1. POPULATIONS

2. POPULATIONS Population: all the members of one species that occupy a certain area during a certain time. Population: all the members of one species that occupy a certain area during a certain time. Ex. The population of bass in Lake Ontario in September of 2010 Ex. The population of bass in Lake Ontario in September of 2010 Biodiversity: the number of different types of species living in an ecosystem. Biodiversity: the number of different types of species living in an ecosystem. Ex. A tropical rainforest is biodiverse. Ex. A tropical rainforest is biodiverse. Ex A ______________ is not biodiverse. Ex A ______________ is not biodiverse.

3. DID YOU KNOW??? As of Sept 22nd, 2010, Earth’s population is estimated to be about 6,872,897,353 !!!!! As of Sept 22nd, 2010, Earth’s population is estimated to be about 6,872,897,353 !!!!! By 2040, the population of Earth is estimated to reach about 9 billion people! By 2040, the population of Earth is estimated to reach about 9 billion people!

4. POPULATION GROWTH PATTERNS Four factors affect the size of a population: Four factors affect the size of a population: 1. Natality is the number of offspring of a species born in one year. 2. Immigration refers to the number of individuals of a species moving into an existing population. (these increase the population)

5. 3. Mortality is the number of individuals of a species that die in one year. 4. Emigration refers to the number of individuals of a species moving out of an existing population. (these decrease the population size) POPULATION GROWTH PATTERNS

6. CARRYING CAPACITY The maximum size of a population that an ecosystem can sustain is called its carrying ecosystem can sustain is called its carrying capacity. Carrying capacity is determined by four factors. 1) Amount of available energy and materials 2) Predation 3) Competition 4) Amount of available space

7. 1. Amount of Available Energy and Materials If a population grows too large, it will eventually crash when resources (nutrients, water, or energy) runs out. Ex. 2. Predation If a population grows too large, predation will increase, reducing the size of the population. (i.e. predators limit the size of the prey population) Ex.

8. If resources become more scarce, members of a population must fight for their survival. This competition reduces the population by weaning out the weak or vulnerable members. There are two types of competition: 3. Competition

9. TYPES OF COMPETITION Intraspecific Competition – competition among members of the same species Intraspecific Competition – competition among members of the same speciesEx. Interspecific Competition – competition between members of different species Interspecific Competition – competition between members of different speciesEx.

10. If a population grows too large, space will run out. Competition for space will reduce the population. If the density is too high, stress, disease, or parasites will reduce the population size Ex. 4. Space

11. Density-Dependent Factors These are factors that affect a population due to its size. Ex. a food shortage,

12. Density-Independent Factors These are factors that affect a population regardless of its size. Ex. a flood,