Search results for "analysis."
showing 10 items of 26008 documents
Resource availability and competition shape the evolution of survival and growth ability in a bacterial community
2013
Resource availability is one of the main factors determining the ecological dynamics of populations or species. Fluctuations in resource availability can increase or decrease the intensity of resource competition. Resource availability and competition can also cause evolutionary changes in life-history traits. We studied how community structure and resource fluctuations affect the evolution of fitness related traits using a two-species bacterial model system. Replicated populations of Serratia marcescens (copiotroph) and Novosophingobium capsulatum (oligotroph) were reared alone or together in environments with intergenerational, pulsed resource renewal. The comparison of ancestral and evol…
Morphology, Genetics and Biology of Pterochloroides persicae Cholodkovsky (Hemiptera: Lachninae) and Their Effect on Pauesia antennata Mukerji (Hymen…
2021
Pauesia antennata Mukerji is a specific parasitoid of the brown peach aphid Pterochloroides persicae Cholodkovsky which causes severe damage on almond and peach in Tunisia. To control this pest, P. antennata was collected from Iran, introduced to Tunisia in 2011 and some of their biological parameters were studied in laboratory conditions. Therefore, in orchard, aphid population and sites/zones of Tunisia and aphid behaviour impact on the parasitoid have not been studied. Morphometric measurements, molecular analysis of P. persicae specimens collected from two Tunisian sites [(Akouda-Sousse (Site 1), Sfax (Site 2)] were studied and compared and aphid behaviour versus P. antennata was follow…
Environmental Fluctuations Drive Species' Competitive Success in Experimental Invasions
2020
Climate change is presumed to increase both the number and frequency of fluctuations in environmental conditions. Fluctuations can affect the ecological and evolutionary processes that make species more successful competitors. For example, fluctuating conditions can create selection pressures for traits that are profitable in adaptation to fast climate change. On an ecological timescale, environmental fluctuations can facilitate species competitive success by reducing other species’ population sizes. Climate change could then enhance species invasions into new areas if fluctuation-adapted invaders displace their native competitors in chancing environments. We tested experimentally whether f…
Interventions have limited effects on the population dynamics of Ips typographus and its natural enemies in the Western Carpathians (Central Europe)
2020
Abstract Outbreaks of the European spruce bark beetle Ips typographus kill extensive areas of Norway spruce forests in Central Europe, affecting both protected areas and neighboring commercial forests. In protected areas, uncontrolled (non-intervention) management allows natural beetle-induced tree mortality, while in commercial forests infested trees are salvage-logged in order to lower I. typographus numbers and stabilize wood production. However, the effects of active pest controls on I. typographus population are often ambiguous, and little is known about how antagonists, beetle density, or intraspecific competition help terminate I. typographus outbreaks. To answer this question, we st…
Spray-Drying Performance and Thermal Stability of L-Ascorbic Acid Microencapsulated with Sodium Alginate and Gum Arabic
2019
[EN] The potential of sodium alginate (ALG) and gum arabic (GA) as wall polymers for Lascorbic acid (AA) encapsulation as a tool for their preservation against the thermo-oxidative degradation was investigated. The influence of such polymers used as wall material on the AAcontent, size, encapsulation efficiency, encapsulation yield and thermo-oxidative stability were evaluated. The AA-microparticles were obtained using the spray-drying technique. An experimental Taguchi design was employed to assess the influence of the variables in the encapsulation process. The microparticles morphology and size distribution were characterized by scanning electron microscopy and laser diffraction. The the…
Essential oil variability in a collection of Ocimum basilicum L. (basil) cultivars.
2016
Ocimum basilicum L. (Lamiaceae) is an aromatic plant of great tradition in the Mediterranean area. Its economic importance is growing up determining an expansion of cultivation. This paper evaluated the morphological traits, the chemical profiles, and antibacterial activity of 21 cultivars of basil belonging to Ê»Genoveseʼ, Ê»Napoletanoʼ, and Ê»Purple basilʼ types. The cultivars were characterized by different growth rate and morphological traits. The chemical composition of the oils analyzed by GC and GC/MS analysis, supported by the PCA analysis, underlined the strong influence of chemotype. It is noteworthy that estragole, never present in Genovese and purple basil types, occurred in …
Effect of a gap on gene flow between otherwise adjacent transgenic Brassica napus crops.
2003
Gene flow resulting from cross pollination becomes an issue when transgenic crops are involved and the genetic modification carries a trait of ecological importance. As crop fields are often separated by a barren gap, such as an intervening roadway or unplanted area, I measured cross contamination between two herbicide-resistant transgenic fields (canola, Brassica napus) across a gap of up to 12 m. I focused on pollen exchange from the field border up to 7 m inside each field over two seasons. In the absence of a gap, I found that gene dispersal diminished rapidly with distance, with more than 40% of transgenic progeny found within the first meter from the edge of the adjacent crop. Cross c…
DNA barcoding of marine fishes from Saudi Arabian waters of the Gulf
2019
We used the cytochrome oxidase subunit I (coI) gene DNA to barcode 117 endemic Gulf and cosmopolitan Indo-West Pacific fish species belonging to 54 families and 13 orders. Novel DNA barcodes were provided for 18 fish species (Trachinocephalus sp., Nematalosa sp., Herklotsichthys lossei, Upeneus doriae, Trachurus indicus, Apogonichthyoides taeniatus, Verulux cypselurus, Favonigobius sp., Suezichthus gracilis, Sillago sp., Brachirus orientalis, Pegusa sp., Lepidotrigla bispinosa, Lepidotrigla sp., Grammoplites suppositus, Hippichthys sp., Paramonacanthus sp. and Triacanthus sp.). The species delimitation analysis, conducted with Poisson tree processes- Bayesian PTP (PTP-bPTP) and nucleotide-d…
Finite Mixture Model-based classification of a complex vegetation system
2020
Aim: To propose a Finite Mixture Model (FMM) as an additional approach for classifying large datasets of georeferenced vegetation plots from complex vegetation systems. Study area: The Italian peninsula including the two main islands (Sicily and Sardinia), but excluding the Alps and the Po plain. Methods: We used a database of 5,593 georeferenced plots and 1,586 vascular species of forest vegetation, created in TURBOVEG by storing published and unpublished phytosociological plots collected over the last 30 years. The plots were classified according to species composition and environmental variables using a FMM. Classification results were compared with those obtained by TWINSPAN algorithm. …
Fossorial but widespread: the phylogeography of the common spadefoot toad (Pelobates fuscus), and the role of the Po Valley as a major source of gene…
2007
International audience; Pelobates fuscus is a fossorial amphibian that inhabits much of the European plain areas. To unveil traces of expansion and contraction events of the species' range, we sequenced 702 bp of the mitochondrial cytochrome b gene. To infer the population history we applied phylogeographical methods, such as nested clade phylogeographical analysis (NCPA), and used summary statistics to analyse population structure under a neutral model of evolution. Populations were assigned to different drainage systems and we tested hypotheses of explicit refugial models using information from analysis of molecular variance, nucleotide diversity, effective population size estimation, NCP…