Search results for " population dynamic"
showing 8 items of 38 documents
La Valle dei Templi in epoca medioevale. Caratterizzazione antropologica e paleopatologica delle sepolture antistanti in Tempio della Concordia
2021
Riassunto ― Il lavoro presenta i risultati delle analisi bio-archeologiche effettuate su resti scheletrici umani rinvenuti in quattordici sepolture di epoca medioevale rinvenute nel Parco Archeologico della Valle dei Templi di Agrigento (Sicilia). L’obiettivo è stato l’acquisizione delle informazioni necessarie per la ricostruzione del profilo biologico di ciascun individuo, al fine di determinarne il sesso, la stima dell’età biologica alla morte, la stima della statura e la valutazione delle patologie e degli indicatori di stress occupazionale mediante le correnti metodologie e tecniche diagnostiche di tipo antropologico. Sebbene il cattivo stato di conservazione di alcuni individui non ne…
LA CICOGNA BIANCA CICONIA CICONIA (Aves Ciconiidae) IN SICILIA: AGGIORNAMENTO A TRENT'ANNI DALLA COLONIZZAZIONE
2020
Il presente lavoro sintetizza le conoscenze sulla Cicogna bianca nidificante in Sicilia negli ultimi 29 anni, dal 1991 (anno della prima nidificazione) al 2020. Per la raccolta dei dati sono state seguite le linee guida dell’International White Stork Census. Vengono presentate una cartina di distribuzione che illustra l’areale della specie attraverso un confronto temporale e alcune tabelle relative all’andamento annuale delle coppie nidificanti in Sicilia (sia HPa che HPm), al numero dei pulli involati e alla media (±SD) per nido. Dopo una crescita della popolazione nidificante, da una coppia fino a un massimo di 82 nel 2013, si è avuto un leggero calo e il numero di nidi si è stabilizzato …
Modification of hosts' behavior by a parasite: field evidence for adaptive manipulation.
2007
9 pages; International audience; Parasites relying on trophic transmission to complete their life cycles often induce modifications of their host's behavior in ways that may increase their susceptibility to predation by final hosts. These modifications have often been interpreted as parasite adaptations, but very few studies have demonstrated that host manipulation has fitness benefits for the parasite. The aim of the present study was to address the adaptive significance of parasite manipulation by coupling observations of behavioral manipulation to estimates of trophic transmission to the definitive host in the natural environment. We show that the acanthocephalan parasite Pomphorhynchus …
Variation of post-dispersal weed seed predation according to weed species, space and time
2008
International audience; Post-dispersal seed predation is an important source of mortality in plant populations. If this phenomenon is better known in tropical and woody systems, information is lacking for weeds in French agrosystems. In this paper, we evaluated seed predation variability in an organic wheat field by conducting experiments on weed seed preference and on spatial and temporal variation in predation rates. Weed seed predation preferences followed a species rank: Viola arvensis = Stellaria media > Alopecurus myosuroides = Chenopodium album > Sinapis arvensis = Anagallis arvensis = Galium aparine > > Plastic globules (for control), with weekly mean predation rates between 19 and …
Progress towards sustainable agriculture – Drivers of change
2021
Sustainable Development Goal (SDG) 2 calls for global action to “end hunger, achieve food security and improved nutrition, and promote sustainable agriculture”. Meeting this challenge requires global partnerships to support more productive, nutritious and equitable food systems, while helping to conserve environmental resources and reduce the greenhouse gas (GHG) emissions responsible for global climate change. The Food and Agriculture Organization of the United Nations (FAO) offers a global vision for a more sustainable agriculture that encompasses economic, social and environmental dimensions of food and agriculture systems. This technical study examines the key factors driving changes in…
Age-Structured Human Population Dynamics
2006
ABSTRACT A von Foerster-McKendrick model to study age-structured human population dynamics is presented in this paper. Forecasts of population density (population per age unit) depending on ages are possible using this model. The model consists of a quasi-linear first order partial differential equation for the dynamics of population density per age-unit (except for the zero-age), a boundary condition for the births flow at zero-age, and an initial condition for the population density at the initial instant. A general solution independent of the particular human-system under study is obtained based on some hypotheses about the mathematical structure of its input variables. The model has bee…
Time evolution of non-lethal infectious diseases: a semi-continuous approach.
2005
A model describing the dynamics related to the spreading of non-lethal infectious diseases in a fixed-size population is proposed. The model consists of a non-linear delay-differential equation describing the time evolution of the increment in the number of infectious individuals and depends upon a limited number of parameters. Predictions are in good qualitative agreement with data on influenza.
CHECK-LIST DEGLI UCCELLI DELLA R.N.O. “SALINE DI TRAPANI E PACECO” CON LISTA COMMENTATA DEI NON PASSERIFORMES
2018
Update of the checklist of the birds of the Nature Reserve “Saline di Trapani e Paceco” (Sicily). The present work provides an update to the checklist of birds of the “Saline di Trapani e Paceco” published nine years ago by IENTILE (2008). The overall number of bird species increased from 209 to the current value of 229. The present work also includes a quantitative estimate of the breeding and wintering species. A table, detailing the number of individuals of each species present for each month of the year at the Saline di Trapani and Paceco, is included. This work aims at underscoring the importance of the Saline as an Important Bird Area (IBA), as a key area for the migration pathways of…