients. We investigated this hypothesis in lakes across an altitudinal gradient in the Pyrenees. We compared the altitudinal distribution, environmental tolerance, and species richness, of nematodes with that of three other invertebrate groups collected during the same sampling: oligochaetes, chironomids, and nonchironomid insects. We tested the altitudinal bias in distributions with t‐tests and the significance of narrow‐ranging altitudinal distributions with randomizations. We compared results between groups with Fisher's exact tests. We then explored the influence of environmental factors on species assemblages in all groups with redundancy analysis (RDA), using 28 environmental variables. And, finally, we analyzed species richness patterns across altitude with simple linear and quadratic regressions. Nematode species were rarely biased from random distributions (5% of species) in contrast with other groups (35%, 47%, and 50%, respectively). The altitudinal bias most often shifted toward low altitudes (85% of biased species). Nematodes showed a lower portion of narrow‐ranging species than any other group, and differed significantly from nonchironomid insects (10% and 43%, respectively). Environmental variables barely explained nematode assemblages (RDA adjusted R² = 0.02), in contrast with other groups (0.13, 0.19 and 0.24). Despite these substantial differences in the response to environmental factors, species richness across altitude was unimodal, peaking at mid elevations, in all groups. This similarity indicates that the spatial distribution of lakes across altitude is a primary driver of invertebrate richness. Provided that nematodes are ubiquitous, their distribution offers potential null models to investigate species richness across environmental gradients in other ecosystem types and biogeographic regions.     

Altitudinal variation of dung beetle (Scarabaeidae: Scarabaeinae) assemblages in the Colombian Andes

Aim We describe the changes in species richness, rarity and composition with altitude, and explore whether the differences in Scarabaeinae dung beetle composition along five altitudinal transects of the same mountain range are related to altitude or if there are interregional differences in these altitudinal gradients. Location Field work was carried out on the eastern slope of the eastern Cordillera, Colombian Andes, between Tamá Peak to the north, in the Tamá National Park (07°23′ N, 72°23′ W) and the San Miguel River (00°28′ N, 77°17′ W) to the south. Methods Sampling was carried out between February 1997 and November 1999 in five regions spanning elevation gradients. In each gradient, six sites were chosen at 250 m intervals between 1000 and 2250 m a.s.l. Results We found a curvilinear relationship between altitude and mean species richness, with a peak in richness at middle elevations. However, the diversity of dung beetle assemblages does not seem to be related to the interregional differences in environmental conditions. The number of geographically restricted species is negatively and significantly related to altitude, with geographically restricted species more frequent at low altitude sites. Ordination delimited the two main groups according to altitude: one with all the highest sites (1750–2250 m a.s.l.) and a second group with the remaining sites (< 1750 m a.s.l.). Analysis of species co‐occurrence shows that these dung beetle assemblages seem to be spatially structured when all sites have the same probability of being chosen. In contrast, the spatial structure of species assemblages seems to be random when the probability of choosing any site is proportional to its altitude. Main conclusions The altitude of sites is the main factor that influences the diversity of these dung beetle assemblages. The peak in species richness at middle elevations, the higher number of geographically restricted species at lower altitudinal levels, and the compositional differences along these mountain gradients seem to result from the mixing at these altitudes of dung beetle assemblages that have different environmental adaptations and, probably, different origins. The relevance of altitude in these assemblages is related to the limited role of these Neotropical high altitude environments as centres of refuge and vicariance for a monophyletic group of warm‐adapted species, for which the vertical colonization of these high mountain environments by lineages distributed at lower altitudes would have been very difficult.     

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.     

Predicting potential responses to future climate in an alpine ungulate: interspecific interactions exceed climate effects

