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Tropical montane forests (TMFs) play an important role as a carbon reservoir at a global scale. However, there is a lack of a comprehensive understanding on the variation in carbon storage across TMF compartments [namely aboveground biomass (AGB), belowground biomass (BGB), and soil organic matter] along altitudinal and environmental gradients and their potential trade-offs. This study aims to: 1) understand how carbon stocks vary along altitudinal gradients in Andean TMFs, and; 2) determine the influence of climate, particularly precipitation seasonality, on the distribution of carbon stocks across different forest compartments. The study was conducted in sixty 0.1 ha plots along two altitudinal gradients at the Podocarpus National Park (Ecuador) and Río Abiseo National Park (Peru). At each plot, we calculated the amount of carbon in AGB (i.e. aboveground carbon stock, AGC), BGB (i.e. belowground carbon stock, BGC), and soil organic matter (i.e. soil organic carbon stock, SOC). The mean total carbon stock was 244.76 ± 80.38 Mg ha and 211.51 ± 46.95 Mg ha in the Ecuadorian and Peruvian plots, respectively. Although AGC, BGC, and SOC showed different partitioning patterns along the altitudinal gradient both in Ecuador and Peru, total carbon stock did not change with altitude in either site. The combination of annual mean temperature and precipitation seasonality explained differences in the observed patterns of carbon stocks across forest compartments between the two sites. This study suggests that the greater precipitation seasonality of colder, higher altitudes may promote faster turnover rates of organic matter and nutrients and, consequently, less accumulation of SOC but greater AGC and BGC, compared to those sites with lesser precipitation seasonality. Our results demonstrate the capacity of TMFs to store substantial amounts of carbon and suggest the existence of a trade-off in carbon stocks among forest compartments, which could be partly driven by differences in precipitation seasonality, especially under the colder temperatures of high altitudes.

Comparing genetic diversity, genetic differentiation, and performance between native and nonnative populations has advanced our knowledge of contemporary evolution and its ecological consequences. However, such between-range comparisons can be complicated by high among-population variation within native and nonnative ranges. For example, native vs. nonnative comparisons between small and non-representative subsets of populations for species with very large distributions have the potential to mislead because they may not sufficiently account for within-range adaptation to climatic conditions, and demographic history that may lead to non-adaptive evolution. We used the cosmopolitan weed Conyza canadensis to study the interplay of adaptive and demographic processes across, to our knowledge, the broadest climatic gradient yet investigated in this context. To examine the distribution of genetic diversity, we genotyped 26 native and 26 nonnative populations at 12 microsatellite loci. Furthermore, we recorded performance traits for 12 native and 13 nonnative populations in the field and in the common garden. To analyze how performance was related to range and/or climate, we fit pedigree mixed-effects models. These models weighed the population random effect for co-ancestry to account for the influence of demographic history on phenotypic among-population differentiation. Genetic diversity was very low, selfing rates were very high, and both were comparable between native and nonnative ranges. Nonnative populations out-performed native populations in the field. However, our most salient result was that both neutral genetic differentiation and common garden performance were far more correlated with the climatic conditions from which populations originated than native vs. nonnative range affiliation. Including co-ancestry of our populations in our models greatly increased explained variance and our ability to detect significant main effects for among-population variation in performance. High propagule pressure and high selfing rates, in concert with the ability to adapt rapidly to climatic gradients, may have facilitated the global success of this weed. Neither native nor nonnative populations were homogeneous groups but responded comparably to similar environments in each range. We suggest that studies of contemporary evolution should consider widely distributed and genotyped populations to disentangle native vs. nonnative range effects from varying adaptive processes within ranges and from potentially confounding effects of demographic history.

