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The Alps played an important role in the biogeography of European plants and acted as a refugium for numerous species during the interglacial cycles. We investigated Nuphar pumila, one of the most emblematic glacial relicts of the Alps, by carrying out exhaustive literature and field surveys to collect relevant data on its distribution and threats. We further evaluated the level of introgression with the closely related N. lutea based on microsatellite data from natural populations across the Alps as well as from all ex situ collections and reintroductions in Switzerland. According to our results, more than 60% of the known N. pumila populations went extinct, and the species currently presents 37 natural populations in the investigated area. A large number of populations were affected by eutrophication (69%) and hybridization with N. lutea (53%). Priority should be given to the in situ conservation of genetically pure populations, while ex situ cultures should be applied to nearly extinct populations and the genetically pure individuals still present in hybrid populations. N. pumila is an excellent representative of the wetland/aquatic glacial relicts that are particularly affected by the combination of climate change and habitat degradation. International integration of research and conservation programs is needed to limit the decline of such rare species in the Alps. [ABSTRACT FROM AUTHOR]

Dioecious plants often exhibit deviations from expected 1:1 sex ratios. Genus Salix is a notable example of the female-biased sex ratio. Quite surprisingly, there are very few studies retesting observed bias patterns from the different parts of the species range. We have determined whether isolated subalpine populations of Salix lapponum exhibit a biased secondary sex ratio, measured the size of the plants, and tested the spatial and ecological correlations of the bias at fine and broad scales. Males were generally taller than females, suggesting that a different allocation of resources may occur in both sexes. Despite this, we found consistent female bias with females on average twice as common as males in most populations studied. No correlations of sex ratio with elevation as a proxy of environmental harshness and proportion of non-flowering individuals were found. Additionally, no differences in spatial sex segregation and microhabitat preferences were found between males and females at a fine scale within the studied populations. Our results suggest that the biased sex ratio in S. lapponum is not environment-dependent and probably originates during early stages of ontogenetic development (seeds). [ABSTRACT FROM AUTHOR]

The occurrence of triploid hybrids in nature is scarce due to the so-called triploid block representing formation of nonviable progeny after mating diploid with tetraploid. Here we describe frequent presence of triploids originating from hybridization of diploid Festuca pratensis with tetraploid F. apennina in the Swiss Alps. F. pratensis is a forage grass grown in lowlands and up to 1800 m a.s.l., while F. apennina is a mountain grass found in elevations from 1100 to 2000 m a.s.l. In the overlapping zone these species often grow sympatrically and triploid hybrids have been observed. We show that elevation is the main factor in the distribution of plants with various ploidy levels. Diploids occupy lower elevations, while triploids predominate in the mid-elevation zones and tetraploids are the most frequent in higher elevations. Other factors, such as topography and soil composition probably have only marginal effects on the distribution of the plants with different ploidy levels. Triploids seem to be frequently formed in the Swiss Alps and crosses in both directions are involved in the formation of triploid hybrids. As shown by chloroplast DNA analysis, F. apennina more frequently serves as female. Our analysis suggests that in the mid-elevation zones, triploids have a higher level of competitiveness than both parents. Triploids can overgrow microhabitats to a much higher extent than tetraploids. Such frequent occurrence and local dominance of triploids can at least be partially explained by asexual reproduction. Using DNA markers, we show that triploids can disperse ramets of a single clone over a distance of at least 14.4 m. [ABSTRACT FROM AUTHOR]

