1. Lesson Overview Lesson Overview How Populations Grow Lesson Overview How Populations Grow and their limits

2. Lesson Overview Lesson Overview How Populations Grow Describing Populations How do ecologists study populations? Researchers study populations’; geographic range density and distribution growth rate age structure

3. Lesson Overview Lesson Overview How Populations Grow Population density  number of individuals per unit area. Distribution  how individuals in a population are spaced out—randomly, uniformly, clumps. age structure— # of males/females of each age a population contains. [this is important for reproduction!!!]

4. Lesson Overview Lesson Overview How Populations Grow What factors affect population growth? Birth rate Death rate Immigration and Emigration

5. Lesson Overview Lesson Overview How Populations Grow What happens during exponential growth? Under ideal conditions with unlimited resources, a population will grow exponentially. (ex. Bacteria in a petri dish)

6. Lesson Overview Lesson Overview How Populations Grow What is logistic growth? Logistic growth  population’s growth slows then fluctuates at carrying capacity: the maximum # of individuals the environment can support.

7. Lesson Overview Lesson Overview How Populations Grow A limiting factor  controls the growth of a population.

8. Lesson Overview Lesson Overview How Populations Grow Human Population Growth- History For most of human existence, the population grew slowly because life was harsh. Food was hard to find. Predators and diseases were common and life-threatening.

9. Lesson Overview Lesson Overview How Populations Grow Renewable and Nonrenewable Resources renewable  produced or replaced by a healthy ecosystem in a short/reasonable amount of time. (solar, wind, water) nonrenewable  natural processes cannot replenish them within a reasonable amount of time. Fossil fuels like coal, oil, and natural gas are nonrenewable resources formed from buried organic materials over millions of years.

10. Lesson Overview Lesson Overview How Populations Grow Global Warming Caused by: Increased amount of CO 2 in the air from burning fossil fuels and deforestation. Results in: Warmer ocean temps and climate change: unusual weather patterns.

11. Lesson Overview Lesson Overview How Populations Grow Hole in the Ozone Layer Caused by: Chloroflourocarbons or CFC’s, chemical released into the atmosphere from old air conditioning units and aerosol spray cans. Results in: Thinner ozone layer that lets in MORE UV light from the sun. UV light is a mutagen, mutates DNA. Now have increased incidence of skin cancer!!

12. Lesson Overview Lesson Overview How Populations Grow Deforestation & Desertification Caused by: Deforestation – cutting down trees Desertification – when drought and over-farming cause farmland to turn to desert. Results in: Deforestation - ↓ soil quality, severe erosion, ↓ # of trees absorbing CO 2 and releasing oxygen. Desertification – soil erosion.