scholarly journals Density-Dependence in Single-Species Populations

10.2307/3863 ◽  
1975 ◽  
Vol 44 (1) ◽  
pp. 283 ◽  
Author(s):  
M. P. Hassell
Keyword(s):  
Density Dependence ◽  
Single Species

Time Delays, Density-Dependence and Single-Species Oscillations

10.2307/3535 ◽  
1974 ◽  
Vol 43 (3) ◽  
pp. 747 ◽  
Author(s):  
R. M. May ◽  
G. R. Conway ◽  
M. P. Hassell ◽  
T. R. E. Southwood
Keyword(s):  
Density Dependence ◽  
Time Delays ◽  
Single Species

Population growth and density dependence

2019 ◽  
pp. 63-80
Author(s):  
Gary G. Mittelbach ◽  
Brian J. McGill
Keyword(s):  
Population Growth ◽  
Density Dependence ◽  
Growth Model ◽  
Species Interactions ◽  
Single Species ◽  
Positive Density ◽  
Allee Effects ◽  
Species Population ◽  
Exponential Growth Model ◽  
Single Species Population

This chapter reviews the basic mathematics of population growth as described by the exponential growth model and the logistic growth model. These simple models of population growth provide a foundation for the development of more complex models of species interactions covered in later chapters on predation, competition, and mutualism. The second half of the chapter examines the important topic of density-dependence and its role in population regulation. The preponderance of evidence for negative density-dependence in nature is reviewed, along with examples of positive density dependence (Allee effects). The study of density dependence in single-species populations leads naturally to the concept of community-level regulation, the idea that species richness or the total abundance of individuals in a community may be regulated just like abundance in a single-species population. The chapter concludes with a look at the evidence for community regulation in nature and a discussion of its importance.

Density dependence, regulation and variability in animal populations

1990 ◽  
Vol 330 (1257) ◽  
pp. 141-150 ◽  
Keyword(s):  
Density Dependence ◽  
Population Regulation ◽  
Time Series Data ◽  
Complex Dynamics ◽  
Natural Populations ◽  
Single Species ◽  
Abundant Species ◽  
Series Data ◽  
Animal Populations ◽  
The Common

This paper reviews a series of approaches to the study of density dependence, regulation and variability in terrestrial animals, by using single-species, multispecies and life table time series data. Special emphasis is given to the degree of density dependence in the level of variability, which is seldom discussed in this context, but which is conceptually related to population regulation. Broad patterns in density dependence, regulation and variability in vertebrates and arthropods are described, with some more specific results for moths and aphids. Vertebrates have generally less variable populations than arthropods, which is the only well documented, consistent pattern in population variability. The degree of density dependence of variability is negatively correlated with the average level of variability, suggesting that generally the more regulated populations are less variable. Most population studies, especially on insects, have involved outbreak species with complex dynamics, which may explain the common failures to detect density dependence in natural populations. In British moths, density dependence is less obvious in the more abundant species. The study of uncommon and rare species remains a major challenge for population ecology.

Graeme Caughley and the fundamentals of population ecology: a personal view

2009 ◽  
Vol 36 (1) ◽  
pp. 16
Author(s):  
Richard M. Sibly
Keyword(s):  
Density Dependence ◽  
Population Ecology ◽  
Ecological Niche ◽  
Population Regulation ◽  
Single Species ◽  
Geographic Range ◽  
Personal View ◽  
Causal Factors ◽  
Species Population ◽  
Single Species Population

Caughley’s contributions to single-species population ecology are here discussed in the light of some of the ideas and studies his work elicited, with particular reference to influences on my own work and that of my collaborators. Major themes are the manner and extent of population regulation; the alternate perspectives on population regulation that are obtained by density-dependence analyses and mechanistic analyses in terms of food availability and other causal factors; and ways in which mechanistic analyses can be elaborated to characterise a species’ ecological niche and relate it to the species’ geographic range.

scholarly journals Predicting conditions for migration: effects of density dependence and habitat quality

2007 ◽  
Vol 3 (3) ◽  
pp. 280-284 ◽  
Author(s):  
Caz M Taylor ◽  
D. Ryan Norris
Keyword(s):  
Population Density ◽  
Density Dependence ◽  
Habitat Quality ◽  
Population Model ◽  
Single Species ◽  
Partial Migration ◽  
Breeding Grounds ◽  
Migration Strategies ◽  
Effects Of Density

Migration is widespread among animals, but the factors that influence the decision to migrate are poorly understood. Within a single species, populations may be completely migratory, completely sedentary or partially migratory. We use a population model to derive conditions for migration and demonstrate how migratory survival, habitat quality and density dependence on both the breeding and non-breeding grounds influence conditions for migration and the proportion of migrants within a population. Density dependence during the season in which migratory and sedentary individuals use separate sites is necessary for partial migration. High levels of density dependence at the non-shared sites widen the range of survival values within which we predict partial migration, whereas increasing the strength of density dependence at the shared sites narrows the range of survival values within which we predict partial migration. Our results have important implications for predicting how contemporary populations with variable migration strategies may respond to changes in the quality or quantity of habitat.

In vitro assembly of 2-D crystals from partially purified EA1 protein secreted by Bacillus anthracis strain Delta Sterne-1

1994 ◽  
Vol 52 ◽  
pp. 276-277
Author(s):  
Mary Beth Downs ◽  
Wilson Ribot ◽  
Joseph W. Farchaus
Keyword(s):  
Cell Wall ◽  
Molecular Sieves ◽  
Cell Envelope ◽  
Single Species ◽  
Supporting Cell ◽  
Surface Layers ◽  
Rabbit Igg ◽  
In Vitro Assembly ◽  
Covalently Linked

Many bacteria possess surface layers (S-layers) that consist of a two-dimensional protein lattice external to the cell envelope. These S-layer arrays are usually composed of a single species of protein or glycoprotein and are not covalently linked to the underlying cell wall. When removed from the cell, S-layer proteins often reassemble into a lattice identical to that found on the cell, even without supporting cell wall fragments. S-layers exist at the interface between the cell and its environment and probably serve as molecular sieves that exclude destructive macromolecules while allowing passage of small nutrients and secreted proteins. Some S-layers are refractory to ingestion by macrophages and, generally, bacteria are more virulent when S-layers are present.When grown in rich medium under aerobic conditions, B. anthracis strain Delta Sterne-1 secretes large amounts of a proteinaceous extractable antigen 1 (EA1) into the growth medium. Immunocytochemistry with rabbit polyclonal anti-EAl antibody made against the secreted protein and gold-conjugated goat anti-rabbit IgG showed that EAI was localized at the cell surface (fig 1), which suggests its role as an S-layer protein.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

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