Populations

A Population group of organisms of the same species living in the same place at the same time

Different populations are all connected! When one population decreases or increases in an ecosystem, another population can be affected! Example: The story of the sea otters!

Figure 1.15 page 18

When the sea otters are absent…

Carrying Capacity The maximum population that an environment can sustain or support. Seychelles Paradise Flycatcher needs one acre of mixed forest per breeding pair. They live on the little island of Madagascar

Carrying Capacity a population remains at its carrying capacity when in balance (number of individuals added and the number of individuals that leave or die are the same)

Factors Determining Carrying Capacity materials & energy: energy, water, carbon, and other essential nutrients (Abiotic Factors)

Factors Determining Carrying Capacity 2. Food chains: the population size is limited by the size of the populations at lower trophic levels

Factors Determining Carrying Capacity 3. Competition: each organism has the same need as any other; they compete for resources such as food, water, mates and space

3. A closer look at Competition: Two types of competition: Intraspecific competition: among members of the same species ex: two wolves compete for a rabbit Interspecific competition: between different species ex: cheetah and lion compete for zebra

4. Population Density: depending on their size, environment and way of life, different species have different needs for space

Density Dependent Factors Occur when the density has gone beyond an appropriate level Over-population can: Increase stress & lead to easier spread of diseases and parasites Increases aggression & causes parents to neglect offspring This causes the population to decrease

Density Independent Factors Limits the population- no matter what the density is. Forest fires Earthquakes Volcanic Eruptions Tornadoes Floods

To Do: Vocabulary Words and questions at the end of your sheet of notes Sheet - Population Terms

Video - Populations Ecology - Crash Course

Population Growth Curves

Population Growth if unlimited resources are present, growth will be exponential the curve will always be a “J” curve or an exponential growth curve

resources are never unlimited as population rises, resources decline if the growth is too rapid, resources are rapidly depleted and a population crash can occur this pattern occurs often with many populations (including humans)

Elk

Video - The Importance of Predators

more often what happens is that the resources slowly decrease, the growth rate slowly increases, and they meet this point that they oscillate around is the carrying capacity of the environment for that particular organism this is called an s-shaped or logistic curve

To do: Notes: Population Growth Curves/ Practice Sheet: Carrying Capacity Practice Sheet: Fruit Flies and population growth

Human Population Growth What are the causes of this huge increase in the human population? What are some possible consequences for us? Our future? (Think: the elk)

To Do: Video: 7 Billion Current World Population Activity: Human Population Growth

Video – How many people can live on planet Earth? (45 min) Video – How Many People Can Earth Support (10 min) Movie – Future Earth (45 min)

Movie - World Population to hit 11 Billion in 2100 (45 minutes) Movie – Overpopulated (1 hour) Video – The Science of Overpopulation (crash course) – 10 minutes