Narrow Elevation Range Research Articles

Environmental Correlates and Reproductive Capacity of Guadalupe Fescue (Festuca ligulata), an Endangered Grass of the Northern Sierra Madre Oriental

Guadalupe fescue (Festuca ligulata Swallen) is an endangered perennial grass species that is endemic to the Sky Island conifer-oak forests and piñonoak-juniper woodlands of the northern Sierra Madre Oriental. Little is known about the habitat requirements, population dynamics, or reproductive ecology of this species. We assessed aspects of the demography, habitat preferences, and germination rates of Guadalupe fescue in two Sky Island sites on each side of the US–Mexico border: the Chisos Mountains of Big Bend National Park (BIBE) in Texas, USA, and the Maderas del Carmen Protected Area (MCPA) in Coahuila, Mexico. Through field and greenhouse measurements, we evaluated the plant vigor, reproductive capacity, and environmental growing conditions of 422 plants (323 in BIBE and 99 in MCPA). Our results reveal that Guadalupe fescue is a very rare species growing within a narrow elevational range (2066–2394 m) on rocky microsites with relatively open canopy and forest floor conditions, compared to the range of available local habitats. For collected seeds, the mean fill rate was 54% (31% for BIBE and 61% for MCPA) and overall germination rate was 14% (8% at BIBE and 33% at MCPA). These results provide important baseline ecological data on Guadalupe fescue, which is critical for informing endangered species recovery planning and restoration activities aimed at bolstering this species' population size.

Diversity and Spatial Distribution of Leaf Litter Curculionidae (Coleoptera: Curculionoidea) in Two Ecuadorian Tropical Forests

Litter weevil communities were investigated in two different types of montane forest in Ecuador: foothill evergreen forest, present in the Otongachi Integral Reserve between 800 and 1000 m, and tropical montane cloud forest (TMCF), present in the Otonga Integral Reserve between 1600 and 2300 m. Sampling was conducted along elevation gradients, applying the entomological sifting method to 19 sampling transects (11 in Otonga and 8 in Otongachi). The taxa collected were identified as morphospecies, since the majority of them are still undescribed. A total of 510 specimens were sampled, belonging to 100 different morphospecies, 85 of which were found in Otonga and 15 in Otongachi. No species in common between the two areas were found, despite the fact that the distance is extremely small (approximately 12 km). The Otonga area, regardless of primary or secondary forest habitats, had higher mean species richness. In both areas, the majority of species were found in a small number of stations and were sampled in a small number of specimens. A dominant and ubiquitous species was present only in Otongachi. The analysis of the community composition was carried out according to different categories of environmental variables (Otonga vs. Otongachi, forest type, elevation, litter and canopy coverage characteristics). Two well-differentiated coenoses were found, influenced firstly by the differences between the two reserves, secondarily by the elevation gradient and, to a lesser extent, by the forest type and other environmental variables. Some morphospecies characteristic of a specific type of biocoenosis could be identified. The study highlighted how most litter weevil species are strictly associated with a peculiar microhabitat and have a very narrow elevation and spatial range; the weevil communities can be strongly affected by heavy human impact. The results confirm that the tropical forests, in particular the TMCFs, host great biodiversity and that the majority of species are strictly associated with a single site; therefore, particular protection for these habitats should be granted. However, the non-significant variation between primary and secondary TMCFs indicates that, when correct management is carried out, a limited disturbance can be tolerated with only a limited loss of biodiversity.

Stress Control of Dike Deflection and Flank Eruption at Akaroa Volcano, New Zealand.