Aim We analysed elevational and microclimatic drivers of thermal tolerance diversity in a tropical mountain frog clade to test three macrophysiological predictions: less spatial variation in upper than lower thermal limits (Bretts’ heat‐invariant hypothesis); narrower thermal tolerance ranges in habitats with less variation in temperature (Janzen's climatic variability hypothesis); and higher level of heat impacts at lower elevations. Location Forest and open habitats through a 4,230‐m elevational gradient across the tropical Andes of Ecuador. Method We examined variability in critical thermal limits (CTmax and CTmin) and thermal breadth (TB; CTmax–CTmin) in 21 species of Pristimantis frogs. Additionally, we monitored maximum and minimum temperatures at the local scale (tmax, tmin) and estimated vulnerability to acute thermal stress from heat (CTmax–tmax) and cold (tmin–CTmin), by partitioning thermal diversity into elevational and microclimatic variation. Results Our results were consistent with Brett's hypothesis: elevation promotes more variation in CTmin and tmin than in CTmax and tmax. Frogs inhabiting thermally variable open habitats have higher CTmax and tmax and greater TBs than species restricted to forest habitats, which show less climatic overlap across the elevational gradient (Janzen's hypothesis). Vulnerability to heat stress was higher in open than forest habitats and did not vary with elevation. Main conclusions We suggest a mechanistic explanation of thermal tolerance diversity in elevational gradients by including microclimatic thermal variation. We propose that the unfeasibility to buffer minimum temperatures locally may explain the rapid increase in cold tolerance (lower CTmin) with elevation. In contrast, the relative invariability in heat tolerance (CTmax) with elevation may revolve around the organisms’ habitat selection of open‐ and canopy‐buffered habitats. Secondly, on the basis of microclimatic estimates, lowland and upland species may be equally vulnerable to temperature increase, which is contrary to the pattern inferred from regional interpolated climate estimators.

Aim. We assessed the relative contribution of ploidy-level variation and adaptive trait diversity to the diversity of taxon realized niches in a plant lineage with several ploidy levels. Location. A large number of sites covering a wide range of environmental conditions in France. Methods. Our material comprised a collection of populations from several taxa of the ‘fine-leaved fescue’ lineage, namely section Aulaxyper (Festuca rubra s.l.) and subsection Festuca (Festuca ovina s.l.) of the subgenus Festuca. This collection was assessed for several traits related to vegetative growth, investment in seed production, morphology and phenology. Environmental parameters that best differentiate taxon-realized niches were identified by multivariate ordination and logistic regression. Canonical correlation analyses were performed to relate plant traits and ploidy-level variation to these environmental parameters. Taxon differentiation was assessed along the first canonical directions of the plant descriptor (plant-trait and ploidy-level) space. Results. The climatic summer water balance, soil texture and land use were identified as the main environmental parameters differentiating taxon realized niches. Canonical correlation analyses revealed associations between plant traits and these environmental parameters, independent of ploidy-level variation. More specifically, the production of long and abundant rhizomes appeared to be an efficient adaptation to poor climatic summer water balance. In contrast, the ploidy level was rather weakly associated with environmental parameters. The marked prevalence of high ploidy levels in the collection suggests that they could have a competitive advantage in the range of environmental conditions investigated. Main conclusions. Adaptive trait diversity appears to contribute more than ploidy-level variation to the present diversity of realized niches for fine-leaved fescue taxa, although plant-trait variations were associated to some extent with ploidy-level variation. However, cytotypes with high ploidy levels could have been efficient colonizers and competitors, favouring the expansion of the lineage and leading to their present prevalence. Furthermore, adaptive trait diversification may have been an efficient factor in niche diversification for the present cytotypes with high ploidy levels.

