Search results for "temporal variation"
showing 10 items of 16 documents
Temporal dynamics of arable weeds communities assembly : interactions between farming practices and ecological processes across crop sequences
2018
Understanding how farming practices affect weed community assembly in arable fields is a core challenge of agro-ecology. Weeds are supposed to share particular ecological characteristics that allow them to colonize arable fields despite environmental constrains exert by farming practices. In addition, interactions between ecological processes operating during a cropping season (eg: abiotic filtering) and at the scale of crop succession (eg: temporal dispersal) are supposed to drive weed community assembly in arable fields. These two hypotheses have been tested in my phD work.First, we compared a pool of weed species to a pool of non-weed herbaceous plants based on several functional traits …
Infection, specificity and host manipulation of Australapatemon sp. (Trematoda, Strigeidae) in two sympatric species of leeches (Hirudinea)
2017
SUMMARYFactors that drive parasite specificity and differences in infection dynamics among alternative host species are important for ecology and evolution of host–parasite interactions, but still often poorly known in natural systems. Here, we investigated spatiotemporal dynamics of infection, host susceptibility and parasite-induced changes in host phenotype in a rarely explored host–parasite system, theAustralapatemonsp. trematode infecting two sympatric species of freshwater leeches,Erpobdella octoculataandHelobdella stagnalis. We show significant variation in infection abundance between the host species in both space and time. Using experimental infections, we also show that most of th…
Soil organic carbon stock on the Majorca Island: temporal change in agricultural soil over the last 10 years
2019
8 Pags.- 5 Tabls.- 3 Figs.
Variability of the human gut microbiota in space, time, and associated with the irritable bowel syndrome
2013
Esta tesis doctoral se centra en el estudio de una de las comunidades microbianas más complejas y de mayor interés biomédico: la microbiota asociada al intestino distal de humanos. El objetivo principal ha sido estudiar las alteraciones potenciales de la microbiota intestinal en relación con el síndrome del intestino irritable (SII), el desorden funcional del tracto gastrointestinal más común en sociedades occidentales. Nuestra aproximación forma parte de una visión actual sobre las relaciones entre microorganismos y hospedadores que trasciende la clásica y estrecha mirada sobre patógenos concretos y enfermedades infecciosas y la desplaza hacia una concepción más de conjunto, que valora los…
Effects of interspecific coexistence on laying date and clutch size in two closely related species of hole-nesting birds
2018
Co-existence between great tits Parus major and blue tits Cyanistes caeruleus, \ud but also other hole nesting taxa, constitutes a classic example of species\ud co-occurrence resulting in potential interference and exploitation competition\ud for food and for breeding and roosting sites. However, the spatial and temporal\ud variation in co-existence and its consequences for competition remain poorly\ud understood. 2.We used an extensive database on reproduction in nest boxes by\ud great and blue tits based on 87 study plots across Europe and Northern Africa\ud during 1957-2012 for a total of 19,075 great tit and 16,729 blue tit clutches to \ud assess correlative evidence for a relationship …
Temporal and spatial variation of the algal community in a southern Mediterranean shallow system
2010
The algal community of a shallow system located in Western Sicily (Mediterranean Sea) has been investigated over 1 year in eight ponds (fredde). The spatio-temporal variation in total algal coverage, species richness and coverage in relation to environmental variables has been analysed. The algal community was very species-poor. A total of 50 taxa, mainly detached algae, were identified. A dominance of filamentous and foliose taxa was observed. Significant spatio-temporal differences in total algal coverage, species richness and coverage between the ponds of group A and those of group B were found. The separation into groups A and B was made a priori on the basis of different levels of prox…
Caution on the assessment of intestinal parasitic load in studying parasite-mediated sexual selection: the case of Blackbirds coccidiosis.
2009
6 pages; International audience; The parasite-mediated sexual selection (PMSS) theory has led to an increasing number of experimental studies essentially focussed on blood parasites. Currently, more research is being carried out on intestinal parasites in relationship to this theory. Before testing the theory with gastrointestinal parasites, it is important: (i) to determine an optimal research methodology to obtain an accurate assessment of parasite burden and (ii) to have information about life-history traits of the parasite to interpret data appropriately. In this study, we present data on oocyst output of Isosporaturdi in the faeces of blackbirds (Turdus merula) that illustrate the impo…
Limited effects of size-selective harvesting and harvesting-induced life-history changes on the temporal variability of biomass dynamics in complex f…
2023
Harvesting has been implicated in destabilizing the abundances of exploited populations. Because selective harvesting often targets large individuals, some studies have proposed that exploited populations often experience demographic shifts toward younger, smaller individuals and become more sensitive to environmental fluctuations. The theory of consumer–resource dynamics has been applied to address the impacts of harvesting in simple modular food webs, but harvested populations are embedded in a complex food web in nature. In addition, exploited populations have been shown to undergo trait evolution or phenotypic changes toward early maturation at smaller sizes. Using an empirically derive…
Seasonal variation in total phenolic content of Dictyopteris polypodioides (Dictyotaceae) and Cystoseira amentacea (Sargassaceae) from the Sicilian c…
2014
This study focuses on the differences in total phenolic content and its seasonal variations in two temperate brown algae, Cystoseira amentacea (C. Agardh) Bory and Dictyopteris polypodioides (A.P. De Candolle) J.V. Lamouroux, inhabiting respectively the infralittoral fringe and the upper infralittoral zone. Phenolic compounds are secondary metabolites, found in almost all brown algal orders, that function as defense against grazers, epiphytes and UV radiation. Total phenolic content was determined colorimetrically with the Folin-Ciocalteu reagent. Results showed significant differences in total phenol content between D. polypodioides and C. amentacea with higher values observed in the first…
Population and reproductive dynamics of the polychaete Pygospio elegans in a boreal estuary complex
2016
Pygospio elegans is an opportunistic, wide-spread spionid polychaete that reproduces asexually via fragmentation and can produce benthic and pelagic larvae, hence combining different developmental modes in one species. We documented the density, size distribution, and reproductive activity of P. elegans at four sites in the Danish Isefjord-Roskilde Fjord estuary complex, where all modes of reproduction were reported. We compared population dynamics of this species to environmental parameters such as salinity, temperature, and sediment characteristics (grain size, sorting, porosity, water content, organic content, C/N). We observed that new cohorts—resulting either from sexual or asexual rep…