Search results for "species abundance"
showing 10 items of 67 documents
Effects of climate and land-use change on species abundance in a Central European bird community.
2007
Although it is known that changes in land use and climate have an impact on ecological communities, it is unclear which of these factors is currently most important. We sought to determine the influence of land-use and climate alteration on changes in the abundance of Central European birds. We examined the impact of these factors by contrasting abundance changes of birds of different breeding habitat, latitudinal distribution, and migratory behavior. We examined data from the semiquantitative Breeding Bird Atlas of Lake Constance, which borders Germany, Switzerland, and Austria. Changes in the regional abundance of the 159 coexisting bird species from 1980-1981 to 2000-2002 were influenced…
Geographical separation and physiology drive differentiation of microbial communities of two discrete populations of the bat Leptonycteris yerbabuenae
2020
In this paper, we explore how two discrete and geographically separated populations of the lesser long‐nosed bat (Leptonycteris yerbabuenae)—one in central and the other in the Pacific region of Mexico—differ in their fecal microbiota composition. Considering the microbiota–host as a unity, in which extrinsic (as food availability and geography) or intrinsic factors (as physiology) play an important role in the microbiota composition, we would expect differentiation in the microbiota of two geographically separated populations. The Amplicon Sequences Variants (ASVs) of the V4 region of the 16s rRNA gene from 68 individuals were analyzed using alpha and beta diversity metrics. We obtained a …
High maternal species density mediates unidirectional heterospecific matings inCalopteryxdamselflies
2012
Hybridization is a well-known phenomenon, but there are still relatively few studies addressing the question of reproductive isolation between related sympatric animal species with largely overlapping ranges. Population density, relative abundance, and operational sex ratio (OSR) are among the factors known to have an influence on the frequency of heterospecific matings in sympatric populations. Here we had two aims. First, we used microsatellite markers and field observations to study the frequency of hybrids, and backcrosses, and the rate of heterospecific matings between two sympatric damselfly species Calopteryx splendens (Harris, 1780) and Calopteryx virgo (Linne, 1758). Second, we inv…
BioTIME: A database of biodiversity time series for the Anthropocene
2018
Abstract Motivation The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, th…
Hospital Wastewater as a Reservoir for Antibiotic Resistance Genes: A Meta-Analysis
2020
Background: The emergence and dissemination of antibiotic resistance genes (ARGs) in the environment poses a huge global health hazard. Hospital wastewater (HWW), in which a high density of antibiotic residues and antibiotic-resistant bacteria are present, may be a reservoir of ARGs dissemination into the environment. Our meta-analysis comprehensively analyzes the prevalence of ARGs in HWW, as well as the influencing factors in ARGs distribution. Methods: Online databases were used to search for literature using the subject terms: “Drug Resistance” AND “Genes” AND “Hospitals” AND “Wastewater.” Two reviewers independently applied predefined criteria to assess the literature and extract data …
Variation in predator species abundance can cause variable selection pressure on warning signaling prey
2012
Predation pressure is expected to drive visual warning signals to evolve toward conspicuousness. However, coloration of defended species varies tremendously and can at certain instances be considered as more camouflaged rather than conspicuous. Recent theoretical studies suggest that the variation in signal conspicuousness can be caused by variation (within or between species) in predators' willingness to attack defended prey or by the broadness of the predators' signal generalization. If some of the predator species are capable of coping with the secondary defenses of their prey, selection can favor reduced prey signal conspicuousness via reduced detectability or recognition. In this study…
Analysis of a herpetofaunal community from an altered marshy area in Sicily; with special remarks on habitat use (niche breadth and overlap), relativ…
2005
A field survey was conducted in a highly degraded barren environment in Sicily in order to investigate herpetofaunal community composition and structure, habitat use (niche breadth and overlap) and relative abundance of a snake predator and two species of lizard prey. The site was chosen because it has a simple community structure and thus there is potentially less ecological complexity to cloud any patterns observed. We found an unexpectedly high overlap in habitat use between the two closely related lizards that might be explained either by a high competition for space or through predator-mediated co-existence i.e. the prevention of the competitive exclusion of one lizard over the other. …
A New, Ecologically Self-Significant Metric of Species-Abundance Unevenness, Reliably Highlighting the Intensity of Interspecific Competition
2021
A wide series of commonly used metrics of abundance-evenness (or -unevenness) have been proposed to characterize synthetically the distributions of species-abundances, accounting for the hierarchic-like organization of species within natural communities. Among them, most – if not all–have been relevantly criticized on their serious limitations regarding both their “descriptive” and their “interpretative” capacities. From the descriptive point of view, many authors have already repeatedly emphasized the formal non-independenceof conventional (un-)evenness metrics with respect to species-richness, leading, in particular, to unacceptable bias when comparing communities differing by their speci…
2004
Background Genetic variability in viral populations is usually estimated by means of polymerase chain reaction (PCR) based methods in which the relative abundance of each amplicon is assumed to be proportional to the frequency of the corresponding template in the initial sample. Although bias in template-to-product ratios has been described before, its relevance in describing viral genetic variability at the intrapatient level has not been fully assessed yet.
Inter-annual variation in macroinvertebrate communities in a shallow forest lake in eastern Finland during 1990–2001
2003
As a part of the Integrated Monitoring (IM) Programme of Air Pollution Effects on Ecosystems, the macroinvertebrate community of a pristine forest lake was monitored from 1990 up to the present. Lake Iso Hietajarvi is a small and shallow, weakly stratified oligotrophic headwater lake situated in Patvinsuo National Park, eastern Finland. Benthic macroinvertebrates were sampled annually, once in autumn at depths of 3 - 4 m (sublittoral zone) and at 7 m (profundal zone). The water quality of the lake and meteorological characteristics in the area were monitored during the same period. The inter-annual variation in macroinvertebrate abundance and taxonomic composition in the lake unaffected by …