Ecology – Part 3

•  Carrying Capacity •  Population Growth •  Human Population •  Biodiversity

Exponential Growth Curve

Population Growth of Houseflies 1 million

500,000

100 One year

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Carrying Capacity vs. Exponential Growth

•  J-shaped curve S-shaped curve

Carrying Capacity

•  The maximum number of organisms that can be supported in an area…

Carrying Capacity

•  This graph shows an S-curve

•  As the population size approaches the carrying capacity (dashed-line), the growth slows down (note the blue arrows)

Time

Population

Figure 52.19 Population cycles in the snowshoe hare and lynx

Figure 41.9 Bulk-feeding: a python

Certain limiting factors are related to population density (size)…

•  Density-dependent factors: – They depend on population size. – Examples: Food availability

Disease Predators

•  Density-independent factors – These do not depend on population size.

Examples: Floods, drought, natural disasters.

Human Population

Human Population (con’t)

Age Structure – number of people at each different age