This document summarizes key concepts in population ecology, including factors that influence population size and distribution patterns. Populations can exhibit clumping, uniform, or random dispersion patterns depending on resource availability and other factors. A population's size is determined by the balance between birth and death rates, which are influenced by biotic potential and environmental resistance. Humans can impact ecosystems through activities like habitat degradation and overharvesting. Sustainable practices can be informed by principles seen in nature, such as nutrient recycling and population control.

1. Population Ecology Chapter 9 G T Miller Jr. Shohail Motahir Choudhury

2. Sea Otters: Back from Extinction

4. Three general patterns: clumping, uniform distribution, and random dispersion. Most species live in clumps or groups. Population Distribution

6. Factors Governing Population Size Births and Immigration Deaths and Emigration Population Change = (Births+Immigration)- (Deaths+Emigration)

7. Factors limiting population growth No Population can grow indefinitely because resources Light Water Nutrients Biotic Potential. Housefly: 5.6 trillion within 13 months. Within few years can cover the earth’s entire surface. (Intrinsic rate of increase (r). Nature limits population growth. Environmental resistance . Together biotic potential and environmental resistance determine the carrying capacity (K).

8. Population Size Growth and Decrease Factors Growth factors (biotic potential) Favorable light Favorable temperature Favorable chemical environment (optimal level of critical nutrients) Abiotic 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 Too much or too little light Temperature too high or too low Unfavorable chemical environment (too much or too little of critical nutrients) Abiotic 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 Decrease factors (environmental resistance) Biotic Biotic

9. Exponential vs logistic growth

10. Reindeer introduction in south coast of Alaska. 26 8 Sheep introduction in Tasmania.

11. Types of population fluctuations

12. Predation in Controlling Population Size Top-down Bottom –up Interaction between predation and food supplies.

13. 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

14. Learning from Nature Principles of sustainability Solar Energy Nutrient Recycling Population Control Biodiversity

15. Next Class Energy Efficiency and Renewable Energy Chapter 18 G T Miller Jr. Shohail Motahir Choudhury Poster Presentation: February 21