Molecular phylogenetics of Atlantic Shield Platynectes diving beetles (Coleoptera: Dytiscidae): a first glance at the evolution of the genus in the Amazon Basin

Neotropical diving beetles of the genus Platynectes are distributed across Central America, the Andes and different Precambrian shields in the Amazon Basin. Species from the northern Guiana Shield form a monophyletic clade, yet the phylogenetic relationships of the eastern Atlantic Shield species remain unknown. Here, we augmented an existing molecular dataset with a species from the Atlantic Shield that was not previously sampled. We reconstructed the phylogenetic relationships and estimated divergence times to understand the evolution of lineages dwelling in this region. The newly sampled specimens from the Atlantic Shield are recovered as sister taxa to Guiana Shield species. The dating analyses suggest a split between these two lineages in the late Oligocene to mid-Miocene, contemporary with the Miocenic geological remodeling of the Amazon Basin. Additional sampling in the Atlantic and Central Brazilian Shields will be determinant to test the monophyly of Platynectes species distributed in these ancient shields, and to fully understand the biogeographical history of diving beetles in the Amazon Basin.     

An objective tropical Atlantic sea surface temperature gradient index for studies of south Amazon dry-season climate variability and change

Future changes in meridional sea surface temperature (SST) gradients in the tropical Atlantic could influence Amazon dry-season precipitation by shifting the patterns of moisture convergence and vertical motion. Unlike for the El Niño-Southern Oscillation, there are no standard indices for quantifying this gradient. Here we describe a method for identifying the SST gradient that is most closely associated with June–August precipitation over the south Amazon. We use an ensemble of atmospheric general circulation model (AGCM) integrations forced by observed SST from 1949 to 2005. A large number of tropical Atlantic SST gradient indices are generated randomly and temporal correlations are examined between these indices and June–August precipitation averaged over the Amazon Basin south of the equator. The indices correlating most strongly with June–August southern Amazon precipitation form a cluster of near-meridional orientation centred near the equator. The location of the southern component of the gradient is particularly well defined in a region off the Brazilian tropical coast, consistent with known physical mechanisms. The chosen index appears to capture much of the Atlantic SST influence on simulated southern Amazon dry-season precipitation, and is significantly correlated with observed southern Amazon precipitation.We examine the index in 36 different coupled atmosphere–ocean model projections of climate change under a simple compound 1% increase in CO₂. Within the large spread of responses, we find a relationship between the projected trend in the index and the Amazon dry-season precipitation trends. Furthermore, the magnitude of the trend relationship is consistent with the inter-annual variability relationship found in the AGCM simulations. This suggests that the index would be of use in quantifying uncertainties in climate change in the region.     

Dry spots and wet spots in the Andean hotspot

Aim To explain the relationship between topography, prevailing winds and precipitation in order to identify regions with contrasting precipitation regimes and then compare floristic similarity among regions in the context of climate change. Location Eastern slope of the tropical Andes, South America. Methods We used information sources in the public domain to identify the relationship between geology, topography, prevailing wind patterns and precipitation. Areas with contrasting precipitation regimes were identified and compared for their floristic similarity. Results We identify spatially separate super‐humid, humid and relatively dry regions on the eastern slope of the Andes and show how they are formed by the interaction of prevailing winds, diurnally varying atmospheric circulations and the local topography of the Andes. One key aspect related to the formation of these climatically distinct regions is the South American low‐level jet (SALLJ), a relatively steady wind gyre that flows pole‐ward along the eastern slopes of the Andes and is part of the gyre associated with the Atlantic trade winds that cross the Amazon Basin. The strongest winds of the SALLJ occur near the ‘elbow of the Andes’ at 18° S. Super‐humid regions with mean annual precipitation greater than 3500 mm, are associated with a ‘favourable’ combination of topography, wind‐flow orientation and local air circulation that favours ascent at certain hours of the day. Much drier regions, with mean annual precipitation less than 1500 mm, are associated with ‘unfavourable’ topographic orientation with respect to the mean winds and areas of reduced cloudiness produced by local breezes that moderate the cloudiness. We show the distribution of satellite‐estimated frequency of cloudiness and offer hypotheses to explain the occurrence of these patterns and to explain regions of anomalously low precipitation in Bolivia and northern Peru. Floristic analysis shows that overall similarity among all circumscribed regions of this study is low; however, similarity among super‐humid and humid regions is greater when compared with similarity among dry regions. Spatially separate areas with humid and super‐humid precipitation regimes show similarity gradients that are correlated with latitude (proximity) and precipitation. Main conclusions The distribution of precipitation on the eastern slope of the Andes is not simply correlated with latitude, as is often assumed, but is the result of the interplay between wind and topography. Understanding the phenomena responsible for producing the observed precipitation patterns is important for mapping and modelling biodiversity, as well as for interpreting both past and future climate scenarios and the impact of climate change on biodiversity. Super‐humid and dry regions have topographic characteristics that contribute to local climatic stability and may represent ancestral refugia for biodiversity; these regions are a conservation priority due to their unique climatic characteristics and the biodiversity associated with those characteristics.     

