1 / 9

Populations &

Explore the characteristics of population growth, geographic distribution, and limiting factors such as competition, predation, and density factors. Discover how populations reach carrying capacity and face growth limits.

poulsen
Download Presentation

Populations &

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Populations & Limits to Growth

  2. Characteristics of a Population • Geographic Distribution: area inhabited by a population • bacteria: 1 cm3 • whale: millions km2 • Density: no. of individuals per area • Growth Rate

  3. Population Growth • number of births • number of deaths • number of individuals that enter/leave a population • Populations Grow: births > deaths • Populations Shrink: births < deaths • Immigration: movement of individuals into the area • Emigration: movement of individuals out of an area • Young leave to find mates, food shortage

  4. Exponential Growth • Ideal conditions & unlimited resources • individuals in a population reproduce at a constant rate • individual number increases slowly but becomes larger and larger until it approaches an infinitely large size

  5. Logistic Growth • with limited resources, population growth slows or stops after a period of exponential growth • produces an S shaped curve • Carrying Capacity: the size of the population when the growth rate is 0

  6. Limits to Growth • Limiting Factor: a factor that causes population growth to decrease • Competition • Predation • Parasitism and disease • Drought and climate extremes • Human Disturbances

  7. Limits to Growth • Density Limiting Factors: depends on the population size • Become limiting only when the population density, or size, becomes a certain level • Doesn’t affect small, scattered populations

  8. Density Limiting Factors • Competition: food, water, space, sunlight • More individuals living in area, the sooner available resources are used up • Between same or different species • Predation: population control • Sea otters and killer whales • Wolves and Moose • As the wolves feed upon the moose, the moose population falls which causes the wolf population to fall; the moose population can then rise which rises the wolf population • Parasitism and Disease: similar to predators • wasp cocoon on a caterpillar

  9. Density-Independent Factors • affect population regardless of size • unusual weather or natural disasters • human activities: damming rivers or clear-cutting forests • crash in population size • population may build up or stay small

More Related