Search results for "ecosystem"
showing 10 items of 1752 documents
Salicornia L. (Amaranthaceae) in South Africa and Namibia: rapid spread and ecological diversification of cryptic species
2013
In Salicornia, morphology does not provide reliable diagnostic characters supporting the true extent of evolutionary divergence in the genus, and species concepts have been challenged by molecular analyses. Here, we report the results of an analysis of 91 accessions of the S. meyeriana complex from South Africa and Namibia using the measurements of 38 morphological traits and external transcribed spacer (ETS) sequence data. Morphological data were analysed using discriminant analysis, principal coordinate analysis and nonmetric multidimensional scaling. Phylogenetic divergence was compared with the geographical and ecological diversity of the sampled populations. Tree topology corresponds t…
Evenness, biodiversity, and ecosystem function of intertidal communities along the Italian coasts: Experimental short-term response to ambient and ex…
2023
Biodiversity can promote ecosystem functioning in both terrestrial and marine environments, emphasizing the neces- sity ofbiodiversity conservation in order to preserve critical ecosystem functions and associated services. However, the role of biodiversity in buffering ecosystem functioning under extreme events caused by climate change remains a major scientific issue, especially for intertidal systems experiencing stressors from both terrestrial and marine drivers. We performed a regional-scale field experiment along the Italian coast to investigate the response of unmanipulated intertidal communities (by using a natural biodiversity gradient) to low tide aerial exposure to both ambient an…
Determining the potential impacts of fire and different land uses on splash erosion in the margins of drylands
2021
Abstract This research aimed to estimate the splash erosion and its evolution during the first months in specific land uses after a forest fire. The study area was located in Congosto (North-West Spain), in the margins of Spanish drylands, after a wildfire occurred in May 2012, which burned 15.56 ha of scrubland and Pinus reforestation. Two different burned land uses were selected and compared to control areas: i) burned pine forest; and, scrublands. Rainfall intensity and the number, sizes and speed of raindrops were measured by an optical disdrometer and soil loss by funnels. Moreover, infiltration, soil moisture content, aggregate stability, water repellence, pH and organic matter were a…
Effects of temperature and desiccation on ex situ conservation of nongreen fern spores
2012
Premise of the study Fern spores are unicellular and haploid, making them a potential model system to study factors that regulate lifespan and mechanisms of aging. Aging rates of nongreen spores were measured to compare longevity characteristics among diverse fern species and test for orthodox response to storage temperature and moisture. Methods Aging of spores from 10 fern species was quantified by changes in germination and growth parameters. Storage temperature ranged from ambient room to -196°C (liquid nitrogen); spores were dried to ambient relative humidity (RH) or using silica gel. Key results Survival of spores varied under ambient storage conditions, with one species dying within …
Consistent isotopic differences between Schistocephalus spp. parasites and their stickleback hosts
2015
Published version available at http://dx.doi.org/10.3354/dao02893 Parasite−host systems show markedly variable patterns in isotopic fractionation: parasites can be either depleted or enriched in 15N and 13C as compared to their hosts. However, it remains unknown whether isotopic fractionation patterns are similar in comparable parasite−host systems from markedly different ecosystems. Results of this study show that large-sized Schistocephalus spp. endoparasites are consistently depleted in 15N (by on average −2.13 to −2.20‰) as compared to their nine-spined stickleback Pungitius pungitius and three-spined stickleback Gasterosteus aculeatus hosts. The differences between parasites and host f…
WOODIV, a database of occurrences, functional traits, and phylogenetic data for all Euro-Mediterranean trees
2021
Trees play a key role in the structure and function of many ecosystems worldwide. In the Mediterranean Basin, forests cover approximately 22% of the total land area hosting a large number of endemics (46 species). Despite its particularities and vulnerability, the biodiversity of Mediterranean trees is not well known at the taxonomic, spatial, functional, and genetic levels required for conservation applications. The WOODIV database fills this gap by providing reliable occurrences, four functional traits (plant height, seed mass, wood density, and specific leaf area), and sequences from three DNA-regions (rbcL, matK, and trnH-psbA), together with modelled occurrences and a phylogeny for all…
Metagenomics reveals our incomplete knowledge of global diversity
2008
Metagenomic sequencing obtains huge amounts of sequences from environmental and clinical samples, thus providing a glimpse of the global prokaryotic diversity of both species and genes in these sources. The current trend in metagenomic analysis follows the so-called gene-centric approach, focused on describing the environments by the study of the functional roles of the proteins encoded in the sequenced genes. In this way, it is clear that metagenomic analysis relies heavily on the accurate knowledge of the universe of proteins stored in the databases. Nevertheless, it is known that some biases exist in the composition of databases (which are rich in sequences from common, cultivable and ea…
Multitype spatial point patterns with hierarchical interactions.
2001
Multitype spatial point patterns with hierarchical interactions are considered. Here hierarchical interaction means directionality: points on a higher level of hierarchy affect the locations of points on the lower levels, but not vice versa. Such relations are common, for example, in ecological communities. Interacting point patterns are often modeled by Gibbs processes with pairwise interactions. However, these models are inherently symmetric, and the hierarchy can be acknowledged only when interpreting the results. We suggest the following in allowing the inclusion of the hierarchical structure in the model. Instead of regarding the pattern as a realization of a stationary multivariate po…
Spatial data of Ixodes ricinus instar abundance and nymph pathogen prevalence, Scandinavia, 2016-2017.
2020
ticks carry pathogens that can cause disease in both animals and humans, and there is a need to monitor the distribution and abundance of ticks and the pathogens they carry to pinpoint potential high risk areas for tick-borne disease transmission. In a joint Scandinavian study, we measured Ixodes ricinus instar abundance at 159 sites in southern Scandinavia in August-September, 2016, and collected 29,440 tick nymphs at 50 of these sites. We additionally measured abundance at 30 sites in August-September, 2017. We tested the 29,440 tick nymphs in pools of 10 in a Fluidigm real-time PCR chip to screen for 17 different tick-associated pathogens, 2 pathogen groups and 3 tick species. We present…
Spatio-temporal patterns in population dynamics
2002
Abstract The transient dynamics of interacting biological species extracted from two ecosystems is investigated. We model the environment interaction by a multiplicative noise and the temperature oscillations by a periodic forcing. We find noise-induced effects such as enhanced temporal oscillations, spatial patterns and noise delayed extinction for the model of two competing species. We extend our analysis to an ecosystem of three interacting species, namely one predator and two preys. We find spatial patterns induced by the noise.