High-fidelity representation of climate variations by Amburana cearensis tree-ring chronologies across a tropical forest transition in South America

Numerous ring-width chronologies from different species have recently been developed in diverse tropical forests across South America. However, the temporal and spatial climate signals in these tropical chronologies is less well known. In this work, annual growth rings of Amburana cearensis, a widely distributed tropical tree species, were employed to estimate temporal and spatial patterns of climate variability in the transition from the dry Chiquitano (16–17°S) to the humid Guarayos-southern Amazon (14–15°S) forests. Four well-replicated chronologies (16–21 trees, 22–28 radii) of A. cearensis were compared with temperature and precipitation records available in the region. The interannual variations in all four A. cearensis tree-ring chronologies are positively correlated with precipitation and negatively with temperature during the late dry-early wet season, the classic moisture response seen widely in trees from dry tropical and temperate forests worldwide. However, the chronologies from the dry Chiquitano forests of southern Bolivia reflect the regional reduction in precipitation during recent decades, while the chronologies from the tropical lowland moist forests in the north capture the recent increase in precipitation in the southern Amazon basin. These results indicate that A. cearensis tree growth is not only sensitive to the moisture balance of the growing season, it can also record subtle differences in regional precipitation trends across the dry to humid forest transition. Comparisons with previously developed Centrolobium microchaete chronologies in the region reveal a substantial common signal between chronologies in similar environments, suggesting that regional differences in climate are a major drivers of tree growth along the precipitation gradient. The difficulty of finding A. cearensis trees over 150-years old is the main limitation involved in the paleoclimate application of this species. The expansion of monocultures and intensive cattle ranching in the South American tropics are contributing to the loss of these old growth A. cearensis trees and the valuable records of climate variability and climate change that they contain.     

Large-Scale Temperature Patterns in Past Centuries: Implications for North American Climate Change

Recent climate reconstructions are analyzed specifically for insights into those patterns of climate variability in past centuries with greatest impact on the North American region. Regional variability, largely associated with the El Nino/Southern Oscillation (ENSO) phenomenon, the North Atlantic Oscillation (NAO), and multidecadal patterns of natural variability, are found to mask the emergence of an anthropogenic temperature signal in North America. Substantial recent temperature anomalies may however indicate a possible recent emergence of this signal in the region. Multidecadal North Atlantic variability is likely to positively reinforce any anthropogenic warming over substantial parts of North America in coming decades. The recent magnitudes of El Nino events appear to be unprecedented over the past several centuries. These recent changes, if anthropogenic in nature, may outweigh the projection of larger-scale climate change patterns onto the region in a climate change scenario. The implications of such changes for North America, however, are not yet clear. These observations suggest caution in assessing regional climate change scenarios in North America without a detailed consideration of possible anthropogenic changes in climate patterns influencing the region.     

Tree-ring based spring precipitation reconstruction in western Nepal Himalaya since AD 1840

Spring (March–June) precipitation has been reconstructed since AD 1840 for the Rara National Park (RNP), western Nepal Himalaya using Abies spectabilis tree-ring width. The reconstruction accounts for 35.8% of the total variance of the instrumental precipitation from 1958 to 2012 and captured distinct wet and dry variability. The longest wet periods occurred during 1850–1862, 1878–1886, 1909–1917, 1971–1984 and 2000–2008 while dry periods were usually shorter and occurred during 1873–1877, 1921–1923, 1925–1929, 1951–1956, 1958–1962 and 1994–1996. Spectral analysis of the reconstruction shows significant peaks at periodicity ranging 2.4–6.5 year, suggesting a covariation in inter-annual variability similar to that of El Niño-Southern Oscillation (ENSO). Spectral analysis of the reconstruction shows significant quasi–cyclic (2.4–3.4 year) and multidecadal (24.8–39.2 year) periodicity, suggesting a potential association with El Niño-Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO).     

