Understanding the Linkage between Elevation and the Activated-Sludge Bacterial Community along a 3,600-Meter Elevation Gradient in China

To understand the relationship between elevation and bacterial communities in wastewater treatment plants (WWTPs), bacterial communities in 21 municipal WWTPs across China, located 9 to 3,660 m above sea level (masl), were investigated by 454 pyrosequencing. A threshold for the association of elevation with bacterial community richness and evenness was observed at approximately 1,200 masl. At lower elevations, both richness and evenness were not significantly associated with elevation. At higher elevations, significant declines with increased elevations were observed for community richness and evenness. The declining evenness trend at the phylum level was reflected by distinct trends in relative abundance for individual bacterial phyla. Betaproteobacteria, Bacteroidetes, and Firmicutes displayed significant increases, while most other phyla showed declines. Spearman correlation analysis indicated that the community richness and evenness at high elevations were more correlated with elevation than with any other single environmental variable. Redundancy analysis indicated that the contribution of elevation to community composition variances increased from 3% at lower elevations to 11% at higher elevations whereas the community composition variance at higher elevations remained much more explained by operational variables (39.2%) than by elevation. The influent total phosphorus concentration, food/microorganism ratio, and treatment process were the three shared dominant contributors to the community composition variance across the whole elevation gradient, followed by effluent ammonia nitrogen and temperature at higher elevations.     

Radiosensitivity of two strains of the codling moth Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) originating from different elevations in Armenia

The purpose of this study was to analyse the radiosensitivity of codling moth Cydia pomonella (L.) strains from different elevations, 850 and 2000 m above the sea level. The level of sterility of parental males and inherited sterility of F₁ males in the strain from the higher elevation at all radiation doses (80, 100 and 150 Gy) was significantly lower, than in the strain from the lower elevation. The frequency of chromosomal aberrations in the F₁ generation in the strain from the higher elevation was significantly lower at 80 and 150 Gy than that in strain from the lower elevation. The average number of eupyrene sperm in the F₁ males descended from irradiated males was higher in the strain from the higher elevation than in the strain from the lower elevation. Inheritance of the resistance/susceptible to ionizing radiation were examined by standard genetic cross‐breeding analysis confirming the polygenic nature of the differences in radiosensitivity. The implications of these findings for the implementation of area‐wide integrated pest management programmes that integrate the use of sterile insects are discussed.     

中国东南部不同海拔亚热带森林中马尾松径向生长对气候的响应

为了解我国东南部亚热带森林不同海拔树木生长对气候响应的差异,建立了福建省武夷山脉东麓2个样点的4个马尾松(Pinus massoniana)轮宽年表,对树木径向生长与气候因子进行了bootstrapped相关分析和线性混合模型(LME)拟合。结果表明,在高海拔地区马尾松径向生长对气候因子年际波动敏感性较强,主要表现为与生长季前冬季光温条件以及生长季内7月降水的正相关,生长-气候关系在不同样点间表现出较强的一致性。线性混合模型可以较好地拟合高海拔树木生长变化,当使用前1年12月平均日最高温、当年1月日照时长和当年7月降雨量3个气候变量进行拟合时,模型解释量达到0.5,其中前1年12月最高温和当年1月日照时数在模型中起到主导作用,累积相对贡献率约占80%,说明生长季前冬季的光热条件是限制高海拔马尾松径向生长最主要的气候因子。因此,我国亚热带地区高海拔的树木径向生长可能对未来气候变化有更强的敏感性,相关森林管理政策的制定需要将此纳入考虑;同时我国亚热带地区高海拔森林中的树木有被用于树轮气候重建的潜力。     

Different trends in phylogenetic and functional structure of plant communities along an elevation gradient

The study of diversity gradients due to elevation dates back to the foundation of biogeography and ecology. Although elevation-driven patterns of plant diversity have been reported for centuries, uncertainty still exists about the assembly rules that drive these patterns. In this study, we revealed the causal factor of community assemblies for the diversity of tree and herb species along an elevation. To this end, we applied an integrated method using both functional traits and phylogeny, called the mean pairwise functional-phylogenetic distance, to understand the assembly rules for woody and herbaceous species communities along an elevation gradient. At higher elevation sites, woody and herbaceous communities were comprised of species having similar traits. The phylogenetic trends for woody species were consistent with the functional trends; closely related species co-occurred more frequently than expected at higher elevations. Phylogenetic trends for herb species were opposite to the functional trends; species with similar traits but having a random phylogenetic distribution co-occurred at higher elevations. We suggest that the community assembly rules for woody and herb species vary with elevation; and functional constraints due to environmental filtering at higher elevation act as assembly rules along gradients in both woody and herbaceous communities, even though their phylogenetic backgrounds differ.     