The altitudinal shifts of many montane populations are lagging behind climate change. Understanding habitual, daily behavioural rhythms, and their climatic and environmental influences, could shed light on the constraints on long‐term upslope range‐shifts. In addition, behavioural rhythms can be affected by interspecific interactions, which can ameliorate or exacerbate climate‐driven effects on ecology. Here, we investigate the relative influences of ambient temperature and an interaction with domestic sheep (Ovis aries) on the altitude use and activity budgets of a mountain ungulate, the Alpine chamois (Rupicapra rupicapra). Chamois moved upslope when it was hotter but this effect was modest compared to that of the presence of sheep, to which they reacted by moving 89–103 m upslope, into an entirely novel altitudinal range. Across the European Alps, a range‐shift of this magnitude corresponds to a 46% decrease in the availability of suitable foraging habitat. This highlights the importance of understanding how factors such as competition and disturbance shape a given species’ realised niche when predicting potential future responses to change. Furthermore, it exposes the potential for manipulations of species interactions to ameliorate the impacts of climate change, in this case by the careful management of livestock. Such manipulations could be particularly appropriate for species where competition or disturbance already strongly restricts their available niche. Our results also reveal the potential role of behavioural flexibility in responses to climate change. Chamois reduced their activity when it was warmer, which could explain their modest altitudinal migrations. Considering this behavioural flexibility, our model predicts a small 15–30 m upslope shift by 2100 in response to climate change, less than 4% of the altitudinal shift that would be predicted using a traditional species distribution model‐type approach (SDM), which assumes that species’ behaviour remains unchanged as climate changes. Behavioural modifications could strongly affect how species respond to a changing climate.     

Are altitudinal limits of equatorial stream insects reflected in their respiratory performance?

1. We measured respiration of the larvae of aquatic insects from streams in the Ecuadorian Andes in relation to oxygen saturation at 5, 8, 11, 14 and 17 °C. Polycentropus (Polycentropodidae), Lachlania (Oligoneuriidae), Anchytarsus (Ptilodactylidae) and Anacroneuria (Perlidae) represented genera absent from the highest altitudes, reaching 2720, 2930, 3120, 3450 m a.s.l., respectively, while Claudioperla (Gripopterygidae) and Anomalocosmoecus (Limnephilidae) occurred only above 2900 m a.s.l. Our purpose was to determine whether natural altitudinal limits were reflected in physiological critical points on respiration versus oxygen curves and by the effect of temperature on the ability to oxy‐regulate. 2. For all six genera, respiration was affected by oxygen saturation and temperature. Respiration (mg O₂ g⁻¹ AFDM h⁻¹) at 70% oxygen saturation (Michaelis–Menten fitted) varied from 2.6 to 7.6 between genera at 17 °C, and from 1.3 to 2.5 at 5 °C. Q₁₀ values for this temperature interval ranged 1.5–2.9 (mean 2.3). The two “high‐altitude” genera had higher respiration rates at low temperature and oxygen saturation, and their respiration rate saturated at lower temperatures, than three of the four “low‐altitude” genera. 3. The oxy‐regulatory capacity (critical points and initial decrease in respiration versus oxygen regressions) varied among genera and was affected by temperature. Lachlania, Claudioperla and Anomalocosmoecus had a higher ability to oxy‐regulate at low than at high temperatures, Anacroneuria was not clearly affected by temperature, while Polycentropus and Anchytarsus had a greater oxy‐regulatory capacity at high than at low temperature. These results indicate that the ability to oxy‐regulate is related to the temperature (altitude) at which species naturally occur. 4. Upper altitudinal limits of the six genera were not reflected in their respiratory performance, because all genera had critical minima of temperature and oxygen saturation much lower than those occurring at the limits of their natural distribution. So, the altitudinal limit could not be attributed to absolute short‐term physiological tolerance of low temperature and oxygen concentration. 5. Multiple regressions (based on respiration experiments and previously obtained relationships between water temperature, oxygen saturation and altitude) were used to predict how respiration rates should vary with altitude. At the upper limit of the four “low‐altitude” genera, respiration rates were 50–68% of those predicted at the centre of the range. With an arbitrary increase of 400 m above the actual limit, the effect of temperature would be a 13% decrease, and that of oxygen a 2% decrease, in respiration rate of Polycentropus, Lachlania and Anacroneuria, while respiration in Anchytarsus would be reduced by 5% by both factors. 6. It seems that, while the immediate decrease in respiration with increased altitude is caused mainly by a decrease in temperature, the long‐term survival of a species at given altitudes might be more affected by oxygen saturation. Further quantitative and long‐term studies on survival and recruitment in populations and communities are needed to determine the importance of temperature and oxygen for altitudinal limits of aquatic insects.     