Understanding the stress evolution of extinct volcanoes can improve efforts to forecast flank eruptions on active systems. Field, petrographic, and seismic data are combined with numerical modeling to investigate the paleo‐stress field of New Zealand's Akaroa Volcano, or Akaroa Volcanic Complex. Field mapping identifies 86 radially oriented dikes and seven lava domes found only within a narrow elevation range along Akaroa's erosional crater rim. These observations suggest that crater rim dike emplacement resulted from lateral deflection of vertically ascending intrusions from a centralized magma source, which in turn may have facilitated formation of the lava domes, as well as two scoria cones. We postulate that dike deflection occurred along a stress barrier, as neither a compositional change nor structural boundary are present. We use a finite element model (FEM) simulating Akaroa to test how different factors may have influenced the system's stress state and dike geometry. Elastic, non‐flexural (“roller”) model configurations containing a large, oblate, and shallow magma chamber produce stress barriers most conducive to radial dike emplacement along Akaroa's crater rim. These configurations also simulate rapid edifice construction above a preexisting lithospheric “bulge.” Conversely, simulating flexural stresses exerted on the lithosphere by Akaroa's large mass hinder rather than promote radial dike emplacement. Temperature‐dependent viscoelastic relaxation promotes gradual increases in stress barrier elevation, though this effect is strongly dependent on magma chamber parameters. These results suggest that Akaroa was constructed rapidly (within ∼100 kyr) prior to crater rim dike emplacement, which occurred throughout the volcano's remaining active lifespan.

Altitude‐dependent variation in leaf structure and pigment content provides the performance of a relict shrub in mountains of Mongolia

AbstractMountain climate and vegetation change rapidly with altitude therefore many plant species may be found within a narrow elevation range. In the mountains of northern Mongolia, a relict shrub Prunus sibirica L. occurs within restricted upland areas. We studied 25 whole‐plant and leaf traits of P. sibirica at 10 locations in the Khentei Mountains. A comparison with a global trait variation of terrestrial plants and a path model of apricot data measured were used to evaluate the pattern of functional response to altitude. The intraspecific variation of pigment content found in Siberian apricot was surprisingly comparable to the ranges of interspecific variation among terrestrial plants over a global scale. Increasing altitude caused a dramatic increase in both chlorophylls and chlorophyll/carotenoid ratio and a decrease in the chlorophyll a/b. We also found a decrease in leaf thickness contributed to transpiration and water use efficiency. Photosynthetic capacity and kinetics, plant sizes and biomass were not affected by altitude. The path modelling revealed that pigment content and leaf structure were two independent ways to maintain the plant carbon and water balance. Our results identify the important role of intraspecific variation in leaf pigments and structure in plant response to altitude. We propose that these leaf traits could be used as predictors for the species altitudinal limits.

Community dynamics of soil-borne fungal communities along elevation gradients in neotropical and palaeotropical forests.

Because of their steep gradients in abiotic and biotic factors, mountains offer an ideal setting to illuminate the mechanisms that underlie patterns of species distributions and community assembly. We compared the composition of taxonomically and functionally diverse fungal communities in soils along five elevational gradients in mountains of the Neo- and Palaeotropics (northern Argentina, southern Brazil, Panama, Malaysian Borneo and Papua New Guinea). Both the richness and composition of soil fungal communities reflect environmental factors, particularly temperature and soil pH, with some shared patterns among neotropical and palaeotropical regions. Community dynamics are characterized by replacement of species along elevation gradients, implying a relatively narrow elevation range for most fungi, which appears to be driven by contrasting environmental preferences among both functional and taxonomic groups. For functional groups dependent on symbioses with plants (especially ectomycorrhizal fungi), the distribution of host plants drives richness and community composition, resulting in important differences in elevational patterns between neotropical and palaeotropical montane communities. The pronounced compositional and functional turnover along elevation gradients implies that tropical montane forest fungi will be sensitive to climate change, resulting in shifts in composition and functionality over time.

