Search results for "Population dynamics"
showing 10 items of 281 documents
Population history in social spiders repeated: colony structure and lineage evolution inStegodyphus mimosarum(Eresidae)
2009
Social cooperative spiders from diverse taxonomic families share life-history and demographic traits, including highly inbred colony structure. The combination of traits suggests constrained pathways for social evolution in spiders. The genus Stegodyphus has three independently evolved social species, which can be used as replicate samples to analyse population constraints in evolutionary time. We tested colony structure and population history of the social S. mimosarum from South and East Africa using mitochondrial DNA variation, and we compared the results to published data for the independently evolved social congener S. dumicola. S. mimosarum had many and diverse haplotypes (5-7% sequen…
An analysis based on trawl-survey data of the state of the ‘Italian’ stock of Mullus barbatus in the Sicilian Channel, including management advice
1993
Abstract Data on the relative abundance of age groups obtained by statistically designed routine trawl surveys in approximately half of the Sicilian Channel were processed with commonly available microcomputer fish population dynamics packages. The species considered was Mullus barbatus , a unit stock of which had been previously identified in the study area. Analytical and management outcomes were also assessed in relative terms. Conditions and limits on both the analyses and the outcomes are discussed with reference to the particular case study.
Biological interactions in the boreal ecosystem under climate change : are the vole and predator cycles disappearing?
2014
Emergence and Phylodynamics of Citrus tristeza virus in Sicily, Italy
2013
Citrus tristeza virus (CTV) outbreaks were detected in Sicily island, Italy for the first time in 2002. To gain insight into the evolutionary forces driving the emergence and phylogeography of these CTV populations, we determined and analyzed the nucleotide sequences of the p20 gene from 108 CTV isolates collected from 2002 to 2009. Bayesian phylogenetic analysis revealed that mild and severe CTV isolates belonging to five different clades (lineages) were introduced in Sicily in 2002. Phylogeographic analysis showed that four lineages co-circulated in the main citrus growing area located in Eastern Sicily. However, only one lineage (composed of mild isolates) spread to distant areas of Sici…
Predicting and mapping human risk of exposure to
2019
Background Tick-borne diseases have become increasingly common in recent decades and present a health problem in many parts of Europe. Control and prevention of these diseases require a better understanding of vector distribution. Aim Our aim was to create a model able to predict the distribution of Ixodes ricinus nymphs in southern Scandinavia and to assess how this relates to risk of human exposure. Methods We measured the presence of I. ricinus tick nymphs at 159 stratified random lowland forest and meadow sites in Denmark, Norway and Sweden by dragging 400 m transects from August to September 2016, representing a total distance of 63.6 km. Using climate and remote sensing environmental …
Geometric Optimal Control of the Generalized Lotka-Volterra Model of the Intestinal Microbiome
2022
We introduce the theoretical framework from geometric optimal control for a control system modeled by the Generalized Lotka-Volterra (GLV) equation, motivated by restoring the gut microbiota infected by Clostridium difficile combining antibiotic treatment and fecal injection. We consider both permanent control and sampled-data control related to the medical protocols.
Build up of patches caused by Rhizoctonia solani
2010
Rhizoctonia solani is a complex species that is composed of different anastomosis groups (AG). Although these different AGs show differences in their host ranges, generally R. solani is a phytopathogenic species with a wide spectrum of hosts. It has the ability to grow as a saprotroph, which further complicates its behaviour as a parasite. The losses caused by R. solani are very important and need a sustainable management strategy. The patchy appearance of the disease caused by this pathogen is well-known. The patches show within and between season dynamics. The factors which affect the spread of the disease can be grouped into three main categories: host plant, pathogen and environment. Ho…
Fish community responses to pulp and paper mill effluents at the southern Lake Saimaa, Finland.
2002
Abstract The fish community in sublittoral and profundal waters, at stony shores, and densities of vendace larvae were studied in the southern Lake Saimaa, Finland. The objective was to investigate the possible recovery of fish populations after modernizations at the pulp and paper mills discharging into the lake. Sublittoral and profundal waters were studied by gill net trial fishings, stony shores by electrofishing, and vendace larvae by beach seine. The research area was divided in a polluted (0.5–4.0% effluent), an intermediate (0.1–0.5%) and a ‘clean’ reference area. The fish community in sublittoral and profundal waters in the lake was dominated (>60%) by perch and roach. Relative abu…
A PDE model for the spatial dynamics of a voles population structured in age
2020
Abstract We prove existence and stability of entropy weak solutions for a macroscopic PDE model for the spatial dynamics of a population of voles structured in age. The model consists of a scalar PDE depending on time, t , age, a , and space x = ( x 1 , x 2 ) , supplemented with a non-local boundary condition at a = 0 . The flux is linear with constant coefficient in the age direction but contains a non-local term in the space directions. Also, the equation contains a term of second order in the space variables only. Existence of solutions is established by compensated compactness, see Panov (2009), and we prove stability by a doubling of variables type argument.
Mathematical models for the management of helminth parasites: from biological processes to the evolution of anthelmintic resistance
2010
International audience; Helminth parasitic diseases are mainly controlled by anthelmintic treatments, but control schemes are now threatened by the large development of anthelmintic resistance. Integrated parasite management needs to be developed but processes underpinning parasite population dynamics and resistant gene evolution are still lacking. Here, we review the mathematical models that have been developed to understand the evolution of anthelmintic resistance in host-helminth parasite models (intestinal helminth parasites of herbivores and human soil-transmitted helminths). A first part is dedicated to generic models that allowed the understanding of processes underlying host-helmint…