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Density-dependent fecundity. Density-dependent fecundity exists, where the birth rate falls as competition increases. In the context of gastrointestinal nematodes, the weight of female Ascaris lumbricoides and its rates of egg production decrease as host infection intensity increases. Thus, the per-capita contribution of each worm to ...
The generally accepted definition of Allee effect is positive density dependence, or the positive correlation between population density and individual fitness. It is sometimes referred to as "undercrowding" and it is analogous (or even considered synonymous by some) to "depensation" in the field of fishery sciences.
The first variable is r (the intrinsic rate of natural increase in population size, density independent) and the second variable is K (the carrying capacity of a population, density dependent). [21] It is important to understand the difference between density-independent factors when selecting the intrinsic rate and density-dependent for the ...
If the dependent variable is referred to as an "explained variable" then the term "predictor variable" is preferred by some authors for the independent variable. [22] An example is provided by the analysis of trend in sea level by Woodworth (1987). Here the dependent variable (and variable of most interest) was the annual mean sea level at a ...
[2] [3] Isodars model density-dependent habitat selection for one or two species in two habitats according to the ideal free and ideal despotic distributions. Isodar is a two-part word: "iso" meaning equal in Latin; "dar" for Darwinian evolution, and is defined as all combinations of population densities in habitats A and B such that both ...
In 1981, a review of the r/K selection literature by Parry demonstrated that there was no agreement among researchers using the theory about the definition of r - and K-selection, which led him to question whether the assumption of a relation between reproductive expenditure and packaging of offspring was justified. [36]
When collision is unavoidable, a different phenomenon occurs whereby growth of the cells of the culture itself eventually stops in a cell-density dependent manner. [ 2 ] Both types of contact inhibition are well-known properties of normal cells and contribute to the regulation of proper tissue growth, differentiation, and development.
The causes of delayed density dependence vary in each situation. In lemmings, food supply and predation are the most important factors that lead to delayed density dependence. [3] Competition between life stages is another cause. In some species of moth the practice of egg cannibalism takes place where older moths eat eggs of their own species. [6]