(environmental resistance) POPULATION SIZE Growth factors (biotic potential) Favorable light Favorable temperature Favorable chemical environment (optimal level of critical nutrients) Abiotic Biotic High reproductive rate Generalized niche Adequate food supply Suitable habitat Ability to compete for resources Ability to hide from or defend against predators Ability to resist diseases and parasites Ability to migrate and live in other habitats Ability to adapt to environmental change Decrease factors (environmental resistance) Too much or too little light Temperature too high or too low Unfavorable chemical environment (too much or too little of critical nutrients) Low reproductive rate Specialized niche Inadequate food supply Unsuitable or destroyed habitat Too many competitors Insufficient ability to hide from or defend Inability to resist diseases and parasites Inability to migrate and live in other Inability to adapt to environmental © 2004 Brooks/Cole – Thomson Learning

Population Dispersion Factors (a) Clumped (elephants) (b) Uniform (creosote bush) (c) Random (dandelions) Population Dispersion Factors

Environmental resistance Figure 9-4 Page 166 Environmental resistance Carrying capacity (K) Population size (N) Biotic potential Exponential growth Time (t)

Number of sheep (millions) 2.0 Overshoot Carrying capacity 1.5 Number of sheep (millions) 1.0 .5 1800 1825 1850 1875 1900 1925 Year

Population overshoots carrying capacity 2,000 Population crashes 1,500 Number of reindeer 1,000 Carrying capacity 500 1910 1920 1930 1940 1950 Year

© 2004 Brooks/Cole – Thomson Learning (d) Irregular (a) Stable Number of individuals (c) Cyclic (b) Irruptive Time

Population size (thousands) 160 Hare 140 Lynx 120 100 Population size (thousands) 80 60 40 20 1845 1855 1865 1875 1885 1895 1905 1915 1925 1935 Year

Reproductive Patterns and Survival Asexual reproduction r-selected species Sexual reproduction K-selected species Fig. 9-10 p. 170

Carrying capacity K K species; experience K selection Number of individuals r species; experience r selection Time

Percentage surviving (log scale) Types of Survivorship Curves Figure 9-11 Page 171 Late loss 100 Constant loss 10 Percentage surviving (log scale) 1 Early loss Age Types of Survivorship Curves

Exponential and Logistic Growth

World 21 9 All developed countries 11 10 All developing countries 24 8 Average crude birth rate Average crude death rate World 21 9 All developed countries 11 10 All developing countries 24 8 Developing countries (w/o China) 27 9 © 2004 Brooks/Cole – Thomson Learning

Factors Affecting Human Population Size Population change equation Population Change = (Births + Immigration) – (Deaths + Emigration) Crude birth rate (BR) Crude death rate (DR) Refer to Figure 10-3, p. 177

Describing Population Changes Doubling Times “Rule of 70” Fertility Replacement-level Fertility Total Fertility Rate (TFR)

© 2004 Brooks/Cole – Thomson Learning Africa 38 Figure 10-3b Page 177 14 Latin America 22 © 2004 Brooks/Cole – Thomson Learning 6 Asia 20 7 Oceania 18 7 United States 14 8 North America 14 8 Europe 10 12

© 2004 Brooks/Cole – Thomson Learning China © 2004 Brooks/Cole – Thomson Learning 1.3 billion Figure 10-4 Page 178 1.4 billion India 1.1 billion 1.4 billion USA 294 million 349 million Indonesia 219 million 308 million Brazil 179 million 211 million Pakistan 159 million 229 million Russia 144 million 137 million Bangladesh 141 million 205 million Japan 128 million 121 million Nigeria 137 million 206 million 2004 2025

Population Age Structure Rapid Growth Guatemala Nigeria Saudi Arabia Slow Growth United States Australia Canada Male Female Zero Growth Spain Austria Greece Negative Growth Germany Bulgaria Sweden

© 2004 Brooks/Cole – Thomson Learning Figure 10-14b Page 184 Male Female Male Female Zero Growth Spain Austria Greece Negative Growth Germany Bulgaria Sweden Ages 0-14 Ages 15-44 Ages 45-85+ © 2004 Brooks/Cole – Thomson Learning

Iraq Population Pyramids Population Pyramid Summary for Iraq                                                                                                                                                                                                                                                                                      

Italy Population Pyramids Population Pyramid Summary for Italy                                                                                                                                                                                                                                                                                      

Somalia Population Pyramids

© 2004 Brooks/Cole – Thomson Learning Age Age Figure 10-18a Page 186 Females Males Females Males 24 20 20 16 16 12 12 8 1955 8 1985 4 4 4 4 8 8 12 12 16 Millions 16 20 Millions 20 24 © 2004 Brooks/Cole – Thomson Learning

© 2004 Brooks/Cole – Thomson Learning Age Age Figure 10-18b Page 186 Females Males Females Males 20 20 20 20 16 16 12 12 8 8 1955 4 2035 4 4 4 8 8 12 12 16 16 20 20 Millions 24 Millions 24 © 2004 Brooks/Cole – Thomson Learning

Relative population size Birth rate and death rate Figure 10-20 Page 189 Stage 1 Preindustrial Stage 2 Transitional Stage 3 Industrial Stage 4 Postindustrial Low High Relative population size (number per 1,000 per year) Birth rate and death rate 80 70 60 50 40 30 20 10 Birth rate Death rate Total population Low Increasing Very high Decreasing Low Zero Negative Growth rate over time