Elevational distribution of birds in an Eastern African montane environment as governed by temperature, precipitation, and habitat availability

AbstractTropical species, many of which have limited thermal tolerances and narrow ecological niches, are likely to experience elevational shifts due to climate change. However, our ability to predict these shifts is limited by a scarcity of baseline data on current distributions and a lack of understanding of drivers of species ranges. To characterize the elevational distributions of a suite of Afromontane birds, we conducted annual point counts between 2013 and 2018 at 297 plots across habitats and elevations (2416–4303 m) in Volcanoes National Park, Rwanda. We assessed elevational and habitat preferences via indicator analyses, and modeled abundance distributions as a function of temperature, precipitation, habitat availability, and congeneric competition. Although most of the 35 focal species were distributed across habitats and elevational ranges, 20 species particularly associated with narrow elevational range (<300 m) and 24 species were strongly associated with one to three habitat types. Abiotic factors significantly correlated with abundance distributions of 33 species (temperature 33, precipitation 17), and biotic factors with distributions of 31 species (habitat 30, competition 7). Temperature and habitat availability were particularly associated with upper elevational limits (31 and 26 species, respectively, vs. 10 and 6 at lower limits), whereas precipitation affected both limits similarly (17 lower, 16 upper), and competition had a limited role at either limit (4 lower, 3 upper). That the elevational distribution of Afromontane birds results from a species‐specific combination of biotic and abiotic factors is crucial information in our effort to predict climate change effects in this region.

Spatial prediction of plant species richness and density in high-altitude forests of Indian west Himalaya

The spatial distributions of plant species are results of variable environmental gradients, including climatic and edaphic factors, biotic factors, different eco-physiological processes, species-specific characteristics, and resource requirements, thus producing spatial heterogeneity. The species distribution and their rate of change across elevational gradients in nineteen forest communities were studied using the quadrat method and statistical modeling tools. Pindari-Sunderdhunga-Kafni (PSK) area of the Kumaun region and the Lata-Tolma-Phagti (LTP) area in the Garhwal region in the buffer zone of Nanda Devi Biosphere Reserve were selected as the extensive study sites. A total of 4278 individual trees belonging to 42 families in the PSK site and 6436 individual trees belonging to 25 families in the LTP site were recorded across elevational gradients between 2050 to 3800 m a.s.l. Because of the narrow elevational range and complexity in the field-based data structure, Generalized Additive Model (GAM) was used to predict the rate of change of species richness and species density. The results showed a significant decrease in density at a rate of 319–355 ind ha-1 per 100 m elevation in the Pindari-Sunderdhunga-Kafni site (P < 0.01) while increasing patterns (53–56 ind ha-1 per 100 m elevation) in the Lata-Tolma-Phagti site (p < 0.01) was recorded. The decreasing trend for species richness was observed in Lata-Tolma-Phagti site significantly (p< 0.02) across elevation. This study, for the first time in the Indian Himalayan region, underlines the rate of change in species richness (per 1000 m elevation) and density (per 100 m elevation) across elevational gradients. The overall vegetation response may perhaps be considered as an influence of boundary constraint associated with different environmental factors; however, more datasets of vegetation dynamics and responses are required to further strengthen this premise.

Does resource availability coincide with exploitation patterns? Inference from distribution and trade of Neopicrorhiza scrophulariiflora (Pennell) D.Y. Hong in the Nepalese Himalayas

Despite the widespread use and trade of the highly valued Himalayan medicinal plant, Neopicrorhiza scrophulariiflora, there is still inadequate information on its distribution and on the environmental factors that define suitable habitats. Such information is needed to identify suitable areas for sustainable resource extraction. We hypothesize that there is a discrepancy between the geographical distribution of trade and climatically suitable areas and suggest that this could lead to a risk of local depletion of the species, which could seriously affect rural livelihoods. To address this hypothesis, we conducted species distribution modeling of N. scrophulariiflora using Maximum Entropy with ten environmental variables and 63 species occurrence records (after rarefaction) from Nepal and related the resulting distribution model to trade assessment statistics from 12 fiscal years (2004–2016). The predicted area of suitable habitat in Nepal was estimated at 11,617 km2, and highly suitable areas were located in a narrow elevational range (4000–4400 m), with a predicted area of 386 km2 (0.3 %). Suitable and highly suitable areas were mostly located in the eastern mountains, probably due to mild temperatures and adequate precipitation around the peak of the plants’ growing season. Available official trade records indicated that Nepal exported only 372 tons of N. scrophulariiflora rhizomes in 2004–2016 (average: 31 tons/annum), mostly from the western mountains where predicted habitats were classified as less suitable. Discordant geographical patterns of habitat suitability, extraction from habitats of low suitability, and increasing trade indicate that the current resource exploitation is likely to be unsustainable. We suggest formulating management strategies for locations with heavy collection and trade, conducting cultivation trials in suitable patches, and identifying sustainable annual harvest limits.

