Search results for "ECOLOGY"
showing 10 items of 15385 documents
¿Me voy o me quedo? Factores que influyen en la decisión de abandonar el lugar de nacimiento.
2014
Múltiples factores influyen en la decisión de dispersarse y en cuándo iniciar la dispersión, y su estudio proporciona evidencias de las causas y los determinantes de la dispersión. Los animales abandonan el lugar de nacimiento para dar solución a tres problemas fundamentales: pérdida de calidad del hábitat, competencia por los recursos, y riesgo de consanguinidad. La dispersión, sin embargo, no se lleva a cabo hasta que los individuos alcanzan una condición física adecuada, que permita alcanzar con éxito un nuevo lugar de asentamiento.
Spatial variation in the evolutionary potential and constraints of basal metabolic rate and body mass in a wild bird
2023
An organism's energy budget is strongly related to resource consumption, performance, and fitness. Hence, understanding the evolution of key energetic traits, such as basal metabolic rate (BMR), in natural populations is central for understanding life-history evolution and ecological processes. Here we used quantitative genetic analyses to study evolutionary potential of BMR in two insular populations of the house sparrow (Passer domesticus). We obtained measurements of BMR and body mass (Mb) from 911 house sparrows on the islands of Leka and Vega along the coast of Norway. These two populations were the source populations for translocations to create an additional third, admixed ‘common ga…
Determinants of the interannual relationships between remote sensed photosynthetic activity and rainfall in tropical Africa
2007
International audience; The response of photosynthetic activity to interannual rainfall variations in Africa South of the Sahara is examined using 20 years (1981-2000) of Normalised Difference Vegetation Index (NDVI) AVHRR data. Linear correlations and regressions were computed between annual NDVI and annual rainfall at a 0.5° latitude/longitude resolution, based on two gridded precipitation datasets (Climate Prediction Center Merged Analysis of Precipitation [CMAP] and Climatic Research Unit [CRU]). The spatial patterns were then examined to detect how they relate to the mean annual rainfall amounts, land-cover types as from the Global Land Cover 2000 data set, soil properties and soil typ…
Biological and Mechanical Characterization of the Random Positioning Machine (RPM) for Microgravity Simulations
2021
The rapid improvement of space technologies is leading to the continuous increase of space missions that will soon bring humans back to the Moon and, in the coming future, toward longer interplanetary missions such as the one to Mars. The idea of living in space is charming and fascinating; however, the space environment is a harsh place to host human life and exposes the crew to many physical challenges. The absence of gravity experienced in space affects many aspects of human biology and can be reproduced in vitro with the help of microgravity simulators. Simulated microgravity (s-μg) is applied in many fields of research, ranging from cell biology to physics, including cancer biology. In…
Current Social and Rangeland Access Trends among Pastoralists in the Western Algerian Steppe
2021
International audience; In the western Algerian steppe, the public authorities have carried out actions aimed at rural development (agricultural development programs) and combating desertification (grazing reserves) to counter the significant and rapid loss of vegetation cover of pastures by overgrazing, and the consequent impacts on local livelihoods. In the Rogassa area, these actions have impacted land tenure and the ancestral and collective way of land use and access. These changes have caused transformations in lifestyle and pasture management. This research aims to characterize how such changes are affecting local pastoralists and what their perceptions are about them. A selective sam…
Fatty acid composition as biomarkers of freshwater microalgae: analysis of 37 strains of microalgae in 22 genera and in seven classes
2013
The fatty acid (FA) composition of algae is an important determinant of their food quality for consumers, and FAs can also be used as biomarkers for biochemical and energetic pathways in food webs. FA analyses of 7 freshwater algal classes and 37 strains showed clear similarity within classes and strong differences amongst classes. Class was a dominant factor (66.4%) explaining variation in FA signatures of microalgae. The 7 algal classes comprised 4 separate groups according to their FA profiles: (1) Chlorophyceae and Trebouxiophyceae, (2) Bacillariophyceae, (3) Cryptophyceae, Chrysophyceae, and Raphidophyceae, and (4) Euglenophyceae. Each group had a characteristic FA composition, althoug…
Balancing food, activity and the dangers of sunlit nights
2019
Living in northern latitudes poses challenges to the animals that live in those habitats. The harsh environment provides a short breeding season where the sunlit summer nights provide little reprieve from visibility to predators and increased risk. In this paper, we tested the activity and food choice patterns of bank voles Myodes glareolus in early spring season, categorized by 18 h of daylight and 6 h of dusk in every day cycle. We found that territorial females showed a less predictable pattern of activity than males that were most active during the hours of dusk. The voles also showed preference to forage on high carbohydrate foods at sunset, while switching over to a more protein and f…
The proposal to transform an old limestone quarry into a botanical garden with a rainforest zone: a case study
2019
Nowadays, a significant part of cities is tackling the problems with post-mining areas. This manuscript is an original research which shows possibilities of their reclamation. The aim of the article is to present the proposal of developing the closed limestone quarry and creating a botanical garden. The proposed spatial solutions allow for creating a new, tourist and recreation space, maintaining the natural heritage. The work also assumed carrying out a dendrological inventory, in order to determine the existing dendrofl ora. The required spatial, nature and communication analyses, which illustrate the current condition of the area and defi ne further design works, have also been carried o…
Catalogue of the Diptera (Insecta) of Morocco— an annotated checklist, with distributions and a bibliography
2022
The faunistic knowledge of the Diptera of Morocco recorded from 1787 to 2021 is summarized and updated in this first catalogue of Moroccan Diptera species. A total of 3057 species, classified into 948 genera and 93 families (21 Nematocera and 72 Brachycera), are listed. Taxa (superfamily, family, genus and species) have been updated according to current interpretations, based on reviews in the literature, the expertise of authors and contributors, and recently conducted fieldwork. Data to compile this catalogue were primarily gathered from the literature. In total, 1225 references were consulted and some information was also obtained from online databases. Each family was reviewed and the c…
Measuring, comparing and interpreting phenotypic selection on floral scent
2022
Natural selection on floral scent composition is a key element of the hypothesis that pollinators and other floral visitors drive scent evolution. The measure of such selection is complicated by the high-dimensional nature of floral scent data and uncertainty about the cognitive processes involved in scent-mediated communication. We use dimension reduction through reduced-rank regression to jointly estimate a scent composite trait under selection and the strength of selection acting on this trait. To assess and compare variation in selection on scent across species, time and space, we reanalyse 22 datasets on six species from four previous studies. The results agreed qualitatively with prev…