1. Ch 8: Population Ecology

2. Population Dynamics and Carrying Capacity • Most populations live in clumps due to resource availability, protection, food capture, mating and/or caring for young. • 4 variables in population changes: • Birth, death, immigration, emigration

3. Population Dynamics and Carrying Capacity • Limits to population growth • Biotic potential: • Intrinsic rate of increase: • Species with high intrinsic rate of increase reproduce early in life, have short generations, reproduce many times and have many offspring. • Ex: Housefly (5.6 trillion in 13 months)

4. Population Dynamics and Carrying Capacity • No population can grow indefinitely due to limiting factors. • Environmental resistance: • Carrying capacity (K): • Exponential growth: • Logistic growth: • Occurs when populations encounter environmental resistance.

5. Reproductive Patterns • Asexual reproduction: • Sexual reproduction: • Disadvantages • Males don’t give birth (females have to produce twice as many offspring) • Increased chance of genetic errors • Courtship and mating consume energy, can transmit disease, and can inflict injury to competing males. • Advantages • Provides a greater genetic diversity (adapt better to changing environments) • Males of some species can gather food for female and young and help train young.

6. Reproductive Patterns • Opportunists and Competitors • R-selected species (opportunists): • Ex: algae, rodents, insects • K-selected species (competitors): • Ex: large animal; elephants, whales, humans • Prone to extinction • Most species are between the 2 extremes.

7. Reproductive Patterns • Survivorship curves: Short to Long Lives • Survivorship curve: • 3 types • Late loss • Early loss • Constant loss