Ecology Notes

1. Ecology Notes Populations – Chapter 5

2. Characteristics of Populations • Population – group of individuals of the same species that live in the same area. • 1. geographic distribution – the area inhabited by a population (range)

3. Population Density2. density – number of individuals per unit area. • Area = L X W • Area = 2m X 1m • Area = 2 meters2 • Population Density = # individuals/area • Population Density = 6/2 = 3 rabbits per square meter 1 meters 2 meters

4. 3. Growth – Constant or Change drastically 4 factors affect population size 1. Natality – birth rate 2. Mortality – death rate 3. Immigration – individuals IN 4. Emmigration – individuals OUT

5. Average Annual Change • The average rise or fall in a population per year. Can be positive or negative • Formula A.A.C.= change in pop./years • Sample Problem What is the average annual change of this monkey population? 2001 – Rainforest 125 monkeys 2001-2005 I=10, N=7, E=8, M=3 Change =+6 Average Annual Change = +6/4yrs.=+1.5 monkeys/year

6. Exponential vs. Logistic Growth • Exponential growth – population grows at a constant rate…with unlimited resources this will occur. • Logistic Growth- occurs when growth slows or stops. The largest number of individuals the environment can support is called the carrying capacity.

7. Limiting Factors • Limiting factors cause population growth to decrease. • Density dependent – a factor that depends on population size. Occurs when populations are large and dense. • Competititon • Predation • Parasitism • Disease

8. Density Independent Factors • A factor that affects all populations in similar ways, regardless of population size. • Unusual weather • Natural disaster • Seasonal cycles • Human activity