2.7 Biotic and Abiotic Influences on Ecosystems Limiting Factors and Carrying Capacity

Limiting Factors The population size of a species can be limited by abiotic and biotic factors

Density dependent: factors that are based on the size of the population. Disease Predation (When one species preys (feeds) on another) Competition (for resources such as nesting sites, water, or food)

Example of Predation: a lynx and hare, if the lynx eat too many hares, the lynx population declines also.

Example of Competition: birds may compete for nesting space

Density independent: affect population growth regardless of population size natural disasters old age hunting Ex) A flood will wipe out the same percentage of population regardless of its size

Symbiosis is the close and often long-term interaction between two different biological species. Mutualism both species benefit from each other ex) Clownfish and sea anemone the clownfish cleans the anemone and the anemone protects the clownfish

Parasitism one organism lives on/feeds on host. one organism benefits while the other is harmed ex) Humans and mosquitoes mosquitoes bite humans to get food, while humans are harmed by blood loss, itching, and sometimes even disease

Commensalism one organism benefits while the other is unharmed. ex) a whale and a barnacle the barnacle attaches to the whale and gets a habitat and a free ride to a new food source while the whale is not harmed

Population Calculation Population numbers can be determined by the following equation: (Birth rate + Immigration) – (Death Rate + Emigration) Immigration = species moving into a region Emigration = species moving out of a region

Influence of Biotic Factors on Population Carrying Capacity The maximum population size of a particular species that a given ecosystem can sustain. As population's size increases, the demand for resources, such as food, water, shelter, and space also increase. Eventually, there will not be enough resources for each individual.

Limiting Factors Carrying Capacity

Types of Population Growth

Human Population Trend Earth’s Population is approximately 7.349 billion as of July 1, 2015. What’s our limit? 8 billion 9 billion 10 billion Are we headed for a crash?

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