Soil and microbial nutrient status are heterogeneous within an elevational belt on a neotropical mountain

Tropical mountains support a variety of vegetation types that are threatened by global change, but our understanding of these threats is limited by our scarce knowledge of nutrient constraints on belowground processes in these sensitive ecosystems. To address this, we quantified chemical and microbiological properties at five sites associated with four vegetation types at high elevations (>3000 m a.s.l.) on Volcán Barú, the highest mountain in Panamá. At each site we quantified total and extractable soil nutrients, microbial biomass nutrients, and the activities of hydrolytic enzymes involved in nutrient cycling. We found high heterogeneity among vegetation types in soil and microbial nutrients. Phosphorus (P) was mainly in organic form (>70%) in high organic matter soils under forest and grassland, but mostly in inorganic form (≥68%) in shrublands. Inorganic nitrogen (N) concentrations were low to moderate in all soils (0.7–8.7 mg N kg-1), whereas extractable P measured by anion-exchange resins was relatively high (5–54 mg P kg-1) compared with tropical lowlands. We found marked variation in microbial N (51–199 mg N kg-1), microbial P (40–170 mg kg-1), and hydrolytic enzyme activities (e.g. ß-glucosidase from 202 to 1399 nmol product g-1 h-1). Stoichiometric ratios in microbial biomass and between enzymes provided further evidence of shifts in the relative investment in N vs P acquisition among vegetation types. For example, the enzymatic N:P ratio (N-acetyl-ß-D-glucosaminidase (NAG) to phosphomonoesterase (PME)) pointed to greater investment in microbial acquisition of N relative to P in bamboo-oak forest (NAG:PME = 0.55) compared to grassland and shrublands (NAG:PME ≤0.30). In conclusion, our results show that tropical mountains can be highly heterogeneous within a relatively narrow elevation range, indicating the likelihood of contrasting responses of plant and microbial communities to global change drivers such as cloud base, precipitation, and nitrogen deposition in tropical mountains.

Distribution, habitat suitability, conservation state and natural history of endangered salamander Bolitoglossa pandi.

BackgroundPandi’s mushroom-tongue salamander (Bolitoglossa pandi) is one of the threatened amphibians in South America, as well as a flagship species for the Colombian conservation agenda. This species is endemic to the Andean cloud forests of the western slope of the Cordillera Oriental of Colombia, occurring only in the department of Cundinamarca within a narrow elevational range. At night, B. pandi can be seen perching on the upper side of leaves at heights ranging from ground level to 2.5 m. During the day, it can be found under leaf litter or cover objects. Few studies have provided relevant information that can help the Colombian government to formulate lines of action for the conservation of this species; consequently, its threat assessments so far have been based on very limited information.MethodsWe conducted surveys for salamanders in four municipalities of Cundinamarca, Colombia, using two approaches: visual encounter surveys (Guaduas and Villeta) and the basic sampling protocol for single-species occupancy modeling (Supatá and Venecia). Multivariate analyses were employed to explore the correlation between habitat structure and natural history traits, abundance, and detection/non-detection of B. pandi. We evaluated the B. pandi activity pattern through kernel density curves for each sampling occasion and explored the variability of salamander abundance during their activity period by performing a nested ANOVA.ResultsWe report the discovery of two new populations of B. pandi, which represent the most northwestern records known. A significant correlation between body length, body mass, and habitat structure was observed. Multivariate analyses indicated that leaf litter depth, mean temperature, percent vegetation cover, and altitude were the habitat variables that together explained 60.3% of the B. pandi abundance variability, as well as the main determinants of its optimal habitat. Bolitoglossa pandi exhibits an activity pattern characterized by two main activity peaks, in which niche time-partitioning was observed. Across the surveyed area, we found a healthy, stable, highly dense population of B. pandi (>1,300 individuals), with seasonal variability between development stages.DiscussionGiven the high habitat specificity of B. pandi, the species is highly vulnerable to local changes. Thus, we recommend that B. pandi be retained as Endangered (EN) on the IUCN Red List, based on the IUCN Criterion B, given its restricted extent of occurrence (ca. 2,500 km2) and the ongoing threats from agriculture, cattle ranching, logging, and urban development, which continue to reduce its suitable habitat.

