Population Dynamics, Carrying Capacity, and Human Population Brian Kaestner Saint Mary’s Hall Brian Kaestner Saint Mary’s Hall Thanks to Miller and Clements

Population Dynamics and Carrying Capacity  Population dynamics  Zero population growth (ZPG)  Biotic potential (intrinsic rat of increase [r])  Environmental resistance  Carrying capacity  Minimum viable population (MVP)

Population Dispersion Clumped(elephants)Uniform (creosote bush) Random(dandelions) Fig. 9.2, p. 199

Factors Affecting Population Size 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) Abiotic Biotic Low reproductive rate Specialized niche Inadequate food supply Unsuitable or destroyed habitat Too many competitors Insufficient ability to hide from or defend against predators Inability to resist diseases and parasites Inability to migrate and live in other habitats Inability to adapt to environmental change Fig. 9.3, p. 200

Exponential and Logistic Growth Year Time (t) Population size (N) Exponential Growth Time (t) Population size (N) K Logistic Growth Year Number of reindeer Number of sheep (millions) ,000 1, , Fig. 9.4, p. 201 Fig. 9.5, p. 201Fig. 9.6, p. 201

Population Density Effects  Density-independent controls  Density-dependent controls

Natural Population Curves Number of individuals Time Irruptive Stable Cyclic Irregular Fig. 9.7, p. 202

The Role of Predation in Controlling Population Size  Predator-prey cycles  Top-down control  Bottom-up control Population size (thousands) Year Hare Lynx Fig. 9.8, p. 203

Reproductive Patterns and Survival  Asexual reproduction  Sexual reproduction  r-selected species  K-selected species r-Selected Species cockroachdandelion Many small offspring Little or no parental care and protection of offspring Early reproductive age Most offspring die before reaching reproductive age Small adults Adapted to unstable climate and environmental conditions High population growth rate (r) Population size fluctuates wildly above and below carrying capacity (K) Generalist niche Low ability to compete Early successional species Fewer, larger offspring High parental care and protection of offspring Later reproductive age Most offspring survive to reproductive age Larger adults Adapted to stable climate and environmental conditions Lower population growth rate (r) Population size fairly stable and usually close to carrying capacity (K) Specialist niche High ability to compete Late successional species elephantsaguaro K-Selected Species Fig. 9.10b, p. 205

Survivorship Curves Percentage surviving (log scale) Age Fig. 9.11, p. 206

Human Impacts on Ecosystems  Habitat degradation and fragmentation  Ecosystem simplification  Genetic resistance  Predator elimination  Introduction of non-native species  Overharvesting renewable resources  Interference with ecological systems

Fig. 9.12, p. 208 Physiological changes Psychological changes Behavior changes Fewer or no offspring Genetic defects Birth defects Cancers Death Organism Level Change in population size Change in age structure (old, young, and weak may die) Survival of strains genetically resistant to stress Loss of genetic diversity and adaptability Extinction Population Level Disruption of energy flow through food chains and webs Disruption of biogeochemical cycles Lower species diversity Habitat loss or degradation Less complex food webs Lower stability Ecosystem collapse Environmental Stress

Key Concepts  Factors affecting human population size  Managing population growth  Human population problems

Fig. 11.2a, p. 239 Average crude birth rateAverage crude death rate World All developed countries All developing countries Developing countries (w/o China)

Fig. 11.2b, p. 239 Africa Latin America Asia Oceania United States North America Europe

Factors Affecting Human Population Size  Population change equation  Zero population growth (ZPG)  Crude birth rate (BR)  Crude death rate (DR) Refer to Fig p. 239 Population Change Population Change = = (Births + Immigration) – (Deaths + Emigration)

Natural Rate of Increase <1% 1-1.9% 2-2.9% 3+% Data not available Annual world population growth Fig. 11.3, p. 240

Fig. 11.6, p. 241 Asia Europe Africa Latin America North America Oceania 3.7 billion 4.7 billion 728 million 714 million 800 million 1.3 billion 518 million 703 million 306 million 374 million 31 million 39 million

Fig. 11.5, p. 241 China India USA Indonesia Brazil Pakistan Russia Bangladesh Japan Nigeria billion 1.4 billion 1 billion 1.4 billion 276 million 338 million 212 million 273 million 170 million 221 million 151 million 227 million 145 million 137 million 128 million 177 million 127 million 121 million 123 million 205 million

Births per woman < No Data Fertility Rates  Replacement-level fertility  Total fertility rate (TFR) Fig. 11.8, p. 242

Fig. 11.7, p. 241 World Developed countries Developing countries Africa Latin America Asia Oceania North America Europe 5 children per women

The Demographic Transition Low High Relative population size Birth rate and death rate (number per 1,000 per year) Birth rate and death rate (number per 1,000 per year) Stage 1 Preindustrial Stage 1 Preindustrial Stage 2 Transindustrial Stage 2 Transindustrial Stage 3 Industrial Stage 3 Industrial Stage 4 Postindustrial Stage 4 Postindustrial Low growth rate Low growth rate Increasing Growth growth rate Increasing Growth growth rate Very high growth rate Very high growth rate Decreasing growth rate Decreasing growth rate Low growth rate Low growth rate Zero growth rate Zero growth rate Negative growth rate Negative growth rate Birth rate Total population Death rate TimeTime Fig , p. 255

Factors Affecting BR and TFR  See bulleted list in text p. 243  US BR’s and TFR’s Births per thousand population Demographic transition Depression Baby boom Baby bust Echo baby boom World War II Year Fig , p. 243 see Fig p. 243

Fig. 11.9, p. 242 High Medium Low High 10.7 Medium 8.9 Low 7.3 Year Population (billion)

Fig , p Year Births per woman

Infant deaths per 1,000 live births <10 <10-35 <36-70 < <100+ Data not available Factors Affecting DR  Life expectancy  Infant mortality rate (IMR) Fig , p. 246

Factors Affecting Natural Rate of Increase Developed Countries Rate per 1,000 people Year Rate of natural increase Crude birth rate Crude death rate Rate of natural increase = crude birth rate = crude death rate Developed Countries Rate per 1,000 people Crude birth rate Rate of natural increase Crude death rate Year Fig , p. 245

Ages 0-14 Ages Ages Rapid Growth Guatemala Nigeria Saudi Arabia Rapid Growth Guatemala Nigeria Saudi Arabia Slow Growth United States Australia Canada Slow Growth United States Australia Canada Male Female Zero Growth Spain Austria Greece Zero Growth Spain Austria Greece Negative Growth Germany Bulgaria Sweden Negative Growth Germany Bulgaria Sweden Population Age Structure Fig a, p. 247

Solutions: Influencing Population Size  Migration  Environmental refugees  Reducing births  Family planning  Empowerment of women  Economic rewards and penalties

Case Study: Slowing Population Growth in India  Poor planning  Bureaucratic inefficiency  Low status of women  Extreme poverty  Lack of support Generally disappointing results:

Case Study: Slowing Population Growth in China  Economic incentives  Free medical care  Preferential treatment  Intrusive and coercive  Locally administered Generally positive results:

Cutting Global Population Growth  Family planning  Reduce poverty  Elevate the status of women