Despite the strong environmental control of seed dormancy and longevity, their changes along latitudes are poorly understood. The aim of this study was to assess seed dormancy and longevity in different populations across the distribution of the arctic-alpine plant Silene suecica. Seeds of seven populations collected from alpine (Spain, Italy, Scotland) and subarctic (Sweden, Norway) populations were incubated at four temperature regimes and five cold stratification intervals for germination and dormancy testing. Seed longevity was studied by exposing seeds to controlled ageing (45 °C, 60% RH) and regularly sampled for germination. Fresh seeds of S. suecica germinated at warm temperature (20/15 °C) and more in subarctic (80-100%) compared to alpine (20-50%) populations showed a negative correlation with autumn temperature (i.e., post-dispersal period). Seed germination increased after cold stratification in all populations, with different percentages (30-100%). Similarly, there was a large variation of seed longevity (p50 = 12-32 days), with seeds from the wettest locations showing faster deterioration rate. Subarctic populations of S. suecica were less dormant, showing a warmer suitable temperature range for germination, and a higher germinability than alpine populations. Germination and dormancy were driven by an interplay of geographical and climatic factors, with alpine and warm versus subarctic and cool autumn conditions, eliciting a decrease and an increase of emergence, respectively. Germination and dormancy patterns typically found in alpine habitats may not be found in the arctic. [ABSTRACT FROM AUTHOR]

The Alborz mountains in N-Iran at 36° N rise from the Caspian Sea to 5671 m a.s.l., with warm-temperate, winter-deciduous forests in the lower montane belt in northern slopes, and vast treeless terrain at higher elevation. A lack of rainfall (ca. 550 mm at high elevations) cannot explain the absence of trees. Hence, it is an open question, which parts of these mountains belong to the alpine belt. Here we use bioclimatic data to estimate the position of the potential climatic treeline, and thus, define bioclimatologically, what is alpine and what is not. We employed the same miniature data loggers and protocol that had been applied in a Europe-wide assessment of alpine climates and a global survey of treeline temperatures. The data suggest a potential treeline position at ca. 3300 m a.s.l., that is ca. 900 m above the upper edge of the current oak forest, or 450 m above its highest outposts. The alpine terrain above the climatic treeline position shows a temperature regime comparable to sites in the European Alps. At the upper limit of angiosperm life, at 4850 m a.s.l., the growing season lasted 63 days with a seasonal mean root zone temperature of 4.5 °C. We conclude that (1) the absence of trees below 2850 m a.s.l. is clearly due to millennia of land use. The absence of trees between 2850 and 3300 m a.s.l. is either due to the absence of suitable tree taxa, or the only potential regional taxon for those elevations, Juniperus excelsa, had been eradicated by land use as well. (2) These continental mountains provide thermal life conditions in the alpine belt similar to other temperate mountains. (3) Topography and snow melt regimes play a significant role for the structure of the alpine vegetation mosaics. [ABSTRACT FROM AUTHOR]

Alpine plants growing along wide elevational gradients experience very different abiotic and biotic conditions across elevations. As a result of genetic differentiation and/or plastic response, conspecific plants growing in high elevations, as compared to low elevations, generally have shorter stems and lower number of flowers, but larger flower size. However, most often, detailed models of elevational variations were not examined. To reveal the pattern of elevational changes in a set of fitness-related morphological traits, tests of linear and unimodal models were performed based on measurements of 1047 Solidago minuta plants collected from 47 sites distributed along a 1000 m elevational gradient in the Tatra Mountains. Nearly all of the investigated floral traits, i.e. inflorescence and flower heads size, and number and size of individual flowers, expressed unimodal relationships with elevation having their maxima in the centre of the elevation range. This pattern suggests the existence of a local optimum with respect to sexual reproduction at the centre of the elevational range. Possible explanations of observed elevational variations are discussed in the context of pollinator selection and the ‘resource-cost compromise’ hypothesis. Best floral performance in the centre of the elevational range of S. minuta may also support the idea that the favourability of habitat conditions declines from the centre to the margin of the distribution, and species are expected to be more abundant, increase reproduction and perform better in the centre of the range. [ABSTRACT FROM AUTHOR]