Assessing the origin of Neotropical mountain dung beetle assemblages (Scarabaeidae: Scarabaeinae): the comparative influence of vertical and horizontal colonization

Aims The fauna of mountains and their surrounding regions are likely to be influenced principally by two biological processes: horizontal colonization along similar altitudinal levels by elements originating from lineages inhabiting higher latitudes; and vertical colonization by lineages from the same latitude, but at lower altitudes. We examine whether the expected patterns derived from the latter process can be observed in mountain dung beetle assemblages. Specifically, we study the variation in species composition and richness with altitude in five regions spanning elevation gradients, analysing whether the altitudinal rates of change in the number of species and genera differ, and whether beta‐diversity scores for adjacent sites in each altitudinal gradient are different for species and genera. Location Eastern Cordillera of the Colombian Andes. Methods Field work was carried out in 1997–99 at 27 sites in five regions with elevation gradients, with 10–32 pitfall traps placed in each site. For each altitudinal level the numbers of species and genera were analysed with respect to altitude, and the slope of the linear regression between these variables was calculated. The slope of the curve of the altitude against the cumulative number of species and genera was also calculated for each altitudinal gradient to describe the compositional change between adjacent sites (beta diversity). Species and generic slopes were compared using analysis of covariance. The turnover of species along each altitudinal gradient was measured using presence/absence data and Cody's beta‐diversity index between adjacent pairs of sites. A cluster analysis was used to detect faunistically homogeneous groups of localities. Results Species richness always decreased with altitude, although the slopes did not differ significantly from zero. The number of genera also decreased with increasing altitude, but generally at a significantly slower rate than for species. Variation in the species beta‐diversity scores between altitudinal levels did not follow a homogeneous pattern in the different regions. Two main altitudinal groups of sites with a boundary c. 1500–1750 m a.s.l. can be detected with respect to faunistic similarity. Low‐ and mid‐altitude sites are inhabited by all of the genera (19) and 80% of all species collected. Eight genera and 61 species (c. 60% of the total) are unable to inhabit high‐altitude sites, and only 20 species appear to be exclusive to these high‐altitude environments (> 2000 m a.s.l.). Main conclusions The dominant processes explaining dung beetle composition in the high north‐eastern Andean mountains are probably those of vertical colonization. The limited role of horizontal colonization processes, or colonization from northern or southern lineages, could be a consequence of the isolation and recent geological origin of these mountains.     

Detecting climate change induced range shifts: Where and how should we be looking?

Abstract: Global climate warming is expected to cause systematic shifts in the distribution of species and consequently increase extinction risk. Conservation managers must be able to detect, measure and accurately predict range shifts in order to mitigate impacts on biodiversity. However, important responses to climate change may go unnoticed or be dismissed if we fail to collect sufficient baseline data and apply the most sensitive analytical tests. Here we use randomizations of a contemporary data set on rainforest birds of north‐eastern Australia to quantify the sensitivity of three measures for assessing range shifts along altitudinal gradients. We find that smaller range shifts are detectable by analysing change in the mean altitude of presence records rather than upper or lower range boundaries. For a moderate survey effort of 96 surveys, measurements of change in the mean altitude of 34 species have the capacity to provide strong inference for a mean altitudinal range shift as small as 40 m across the species assemblage. We also show that range shifts measured at range boundaries can be potentially misleading when differences in sampling effort between contemporary and historical data sets are not taken into account.     

Altitudinal variation in egg retention and rates of embryonic development in oviparous Zootoca vivipara fits predictions from the cold-climate model on the evolution of viviparity

The evolution of reptilian viviparity is favoured, according to the cold‐climate hypothesis, at high latitudes or altitudes, where egg retention would entail thermal benefits for embryogenesis because of maternal thermoregulation. According to this hypothesis, and considering that viviparity would have evolved through a gradual increase in the extent of intrauterine egg retention, highland oviparous populations are expected to exhibit more advanced embryo development at oviposition than lowland populations. We tested for possible differences in the level of egg retention, embryo development time and thermal biology of oviparous Zootoca vivipara near the extreme altitudinal limits of the species distribution in the north of Spain (mean altitude for lowland populations, 235 m asl.; for highland populations, 1895 m asl.). Altitude influenced neither temperature of active lizards in the field nor temperature selected by lizards in a laboratory thermal gradient, and pregnant females selected lower temperatures in the thermal gradient than did males and nonpregnant females across altitudinal levels. Eggs from highland populations contained embryos more developed at the time of oviposition (Dufaure and Hubert's stages 33–35) than eggs of highland populations (stages 30–34) and partly because of this difference incubation time was shorter for highland embryos. When analysed for clutches from both altitudinal extremes at the same embryonic stage at oviposition (stage 33), again incubation time was shorter for highland populations, indicating genuine countergradient variation in developmental rate. Our results indicate that temperature is an environmental factor affecting the geographical distribution of different levels of egg retention in Z. vivipara, as predicted by the cold‐climate hypothesis on the evolution of viviparity.     

