What is positive density dependence?

What is positive density dependence?

Positive density-dependence Positive density-dependence, density-dependent facilitation, or the Allee effect describes a situation in which population growth is facilitated by increased population density.[[

What is density dependence in ecology?

Density dependence usually is seen as a linear, inverse relationship between population growth rate and population density (i.e., population growth decreases as density increases) and may occur if individuals compete or predators are more effective as a prey population increases.

What are some causes of positive density dependence?

Conspecific positive density dependence has been described for most major animal taxa (reviewed by Courchamp et al., 1999; Stephens et al., 1999; Kramer et al., 2009), and can be caused by a variety of mechanisms, such as mate limitation (Gascoigne et al., 2009), cooperative feeding (Carbone et al., 1997), cooperative …

What is an example of positive density dependence?

A known example of positive density dependence is the Allee-effect (Allee 1931), when population growth rate is very low at low density, due to the low chance to find mates (or to be pollinated, in plants).

What is two examples of density-dependent factors?

Some common examples of density-dependent limiting factors include:

• Competition within the population. When a population reaches a high density, there are more individuals trying to use the same quantity of resources.
• Predation.
• Disease and parasites.
• Waste accumulation.

How can we differentiate between negative and positive density-dependent rates?

The negative effects of density dependence are usually better known than the positive ones. Negative density-dependent effects occur if a vital rate decreases as density increases, positive effects occur if both increase.

Which of the following is an example of a density-dependent effect on population growth?

Density-dependent factors include disease, competition, and predation.

Which of the following is an example of a density independent factor?

The two examples of density independent factors are natural disasters and human activity. Natural disasters, like wildfires, are factors that limit population sizes irrespective to density of the population.

What are some examples of density independent factors?

Most density-independent factors are abiotic, or nonliving. Some commonly used examples include temperature, floods, and pollution.

Is predation a density-dependent factor?

Density-dependent limiting factors tend to be biotic—having to do with living organisms. Competition and predation are two important examples of density-dependent factors.

What evidence would you need to determine whether a population experiences negative density dependence or positive density dependence?

What evidence would you need to determine whether a population experiences negative density dependence or positive density dependence? Negative density dependence occurs when the rate of population growth decreases as population density increases.

Does density dependence always occur in all populations?

The assumption that density dependence must always occur in all populations is likely unwarranted, and restricts consideration of other factors in population growth. The condition that environmental factors influence population growth rate in relation to population size.

Why is density dependence important to conservation?

Density dependence is important to conservation because it can lead to either population regulation (i.e., stabilization of population size) or population destabilization (thus increasing the probability of population crashes and extinction).

What is density dependent model in ecology?

Density-Dependent Models. If weed density is high enough to result in intraspecific competition, density dependence should be considered in the models. Density dependence has been shown as a rather general rule for plant populations which acts at different life-cycle stages.

How does density dependence affect population growth in tropical forests?

Density dependence can affect population growth either positively or negatively. Positive density dependence is often observed, for instance, within large stands of a single tree species such as lodgepole pine, where a single tree species dominates an entire landscape. But in tropical forests, negative density dependence is extremely important.