濒危植物秦岭冷杉结实特性的研究

秦岭冷杉 (Abieschensiensis) 是松科冷杉属常绿乔木, 为我国特有珍稀濒危植物。该文在秦岭冷杉分布最为集中的秦岭地区分高、低 2个海拔高度采集当年球果和种子, 通过野外观察、室内实验和对比分析, 研究秦岭冷杉的结实特征以及球果和种子的基本性状, 并探讨这些特征在不同海拔高度的差异。结果表明, 与冷杉属其它树种相比, 秦岭冷杉球果和种子较大、单果种子数较多, 但空粒多、饱满度低。自然状况下饱满度为 12.0 %, 人工目视分选后饱满度 2 1.6 %, 风选后可达到 38.1%, 其余种子大部分为空粒、涩粒, 有少量虫粒。随海拔高度增加, 秦岭冷杉天然群体成龄个体中结实母树比例降低, 结实量减少。秦岭冷杉总体结实母树比例为 5 5 %, 低海拔处结实母树比例较高, 为 76 %, 高海拔结实母树比例为 34%。秦岭冷杉单株母树的平均结实量为 113个, 结实量小于 10 0个的母树占 6 4.5 %, 其中 5 0 %的母树结实量在 5 0~ 10 0个, 结实量在 10 0~ 2 0 0个的占 16.1%, 2 0 0个以上的占 19.4 %。 2 0 0个以上球果的个体均生长在低海拔区间, 高海拔处结实量多在 10 0个以下。方差分析表明, 两个海拔高度间球果和种子特征差异是显著的, 绝大部分球果和种子性状指标的平均值在低海拔处大于高海拔处。因此, 从结实特性以及球果和种子的特征来看, 低海拔处秦岭冷杉生殖生长好于高海拔处。     

Positive associations between the cushion plant Arenaria polytrichoides (Caryophyllaceae) and other alpine plant species increase with altitude in the Sino‐Himalayas

Question: Does the facilitative effect of cushion plants increase with elevation as a result of increases in environmental harshness? Does this hypothesis apply in the Sino‐Himalayan Mountains? Location: Lakaka Pass on the Baima Snow Mountains (28°20′N, 99°05′E), SW China. Methods: We evaluated the spatial association of several plant species with the cushion plant Arenaria polytrichoides (Caryophyllaceae) at two elevations (4500 m and 4700 m) in the study site and monitored temperature, moisture and nutritional status of soil beneath and outside the cushions. Results: While 14 species grow more frequently associated with the cushions at the higher elevation, at the lower site only three species were positively associated with cushions. Eleven of the species that occurred at both elevations changed their spatial association from neutral or negative with cushions at the lower site to positive at the higher elevation site. Substrate temperatures were rather similar between the cushions and areas of bare ground. Cushions maintained higher moisture than areas of bare ground at both elevations. Soils beneath cushions contained significantly more available nitrogen and potassium compared to open areas at the higher elevation. Conclusions: Our results show that facilitation by A. polytrichoides cushions increases with elevation in the Sino‐Himalayan region. This facilitation effect of A. polytrichoides cushions is probably due to the improved nutrient availability provided by cushion plants in the higher elevation, and these conditions probably permit increased plant recruitment, growth and survival.     

Can Rapoport's rule explain tree species richness along the Himalayan elevation gradient,Nepal?

Rapoport's rule applied to an elevation gradient predicts a positive correlation between elevation ranges and elevation. This is supposed to be caused by the increasing magnitude of the climatic extremes at higher elevations, and thus, it is deduced that species richness should decrease with increasing elevation. The distribution of 614 tree species was used to test Rapoport's elevational rule along a gradient from 100 to 4300 m a.s.l., in the Nepalese Himalaya. The relationship between species richness and elevation was analysed by using generalized linear models (GLM). Generalized additive models (GAM) were used to examine the relationship between elevational range and the elevational mid-point of a species along the gradient. The widest elevation ranges are observed at mid-elevations, and narrow elevation ranges are observed at both ends of the gradient. This does not support Rapoport's elevation rule, as proposed by Stevens. There is a peak in species richness between 900 and 1000 m, and not in the tropical lowland as projected by Rapoport's elevation rule.     