We surveyed the empirical literature to determine how well six diversity hypotheses account for spatial patterns in species richness across varying scales of grain and extent. Worldwide. We identified 393 analyses ('cases') in 297 publications meeting our criteria. These criteria included the requirement that more than one diversity hypothesis was tested for its relationship with species richness. We grouped variables representing the hypotheses into the following 'correlate types': climate/productivity, environmental heterogeneity, edaphics/nutrients, area, biotic interactions and dispersal/history (colonization limitation or other historical or evolutionary effect). For each case we determined the 'primary' variable: the one most strongly correlated with taxon richness. We defined 'primacy' as the proportion of cases in which each correlate type was represented by the primary variable, relative to the number of times it was studied. We tested for differences in both primacy and mean coefficient of determination of the primary variable between the hypotheses and between categories of five grouping variables: grain, extent, taxon (animal vs. plant), habitat medium (land vs. water) and insularity (insular vs. connected). Climate/productivity had the highest overall primacy, and environmental heterogeneity and dispersal/history had the lowest. Primacy of climate/productivity was much higher in large-grain and large-extent studies than at smaller scales. It was also higher on land than in water, and much higher in connected systems than in insular ones. For other hypotheses, differences were less pronounced. Throughout, studies on plants and animals showed similar patterns. Coefficients of determination of the primary variables differed little between hypotheses and across the grouping variables, the strongest effects being low means in the smallest grain class and for edaphics/nutrients variables, and a higher mean for water than for land in connected systems but vice versa in insular systems. We highlight areas of data deficiency. Our results support the notion that climate and productivity play an important role in determining species richness at large scales, particularly for non-insular, terrestrial habitats. At smaller extents and grain sizes, the primacy of the different types of correlates appears to differ little from null expectation. In our analysis, dispersal/history is rarely the best correlate of species richness, but this may reflect the difficulty of incorporating historical factors into regression models, and the collinearity between past and current climates. Our findings are consistent with the view that climate determines the capacity for species richness. However, its influence is less evident at smaller spatial scales, probably because (1) studies small in extent tend to sample little climatic range, and (2) at large grains some other influences on richness tend to vary mainly within the sampling unit.

The present study investigates the ecology and distribution of ostracod species and assemblages from 62 inland waterbodies in the Eastern Cape province of South Africa and tests the influence of two major climatic zones (Arid steppe climate BS and Warm temperate humid climate Cf) and two primary catchments (Kowie and Great Fish Rivers), as well as broad gradients of altitude and several local environmental factors. Distance-based linear models were used to test these species-environment relationships and indicated that eight variables (water temperature, pH, conductivity, waterbody size, habitat type, altitude, hydrological-drainage, climate) individually showed significant correlations with the response ostracod dataset of 35 species. However, owing to substantial collinearity, the most parsimonious model identified only two predicting variables (climatic zone and water pH) which best explained variation in ostracod assemblage composition. The assemblages of the two climatic zones differed significantly, with Plesiocypridopsis newtoni and Sarscypridopsis ochracea being most commonly found in the BS climates, while Sarscypridopsis trigonella and Physocypria capensis occurred most frequently in the Cf climates. Finally, tolerance ranges to water pH and electrical conductivity for 21 ostracod species are provided to facilitate application of ostracods in further biodiversity and water-quality assessments, as well as in palaeo-environmental reconstructions.

Eyespots are functionally complex and highly variable elements of butterfly wing patterns. The Meadow Brown, Maniola jurtina, is a classic model species studied for variation in eyespots as an index of evolutionary divergence and adaptation. However, the role of fine-scale ecogeographic conditions on eyespot variation remains poorly understood. In this study, we examined hindwing eyespot number, distribution, and combination patterns in male M. jurtina across climatically and topographically diverse north-western Balkans. Compared to the species average, males in this region displayed greater spottiness and phenotypic diversity. While the typical two-spot phenotype was dominant and stable, in some populations, three-spotted and even four-spotted males occurred at similar frequencies. Rare six-spotted individuals were recorded only at mountain localities above 1200 m. Geographic and climatic factors together influenced this variation: higher altitudes and cooler, thermally stable environments promoted increased eyespot number and greater phenotypic plasticity than warmer, more variable environments. This pattern contrasts with large-scale latitudinal trends previously described for the species, emphasizing the importance of local climatic heterogeneity. Our findings suggest the north-western Balkans as a possible transitional zone where environmental complexity promotes elevated eyespot variability, contributing to the understanding of adaptive morphological plasticity in M. jurtina.