Cebus phylogenetic relationships: a preliminary reassessment of the diversity of the untufted capuchin monkeys

The untufted, or gracile, capuchin monkeys are currently classified in four species, Cebus albifrons, C. capucinus, C. olivaceus, and C. kaapori, with all but C. kaapori having numerous described subspecies. The taxonomy is controversial and their geographic distributions are poorly known. Cebus albifrons is unusual in its disjunct distribution, with a western and central Amazonian range, a separate range in the northern Andes in Colombia, and isolated populations in Trinidad and west of the Andes in Ecuador and northern Peru. Here we examine previous morphological and molecular hypotheses of the taxonomy and phylogeny of Cebus. We construct a time-calibrated phylogeny based upon mitochondrial DNA sequences from 50 Cebus samples from across their range. Our data indicate that untufted capuchins underwent a radiation at about 2 Ma, and quickly diversified in both the Andes and the Amazon. We provide a provisional reassessment for the taxonomy of untufted capuchins in the Amazon, the Llanos, the Andes, Trinidad, and Central America, splitting currently paraphyletic taxa into several species, including: at least two Amazonian species (C. yuracus and C. unicolor); a species from the Guiana Shield (most likely the same as Humboldt's C. albifrons); two northern Andean species, C. versicolor, C. cesarae; C. brunneus (with trinitatis a junior synonym) on the Venezuelan coast, and C. adustus in the region of Lake Maracaibo; C. capucinus in northwestern Ecuador and Colombia, and Panama; C. imitator in Central America; C. olivaceus and C. castaneus occupying a large part of the Guiana Shield; and C. kaapori in the eastern Amazon, south of the Rio Amazonas. More intensive and extensive geographic sampling is needed, including that for some subspecies not represented here. Taxa from the southwestern Amazon (yuracus, cuscinus, and unicolor) and the phylogenetic position of Humboldt's Simia albifrons from the Orinoco remain particularly poorly defined.     

Dendroclimatological assessment of Polylepis rodolfo-vasquezii: A novel Polylepis species in the Peru highlands

In spite of enormous diversity in tree species, dendrochronological records in the tropical Andes are very scarce. Therefore, it is necessary to increase the search for new tree species with high dendrochronological characteristics in the tropical Andes, including the humid Puna of Peru. We present the first tree-ring chronology from Polylepis rodolfo-vasquezii, a recently described tree species in the Central Andes of Peru between 4000 and 4400 m elevation. Fifty trees were sampled in the district of Comas, Peru. After establishing the anatomical characteristics that delimit the annual growth rings, we developed a ring-width chronology by applying conventional dendrochronological techniques. The chronology covers the period 1869–2015 (157 years) and is well replicated from 1920 to present (> 20 samples). The statistics used to evaluate the quality of the chronology indicate that the P. rodolfo-vasquezii has similar values of MS, RBAR and EPS to those shown by other Polylepis spp chronologies. To determine the main climatic factors controlling the growth of P. rodolfo-vasquezii, we compared our chronology with local and regional temperature and precipitation records. Growth season temperature (November to May) seems to be the main climatic factor modulating inter-annual variations in the growth of this species. The sensitivity to inter-annual temperature variations highlights the potential of P. rodolfo-vasquezii to provide climatically sensitive dendrochronological records in the Central Andes. To our knowledge, this is the first tree-ring record in South America displaying significant relationships with temperature over the tropical Atlantic Ocean.     

Systematics of the Rhinella margaritifera complex (Anura,Bufonidae) from western Ecuador and Panama with insights in the biogeography of Rhinella alata

