Population Growth Agenda 1 CH 5 1 Population

Population Growth

Agenda 1. CH 5 -1 Population Growth 2. CH 5 -2 Limits to Growth

Population • A population has 4 characteristics – Geographic distribution – Density – Growth rate • So how many students are in here? How about in two rooms? • Population density – the number of individuals per unit area

Volunteers • How can a population change?

Populations can change by: • • Immigration – moving into a population Emigration – moving out of a population Birthrate Deathrate

Population growth graph • X axis = time • Y axis = number of individuals • Exponential Growth (J curve) – Ideal conditions with unlimited resources – Population grows exponentially • Logistic growth (S curve) – Resources are less available – Population growth slows or stops

Number of Mice Carrying capacity Time (hours)

Concept Map Population Growth can be Logistic growth Exponential growth characterized by No limits on growth Unlimited resources represented by Constant growth rate J-shaped curve characterized by Limits on growth which cause a Falling growth rate represented by S-shaped curve

Limiting Factors ► Limiting factor § A situation that causes the growth of a population to decrease Some limiting factors depend on the size of the population. 2. Other limiting factors affect all populations in similar ways. 1.

Limiting factors 1. Density dependent factors § Affected by population § Food, space, competition, waste, so on 2. Density independent factors § Population does not affect it § Natural disasters, weather ► Both are limiting factors that affect the overall population

Wolf and Moose Populations on Isle Royale 60 2400 50 2000 40 1600 30 1200 20 800 10 400 0 1955 1960 1965 1970 1975 Moose 1980 Wolves 1985 1990 1995 0

Homework • SA 5 -1 #1 -6 • SA 5 -2 #1 -5 • Read Ch 5 -3