Liverworts are an ancient plant lineage that occurs worldwide with the highest species richness in cool and humid habitats such as tropical montane and temperate rain forests. It has been proposed that liverworts originated under such temperate climatic conditions and have later expanded into more tropical conditions, but how this is reflected in their phylogenetic diversity along the strong climatic gradients associated with elevation remains unexplored. We studied the phylogenetic diversity of regional liverwort floras along the elevational gradient in the tropical Andes, comparing indices that emphasize deeper and shallower phylogenetic relationships, and relating these to temperature‐ and precipitation‐related variables, as well as to climatic extremes and seasonality. We found that whereas liverwort species richness peaks at around 2000 m a.s.l., richness‐corrected phylogenetic diversity increases with elevation, and the standardized effect of size of phylogenetic diversity is highest at 2500–4000 m a.s.l. This is in accordance with an origin of liverworts under cool conditions, followed by more recent diversification in warmer climates at lower elevations. We further found temperature‐related climatic parameters to be stronger predictors of phylogenetic diversity of liverworts than precipitation‐related variables, and climatic extremes to have a stronger influence than climatic seasonality. We interpret these patterns as reflecting the physiological challenges of adapting to low temperatures as well as rare occurrences of extreme climatic events. All this reveals a strong signal of the evolutionary dynamics of this ancient plant lineage linked with its physiological adaptations to climatic conditions. The age of this group and its poikilohydric nature, i.e. its inability to regulate water loss, lead to patterns that contrast with those of vascular plants, allowing for discerning evolutionary generalities that are independent of physiology and lineage age.

Aim: Faced with the dispute regarding spatial gradients of body size in ectotherms, we build upon their long-known allometric relationship with water economy, which scales with thermal and hydric regimes, to revisit and refine the water conservation hypothesis (WCH). We provide a brief description of the WCH, including its physiological basis and geographical predictions for body size clines in terrestrial amphibians, and test it against heat-based hypotheses in four amphibian clades. Location: The Americas. Methods: We employ phylogenetic comparative analyses to examine relationships between body size and both temperature, as a descriptor of the effect of heat alone, and potential evapotranspiration, which describes the water constraint along evaporative gradients. We assess these relationships in four amphibian clades: the subfamily of leaf frogs (Phyllomedusinae), genera of gladiator frogs (Hypsiboas), salamanders (Plethodon) and the family of glass frogs (Centrolenidae). Results: Three clades did not show phylogenetic signals in body size variation. In addition, three clades showed a positive relationship with potential evapotranspiration as predicted, and all of them were unrelated to temperature. When present, however, the explanatory power of evaporative energy on body size variation was relatively weak. Main conclusions: The conservation of water across evaporative gradients is both a more comprehensive explanation and a more pervasive driver of spatial clines in body size among terrestrial amphibians than is the balance of heat alone. However, the relatively low predictive ability of evaporative energy and its dependence on specific climatic configurations both emphasize and elucidate the non-universality of the phenomenon.

The latitudinal herbivory-defense hypothesis (LHDH) posits that herbivory and plant defenses increase toward lower latitudes. Recent studies provide contradictory evidence and suggest alternative explanations for biogeographic patterns in plant-herbivore interactions. Here we test the LHDH by sampling herbivory from multiple generalist and specialist insect herbivores over the entire latitudinal native range of the plant species Oenothera biennis L . (Onagraceae). We sampled 79 populations on a 16° north-south gradient from Ontario and Maine to Alabama and Florida. From each population, we quantified herbivory across feeding guilds by considering leaf herbivory caused by generalist insects, damage by a specialist stem-boring beetle, and flower/seed herbivory by three Lepidoptera that specialize on Oenothera . We also related environmental and population density variables to herbivory. Our results show that latitudinal patterns vary dramatically among herbivore species. While generalist leaf herbivory showed no latitudinal pattern, stem borer damage increased with decreasing latitude. By contrast, the specialist flower/seed herbivores all caused less damage at lower latitudes. Temperature explained slightly more variation in herbivory than latitude, while precipitation and population density were less important. Overall, we show that every pattern of herbivory (positive, negative and no relationship) is possible across a latitudinal gradient, and this variation depends on the insects' degree of specialization and feeding guild.