The Rhinella margaritifera species group consists of 17 species of toads distributed in tropical and subtropical South America and eastern Central America. The identity of some of its species is poorly understood and there are numerous undescribed cryptic species. Among them, the status of Rhinella margaritifera is one of the most problematic. Its range includes lowland rainforests separated by the Andes, the Chocoan rainforest to the west and the Amazonian rainforest to the east. This distribution is puzzling because the Andes are an old and formidable barrier to gene flow and therefore should generate vicariant speciation between disjunct lowland populations. Herein we clarify the taxonomy of populations of the Rhinella margaritifera complex from Central America and the Chocó region of South America. The morphological and genetic variation of Rhinella margaritifera was examined from 39 populations from Chocó, 24 from the upper Amazon region of Ecuador, and 37 from Panama, including the holotype of the Panamanian Rhinella alata. Phylogenetic analyses were performed based on mitochondrial genes 12S rRNA, 16S rRNA, and cytochrome c oxidase I (COI) and the nuclear gene Tyrosinase (Tyr). The genetic and morphological data show that Panamanian and Chocoan populations are conspecific. In the phylogeny, populations from Chocó and Panama form a well-supported clade. The morphology of the holotype of Rhinella alata falls within the variation range of Panamanian and Chocoan populations. Based on all this evidence, we assign the populations from western Ecuador and Panama to Rhinella alata and demonstrate that the unusual distribution pattern of “Rhinella margaritifera” on both sides of the Andes was an artifact of incorrectly defined species boundaries.     

A tree-ring based comparison of Terminalia superba climate–growth relationships in West and Central Africa

Tropical lowland forests are characterized by humid climate conditions with interannual variations in amount of precipitation, length of dry season, and relative humidity. The African tree species, Terminalia superba Engl. & Diels has a large distribution area and potentially incorporates these variations in its tree rings. Tree ring analysis was performed on 60 plantation trees (increment cores) and 41 natural trees (stem disks) from Ivory Coast and the Congolese Mayombe Forest. Natural forests and old plantations (50–55 years) showed similar growth patterns. Regional chronologies were developed for the two sample regions and showed a long-distance relationship for the period 1959–2008. Growth in the Mayombe was associated with early rainy season precipitation, but no relation was found between tree growth and precipitation in Ivory Coast. Congolese trees possibly show a higher climate-sensitivity than Ivorian trees, because precipitation in the Mayombe is more limiting, and Congolese T. superba trees are found closer to the margins of their distribution. Likewise, tree growth in the Mayombe was also influenced by the SSTs of the Gulf of Guinea and the South Atlantic Ocean during the early rainy season. However, tree growth was influenced by ENSO in both regions. In the Mayombe, La Niña years were associated with stronger tree growth whereas in Ivory Coast, El Niño years corresponded with stronger tree growth. The presented relation between ENSO, precipitation and tree growth is original for equatorial African forests, suggesting an influence of global climate variability on tree growth.     

Biogeographic area relationships of lowland Neotropical rainforest based on raw distributions of vertebrate groups

Hypotheses of the historic biogeography of Neotropical anurans inhabiting lowland forests were generated using Parsimony Analysis of Endemicity. In order to establish comparisons with the biogeographical patterns of other vertebrates, previous cladistic analyses reported in the literature (for lizards and primates) were extended and reanalysed to match the geographical scope of the anuran analysis. Cladistic analysis of the distribution of 335 anuran species at 14 localities showed two regions that form a basal dichotomy: (1) Central America + Choco and (2) Amazon Basin + Brazilian Atlantic Forest. This result is interpreted as the first vicariance event that separated lowland Neotropical rainforests into Cis-Andean (east from the Andes) and Trans-Andean (west from the Andes) areas. Within the Cis-Andean localities, the earliest separation occurred between the Amazon Basin and the Brazilian Atlantic Forest. Within the Amazon Basin, three distinctive clusters are defined: (1) Belem, (2) Guianan Region, and (3) Upper Amazon Basin. Data sets on the distribution of anurans, lizards, and mammals have strong cladistic signal. Strong congruence exists among the area cladograms of anurans, lizards, and primates. All of them have, or at least did not conflict with: (1) a basal separation between Cis- and Trans-Andean regions, (2) a Central American clade, (3) the Choco Region is sister to the Central American clade, (4) an Amazon Basin clade, (5) an Upper Amazon Basin clade, and (6) a Guianan clade. The area cladograms are dichotomous and therefore do not support biogeographic theories that hypothesize simultaneous isolations of biotas in the Neotropics.     

Origins, diversification, and historical structure of the helminth fauna inhabiting neotropical freshwater stingrays (Potamotrygonidae).

Members of the freshwater stingray family Potamotrygonidae occur throughout the major river systems of eastern South America that empty into the Atlantic Ocean. Ichthyologists have tended to assume that the ancestor of the potamotrygonids was an Atlantic marine or euryhaline stingray that dispersed into freshwater, presumably during the last marine ingression 3-5 million years ago. The helminth parasites that inhabit potamotrygonids suggest an alternative perspective on their origin. Phylogenetic and biogeographic analysis of the helminths inhabiting potamotrygonids suggest that the hosts are derived from an ancestral Pacific urolophid stingray that was trapped in freshwater by the uplifting of the Andes beginning perhaps as early as the early Cretaceous period and ending by the mid-Miocene epoch, changing the course of the Amazon River, which previously had flowed into the Pacific Ocean.     