Elevational specialization and the monitoring of the effects of climate change in insects: Beetles in a Brazilian rainforest mountain

Mountains have provided important insights on the impacts of climate change on species distribution. Organisms living in tropical mountains are expected to specialize in narrow temperature limits (demonstrating low thermal tolerance), often with narrow elevational distributions relative to temperate species, and may shift their elevational range in response to climate change. Importantly, insects are sensitive, and respond rapidly, to temperature variation, making them suitable bioindicators to monitor the effects of climate change. However, to monitor the effects of climate change in mountains it is important to understand present elevational distribution and other ecological characteristics of local insect populations. In this context, we suggest a method to identify beetle taxa that can be used to monitor climate change effects in tropical mountainous insect species. We illustrate the method by describing the elevational distribution of different beetle groups, associating this distribution with species’ thermal range in a tropical mountain forest in Southeast Brazil. Sampling was conducted at Serra dos Órgãos National Park, RJ, Brazil, in the Atlantic Rainforest, one of the main global biodiversity hotspots. In order to systematically sample beetle diversity across elevations, we used flight interception ‘Malaise’ traps at fifteen different sites, from 130 m to 2170 m a.s.l., over three consecutive months during the rainy season. To investigate species’ climatic niches, we recorded climatic variables for this period. We collected 2963 individuals of 272 species, belonging to six Coleoptera groups over a temperature gradient that decreased about 0.5 °C for each 100 m in elevation. Considering the thermal tolerance of species from tropical mountains and their narrow elevational range and abundance, five Coleoptera species belonging to Cerambycidae, Eumolpinae (Chrysomelidae), Lampyridae and Phengodidae were considered suitable bioindicators, and the Eumolpinae and Lampyridae were the ones with the narrowest elevational range. We suggest that the use of abundant species (or groups of species) with narrow elevational range as bioindicators can be valuable to monitor the effects of climate change on the biota, allowing us to evaluate how species are responding to changes over time.

Thermal tolerance and the importance of microhabitats for Andean frogs in the context of land use and climate change.

Global warming is having impacts across the Tree of Life. Understanding species' physiological sensitivity to temperature change and how they relate to local temperature variation in their habitats is crucial to determining vulnerability to global warming. We ask how species' vulnerability varies across habitats and elevations, and how climatically buffered microhabitats can contribute to reduce their vulnerability. We measured thermal sensitivity (critical thermal maximum-CTmax ) of 14 species of Pristimantis frogs inhabiting young and old secondary, and primary forests in the Colombian Andes. Exposure to temperature stress was measured by recording temperature in the understorey and across five microhabitats. We determined frogs' current vulnerability across habitats, elevations and microhabitats accounting for phylogeny and then ask how vulnerability varies under four warming scenarios: +1.5, +2, +3 and +5°C. We found that CTmax was constant across species regardless of habitat and elevation. However, species in young secondary forests are expected to become more vulnerable because of increased exposure to higher temperatures. Microhabitat variation could enable species to persist within their thermal temperature range as long as regional temperatures do not surpass +2°C. The effectiveness of microhabitat buffering decreases with a 2-3°C increase, and is almost null under a 5°C temperature increase. Microhabitats will provide thermal protection to Andean frog communities from climate change by enabling tracking of suitable climates through short distance movement. Conservation strategies, such as managing landscapes by preserving primary forests and allowing regrowth and reconnection of secondary forest would offer thermally buffered microhabitats and aid in the survival of this group.

