Question

5-2 Limits to Growth
Limiting Factors

Answer 1

What factors limit population growth?

Limiting Factors
Limiting Factors
The primary productivity of an ecosystem can be reduced when there is an insufficient supply of a particular nutrient.
Ecologists call such substances limiting nutrients.

Limiting Factors
A limiting nutrient is an example of a more general ecological concept: a limiting factor.
In the context of populations, a limiting factor is a factor that causes population growth to decrease.
Density-Dependent Factors
Density-Dependent Factors
A limiting factor that depends on population size is called a density-dependent limiting factor.

Density-Dependent Factors

Density-dependent limiting factors include:
• competition
• predation
• parasitism
• disease
Density-Dependent Factors
Density-dependent factors operate only when the population density reaches a certain level. These factors operate most strongly when a population is large and dense.
They do not affect small, scattered populations as greatly.

Density-Dependent Factors
Competition
When populations become crowded, organisms compete for food, water space, sunlight and other essentials.
Competition among members of the same species is a density-dependent limiting factor.



Density-Dependent Factors
Competition can also occur between members of different species.
This type of competition can lead to evolutionary change.
Over time, the species may evolve to occupy different niches.
Density-Dependent Factors
Predation
Populations in nature are often controlled by predation.
The regulation of a population by predation takes place within a predator-prey relationship, one of the best-known mechanisms of population control.

Density-Dependent Factors

Density-Dependent Factors
Parasitism and Disease
Parasites can limit the growth of a population.
A parasite lives in or on another organism (the host) and consequently harms it.
Density-Independent Factors
Density-Independent Factors
Density-independent limiting factors affect all populations in similar ways, regardless of the population size.

Density-Independent Factors
Examples of density-independent limiting factors include:
• unusual weather
• natural disasters
• seasonal cycles
• certain human activities—such as damming rivers and clear-cutting forests
5-2
5-2
A limiting factor that affects all populations in similar ways regardless of their size might be
• drought.
• disease.
• predation.
• crowding.
5-2
Which of the following would be a limiting factor affecting the panda population of China?
• programs that educate people about endangered species
• capture of some pandas for placement in zoos
• laws protecting habitat destruction
• a disease that kills bamboo plants
5-2
Density-dependent factors operate most strongly when a population is
• large and dense.
• large but sparse.
• small and sparse.
• small, but growing.
5-2
Within a limited area, if the population of a predator increases, the population of its prey is likely to
• increase.
• decrease.
• remain about the same.
• become extinct.
5-2
Which of the following is a density-independent factor affecting populations?
• predation
• disease
• a destructive hurricane
• parasites

Answer 2

How do limiting factors affect populations in ecosystems?
Food supply - Not enough can affect ecosystem and endanger species.

Water Supply - Not enough can affect ecosystems and also endanger species.

Diseases - Will spread rapidly and will affect on the population and so they will affect o the ecosystem.

Predation - The number of predetors increase, the more organisms are eatan than those which are reproduced, this will rapidly affect the ecosystem.

Shelter/rocks - Animals will not have a place to live and without shelter, bad weather can wear on animals (such as snow, rain, hail, etc.) -affects ecosystem.

Sunlight - it is important for plants to make their food as they use sunlight to help make sugars and animals eat the plants. No plants, no animals! - affects ecosystem.

Space - If there are too much animals (too crowded) in an ecosystem, it will take a lot of space; on top of that, each animal will not get enough food, water and shelter that may lead animals being endangered or maybe even extinction. - which again, affects the ecosytem.

Nutrients/Soil - Soil is something that plants/foods need to survive/to grow. Without food and plants, animals and any other biotic organisms cannot survive. A fact is that it provides o2 and we give it c2.

Weather/Oxygen -
Weather - Wind, humidity, temperature, air pressure, and the precipitation is a part of why animals and other organisms need their shelter. If its too windy, hot, cold, pressure of air, or any kind of storm, the shelter will help the animals survive and cause no effection of the ecosystem.
Oxygen - animals take in oxygen and breath out carbon dioxide. plants take in carbon dioxide and give out oxygen, and the two provide for each other.