What are the 6 factors that affect population size?
- Economic development. …
- Education. …
- Quality of children. …
- Welfare payments/State pensions. …
- Social and cultural factors. …
- Availability of family planning. …
- Female labour market participation. …
- Death rates – Level of medical provision.
What limits the size of a population?
What factors limit population sizes? In nature, population size and growth are limited by many factors. Some are density-dependent, while others are density-independent. Density-dependent limiting factors cause a population's per capita growth rate to change—typically, to drop—with increasing population density.
What are the two main factors that regulate population growth?
Broadly speaking, we can split the factors that regulate population growth into two main groups: density-dependent and density-independent. Let's start off with an example.
What are density dependent limiting factors?
Density dependent limiting factors depend on population size. These types of factors include disease, pollution, competition, and predation between species in a population. How do limiting factors most affect population size?
What are the limiting factors in ecology?
Limiting factors in ecology include the water and sunlight a plant needs to complete photosynthesis. Biological factors that limit population growth include predator-prey relationships such as that between a cat and a bird. The human population can also be impacted by limiting factors.
How long is the cycle of a lemming?
For years, this population had cyclical oscillations in size, with a period—the length of a full cycle—of about four years. Ecologists found that the cycle could be explained by interactions between the lemming and four predators: the owl, fox, skua—a bird—and stoat. The owl, fox, and skua are opportunistic predators that can use various food sources and tend to eat lemmings only when they are abundant. The stoat, in contrast, eats pretty much only lemmings.
What are density dependent limiting factors?
Density-dependent limiting factors tend to be biotic —living organism-related—as opposed to physical features of the environment. Some common examples of density-dependent limiting factors include: 1 Competition within the population. When a population reaches a high density, there are more individuals trying to use the same quantity of resources. This can lead to competition for food, water, shelter, mates, light, and other resources needed for survival and reproduction. 2 Predation. Higher-density populations may attract predators who wouldn’t bother with a sparser population. When these predators eat individuals from the population, they decrease its numbers but may increase their own. This can produce interesting, cyclical patterns, as we'll see below. 3 Disease and parasites. Disease is more likely to break out and result in deaths when more individuals are living together in the same place. Parasites are also more likely to spread under these conditions. 4 Waste accumulation. High population densities can lead to the accumulation of harmful waste products that kill individuals or impair reproduction, reducing the population’s growth.
How do oscillations occur?
Where do these oscillations come from? In many cases, oscillations are produced by interactions between populations of at least two different species. For instance, predation, parasite infection, and fluctuation in food availability have all been shown to drive oscillations. These density-dependent factors don't always create oscillations, however. Instead, they only do so under the right conditions, when populations interact in specific ways.
What are the two main groups of environmental limiting factors?
What exactly are these environmental limiting factors? Broadly speaking, we can split the factors that regulate population growth into two main groups: density-dependent and density-independent.
How do rodents respond to density?
For example, rodents called lemmings respond to high population density by emigrating in groups in search of a new, less crowded place to live. This process has been misinterpreted as a mass suicide of sorts in popular culture because the lemmings sometimes die while trying to cross bodies of water.
What are some examples of density-independent factors?
Density-independent factors affect per capita growth rate independent of population density. Examples include natural disasters like forest fires. Limiting factors of different kinds can interact in complex ways to produce various patterns of population growth.
Why do deer die?
Because of the competition, some deer may die of starvation or fail to have offspring, decreasing the per capita —per individual—growth rate and causing population size to plateau or shrink. In this scenario, competition for food is a density-dependent limiting factor.