The pattern of bird distribution along the elevation gradient of the Sutlej River basin, western Himalaya, India

We examined the species richness of birds along the elevation gradient of the Sutlej River basin in Himachal Pradesh in the western Himalaya of India. Birds were sampled at 318 sites categorized into 16 elevation bands ranging from 498 to 3700 m between June 2012 and April 2013. A total of 203 bird species were recorded. Species richness showed a monotonic decline with increasing elevation, with 27% of species recorded within a narrow elevation range. We tested the roles of explanatory variables such as environment (temperature, precipitation, area, &amp; Mid-domain Effect (MDE) richness) and habitat (Normalized Differential Vegetation Index (NDVI): July, November &amp; March) on the observed distribution pattern. The observed species richness pattern was strongly correlated with temperature, while three other variables—precipitation, area, and MDE richness—contributed negligibly to the observed pattern. The present study indicates that climatic conditions and vegetation are the major contributors for determining species richness along the Sutlej River basin. Thus, a customized approach is crucial for conservation of species in the elevation range.

Incadendron : a new genus of Euphorbiaceae tribe Hippomaneae from the sub-Andean cordilleras of Ecuador and Peru

Incadendron esseri K.Wurdack & Farfan, gen. & sp. nov., from the wet sub-Andean cordilleras of Ecuador (Cordillera del Cóndor) and Peru (Cusco, Oxapampa) is described and illustrated. This recently discovered large canopy tree with a narrow elevational range presents an unusual combination of rare morphological characters in Hippomaneae including mucilage-secreting sheathing stipules, conduplicate ptyxis, and large, woody fruits. The broader significance of these characters in Hippomaneae is discussed. The morphology and anatomy of Incadendron were investigated, highlighting its fruit similarities with Guiana Shield endemic Senefelderopsis, and the systematics value of ptyxis variation, which remains poorly studied for the family.

Tropical Montane Cloud Forests: Hydrometeorological variability in three neighbouring catchments with different forest cover

Mountain areas are characterized by a large heterogeneity in hydrological and meteorological conditions. This heterogeneity is currently poorly represented by gauging networks and by the coarse scale of global and regional climate and hydrological models. Tropical Montane Cloud Forests (TMCFs) are found in a narrow elevation range and are characterized by persistent fog. Their water balance depends on local and upwind temperatures and moisture, therefore, changes in these parameters will alter TMCF hydrology. Until recently the hydrological functioning of TMCFs was mainly studied in coastal regions, while continental TMCFs were largely ignored. This study contributes to fill this gap by focusing on a TMCF which is located on the northern eastern Andes at an elevation of 1550–2300m asl, in the Orinoco river basin highlands. In this study, we describe the spatial and seasonal meteorological variability, analyse the corresponding catchment hydrological response to different land cover, and perform a sensitivity analysis on uncertainties related to rainfall interpolation, catchment area estimation and streamflow measurements. Hydro-meteorological measurements, including hourly solar radiation, temperature, relative humidity, wind speed, precipitation, soil moisture and streamflow, were collected from June 2013 to May 2014 at three gauged neighbouring catchments with contrasting TMCF/grassland cover and less than 250m elevation difference.We found wetter and less seasonally contrasting conditions at higher elevations, indicating a positive relation between elevation and fog or rainfall persistence. This pattern is similar to that of other eastern Andean TMCFs, however, the study site had higher wet season rainfall and lower dry season rainfall suggesting that upwind contrasts in land cover and moisture can influence the meteorological conditions at eastern Andean TMCFs. Contrasting streamflow dynamics between the studied catchments reflect the overall system response as a function of the catchments’ elevation and land cover. The forested catchment, located at the higher elevations, had the highest seasonal streamflows. During the wet season, different land covers at the lower elevations were important in defining the streamflow responses between the deforested catchment and the catchment with intermediate forest cover. Streamflows were higher and the rainfall-runoff responses were faster in the deforested catchment than in the intermediate forest cover catchment. During the dry season, the catchments’ elevation defined streamflows due to higher water inputs and lower evaporative demand at the higher elevations.

