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Clustering of species with similar niches or traits occurs in communities, but the mechanisms behind this pattern are still unclear. In the emergent neutrality model, species with similar niches and competitive ability self-organise into clusters. In the hidden-niche model, unaccounted-for niche differences stabilise coexistence within clusters. Finally, clustering may occur through alliances of species that facilitate each other. We tested these hypotheses using population-growth models that consider interspecific interactions parameterised for 35 species using field data. We simulated the expected community dynamics under different species-interaction scenarios. Interspecific competition was weaker within rather than between clusters, suggesting that differences in unmeasured niche axes stabilise coexistence within clusters. Direct facilitation did not drive clustering. In contrast, indirect facilitation seemingly promoted species alliances in clusters whose members suppressed common competitors in other clusters. Such alliances have been overlooked in the literature on clustering, but may arise easily when within cluster competition is weak.

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Morphologically similar but genetically distinct species have been termed cryptic and most have been assumed to be ecologically similar. However, if these species co-occur at a certain spatial scale, some niche differences at finer scales should be expected to allow for coexistence. Here, we demonstrate the existence of a disjointed distribution of cryptic bladed Bangiales along spatial (intertidal elevations) and temporal (seasons) environmental gradients. Bladed Bangiales were identified and quantified across four intertidal elevations and four seasons for one year, at five rocky intertidal sites (between 39° S and 43° S) in southern Chile. Species determination was based on partial sequences of the mitochondrial cytochrome c oxidase 1 (COI) gene amplification. To assess species gross morphology, thallus shape, color, and maximum length and width were recorded. Hundreds of organisms were classified into nine Bangiales species belonging to three genera (i.e., Fuscifolium, Porphyra, and Pyropia), including five frequent (>97% of specimens) and four infrequent species. All species, except for Pyropia saldanhae, had been previously reported along the coasts of Chile. The thallus shape and color were very variable, and a large overlap of the maximum width and length supported the cryptic status of these species. Multivariate analyses showed that the main variable affecting species composition was intertidal elevation. Species such as Py. orbicularis were more abundant in low and mid intertidal zones, while others, such as Po. mumfordii and Po. sp. FIH, were principally observed in high and spray elevations. Despite all numerically dominant species being present all year long, a slight effect of seasonal variation on species composition was also detected. These results strongly support the existence of spatial niche partitioning in cryptic Bangiales along the Chilean rocky intertidal zone.

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A new approach for visual fish survey in reservoirs using underwater drones (remotely operated vehicle- ROV) is presented. The ROV was applied to identify abiotic gradients and to compare fish assemblages on the steep slopes in a tropical reservoir. The tested hypothesis is that fish are concentrated in the littoral zone due to the better physicochemical and habitat conditions, compared to deep and hypoxic layers. Twelve species were recorded (seven native, five exotic), with all species occurring in the littoral zone, seven species in the transition, and four in the profundal zone. A greater fish abundance and richness was found in the littoral zone corroborating the main hypothesis. The littoral zone was dominated by exotic cichlids (Cichla spp., Coptodon rendalli), while native catfish (Loricariichthys castaneus, Pimelodella lateristriga) occupied deeper areas. The fish distribution seems to be driven by local factors, such as oxygen availability and habitat structure. The preference for the littoral zone by alien cichlids may have led to the extirpation/decrease of native characids and induced catfishes to occupy deep habitats. Underwater drones can be a valuable tool for the simultaneous collection of abiotic/biotic data, especially in deep reservoirs with complex habitats, resulting in advances in the environmental monitoring. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10750-021-04790-9.

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Addressing the intraspecific variability of functional traits helps understand how climate change might influence the distribution of organismal traits across environments, but this is notably understudied in the Amazon, especially for plant hydraulic traits commonly used to project drought responses. We quantified the intraspecific trait variability of leaf mass per area, wood density, and xylem embolism resistance for two dominant central Amazonian tree species, along gradients of water and light availability, while accounting for tree age and height. Intraspecific variability in hydraulic traits was high, with within-species variability comparable to the whole-community variation. Hydraulic trait variation was modulated mostly by the hydrological environment, with higher embolism resistance of trees growing on deep-water-table plateaus compared with shallow-water-table valleys. Intraspecific variability of leaf mass per area and wood density was mostly modulated by intrinsic factors and light. The different environmental and intrinsic drivers of variation among and within individuals lead to an uncoupled coordination among carbon acquisition/conservation and water-use traits. Our findings suggest multivariate ecological strategies driving tropical tree distributions even within species, and reflect differential within-population sensitivities along environmental gradients. Therefore, intraspecific trait variability must be considered for accurate predictions of the responses of tropical forests to climate change.