Controls on Litter Decomposition of Emergent Macrophyte in Dongting Lake Wetlands

Both litter composition and site environment are important factors influencing litter decomposition, but their relative roles in driving spatial variation in litter decomposition among wetlands remain unclear. The responses of mass loss and nutrient dynamics to site environment and litter source were investigated in Carex brevicuspis leaves from the Dongting Lake wetlands, China, using reciprocal transplants of litterbags. Litters originating from lower elevation (24–25 m; flooded for 180–200 days every year) and higher elevation (27–28 m; flooded for 60–90 days every year) sites were incubated simultaneously at lower and higher sites at three locations for 1 year. The remaining litter mass, N, P, and lignin contents were analyzed during decomposition. Initial N and P contents were richer in litters from lower sites than those from higher ones. The decomposition rate was higher for the litters originating from lower sites (0.0030 day^?1) than those from higher ones (0.0025 day^?1) and higher at lower sites (0.0031 day^?1) than at higher sites (0.0024 day^?1). Litters from lower sites displayed greater N and P mineralization than those from higher sites, whereas only P dynamics were affected by site elevation. The variation in litter decomposition rate among the different litter source groups was twice that among the different site elevation groups. These data indicate that, in wetlands ecosystems, litter composition plays a more important role in the speed of litter decomposition than site environment (here represented by site elevation).     

Effect of elevation on the insect herbivory of Mongolian oaks in the high mountains of southern South Korea

Elevation is strongly associated with the diversity and ecology of plants and animals. We explored how elevation affects herbivores on one of the major cool-temperate trees, Quercus mongolica, in southern South Korea. The feeding activities of insect herbivores were measured through insect-feeding damage on leaves. Of 78 types of insect-feeding damage that were observed from Jirisan Mountain (Mount.) and Hallasan Mount. in Korea, 61.6% was associated with externally feeding insects. The sum of feeding damages per leaf was significantly higher on Jirisan Mount. than on Hallasan Mount., and higher at higher elevation in both mountains. Two feeding guilds, externally feeding, and piercing and sucking were strongly related with elevation, but the relationship was opposite depending on feeding guild. Leaf damage by the internal feeding guild showed no effect of elevation at the two mountains. These study results showed that insect herbivory responds to elevational differences in temperate forests, and that such response can vary among feeding guilds.     

天山东部不同海拔西伯利亚落叶松对气候变暖的响应分析

利用树木年轮气候学方法,探讨了在气候变暖情景下,天山东部上中下限西伯利亚落叶松（Larix sibirica）树木径向生长与气候因子之间的响应关系,并利用冗余分析对其关系进行了验证。结果表明：不同海拔的差值年表（RES）要比标准年表（STD）的特征参数大,具有更高的信噪比和平均敏感度,含有较多的环境信息且更能代表树木总体变化;海拔2160m处的年表（L1）在快速升温（1985年）后,树木年轮宽度与降水和温度的相关性明显减弱;海拔2430m处的年表（L2）在两个时段内与降水和温度的关系均较弱;海拔2700m处的年表（L3）在1985~2013年时段内对降水和气温的正响应均增强。树木径向生长对单月气候因子的响应在前一年11、12月份显著性更高,当年6、7月份气温与树轮宽度指数具有更高的相关性。气候变暖使树木径向生长不断减小的特征在低海拔地区表现更为明显。上中下限西伯利亚落叶松对气温升高的敏感性降低。高海拔地区西伯利亚落叶松的径向生长主要受温度的影响,而中低海拔地区主要受降水与温度的共同影响。     

Responses of growth to elevation fail to explain vertical zonation of suspension-feeding bivalves on a tidal flat

Summary Five species of suspension-feeding bivalves were transplanted to each of two elevations on a tidal flat at Shark Bay, Western Australia, at six replicate locations spaced at 1-km intervals along the shore. Four species exhibited greatly reduced growth at the higher elevation, while the fifth species did not respond to elevation. The magnitude of the % reductions in growth with increased elevation was 2–3 times the % reduction in average daily submergence, confirming a previous suggestion that differences in feeding time alone are insufficient to explain completely the reduced growth of suspension-feeding bivalves at higher tidal elevatios. All four species that responded showed the same pattern of higher growth lower on the shore, even though transect sampling showed that two were normally abundant only high on the shore while the other tow were naturally restricted to elevations low on the shore. Consequently, knowledge of how individual growth within species varies with tidal elevation fails to explain observed zonation patterns with elevation in this guild of suspension-feeding bivalves. The paradoxical distribution pattern of those two species that were rare at the lower tidal elevations, where they actually grew more rapidly, implies that some biological agent(s) of mortality not physiological stress set(s) their lower distributional limit on the shore. Biological rather than physical factors commonly, although not universally, set lower distributional limits of invertebrates in rocky intertidal zones, but this study provides the first experimental data to explore this concept in marine soft sediments.     