Flower diversity and bee reproduction in an arid ecosystem.

Background: Diverse flower communities are more stable in floral resource production along the flowering season, but the question about how the diversity and stability of resources affect pollinator reproduction remains open. High plant diversity could favor short foraging trips, which in turn would enhance bee fitness. In addition to plant diversity, greater temporal stability of floral resources in diverse communities could favor pollinator fitness because such communities are likely to occupy the phenological space more broadly, increasing floral availability for pollinators throughout the season. In addition, this potential effect of flower diversity on bee reproduction could be stronger for generalist pollinators because they can use a broader floral spectrum. Based on above arguments we predicted that pollinator reproduction would be positively correlated to flower diversity, and to temporal stability in flower production, and that this relationship would be stronger for the most generalized pollinator species.Materials and Methods: Using structural equation models, we evaluated the effect of these variables and other ecological factors on three estimates of bee reproduction (average number of brood cells per nest per site, total number of brood cells per site, and total number of nests per site), and whether such effects were modulated by bee generalization on floral resources.Results: Contrary to our expectations, flower diversity had no effect on bee reproduction, stability in flower production had a weakly negative effect on one of the bee reproductive variables, and the strength of the fitness-diversity relationship was unrelated to bee generalization. In contrast, elevation had a negative effect on bee reproduction, despite the narrow elevation range encompassed by our sites.Discussion: Flower diversity did not affect the reproduction of the solitary bees studied here. This result could stem from the context dependence of the diversity-stability relationship, given that elevation had a positive effect on flower diversity but a negative effect on bee reproduction. Although high temporal stability in flower production is expected to enhance pollinator reproduction, in our study it had a weakly negative—instead of positive—effect on the average number of brood cells per nest. Other environmental factors that vary with elevation could influence bee reproduction. Our study focused on a small group of closely-related bee species, which cautions against generalization of our findings to other groups of pollinators. More studies are clearly needed to assess the extent to which pollinator demography is influenced by the diversity of floral resources.

ELEVATIONAL RANGES AND LOCAL EXTINCTION RISK OF BEETLES OCCURRING IN THE “CAMPOS DE ALTITUDE” IN SOUTHEASTERN BRAZIL

The mountaintops of the Atlantic Rainforest in Southeastern Brazil are dominated by high altitude grasslands, named Campos de Altitude (CA). Considering the location and the smaller habitat areas of communities on the mountaintops and the high frequency of endemic species, the assemblages in these habitats are particularly threatened by climate change, and the vulnerability of a species should then be higher if its elevational range is narrow. In this study we aim to describe the elevational range of beetle species occurring in the CA and discuss their vulnerability to local extinction in the context of climate change, also considering their trophic group. We selected beetles in five taxa from three trophic groups in the CA of Serra dos Orgaos National Park (SONP) and Itatiaia National Park (INP): detritivores (Scarabaeidae - INP), herbivores (Chrysomelidae - SONP and INP, and Curculionidae - SONP) and predators (Coccinellidae - SONP, and Lampyridae - SONP). We found different elevational ranges among the studied taxa and among species within each taxon. Herbivores tended to have narrower ranges than the detritivores, and predators were the trophic group with the broadest species range. The relatively high frequency of species with narrow elevational range, particularly within the herbivores, suggests that this entomofauna is particularly endangered due to predicted climate warming and an expected range shift upwards. Considering that many endemic species are expected in the CA and that many undescribed species of insects have been found in this habitat, we may lose many yet unknown species.

