1. Population Ecology Mrs. Gamari

2. Ecology  The study of the interaction between organisms and their environment (living and non-living).  Biotic – living factors  Example: living organisms in the environment and their effects on other living things  Abiotic – non-living factors  Example: water, oxygen, light, temperature, inorganic and organic nutrients

3. Organization in the Living Environment  Ecologists often study a group of organisms in a particular environment.  Population  All individuals of a single species that live within a certain area  EXAMPLE: All of the bullfrogs in a pond = population  Community  A group of different populations/organisms in a certain area.  Example: The bullfrogs, fish, algae, plants, etc. in that same pond  Ecosystem  A community and its physical environment; made of abiotic and biotic factors.  Continual exchange between all parts (living and nonliving) of the ecosystem

4. Population Size  The number of individuals that a population contains.  Can be difficult to measure directly, especially if there are too many organisms over a large area, and they are very mobile.  Therefore, an ecologist may need to ESTIMATE the number of individuals in a population

5. CRITICAL THINKING  An ecologist counts 25 oak trees in a small patch of forest. S/he needs to estimate how many oak trees would be in an area that is 10x larger than the small patch. How many oak trees could be in that larger area? Explain your reasoning.

6. Population Density  Measures how crowded a population is.  Number of individuals per unit of area  Some areas are sparsely populated, while others are very densely populated.  Why do you think this may be?

7. Measuring the Number of Individuals in a Population  Random Sampling – count the number of individuals in a small area. Extrapolate to find the number of individuals in a larger area.  Mark and Recapture – mark a sample of individuals and return them to the wild. Come back and capture another sample to see how many have already been marked. Use a formula to estimate population size

8. Dispersion  The spatial distribution of individuals within the population http://www.uwyo.edu/dbmcd/popecol/feblects/lect06.html The distribution of a population may be impacted by availability of resources, social behavior, or habitat conditions.

9. Age Structure Total number of people Females Percentage of individuals within a particular age range Age ranges The Regional Institute © 2007 Western New York Age Pyramid, 2000 http://www.uwyo.edu/dbmcd/popecol/feblects/lect06.html Males

10. Population Dynamics  A population will change in size depending on how many organisms are added to it and how many organisms are removed from it.  If resources are not limited, then the population will grow when the number of new individuals added to the population (births) is greater than the number of individuals who leave the population (deaths).  Immigration vs. Emigration

11. J- Shape Curve  The population keeps growing over time. Starts slowly, but then rapidly increases.  Number of individuals coming into the population exceeds the number leaving the population The Biology Corner http://www.biologycorner.com/bio4/notes/popgrowth.php

12. Carrying Capacity  The maximum population that can be supported by resources in the environment. In reality, resources are not “unlimited.”

13. S- Shape Curve  Shows how a population becomes limited by environmental factors  The “plateau” is the carrying capacity for the area – the maximum number of individuals that the environment can support. The Biology Corner http://www.biologycorner.com/bio4/notes/popgrowth.php

14. Factors That Limit Population Growth  Nutrients  Water  Disease  Competition  Predation  Space

15. Population Regulation  Density-Independent Factors  Weather, floods, fires  Reduce the size of populations, regardless of the original size or density of a particular population.  Density-Dependent Factors  Resource limitations, shortage of food, habitats (competition, predation, disease, parasitism and disease)  Triggered by increasing populations  An individual’s chance of surviving depends on the number of other individuals in that area.

16. Predation

17. Competition  Intraspecific competition: competition within a species for resources (food, light, space, nutrients, habitats)  Interspecific competition: competition between members of different species. HUGE impact on evolutionary change because survival rates can be affected over time.