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Negative density-dependence, or density-dependent restriction, describes a situation in which population growth is curtailed by crowding, predators and competition. [citation needed] In cell biology, it describes the reduction in cell division. When a cell population reaches a certain density, the amount of required growth factors and nutrients ...
Population. A group of conspecific individuals that is demographically, genetically, or spatially disjunct from other groups of individuals. Aggregation. A spatially clustered group of individuals. Deme. A group of individuals more genetically similar to each other than to other individuals, usually with some degree of spatial isolation as well.
Allee effects are classified by the nature of density dependence at low densities. If the population shrinks for low densities, there is a strong Allee effect. If the proliferation rate is positive and increasing then there is a weak Allee effect. The null hypothesis is that proliferation rates are positive but decreasing at low densities.
An example of direct competition. Intraspecific competition is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to reproduce. [1] By contrast, interspecific competition occurs when ...
Delayed density dependence has been used by ecologists to explain population cycles. [2] Ecologists have been unable to successfully explain regular population cycles for many decades; delayed density dependence may hold the answer. [2] Here populations are allowed to increase above their normal capacity because there is a time lag until ...
Definition. A polyphenism is the occurrence of several phenotypes in a population, the differences between which are not the result of genetic differences. [2] For example, crocodiles possess a temperature-dependent sex determining polyphenism, where sex is the trait influenced by variations in nest temperature.
Ecosystem ecology is the integrated study of living (biotic) and non-living (abiotic) components of ecosystems and their interactions within an ecosystem framework. This science examines how ecosystems work and relates this to their components such as chemicals, bedrock, soil, plants, and animals. Ecosystem ecology examines physical and ...
An isodar, or habitat isodar, is a theory in evolutionary ecology developed in the late 1980s by Douglas W. Morris. [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 ...