Search results for "Specie"
showing 10 items of 4389 documents
Community size affects the signals of ecological drift and niche selection on biodiversity
2019
AbstractEcological drift can override the effects of deterministic niche selection on small populations and drive the assembly of small communities. We tested the hypothesis that smaller local communities are more dissimilar among each other because of ecological drift than larger communities, which are mainly structured by niche selection. We used a unique, comprehensive dataset on insect communities sampled identically in a total of 200 streams in climatically different regions (Brazil and Finland) that differ in community size by fivefold. Null models allowed us to estimate the magnitude to which beta diversity deviates from the expectation under a random assembly process while taking di…
The role of watercourse versus overland dispersal and niche effects on ostracod distribution in Mediterranean streams (eastern Iberian Peninsula)
2016
Abstract The processes behind the heterogeneous distribution of species involve a combination of environmental and spatial effects. In the spatial context, stream networks constitute appropriate systems to compare the relative importance of two dispersal modes in aquatic organisms: overland and watercourse dispersal. In the present study, we analyzed the distribution of ostracod species in a river network in the eastern Iberian Peninsula, with variation partitioning between environmental and spatial factors, using Moran and Asymmetric Eigenvector Maps (MEMs, AEMs) as spatial variables. Our aims were to determine the relative importance of environmental and spatial control and to compare the…
The role of spatial environmental factors as determinants of large branchiopod distribution in Tunisian temporary ponds
2016
The influence of spatial and environmental factors in explaining the structure of large branchiopod assemblages at different spatial scales is still poorly explored. We hypothesized that the extent of actual spatial connectivity, and thus the spatial distribution of a metacommunity, may depend on the environmental conditions as represented by climatic gradients and the structural characteristics of the landscape. To test this hypothesis, the distributional patterns of 14 large branchiopod species in a set of 177 temporary water bodies repeatedly sampled across Tunisia and on its main islands were analysed. Physical, chemical, morphological and climatic characteristics of the studied water b…
Phytoplankton colonization patterns. Is species richness depending on distance among freshwaters and on their connectivity?
2015
Phytoplankton assemblages in two Sicilian water bodies were compared to test the hypothesis that colonization events and the successful establishment of a new species in an aquatic ecosystem may depend on the number of water bodies in a given area and on their relative distance. The two ecosystems are both natural, shallow lakes and they are protected sites hosting a rich avifauna. Lake Biviere di Gela is located in an area with a high density of ponds, whereas Lake Pergusa is an isolated waterbody without other aquatic ecosystems in its surroundings. Both lakes had almost disappeared about 10 years ago because of the over-exploitation of their main inflows. They were therefore re-filled us…
Metacommunity dynamics of Ostracoda in temporary lakes: Overall strong niche effects except at the onset of the flooding period
2017
Abstract Metacommunity research usually focuses on the structure of species assemblages and their influencing factors, chiefly environment and space. However, the temporal dynamics of metacommunities and their structuring processes are rarely investigated. Here, we analyze the temporal variations in a metacommunity of ostracods from temporary shallow lakes of the Iberian Peninsula. Our aims were to determine the variability of the ostracod assemblages throughout a hydrological cycle by means of partial triadic analysis (PTA), and to analyze the response of these communities to both environmental and spatial variables. The metacommunity was moderately stable through the study period, with la…
Spatial and environmental effects on a rock-pool metacommunity depend on landscape setting and dispersal mode
2017
Empirical studies on structuring mechanisms of metacommunities usually focus on the major roles of environmental filtering and dispersal. Recent works suggest that the relative importance of these structuring mechanisms differs among organisms with different body size, taxonomic affiliation, and dispersal abilities, and also depends on spatial extent and environmental heterogeneity. However, the effects of physical connectivity among sites and dispersal mode are less commonly considered explicitly in field metacommunity studies. We analysed a rock‐pool animal metacommunity, comparing both environmental and spatial effects between a set of pools in a ravine setting, with ephemeral connecting…
Does trait-based joint species distribution modelling reveal the signature of competition in stream macroinvertebrate communities?
2021
1. The occupancy and abundance of species are jointly driven by local factors, such as environmental characteristics and biotic interactions, and regional‐scale factors, such as dispersal and climate. Recently, it has been shown that biotic interactions shape species occupancies and abundances beyond local extents. However, for small ectothermic animals, particularly for those occurring in freshwater environments, the importance of biotic interactions remains understudied. Species‐to‐species associations from joint species distribution models (i.e. species associations while controlling for environmental characteristics) are increasingly used to draw hypotheses of which species possibly sho…
Molecular evidence supports simultaneous association of the achlorophyllous orchid Chamaegastrodia inverta with ectomycorrhizal Ceratobasidiaceae and…
2020
Abstract Background Achlorophyllous orchids are mycoheterotrophic plants, which lack photosynthetic ability and associate with fungi to acquire carbon from different environmental sources. In tropical latitudes, achlorophyllous forest orchids show a preference to establish mycorrhizal relationships with saprotrophic fungi. However, a few of them have been recently found to associate with ectomycorrhizal fungi and there is still much to be learned about the identity of fungi associated with tropical orchids. The present study focused on mycorrhizal diversity in the achlorophyllous orchid C. inverta, an endangered species, which is endemic to southern China. The aim of this work was to identi…
Dwarf shrub vegetation of rock ledges and clefts in the Pamir Alai Mountains (Middle Asia: Tajikistan)
2016
AbstractThe paper presents the results of phytosociological researches on rocky slope vegetation in Tajikistan with the aim to establish a comprehensive syntaxonomical classification system. Field studies were conducted in 2010-2014 in Pamir Alai ranges and Pamirian plateau. Nearly 500 relevés documenting rock and scree vegetation were made according to the Braun-Blanquet method. Numerical analyses of selected 58 relevés representing dwarf shrub vegetation on rock ledges made it possible to distinguish: Ephedro glaucae- Spiraeion baldschuanicae and Ephedrion regeliano-fedtschenkoi alliances, as well as Spiraeetum baldschuanicae, Rhamnetum coriaceae, Pentaphylloidetum parvifoliae and Pentaph…
Levels of genetic differentiation and gene flow between four populations of the Scaly-naped Pigeon, Patagioenas squamosa : implications for conservat…
2021
Island-endemic columbid species are particularly vulnerable to environmental degradation, extreme climatic events, and interactions with exotic species. The situation might be even more critical in the case of exploited species, where legal hunting and poaching can severely affect population dynamics. Here we document for the first time the genetic structure of the Scaly-naped Pigeon, Patagioenas squamosa, a Caribbean-endemic columbid species of cynegetic interest, over a large part of its range. Using both mitochondrial DNA and nuclear markers (microsatellites), we investigated gene flow, genetic diversity, and genetic structure among four islands populations originating from Puerto-Rico, …