🌍 Strand E: Population Dynamics

Course: SBI4U — Biology, Grade 12
Focus: Population growth, carrying capacity, human impact on ecosystems

1. Population Growth Models

Exponential growth: J-curve, unlimited resources, N(t) = N₀ × e^(rt)
Logistic growth: S-curve, limited by carrying capacity (K), growth slows as population approaches K

2. Factors Affecting Population

Factor Type	Density-Dependent	Density-Independent
Definition	Effect increases with population density	Effect same regardless of density
Examples	Competition, predation, disease, parasites	Natural disasters, weather, climate change
Effect on growth	Usually causes logistic growth	Can cause sudden population crashes

3. Human Impact

Key issues: habitat destruction, invasive species, overexploitation, pollution, climate change (collectively: HIPPO)

📝 Worksheet — Strand E: Population Dynamics

1. [K/U — 3 marks] Compare exponential and logistic growth. Include: shape of curve, role of carrying capacity, and when each model applies.

2. [Thinking — 4 marks] A deer population on an island starts at 50 with r = 0.1 per year and K = 500.

a) Sketch the expected population growth curve over 50 years.

b) At what population size is the growth rate highest? Explain why.

c) If wolves are introduced to the island, predict how K would change and explain.

3. [Communication — 3 marks] Explain the difference between density-dependent and density-independent factors. Give two examples of each and explain how they regulate population size.

4. [Application — 4 marks] An invasive species of Asian carp has been introduced to the Great Lakes.

a) Predict the initial growth pattern of the carp population and explain why.

b) What impact might this have on native fish populations? Use the concept of competitive exclusion.

c) Suggest two strategies to manage the invasive population and evaluate their effectiveness.

SBI4U — Biology, Grade 12 | Strand E: Population Dynamics | Ontario Curriculum 2008