1. Ecology: Populations Ch. 24.2

2. Food and Space Organisms living in the wild do not always have enough food or living space. Competition occurs when two or more organisms seek the same resource at the same time. Competition for food, living space, or other resources can prevent population growth.

3. Population Size Population counts can help identify populations that could be in danger of disappearing. The size of a population that occupies a specific area is called population density. Trap-mark counts and sample counts are methods used to estimate the population size of animals in a particular region.

4. Limiting Factors The availability of food, water, living space, mates, nesting sites, and other resources is often limited. A limiting factor is anything that restricts the number of individuals in a population. Limiting factors include living and nonliving features of the ecosystem. A limiting factor can affect more than one population in a community.

5. Carrying Capacity Carrying capacity is the largest number of individuals of one species that an ecosystem can support over time. If a population begins to exceed the environment's carrying capacity, some individuals will not have enough resources. Individuals could die or be forced to move elsewhere.

6. Biotic Potential The highest rate of reproduction under ideal conditions is a population’s biotic potential. The larger number of offspring that are produced by parent organisms, the higher the biotic potential of the species will be. Under ideal conditions (unlimited supply of food, water, and living space) the population will continue to grow.

7. Changes in Populations Birthrates and death rates influence the size of a population and its rate of growth. Animals moving from one place to another can affect population size in a particular area. Even plants and microscopic organisms can move from place to place, carried by wind, waster, and animals.

8. Exponential Growth Exponential growth means that the larger a population becomes, the faster it grows. This can cause competition for food and den sites that will lead to an equilibrium in the population’s growth.

9. Population Practice Problem An ecologist wants to know the size of wild tulip population growing in a meadow. The meadow measures 1,000 m (squared). There are 50 tulips in an area that is 100 m (squared). What is the estimated population of tulips in the whole meadow?

10. Solution 1000 / 100 = 10 50 x 10 = 500 tulips

11. Predator- the organism that is seeking out another organism to eat, the hunter Prey- the organism being hunted