Cherleria sedoides, a plant species widespread in alpine areas of the major European mountain ranges and in Scotland, contains two highly divergent chloroplast haplotype groups, one widespread (WH) and one present only in some populations in the Alps (AH). We investigated whether this haplotype diversity is the result of (1) intraspecific differentiation, (2) retention of an ancestral polymorphism or (3) hybridisation. For this purpose, 106 matK sequences from throughout the Caryophyllaceae and 80 trnQ- rps16 and psbD- trnT sequences of C. sedoides (51) and other species of Cherleria (29) were used for the construction of phylogenies and haplotype networks. As the two haplotype groups were never each other's closest relatives, haplotype diversity as a result of intraspecific differentiation is unlikely. Patterns of genetic differentiation within the WH and AH groups are very different. Whereas WH shows a radial pattern typical of rapid expansion, AH is divided into two divergent subgroups each containing more variation than the WH group. This suggests that the two haplotype groups have dissimilar histories and are therefore unlikely to represent an ancestral polymorphism. Instead, we conclude that the polymorphism is best interpreted as the result of hybridisation. As the WH and AH haplotype groups fall into Cherleria, but do not group with any extant species, we conclude that the rare AH group represents the original C. sedoides, and that the WH group was captured from another, now extinct, species of Cherleria. [ABSTRACT FROM AUTHOR]

The phylogeography and possible origins of the moss Rhytidium rugosum (Hedw.) Kindb. in the European Alps are studied based on information from the nuclear internal transcribed spacers 1 and 2 and a portion of the gene region for glyceraldehyde 3-phosphate dehydrogenase for 364 European specimens. Seventy-three Alps specimens were sampled from W Switzerland to W Austria, and were divided into four regional populations along a West-South-West (WSW) to East-North-East (ENE) gradient. These populations were compared with similar ones previously studied in other parts of Europe. The ENE-most Alps population, located ENE of the Adige break zone, deviates genetically from the other three. The two WSW-most populations of the Alps appear to be relatively isolated from most of the European populations outside the Alps, whereas the two ENE ones are similar to populations of northern Scandinavia. Populations in between the Alps and the Scandinavian mountain range deviate from those to the north and south, possibly due to low effective population sizes, earlier bottleneck events, or colonization from different source populations. Haplotype diversity and number of private haplotypes are marginally higher in the Alps than in Scandinavia. It is suggested that European Rhytidium originated from late glacial maximum refugia in (1) E-NE Europe, (2) in between the Late Glacial Maximum ice shields of Scandinavia and the Alps, and (3) S, SW, and W of the Swiss Alps. Those of the E Alps potentially originated mainly in E-NE Europe and those of the W Alps in the S, SW, and W. [ABSTRACT FROM AUTHOR]

The tropical alpine ecosystem in eastern Africa is highly fragmented among biological 'sky islands', where populations of frost-tolerant organisms are isolated from each other by a 'sea' of tropical lowlands. One-third of the species in the afroalpine flora are exclusively alpine, but the other species can to varying degrees extend into grasslands and open forests of lower vegetation belts. A long-debated question is whether colonization of the alpine zone of these mountains and subsequent intermountain gene flow entirely depend on long-distance dispersal across unsuitable habitats, or whether suitable habitats shifted far enough downslope under past colder climates to form bridges enabling gradual migration. Here we address this question using a classification tree model. We mapped the extent of the current alpine habitat and projected it to the last glacial maximum (LGM) climate to assess whether gradual migration was possible for exclusively alpine taxa during this glacial period, and thus potentially also during earlier Pleistocene glaciations. Next, we modelled landcover under current and LGM climates to assess whether grassland and open forests could have served as migration corridors for alpine taxa that today extend into lower vegetation belts. We estimated that the LGM treeline was about 1000 m lower and the alpine habitat was about eight times larger than that today. At the LGM, we found that most of the currently fragmented alpine habitat of the Ethiopian highlands was interconnected except across the Great Rift Valley, whereas the solitary mountains of East/Central Africa remained isolated for exclusively alpine species. However, for drought-tolerant alpine species that today extend below the treeline, gradual migration through habitat corridors may have been possible among mountains during the dry glacial periods, and possibly also under the current climate before agriculture transformed the low-lying landscapes. [ABSTRACT FROM AUTHOR]