Butterfly diversity and historical land cover change along an altitudinal gradient

Land cover and climate change are both major threats for biodiversity. In mountain ecosystems species have to adapt to fragmented habitats and harsh environmental conditions but so far, altitudinal effects in combination with land cover change have been rarely studied. The objective of this study was to determine the effects of altitude and historical land cover change on butterfly diversity. We studied species richness patterns of butterflies occuring in wetlands and other open habitats along an altitudinal gradient in a low mountain region (340–750 m a.s.l., Bavaria, Germany) with drastic loss of open habitats within the last 40–60 years. We recorded in 27 sites a total of 4,523 individuals of 49 butterfly species and five species of burnet moths. Species richness peaked at mid elevation and increased with patch size. Land cover change was most pronounced at high altitudes, but neither current open habitats, nor the historical loss of open habitats affected the species richness of butterflies. Neither open land specialized butterflies nor generalist and forest species were significantly affected by the loss of open habitats. However, increasing forest area in high altitudes reduces possible refuge open habitats for butterflies at their thermal distribution limits. This could lead to extinction of such butterfly species when temperatures further rise due to global warming.     

An elevational shift of cryophilous bryophytes in the last century – an effect of climate warming?

Aim To investigate altitudinal range shifts of bryophytes in Switzerland by comparing recent altitudinal distributions with historical distributions derived from herbarium specimens. Location Switzerland, covering 41,285 km² in Central Europe. Methods We used a dataset of 8520 herbarium specimens of 61 bryophyte species and compared altitudinal data between the two periods 1880–1920 and 1980–2005. The records we used were not specifically sampled for climatological analyses, but originate from non‐systematic fieldwork by various collectors. Historical and recent records were distributed all over Switzerland with occurrences in all major biogeographical areas. To account for different sampling efforts in the two time periods, different subsampling procedures were applied. Results Overall, we found a significant mean increase in altitude of 89 ± 29 m which was mainly driven by the cryophilous species (+222 ± 50 m). The mean increase in altitude of cryophilous species corresponds to a decadal upward shift of 24 m. The upper range limit of cryophilous species also increased by 189 ± 55 m, but there was no effect on the lower range limit. For intermediate and thermophilous species neither mean, nor upper or lower range limits changed. However, the proportion of records of thermophilous to cryophilous species increased considerably at lower altitudes, but levelled off above approximately 1800 m. Main conclusions We conclude that cryophilous bryophytes are expanding their range to higher elevations in Switzerland and that at lower elevations, a slow extinction process is going on, probably as a result of climate warming trends. The observed decadal upward shifts of cryophilous species closely match those reported from vascular plants in Europe and those expected, given recent estimates of climate warming trends. We emphasize that herbaria provide valuable data that can be used to detect ongoing changes in the distribution of species.     

Cryptic diversity within the rotifer Polyarthra dolichoptera along an altitudinal gradient

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Bryophyte diversity and distribution along an altitudinal gradient on a lava flow in La Réunion

Non‐vascular plant distribution patterns were examined in three microhabitats along an altitudinal gradient on a recent lava flow of the Piton de la Fournaise volcano (La Réunion, Mascarene archipelago). The uniform nature of the lava flow provides an excellent system to study the relationship between altitude and species diversity and distribution, and at the same time avoiding confusing multiple effects of substrate and vegetation heterogeneity. Non‐vascular plants were surveyed with quadrats within an altitudinal range from 250 m to 850 m a.s.l. Fine‐scale variations in bryophyte communities between three ecological microhabitats (the ground and on the rachises of two fern species) were investigated. Three specific questions were addressed: (1) What is the species diversity of bryophyte communities on a 19‐year‐old lava flow? (2) How does altitude influence the diversity and distribution of bryophytes on a lava flow? (3) Does microhabitat variation control bryophyte diversity? In our study, bryophyte diversity increased with altitude. Unexpectedly, species richness was very high; 70 species of bryophytes were recorded including nine new records for the island. Diversity was also controlled by ecological microhabitats. Bryophyte species were structured into six categories according to altitude and microhabitat preferences. Results suggested that the high diversity of these cryptic organisms on this lava flow is fostered in part by their host substrate and their adaptative strategies on new substrates. On a broader scale, it was concluded that lava flows as primary mineral environments are important to conserve, as they support a high diversity of pioneer organisms that constitute the early stages of the development of La Réunion's remnant lowland rainforest.     

