Chapter 5 Populations

Characteristics of Populations (5.1) 1. Geographical distribution (range) 2. Density  pop. density = # individuals / unit area 3. Growth rate -number of births -number of deaths -number of individuals that enter/leave

When does a population grow? When does a population shrink?

____________- the movement of individuals into an area, results in population growth ____________- movement of individuals out of an area, population decreases Why does immigration/emigration occur?

Exponential Growth Plenty of space, food, and protection from predators and disease/unlimited resources Bacteria reproduce asexually, split in half What if doubling time is 20 min?...in one day 1 bacteria will grow to 4,720,000,000,000,000,000,000 J-shaped curve shows exponential growth

Exponential Growth, p. 121 How are the graphs alike? How are the graphs different? What do the differences indicate? Are the rates of reproduction for bacteria and elephants the same?

Logistic Growth What happens as resources become less available? S-shaped curve shows logistic growth Occurs when a population’s growth slows or stops after a period of exponential growth

How can this happen?

Carrying capacity- the largest number of individuals an environment can support