Since the Little Ice Age maximum in mid-nineteenth century, glaciers of the Alps lost more than half of their respective area. The chance to observe primary succession in deglaciated areas has motivated researchers ever since with quite a number of studies on vegetation dynamics in glacier forelands dating back to the nineteenth and early twentieth century. Harsh site conditions make glacier forelands challenging environments for the colonization. Due to high mortality rates during establishment, plant colonization and vegetation dynamics in glacier forelands are commonly considered slow and delayed. Recent research, however, shows that primary succession of plants in glacier forelands is accelerated, most likely due to climate warming. This is demonstrated by a speedup of the colonization process itself as well as by changed colonization strategies of the plant species involved. Employing a virtually complete species list for 1911 provided by Raimund v. Klebelsberg and our data collected along a chronosequence roughly a century later, we compare the floristic composition and structural attributes of the plant species governing primary succession within the glacier foreland of Lenksteinferner (ferner is a Tyrolean toponym for glacier) (South Tyrol, Italy). We address questions of changes in the dynamics of colonization, the plant species involved and their respective biological traits. Our study confirms that present-day vegetation dynamics in the glacier foreland are accelerated, colonization occurs faster and more species are involved in early colonization than a century ago. However, the dominant early colonizers are essentially the same and there are no fundamental differences concerning the spectra of biological traits between the two sampling dates. Altered colonization strategies due to climate change could not be detected within the glacier foreland of the Lenksteinferner, probably due to a compensation of climate warming during the twentieth century by the shift of the glacier terminus to a higher elevation. As the difference in temperature between the two sampling areas matches the magnitude of warming between the two sampling dates, similar temperature conditions in front of the glacier terminus today and at Klebelsberg's times can be assumed. [ABSTRACT FROM AUTHOR]

Mountains are hotspots of biodiversity. Yet, evaluating their importance in global biodiversity inventories requires the adoption of a pertinent definition of mountains. Here, we first compare the well-established WCMC and GMBA definitions, which both use geographical information systems. We show that the WCMC approach arrives at twice the global mountain area and much higher human population numbers than the GMBA one, which is explained by the inclusion of (mostly) low latitude hill country below 600 m elevation. We then present an inventory of the world's mountains based on the GMBA definition. In this inventory, each of the 1003 entries corresponds to a polygon drawn around a mountain or a mountain range and includes the name of the delineated object, the area of mountainous terrain it covers stratified into different bioclimatic belts (all at 2.5′ resolution), and demographic information. Taken together, the 1003 polygons cover 13.8 Mio km of mountain terrain, of which 3.3 Mio km are in the alpine and nival belts. This corresponds to 83.7% of the global mountain area sensu GMBA, and 94% of the alpine/nival area. The 386 Mio people inhabiting mountainous terrain within polygons represent 75% of the people globally inhabiting mountains sensu GMBA. This inventory offers a robust framework for the integration of mountain biota in regional and larger scale biodiversity assessments, for biogeography, bioclimatology, macroecology, and conservation research, and for the exploration of a multitude of socio-ecological and climate change-related research questions in mountain biota, including the potential pressure on alpine ecosystems. [ABSTRACT FROM AUTHOR]

Recent years have seen a surge of interest in understanding patterns and processes of plant invasions into mountains. Here, we synthesise current knowledge about the spread of non-native plants along elevation gradients, emphasising the current status and impacts that these species have in alpine ecosystems. Globally, invasions along elevation gradients are influenced by propagule availability, environmental constraints on population growth, evolutionary change and biotic interactions. The highest elevations are so far relatively free from non-native plants. Nonetheless, in total nearly 200 non-native plant species have been recorded from alpine environments around the world. However, we identified only three species as specifically cold-adapted, with the overwhelming majority having their centres of distribution under warmer environments, and few have substantial impacts on native communities. A combination of low propagule availability and low invasibility likely explain why alpine environments host few non-native plants relative to lowland ecosystems. However, experiences in some areas demonstrate that alpine ecosystems are not inherently resistant to invasions. Furthermore, they will face increasing pressure from the introduction of pre-adapted species, climate change, and the range expansion of native species, which are already causing concern in some areas. Nonetheless, because they are still relatively free from non-native plants, preventative action could be an effective way to limit future impacts of invasions in alpine environments. [ABSTRACT FROM AUTHOR]