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Ecosystem services of Amazonian forests are disproportionally produced by a limited set of hyperdominant tree species. Yet the spatial variation in the delivery of ecosystem services by individual hyperdominant species across their distribution ranges and corresponding environmental gradients is poorly understood. Here, we use the concept of habitat quality to unravel the effect of environmental gradients on seed production and aboveground biomass (AGB) of the Brazil nut, one of Amazonia's largest and most long-lived hyperdominants. We find that a range of climate and soil gradients create trade-offs between density and fitness of Brazil nut trees. Density responses to environmental gradients were in line with predictions under the Janzen-Connell and Herms-Mattson hypotheses, whereas tree fitness responses were in line with resource requirements of trees over their life cycle. These trade-offs resulted in divergent responses in area-based seed production and AGB. While seed production and AGB of individual trees (i.e., fitness) responded similarly to most environmental gradients, they showed opposite tendencies to tree density for almost half of the gradients. However, for gradients creating opposite fitness-density responses, area-based seed production was invariable, while trends in area-based AGB tended to mirror the response of tree density. We conclude that while the relation between environmental gradients and tree density is generally indicative of the response of AGB accumulation in a given area of forest, this is not necessarily the case for fruit production.

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Phyllostomid bats (Chiroptera: Phyllostomidae) are key elements for the maintenance of New World forests, but little information on their distribution is available in some regions of Brazil. Here we use occurrence records and bioclimatic variables to model the distribution of phyllostomid bats in Santa Catarina, a subtropical Brazilian state. Estimates of geographic variation in species richness were then obtained by stacking the generated maps. Lastly, we tested how associated species richness is to ecoregions and Protected Areas. Our results suggest that the phyllostomid bats species richness is closely linked to the regions climate gradient. Most species are restricted to the Serra do Mar ecoregion, where the temperature is high and varies less throughout the year. In contrast, the colder areas seem to house extremely simple communities, composed of a subset of the species present in the warmer areas. We found significant evidence that Protected Areas in Santa Catarina play an important role in the conservation of species, although there are still several places where species richness is high, but no Protected Area is available. The creation of new Protected Areas in these places can boost the species conservation, and, consequently, the ecological services provided by phyllostomid bats.(AU)

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Aedes (Stegomyia) albopictus (Skuse) is a major global invasive mosquito species that, in Japan, co-occurs with Aedes (Stegomyia) flavopictus Yamada, a closely related species recently intercepted in Europe. Here, we present results of a detailed 25-month long study where we biweekly sampled pupae and fourth instar larvae of these two species from ovitraps set along Mt. Konpira, Nagasaki, Japan. This setting allowed us to ask whether these species had different responses to changes in environmental variables along the altitudinal gradient of an urban hill. We found that spatially Ae. albopictus abundance decreased, while Ae. flavopictus abundance increased, the further away from urban land. Ae. flavopictus also was more abundant than Ae. albopictus in locations with homogenous vegetation growth with a high mean Enhanced Vegetation Index (EVI), platykurtic EVI, and low SD in canopy cover, while Ae. albopictus was more abundant than Ae. flavopictus in areas with more variable (high SD) canopy cover. Moreover, Ae. flavopictus abundance negatively impacted the spatial abundance of Ae. albopictus. Temporally we found that Ae. flavopictus was more likely to be present in Mt. Konpira at lower temperatures than Ae. albopictus. Our results suggest that spatial and temporal abundance patterns of these two mosquito species are partially driven by their different response to environmental factors.

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Abstract Phyllostomid bats (Chiroptera: Phyllostomidae) are key elements for the maintenance of New World forests, but little information on their distribution is available in some regions of Brazil. Here we use occurrence records and bioclimatic variables to model the distribution of phyllostomid bats in Santa Catarina, a subtropical Brazilian state. Estimates of geographic variation in species richness were then obtained by stacking the generated maps. Lastly, we tested how associated species richness is to ecoregions and Protected Areas. Our results suggest that the phyllostomid bats species richness is closely linked to the regions climate gradient. Most species are restricted to the Serra do Mar ecoregion, where the temperature is high and varies less throughout the year. In contrast, the colder areas seem to house extremely simple communities, composed of a subset of the species present in the warmer areas. We found significant evidence that Protected Areas in Santa Catarina play an important role in the conservation of species, although there are still several places where species richness is high, but no Protected Area is available. The creation of new Protected Areas in these places can boost the species conservation, and, consequently, the ecological services provided by phyllostomid bats.

