Search results for "Population growth"

Kin interactions and population growth

2011

Phenotypic variation in infectivity of Diplostomum spathaceum cercariae within a population.

2007

The present study examined phenotypic variation in infectivity of Diplostomum spathaceum (Trematoda) cercariae within a natural population. Twelve infected Lymnaea stagnalis were collected from the field, and the infectivity of cercariae from individual snails was assessed under constant laboratory conditions. At a water temperature of 16.3 C, the mean infectivity of cercariae from the snails varied between 55.5% and 87.5%. Depending on the source of variation, this may have important ecological and evolutionary implications for both natural parasite populations and those occurring in aquaculture.

Seasonal cardenolide production and Dop5βr gene expression in natural populations of Digitalis obscura

2004

Productivity variations and seasonal fluctuations of cardenolides have been studied in 10 natural populations of Digitalis obscura distributed in three bioclimatic belts. Main cardenolides in D. obscura plants are those of the series A and such predominance (ca. 80-85%) over the series B metabolites is independent of the population studied or the degree of maturity of the leaves. Primary glycosides represent ca. 50-60% of total cardenolides; this percentage did not vary among populations or with the leaf age but increased in summer and decreased in winter. A correlation analysis between plant biomass and cardenolide content showed a positive relationship of these parameters, which, accordin…

Mussels as a model system for integrative ecomechanics.

2015

Copyright © 2015 by Annual Reviews. All rights reserved. Mussels form dense aggregations that dominate temperate rocky shores, and they are key aquaculture species worldwide. Coastal environments are dynamic across a broad range of spatial and temporal scales, and their changing abiotic conditions affect mussel populations in a variety of ways, including altering their investments in structures, physiological processes, growth, and reproduction. Here, we describe four categories of ecomechanical models (biochemical, mechanical, energetic, and population) that we have developed to describe specific aspects of mussel biology, ranging from byssal attachment to energetics, population growth, an…

Contrasting age-specific recruitment and survival at different spatial scales: A case study with the European storm petrel

2009

Evolutionary studies on optimal decisions or conservation guidelines are often derived by generalising patterns from a single population, while inter-population variability in life-history traits is seldom considered. We investigated here how survival and recruitment probabilities changed with age at different geographical scales using the encounter histories of 5523 European storm petrels from three Mediterranean colonies, and also how our estimates of these parameters might be expected to affect population growth rates using population matrix models. We recorded similar patterns among colonies, but also important biological differences. Local survival, recruitment and breeding success inc…

In-Between ‘Smart’ Urban Growth and ‘Sluggish’ Rural Development? Reframing Population Dynamics in Greece, 1940–2019

2020

Multifaceted demographic dynamics have shaped population growth in Mediterranean Europe, reflecting a metropolitan cycle from urbanization to re-urbanization. To assess the distinctive impact of economic downturns on population dynamics, the present study illustrates the results of an exploratory analysis that assesses urban expansion and rural decline at various temporal scales in Greece, a peripheral country in southeastern Europe. Statistical analysis based on multivariate exploratory techniques outlined the persistent increase of regional populations, evidencing the distinctive role of agglomeration/scale with urbanization and early suburbanization phases (1940&ndash

Conclusion: Towards Sustainable Development in the Philippines?

2017

For many years, the Philippine archipelago, as we hope to have shown throughout this book, has suffered from many ills, some related to its geography and natural environment, some to its major demographic trends, many also from its social, economic and political structures and choices and its early insertion within a globalized economy. Resources have been depleted or severely damaged (forests, soils, water, coral reefs, mangroves, fisheries). Environmental losses may be linked to extensive factors (economic and population growth) as well as intensive factors (unequal distribution and access to market resources) (Montes and Lim 1996). Everything is linked, such as climate change and poverty…

Exploring relationships between drought and epidemic cholera in Africa using generalised linear models

2021

AbstractBackgroundTemperature and precipitation are known to affect Vibrio cholerae outbreaks. Despite this, the impact of drought on outbreaks has been largely understudied. Africa is both drought and cholera prone and more research is needed in Africa to understand cholera dynamics in relation to drought.MethodsHere, we analyse a range of environmental and socioeconomic covariates and fit generalised linear models to publicly available national data, to test for associations with several indices of drought and make cholera outbreak projections to 2070 under three scenarios of global change, reflecting varying trajectories of CO2 emissions, socio-economic development, and population growth…

On the emergence of the urban phenomenon. Part I

2001

In this paper we develop a relatively simple but general model describing the formation of urban agglomerations in a pre-industrial setting. Rural agglomeration on a local scale arises from the multiplication and specialization of intermediate goods and labor services, while dispersion is due to the commuting costs of agricultural workers. Urban agglomeration on a more global scale stems from the trade-off between increasing returns to scale and transport costs of goods. We derive a general equilibrium model of the formation of urban structures and show how population growth, strict indivisibilities and structural changes in the production sector can modify quantitatively and qualitatively …

Identification of Traits Implicated in the Rhizosphere Competence of Fluorescent Pseudomonads: Description of a Strategy Based on Population and Mode…

2009

E-book; International audience; The lack of consistency of the beneficial effects of inoculated fluorescent pseudomonads has often been related to their bad survival in the rhizosphere. In this review, we describe the strategy followed over the last decade to study traits involved in the rhizosphere competence of these bacteria. The diversity of indigenous populations associated with plant roots was first compared to that of populations associated with uncultivated soils in order to identify traits that discriminate these populations. The involvement of these bacterial traits in the rhizosphere competence was then assessed by comparing the competitiveness of a wild-type strain to that of mu…