δ 18O in the Tropical Conifer Agathis robusta Records ENSO-Related Precipitation Variations

Long-lived trees from tropical Australasia are a potential source of information about internal variability of the El Niño-Southern Oscillation (ENSO), because they occur in a region where precipitation variability is closely associated with ENSO activity. We measured tree-ring width and oxygen isotopic composition (O) of -cellulose from Agathis robusta (Queensland Kauri) samples collected in the Atherton Tablelands, Queensland, Australia. Standard ring-width chronologies yielded low internal consistency due to the frequent presence of false ring-like anatomical features. However, in a detailed examination of the most recent 15 years of growth (1995–2010), we found significant correlation between O and local precipitation, the latter associated with ENSO activity. The results are consistent with process-based forward modeling of the oxygen isotopic composition of -cellulose. The O record also enabled us to confirm the presence of a false growth ring in one of the three samples in the composite record, and to determine that it occurred as a consequence of anomalously low rainfall in the middle of the 2004/5 rainy season. The combination of incremental growth and isotopic measures may be a powerful approach to development of long-term (150+ year) ENSO reconstructions from the terrestrial tropics of Australasia.     

Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing

Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982–2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño‐ Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build‐up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high‐frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire‐peak seasons (t‐1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build‐up cyclicity.     

Finding needles in the haystack: where to look for rare species in the American tropics

Tropical America (the Neotropics) harbours more plant species than any other region on Earth. The contribution of rare species to this diversity has been recently recognised, but their spatial distribution remains poorly understood. Here, we use all collection records of angiosperms from the Global Biodiversity Information Facility to delineate Neotropical bioregions, and to identify putatively rare species within the Neotropics and the Amazonian rainforest. We analyse the spatial distribution of these species and validate the results on a largely independent dataset based on vegetation plots from the Amazon Tree Diversity Network. We find that rare species are homogeneously distributed through most parts of the lowland Neotropics and Amazonia, but more concentrated in highlands. The second collection of any rare species is most often found in the close vicinity of the first, but in 20% of cases they are more than 580 km apart. We also find cross‐taxonomic patterns of disjunct distributions within the Andes, the Atlantic forest in eastern Brazil, and between Amazonia and the Atlantic forest, but no clear disjunction patterns within lowland areas. These results suggest that a considerable proportion of rare plant species have surprisingly large distribution ranges, and that collections of rare species across most of the lowland Neotropics, and in particular in Amazonia, show no clear directionality. The second record of many rare species may be found virtually anywhere, urging the need for intensifying and broadening biological sampling.     

Dendroclimatic potential of the Adesmia pinifolia shrub growing at high altitude in the Andes foothills

Highland ecosystems of western Andes foothills are currently poorly represented by dendrochronological information. The dendroclimatological potential of the Acerillo plant (Adesmia pinifolia), a shrub species well represented at these latitudes, was investigated. We reported the first ring width chronology of A. pinifolia growing at the central semi-arid Andes foothills of Argentina. We collected living and dead wood samples of Acerillo resulting in a chronology covering the period 1609–2020 (412 years) with a well replication from 1655 to present (> 13 samples). Bootstrapping correlation analysis revealed a strong positive relationship between our chronology and monthly precipitation and with the Standardized Precipitation Evapotranspiration Index (SPEI-12 months). For the last 40 years however, strong negative correlations with temperature are evidenced. The dendrochronological record also showed a negative relationship with sea surface temperatures from the Tropical Pacific, suggesting teleconnections with the El Niño Southern Oscillation (ENSO) phenomenon. The strong hydroclimatic signal recorded in the A. pinifolia chronology represents a high opportunity to produce long-term proxy climate data for the Central Andes foothills, an extensive region devoid of trees but of hydrological relevance for the support of important economic activities.     