Comparative study of spatial patterns and ecological niches of beetles in two Malaysian mountains elevation gradients

The study of beetle communities is a valuable approach for biogeographical and conservation studies because their species and ecological diversities are very high, and they take different roles in ecosystems. However, beetle macroecology and conservation studies are disproportionately scarce, especially in tropical Asia. The objective of this study is to compare beetle abundance, diversity and species richness along the elevation gradients in two mountains in Peninsular Malaysia. Three passive sampling methods were utilized for beetle sampling with four marked elevation gradients: 500 m, 1000 m, 1500 m and 1800 m. Species richness in Fraser’s Hill was higher at highest elevation, but this value was not-significantly different from these in other elevations, except for the site at 1000 m with significantly lower estimates. Genting Highlands showed a significant decrease in species richness with the increase in elevation, without differences between the higher elevation sites. Pairwise comparison of species richness, Simpson Dominance and Shannon diversity between same elevation sites of Fraser’s Hill and Genting Highlands were all significantly different. The levels of vertical and horizontal colonization have had comparatively different weights in terms of their effect on the pattern of diversity and the integration of the beetle community in these two localities. At Fraser’s Hill, similar conditions at different elevations drives different responses, whereas at Genting Highlands contrasting and different environmental conditions at each elevation, drives different responses. We suggest the potential use of these results for biodiversity conservation in terms of climate variables in accordance with niche patterns.     

Responses of arbuscular mycorrhizal symbionts to contrasting environments: field evidence along a Tibetan elevation gradient

Plant adaptation to alpine ecosystems is not fully explained by plant physiological and morphological traits. Arbuscular mycorrhizal (AM) associations may be involved in mediating plant performance in response to environmental differences. Little is known, however, as to whether or not a close relationship exists between plant performance and arbuscular mycorrhizal fungus status across environmental gradients. We conducted a field investigation of the performance of six plant species and their associated AM fungi along higher and lower elevation gradients on Mount Segrila in Tibet. In most of our species, we observed higher shoot and inflorescence biomass production and a lower root-to-shoot ratio in the populations at those sites where the species was dominant (intermediate elevation sites) than in populations sampled at the limits of the distribution. The elevation pattern of root colonization differed with plant species on both gradients, and the extraradical hypha development of most species showed a unimodal pattern as did plant growth. The relationship between plant and fungus traits shows that AM fungus development generally matched host plant performance on the lower elevation gradient but not on the higher elevation gradient. This study provides evidence that plant distribution and productivity were significantly related to root and soil colonization by AM fungi, especially under less physically stressful conditions.     

Proximate causes of altitudinal differences in body size in an agamid lizard

Body size is directly linked to key life history traits such as growth, fecundity, and survivorship. Identifying the causes of body size variation is a critical task in ecological and evolutionary research. Body size variation along altitudinal gradients has received considerable attention; however, the underlying mechanisms are poorly understood. Here, we compared the growth rate and age structure of toad‐headed lizards (Phrynocephalus vlangalii) from two populations found at different elevations in the Qinghai‐Tibetan Plateau. We used mark‐recapture and skeletochronological analysis to identify the potential proximate causes of altitudinal variation in body size. Lizards from the high‐elevation site had higher growth rates and attained slightly larger adult body sizes than lizards from the low‐elevation site. However, newborns produced by high‐elevation females were smaller than those by low‐elevation females. Von Bertalanffy growth estimates predicted high‐elevation individuals would reach sexual maturity at an earlier age and have a lower mean age than low‐elevation individuals. Relatively lower mean age for the high‐elevation population was confirmed using the skeletochronological analysis. These results support the prediction that a larger adult body size of high‐elevation P. vlangalii results from higher growth rates, associated with higher resource availability.     