Stable carbon and nitrogen isotopes provide time-integrated signals of plant carbon and nitrogen relations. We assessed an entire alpine flora in the Swiss Alps at ca. 2400 m elevation, using year 2007 herbarium samples of 245 species, 141 genera and 42 families to explore functional trait diversity. Despite overall similar macro-environmental conditions (moisture, soils, elevation), signal variation covered the full spectrum known for C plants. Variation among means for plant families for both δC and δN was smaller than variation among species within families. Species identity was of far greater importance than family affiliation. Similarly, tissue nitrogen and carbon concentrations varied in a rather species-specific manner, not permitting any a priori plant functional group definition based on such traits. The study also yielded tissue-type specificity of isotope signals. The elevation signal in δC (known to be less negative at high elevation) was much less pronounced than observed previously in con-generic comparisons. Thus, elevational δC trends are hard to distinguish from species effects in mixed populations over narrow ranges of elevation. δN data offer more space for ecological interpretation and show family specificity of signals in few cases. Cyperaceae, the most prominent family in this region, show no discrimination against N (like Fabaceae) and must have access to N sources different from most other families. This deserves experimental clarification, given the significance of Cyperaceae in cold environments. Overall, our study evidenced very high functional diversity among alpine plant species, as captured by these isotope signals. [ABSTRACT FROM AUTHOR]

Phenolic compounds play important ecological roles in alpine plants such as offering efficient UV protection at high level of incident sunlight. Methods to study those compounds are limited, as they require sophisticated analytical tools and are time-consuming. An alternative and portable device-Dualex-has been recently developed to estimate the plant epidermal flavonoids by fluorescence sensing. Here, we assessed if the Dualex device accurately estimates the phenolic contents of three alpine plant species along an elevational gradient and be an alternative to the commonly used chemical methods. We characterized their leaf epidermal absorbance measured by the Dualex device, total phenol content assessed by the Folin-Ciocalteu assay and total flavonoid content estimated by high-performance liquid chromatography. The results showed that leaf epidermal absorbance was slightly positively correlated to total phenols for Rhododendron ferrugineum and Dryas octopetala, but not for Vaccinium myrtillus and to total flavonoids for the first species, but not for the two others. The leaf epidermal absorbance estimated by the Dualex device is not an accurate and universal predictor of total phenols or total flavonoid contents for alpine plant species. The limitations of this optical method could be mainly explained by the high intraspecific variability of plant chemical composition in heterogeneous environmental conditions met in alpine areas. We thus recommend a cautious use of this device to avoid misinterpretations. [ABSTRACT FROM AUTHOR]

Fossil evidence, phylogeographic analyses, species distribution modelling and ancient DNA analyses have all shown that plant distributions have been highly dynamic through time. We use the geographical distribution of intra- and interspecific hybrids in Sempervivum, a western Eurasian high mountain oreophyte, as evidence for the past range dynamics of their parents. Sequences of the nuclear ribosomal internal transcribed spacer (ITS), parts of the nuclear ribosomal intergenic spacer region (IGS), and the three chloroplast markers atpI- atpH, rps16-intron and trnQ- rps16 were generated for 101 individuals of Sempervivum from across its entire distribution range. Hybrid individuals were identified by the presence of double base calls in direct sequencing of polymerase chain reaction products of ITS and IGS. Parentage was inferred from comparison with sequences without double base calls and with cpDNA sequences. We identified 27 hybrid individuals, which were found outside the current distribution range of one parent in 10 cases and with both (or all three) parents in eight cases. Geographical distance of hybrids and allopatric parents ranged from 25 to 2100 km. The distribution of hybrid individuals in relation to their parents provides evidence for past range dynamics and migration over sometimes large geographical distances. As all taxa involved had been postulated to be of Quaternary origin in an earlier study, we hypothesise that hybridisation took place in glacial refugia where the parental species came into contact. [ABSTRACT FROM AUTHOR]