Habitat area and climate stability determine geographical variation in plant species range sizes

Despite being a fundamental aspect of biodiversity, little is known about what controls species range sizes. This is especially the case for hyperdiverse organisms such as plants. We use the largest botanical data set assembled to date to quantify geographical variation in range size for ~ 85 000 plant species across the New World. We assess prominent hypothesised range‐size controls, finding that plant range sizes are codetermined by habitat area and long‐ and short‐term climate stability. Strong short‐ and long‐term climate instability in large parts of North America, including past glaciations, are associated with broad‐ranged species. In contrast, small habitat areas and a stable climate characterise areas with high concentrations of small‐ranged species in the Andes, Central America and the Brazilian Atlantic Rainforest region. The joint roles of area and climate stability strengthen concerns over the potential effects of future climate change and habitat loss on biodiversity.     

Climate/growth relationships of Brachystegia spiciformis from the miombo woodland in south central Africa

We present five Brachystegia spiciformis Benth. (BrSp) tree-ring chronologies from the seasonally dry miombo woodland in south central Africa. Between 9 and 34 stem discs were collected from three dry and two wet miombo sites. All samples showed distinct growth rings, which were marked by terminal parenchyma bands. Site chronologies varied in length between 43 and 149 years. An increase in the number of growth ring anomalies in older trees, however, resulted in an increase in dating error and a decrease in between-tree correlations with increase in the chronology length. Annual precipitation variability accounted for some 28% of the common variance in the BrSp chronologies and we found no difference in climate sensitivity between wet and dry miombo sites. The influence of climate, and of precipitation in particular, on tree growth was strongest at the core of the rainy season (December–February). This is also the time of the year when ENSO peaks in amplitude and ENSO effects on precipitation variability in southern Africa are the strongest. We found a negative response of tree growth to ENSO throughout most of the growth year, suggesting that the development of longer chronologies from the miombo region would allow for the investigation of temporal ENSO variability. A spatial extension of the miombo tree-ring network should therefore focus on regions where ENSO effects are the strongest (e.g., southeastern Africa).     

Environmental controls on the distribution and diversity of lentic Chironomidae (Insecta: Diptera) across an altitudinal gradient in tropical South America

To predict the response of aquatic ecosystems to future global climate change, data on the ecology and distribution of keystone groups in freshwater ecosystems are needed. In contrast to mid‐ and high‐latitude zones, such data are scarce across tropical South America (Neotropics). We present the distribution and diversity of chironomid species using surface sediments of 59 lakes from the Andes to the Amazon (0.1–17°S and 64–78°W) within the Neotropics. We assess the spatial variation in community assemblages and identify the key variables influencing the distributional patterns. The relationships between environmental variables (pH, conductivity, depth, and sediment organic content), climatic data, and chironomid assemblages were assessed using multivariate statistics (detrended correspondence analysis and canonical correspondence analysis). Climatic parameters (temperature and precipitation) were most significant in describing the variance in chironomid assemblages. Temperature and precipitation are both predicted to change under future climate change scenarios in the tropical Andes. Our findings suggest taxa of Orthocladiinae, which show a preference to cold high‐elevation oligotrophic lakes, will likely see range contraction under future anthropogenic‐induced climate change. Taxa abundant in areas of high precipitation, such as Micropsectra and Phaenopsectra, will likely become restricted to the inner tropical Andes, as the outer tropical Andes become drier. The sensitivity of chironomids to climate parameters makes them important bio‐indicators of regional climate change in the Neotropics. Furthermore, the distribution of chironomid taxa presented here is a vital first step toward providing urgently needed autecological data for interpreting fossil chironomid records of past ecological and climate change from the tropical Andes.     

Cedrela nebulosa: A novel species for dendroclimatological studies in the montane tropics of South America

Up to now, the development of dendrochronological records from tropical regions in South America has been limited to the lowlands with emphasis in the Amazon basin. In this contribution, we present the first chronology of Cedrela nebulosa, a species that develops in the tropical mountainous regions of South America. We collected samples from trees in Monobamba district in Peru, analysed the anatomical features that determine the growth rings, and processed following the methods commonly used in dendrochronology. The 133-years chronology covering the 1883–2015 period, showed large correlation between series. In order to determine the climatic variables that control tree growth, we performed correlation analyses between tree-growth and local and regional precipitation and temperature records. We found that precipitation triggers tree growth at the beginning of the spring season but temperature seems to be the main control in annual growth. Also, C. nebulosa chronology present coherent variations with Multivariate Enso Index (MEI) and Pacific Ocean sea surface temperatures during summer months. This climate-sensitive tree-ring record indicates good potential for dendroclimatic studies and provides an opportunity to reconstruct climatic variations in montane forests of the tropical Andes.