Spectral reflectance and photosynthetic properties of Betula papyrifera (Betulaceae) leaves along an elevational gradient on Mt. Mansfield, Vermont, USA

We studied relationships between spectral reflectance and photosynthesis of mountain paper birch, Betula papyrifera var. cordifolia (Regel) Fern., leaves from three different elevations on Mt. Mansfield (summit elevation 1339 m above sea level) in the Green Mountains of Vermont, USA. The different reflectance indices we used all suggested progressively increasing stress with increasing elevation. The photochemical reflectance index (PRI) indicated lower photosynthetic radiation use efficiency at higher elevations, the red edge position (λRE) indicated lower chlorophyll concentrations at higher elevations, and the structure-independent pigment index (SIPI) indicated a higher carotenoid?:?chlorophyll a ratio at higher elevations. The rate of change in these indices with changes in elevation was much higher than we have observed in our studies of red spruce and balsam fir reflectance along a similar elevational gradient; we take this to be an indicator of the greater susceptibility of paper birch to elevation-related stressors compared to the very stress-tolerant conifers. At all light levels, photosynthesis decreased with increasing elevation; this pattern was most noticeable in the light-saturated rate of photosynthesis (A(sat)), which was nearly twice as high in low-elevation leaves (17.0 ± 1.0 μmol·m(-2)·s(-1)) than in high-elevation leaves. The quantum yield of photosynthesis (Φ) exhibited a similar trend. Furthermore, the highest elevation leaves showed a much sharper transition from the light-limited to the light-saturated part of the light response curve than did the lowest elevation leaves. The photochemical reflectance index was highly correlated with A(sat) (r(2) = 0.99) and Φ (r(2) = 0.96). In addition to contributing to our knowledge of the ecophysiology of paper birch along a steep environmental gradient, these results are further evidence of the usefulness of reflectance measures for the rapid and noninvasive detection of plant stress, especially when used in conjunction with direct measurements of photosynthesis.     

Change in ecological stoichiometry of Carex brevicuspis in response to seasonal dynamics and elevation in Dongting Lake,China

Plant nutrient stoichiometry is affected by both environmental factors and plant physiological processes. However, we know little about how small elevation gradients (influencing e.g. flooding regimes) and seasonality combine with soil physicochemical properties to influence nutrient stoichiometry in wetland plants. In this study, we examined these factors in Carex brevicuspis at Dongting Lake, China, during the non‐flooding periods in March, May and December of 2015 and February of 2016. We found that total foliar C concentration increased as elevation increased, especially during December 2015 and February 2016. At the low‐elevation site, total foliar C concentration decreased over the season, whereas it first increased and then decreased over time at higher elevations. Foliar total N and P concentrations decreased from March to May and subsequently increased throughout the season, and these concentrations were always much higher at the low‐elevation site. The C:N and C:P ratios first increased and then decreased over the season, while increasing with rising elevation. The N:P ratio was lower at the low‐elevation site, especially during May 2015 and February 2016; its variation over time differed across the elevations. A canonical correspondence analysis revealed that soil organic C, total N and soil nitrate N are important for determining C. brevicuspis stoichiometry. Our results suggest that both elevation and plant life stage have a significant influence on plant stoichiometry. This study improves our understanding of the seasonal dynamics of plant nutrients under different geographical conditions.     

Breeding success at the range margin of a desert species: implications for a climate‐induced elevational shift

If the breeding range of a species is limited by biotic or abiotic environmental factors that depress breeding success at the range margin, then range expansion is expected when those limiting factors are alleviated. Over a three‐year period, we measured breeding success of a desert species, black‐throated sparrow Amphispiza bilineata, along a steep elevation gradient between the Peninsular Mountains and Colorado Desert (San Diego County, California) that is undergoing a warming trend. We compared breeding success at geographically marginal locations (higher‐elevation chaparral sites) to more central locations (lower‐elevation desert scrub sites) only a short distance apart. Breeding success was measured at the nest level, territory level, and population level. At each level measured, breeding success tended to be greater at higher‐elevation chaparral sites at the distribution margin compared to lower‐elevation sites where the bird was more common. Black‐throated sparrows had 100% reproductive failure at lower‐elevation sites during the two driest years of our study (2006–2007), but did relatively well at higher‐elevation sites. Only in a wetter year (2008) was breeding success improved at lower‐elevation sites. Surprisingly, there was no evidence of an upward elevational shift in distribution over a 26‐year period despite a clear warming trend and drier conditions. Greater territory density at lower‐elevation sites with reproductive failure during dry years suggests the possibility of an ecological trap in this system, which could prevent or delay climate‐induced range shifts. A common presumption has been that desert species will undergo relatively mild negative impacts due to a warming climate, but it is possible that some desert species are already at or near their temperature and aridity tolerance limits within their current range and shifts may not always be possible.     