Climatic niche breadth can explain variation in geographical range size of alpine and subalpine plants

ABSTRACTUnderstanding the environmental factors determining the distribution of species with different range sizes can provide valuable insights for evolutionary ecology and conservation biology in the face of expected climate change. However, little is known about what determines the variation in geographical and elevational ranges of alpine and subalpine plant species. Here, we examined the relationship between geographical and elevational range sizes for 80 endemic rhododendron species in China using Spearman’s rank-order correlation. We ran the species distribution model – maximum entropy modelling (MaxEnt) – with 27 environmental variables. The importance of each variable to the model prediction was compared for species groups with different geographical and elevational range sizes. Our results showed that the correlation between geographical and elevational range sizes of rhododendron species was not significant. Climate-related variables were found to be the most important factors in shaping the distributional ranges of alpine and subalpine plant species across China. Species with geographically and elevationally narrow ranges had distinct niche requirements. For geographical ranges, the narrow-ranged species showed less tolerance to niche conditions than the wide-ranged species. For elevational ranges, compared with the wide-ranged species, the narrow-ranged species showed an equivalent niche breadth, but occurred at different niche position along the environmental gradient. Our findings suggest that over large spatial extents the elevational range size can be a complementary trait of alpine and subalpine plant species to geographical range size. Climatic niche breadth, especially the range of seasonal variability, can explain species’ geographical range sizes. Changes in climate may influence the distribution of rhododendrons, with the effects likely being felt most by species with either a narrow geographical or narrow elevational range.

Sharp acoustic boundaries across an altitudinal avian hybrid zone despite asymmetric introgression.

Birdsong is a sexually selected trait that could play an important evolutionary role when related taxa come into secondary contact. Many songbird species, however, learn their songs through copying one or more tutors, which complicates the evolutionary outcome of such contact. Two subspecies of a presumed vocal learner, the grey-breasted wood-wren (Henicorhina leucophrys), replace each other altitudinally across the western slope of the Ecuadorian Andes. These subspecies are morphologically very similar, but show striking differences in their song. We examined variation in acoustic traits and genetic composition across the altitudinal range covered by both subspecies and between two allopatric populations. The acoustic boundary between the subspecies was found to be highly abrupt across a narrow elevational range with virtually no evidence of song convergence. Mixed singing and use of hetero-subspecific song occurred in the contact zone and was biased towards the use of leucophrys song types. Hetero-subspecific song copying by hilaris and not by leucophrys reflected a previously found asymmetric pattern of response to song playback. Using amplified fragment length polymorphisms (AFLP) markers, we detected hybridization in the contact zone and asymmetric introgression in parapatric populations, with more leucophrys alleles present in hilaris populations than vice versa. This pattern may be a trail of introgression due to upslope displacement of leucophrys by hilaris. Our data suggest that song learning may impact speciation and hybridization in contrasting ways at different spatial scales: although learning may speed up population divergence in songs, thereby enhancing assortative mating and reducing gene flow, it may at a local level also lead to the copying of heterospecific songs, therefore allowing some level of hybridization and introgression.

Spatial and temporal patterns of lightning strikes in the eastern Lesotho Highlands, southern Africa

The lightning climatology of alpine regions is not well known, in particular spatial patterns of the altitude and facing direction of rock surfaces affected by cloud-to-ground lightning strikes. This study describes the spatial and temporal variability of mesoscale lightning flash climatology of the eastern Lesotho Highlands, southern Africa, during the period 2006–2011, based on data from the South African Weather Service (SAWS). Three study sites located within 8 km of each other show different temporal and elevational patterns of flash density, likely related to the trajectory and properties of incoming weather systems. Lightning flash density does not precisely match with land surface hypsometry at the three sites; rather, flashes occur preferentially at higher elevations that correspond to locations with exposed bedrock summits. We also compare spatial patterns of lightning flash density from the SAWS database with evidence for lighting strike impacts on bedrock surfaces in the field. Strike impacts, based mainly on geomorphological criteria, are identified within a very narrow elevational range which is determined largely by geological factors. The mesoscale lightning flash climatology cannot be used as a predictor of strike impact location or frequency. This has implications for both lightning hazard risk and the rate of alpine debris production by lightning strikes.