Vertebrate dispersal syndromes along the Atlantic forest: broad-scale patterns and macroecological correlates

Aim To assess the geographical variation in the relative importance of vertebrates, and more specifically of birds and mammals, as seed dispersal agents in forest communities, and to evaluate the influence of geographical and climatic factors on the observed trends. Location One hundred and thirty‐five forest communities in the Brazilian Atlantic forest. Methods We collected data on dispersal modes for 2292 woody species. By combining species × site with species × trait matrices, we obtained the percentages of endozoochory, ornithochory, mastozoochory and the mean fruit diameter for the local forest communities. We used Spearman's correlation to assess bivariate relationships between variables. Subsequently, we performed paired t‐tests to verify if variations in frequency of dispersal modes and mean fruit diameter were influenced by altitude or temperature. Then, we applied multiple linear regressions to evaluate the effect of geographical and climatic variables on variation in the relative frequency of dispersal modes and mean fruit diameter across communities. Results We found no consistent latitudinal or longitudinal trend in the percentage of vertebrate‐dispersed species, neither bird‐ nor mammal‐dispersed species along the Atlantic forest. Endozoochory was affected chiefly by annual mean rainfall, increasing towards moister sites. Forest communities located at higher altitudes had a higher percentage of bird‐dispersed species. Even when sites with identical values of annual mean temperature were compared, altitude had a positive effect on ornithochory. Conversely, we found a higher percentage of mammal‐dispersed species in warmer forests, even when locations at the same altitudinal belts were contrasted. Fruit diameter was clearly related to altitude, decreasing towards higher elevations. Main conclusions This is the first analysis of a large data set on dispersal syndromes in tropical forest communities. Our findings support the hypotheses that: (1) geographical variation in the relative number of fleshy fruit species is mainly driven by moisture conditions and is relatively independent of geographical location, and (2) broad‐scale trends in fruit size correspond to geographical variation in the relative importance of mammals and birds as seed dispersal agents at the community level.     

The role of altitude and associated habitat stability in determining patterns of population genetic structure in two species of Atalophlebia (Ephemeroptera: Leptophlebiidae)

1. Previous studies have identified lowland areas as barriers to gene flow (dispersal) between distinct mountain ranges in montane species of aquatic insects. In this study, we investigated the population genetic structure of two closely related Atalophlebia (mayfly) species inhabiting lowland areas of south‐east Queensland, Australia, with the expectation of widespread gene flow throughout the low‐altitude environment and associated homogeneous genetic structure. 2. In particular, we asked whether species with lower‐altitude distributions demonstrate greater spatial distribution of mtDNA (COI) alleles than the upland species studied previously. This pattern would be expected if good dispersal ability is associated with population persistence in these drought‐prone habitats. 3. The two species demonstrated contrasting genetic population structure. Atalophlebia sp. AV13 D revealed strong population structure, with populations on each side of the low‐altitude area isolated from each other for a long time (c.350 kya), and the presence of an isolation‐by‐distance pattern over relatively small geographical distances (<40 km). In contrast, Atalophlebia sp. AV13 A was panmictic at the scale investigated (≤160 km), with no history of past population fragmentation. 4. Examination of sample distribution along the altitudinal gradient reveals that Atalophlebia sp. AV13 D may have a more upland distribution (associated with greater habitat stability) than previously supposed, while Atalophlebia sp. AV13 A inhabits more xeric lowland areas, where freshwater habitats are less stable. We consequently hypothesise that these contrasting genetic population structures result from differences in habitat stability along the altitudinal gradient, only species with good dispersal ability being able to persist in unstable habitats. These findings may be applicable to other regions of the globe where habitat instability is associated with altitudinal gradients.     

The distribution of ground spiders (Araneae, Gnaphosidae) along the altitudinal gradient of Crete, Greece: species richness, activity and altitudinal range