Store-operated calcium channels in HL-60 cells effects of temperature,differentiation and loperamide

The effect of temperature on calcium release and influx has been compared in differentiated and undifferentiated HL-60 cells. Receptor-mediated release of intracellular calcium by ATP was little affected by temperature in HL-60 cells. In differentiated HL-60 cells the store-operated calcium (SOC) channel-dependent sustained elevation of calcium levels after ATP was maximal at 25-29 degrees C; at higher temperatures calcium levels returned relatively rapidly towards basal levels. In undifferentiated cells, a SOC channel-dependent sustained elevation of calcium levels was not observed with levels returning to basal levels much more rapidly than in differentiated cells. The initial thapsigargin-initiated elevation of calcium did not become maximal until about 25 degrees C in both differentiated and undifferentiated HL-60 cells. In differentiated cells, the SOC channel-dependent sustained elevation of calcium after thapsigargin was maximal at 30-37 degrees C, while in undifferentiated cells, the sustained elevation was maximal at 25-30 degrees C. Loperamide, which augments the SOC channel-dependent sustained elevation of calcium, showed a temperature-dependent response that was maximal at about 22 degrees C after either ATP or thapsigargin and was minimal at 37 degrees C. In contrast, inhibition of SOC channel-dependent elevation of calcium by miconazole or trifluoperazine was not greatly affected by temperature.     

Effects of Flooding Regime and Seedling Treatment on Early Survival and Growth of Nuttall Oak

Effects of flooding on survival and growth of three different types of Nuttall oak (Quercus texana Buckl.) seedlings were observed at the end of third and fifth growing seasons at Yazoo National Wildlife Refuge, Mississippi, U.S.A. Three types of seedlings were planted in January 1995 in a split‐plot design, with four replications at each of two elevations on floodprone, former cropland in Sharkey clay soil. The lower of the two planting elevations was inundated for 21 days during the first growing season, whereas the higher elevation did not flood during the 5‐year period of this study. The three types of 1‐0 seedlings were bareroot seedlings, seedlings grown in containers (3.8 × 21–cm plastic seedling cones), and container‐grown seedlings inoculated with vegetative mycelia of Pisolithus tinctorius (Pers.) Coker. Survival of all the three seedling types was greatest at the lower, intermittently flooded elevation, indicating that drought and related effects on plant competition were more limiting to seedling survival than flooding. At the lower elevation, survival of mycorrhizal‐inoculated container seedlings was greater than that of noninoculated container seedlings. Survival among bareroot seedlings and inoculated container seedlings was not significantly different at either elevation. At the higher, nonflooded elevation, however, bareroot seedling survival was greater than the survival of container seedlings without inoculation. Differences were significant among the inoculated and the noninoculated container seedlings, with higher survival of inoculated seedlings at both elevations, though differences were only significant in year 3. At the end of the fifth year, height of bareroot seedlings was significantly greater than the heights of both types of container‐grown seedlings at both planting elevations. Because seedlings grown in the plastic seedlings cones did not survive better than the bareroot seedlings at either planting elevation, the bareroot stock appear to be the economically superior choice for regeneration in Sharkey soil.     

Social structure varies with elevation in an Alpine ant

Insect societies vary greatly in social organization, yet the relative roles of ecological and genetic factors in driving this variation remain poorly understood. Identifying how social structure varies along environmental gradients can provide insights into the ecological conditions favouring alternative social organizations. Here, we investigate how queen number variation is distributed along elevation gradients within a socially polymorphic ant, the Alpine silver ant Formica selysi. We sampled low‐ and high‐elevation populations in multiple Alpine valleys. We show that populations belonging to different drainage basins are genetically differentiated. In contrast, there is little genetic divergence between low‐ and high‐elevation populations within the same drainage basin. Thus, elevation gradients in each of the drainage basins represent independent contrasts. Whatever the elevation, all well‐sampled populations are socially polymorphic, containing both monogynous (= one queen) and polygynous (= multiple queen) colonies. However, the proportion of monogynous colonies per population increases at higher elevation, while the effective number of queens in polygynous colonies decreases, and this pattern is replicated in each drainage basin. The increased prevalence of colonies with a single queen at high elevation is correlated with summer and winter average temperature, but not with precipitation. The colder, unpredictable and patchy environment encountered at higher elevations may favour larger queens with the ability to disperse and establish incipient monogynous colonies independently, while the stable and continuous habitat in the lowlands may favour large, fast‐growing polygynous colonies. By highlighting differences in the environmental conditions favouring monogynous or polygynous colonies, this study sheds light on the ecological factors influencing the distribution and maintenance of social polymorphism.