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Abstract Phyllostomid bats (Chiroptera: Phyllostomidae) are key elements for the maintenance of New World forests, but little information on their distribution is available in some regions of Brazil. Here we use occurrence records and bioclimatic variables to model the distribution of phyllostomid bats in Santa Catarina, a subtropical Brazilian state. Estimates of geographic variation in species richness were then obtained by stacking the generated maps. Lastly, we tested how associated species richness is to ecoregions and Protected Areas. Our results suggest that the phyllostomid bats species richness is closely linked to the region's climate gradient. Most species are restricted to the Serra do Mar ecoregion, where the temperature is high and varies less throughout the year. In contrast, the colder areas seem to house extremely simple communities, composed of a subset of the species present in the warmer areas. We found significant evidence that Protected Areas in Santa Catarina play an important role in the conservation of species, although there are still several places where species richness is high, but no Protected Area is available. The creation of new Protected Areas in these places can boost the species conservation, and, consequently, the ecological services provided by phyllostomid bats.

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The Mid-Domain Effect (MDE) and the Rapoport (RE) effect are two biogeographical theories that make predictions about biogeogaphic patterns. MDE predicts higher richness in the central portions of a gradient if it is within a bounded domain. RE predicts a positive relation between altitude and species range size along an altitudinal gradient. Our aim was to document the distribution of spider species richness along an altitudinal gradient in the Brazilian Amazon, and to test the influence of MDE and RE on the diversity patterns. Our study was conducted at the Pico da Neblina (Amazonas state, Brazil), and we sampled spiders at six different altitudes using two methods: nocturnal hand sampling and a beating tray. We obtained 3,140 adult spiders from 39 families, sorted to 529 species/morphospecies. Richness declined continuously with an altitude increase, but the fit with the MDE richness estimates was very weak and was not significant. Range size was not related to altitude, i. e., no RE. Finally, the abundance distribution within each species range varied more specifically, which prevented the occurrence of a RE at the community level. The influence of MDE was extremely low, a consequence of our community characteristics, formed mostly by small range size species. Short and medium range species were located at all altitudes, preventing a significant relation between range size and altitude. The distribution of abundance within a species range varied specifically and do not support a RE hypothesis.

O Efeito do Domínio Central (MDE) e o Efeito Rapoport (ER) são duas teorias biogeografias que fazem previsões sobre a distribuição da diversidade ao longo de gradientes. O MDE prevê maior riqueza nas porções centrais de um gradiente, se este estiver dentro de um domínio fechado. O ER prevê uma relação positiva entre altitude e tamanho da distribuição ao longo do gradiente altitudinal. Nosso objetivo foi o de registrar a distribuição de uma comunidade de aranhas ao longo de um gradiente altitudinal na Amazônia Brasileira, e testar se há uma influência do EDC e do ER sobre os padrões de diversidade da comunidade. Nosso estudo foi feito no Parque Nacional do Pico da Neblina (AM, Brasil), e nós amostramos aranhas em seis altitudes diferentes. Nós coletamos 3.140 exemplares adultos de 39 famílias, que foram divididos em 529 espécies/morfoespécies. A riqueza declinou com o aumento de altitude, mas o padrão não mostrou ajuste com as previsões feitas pelo EDC. O tamanho da distribuição altitudinal também não esteve relacionado ao previsto pelo ER. Por fim, a distribuição de abundância ao longo da distribuição altitudinal das espécies variou de maneira específica, o que impediu a ocorrência de um ER nos padrões da comunidade. A influência do EDC sobre os padrões observados foi baixíssima, uma consequência de características de nossa comunidade, já que esta é formada por espécies com pequena distribuição altitudinal. Espécies de distribuição altitudinal médias e grandes ocorreram em todas as partes do gradiente o que impediu a ocorrência de um ER. Por fim, o ER também não foi observado na distribuição de abundância das espécies ao longo do gradiente, já que essa variou de maneira específica.