Aim To study the altitudinal variation of ground spiders (Araneae, Gnaphosidae) of Crete, Greece, as far as species composition, species richness, activity and range of distribution are concerned. Location Altitudinal zones (0–2400 m) along the three main mountain massifs of the island of Crete. Methods Thirty‐three sampling sites were located from 0 to 2400 m a.s.l. on Crete, and sampled using pitfall traps. Material from the high‐activity period of Gnaphosidae (mid‐spring to mid‐autumn) was analysed. Sampling sites were divided into five altitudinal zones of 500 m each. Statistical analysis involved univariate statistics (anova ) and multivariate statistics, such as multidimensional scaling (MDS) and cluster analysis (UPGMA) using binomial data of species presence or absence. Results Species richness declines with altitude and follows a hump‐shaped pattern. The activity pattern of the family, as a whole, is not correlated with altitude and is highly species‐specific. In the highest zone, both species richness and activity decline dramatically. The altitudinal range of species distribution increases with altitude. On the Cretan summits live highly tolerant lowland species and isolated residents of the high mountains of Crete. Two different patterns of community structure are recorded. Main conclusions Communities of Gnaphosidae on Crete present two distinct structures following the altitudinal gradient, these being separated by a transitional zone between 1600 and 2000 m. This study supports previous results which show a hump‐shaped decline in species richness of Gnaphosidae along altitudinal gradients, leading to a peak at 400–700 m, where an optimum of environmental factors exists. This makes this zone the meeting point of the often opportunistic lowland species with the older and most permanent residents of the island. Rapoport's rule on the positive correlation of the altitudinal range of species distributions with altitude is also supported. The high activity recorded for the species that persist on the high mountains of Crete is indicative of a tolerant arachnofauna, and is considered to result from relaxation of competitive interactions with other species. This is related to a reduction in species numbers, shortening of the activity period on high mountains and the unique presence of high mountain species that thrive only there. As shown in our study, strategies to cope with altitude are species‐specific. Therefore, there cannot exist one single model to describe how animals react to the change in altitude, even under the same environmental conditions.     

Tracking lags in historical plant species’ shifts in relation to regional climate change

Can species shift their distributions fast enough to track changes in climate? We used abundance data from the 1950s and the 2000s in Wisconsin to measure shifts in the distribution and abundance of 78 forest‐understory plant species over the last half‐century and compare these shifts to changes in climate. We estimated temporal shifts in the geographic distribution of each species using vectors to connect abundance‐weighted centroids from the 1950s and 2000s. These shifts in distribution reflect colonization, extirpation, and changes in abundance within sites, separately quantified here. We then applied climate analog analyses to compute vectors representing the climate change that each species experienced. Species shifted mostly to the northwest (mean: 49 ± 29 km) primarily reflecting processes of colonization and changes in local abundance. Analog climates for these species shifted even further to the northwest, however, exceeding species’ shifts by an average of 90 ± 40 km. Most species thus failed to match recent rates of climate change. These lags decline in species that have colonized more sites and those with broader site occupancy, larger seed mass, and higher habitat fidelity. Thus, species’ traits appear to affect their responses to climate change, but relationships are weak. As climate change accelerates, these lags will likely increase, potentially threatening the persistence of species lacking the capacity to disperse to new sites or locally adapt. However, species with greater lags have not yet declined more in abundance. The extent of these threats will likely depend on how other drivers of ecological change and interactions among species affect their responses to climate change.     

Observed range dynamics of South African amphibians under conditions of global change

Changes in the size and location of species ranges are a recognized response to environmental changes. We assessed recent range dynamics of South African amphibians using data consolidated by the South African Frog Atlas Project, which provided both historical (1905–1995) and recent distribution data (1996–2003). Sampling differences were accounted for using a correction factor and subsampling protocols. Changes to the size of species ranges and shifts in the mean range centre for latitude, longitude and altitude were assessed. Most (70%) of the assessed species showed range contractions. Of the expected climate change predictions, only upslope shifts were supported (mean 47.6 m). There were no significant mean latitudinal shifts for the assessed group of species. Species of the Bushveld region shifted northwesterly and upslope, while species of the Winter Rainfall region also shifted northwesterly. The small, though significant, general taxon‐wide trends where minor in comparison to the wide variety of idiosyncratic, species‐specific range changes that were observed. The species‐specific observed range changes that were documented should be used to further investigate range change drivers on an individual species basis.     

Breeding upwards when climate is becoming warmer: no bird response in the French Alps

Altitudinal shifts in distribution were investigated in forest breeding birds, along two elevational gradients in the French northern and southern Alps, from counts repeated at exactly the same locations in the 1970s and the 2000s. Significant shifts were reported for eight of 24 species in the northern alpine site (five downwards, three upwards) and for two of the 17 species in the southern site (one downwards, one upwards). Apart from the Crested Tit Parus cristatus , which shifted significantly downwards at both sites, altitudinal shifts were not significantly correlated between sites. Bird communities did not shift their distribution upwards despite a 2.3 °C increase in spring temperatures in the two study areas. These results suggest that bird distributions by altitude have not yet been affected by climatic warming, and that most specific elevational shifts are probably related to site-specific factors.