Module 5: Population Ecology and Community Ecology
Week of Tue, Sep 29 · module closes Mon, Oct 5 · 30 points
Take Meerk's quiz for Module 5
This module's items
- Case Study #430 pts
Exact due times are in Canvas. Late assignments are not accepted without a valid, documented reason. Make-up exams are not given.
Know these cold
- Population ecology studies the size, density, distribution, and growth rate of populations. Key metrics: birth rate (natality), death rate (mortality), immigration, and emigration.
- Exponential growth (J-curve) occurs when resources are unlimited — population doubles at a constant rate. Real populations only show this temporarily (invasive species, after a disaster).
- Logistic growth (S-curve) slows as population density approaches the carrying capacity (K) — the maximum population a given environment can sustain indefinitely.
- Limiting factors cap population growth: food, water, space, predators, disease, and competition. Density-dependent limiting factors get stronger as population density increases.
- r-selected species: small body, short life, many offspring, little parental care, fast growth (insects, annual plants). K-selected species: large body, long life, few offspring, high parental care, slow growth (elephants, humans).
- Interspecific competition (between species) over shared resources reduces fitness for both. Intraspecific competition (within a species) intensifies as population density rises.
- Symbiosis: mutualism (+/+) both benefit; commensalism (+/0) one benefits, one unaffected; parasitism (+/−) one benefits at the host's expense.
- Ecological succession: primary succession starts on bare rock (no soil); secondary succession occurs after disturbance where soil remains. A pioneer community gives way to a climax community.
Discussion and forum — how to show up
Netiquette from the syllabus: address ideas, not people. Complete sentences, correct spelling. Personal matters go to email, never the board.
Meerk's quiz — open the Module 5 gate
10 questions, no time limit. 85% on your first attempt in a 24-hour window opens the gate. Retakes inside the window are practice — they help you learn, they don't count. Work alone; the point is to know it, not to have seen it.
Dinner Table Question
Ask at home: Humans are a K-selected species but our global population has grown faster than almost any other large animal. What has removed our usual limiting factors?
En español: Los humanos somos una especie seleccionada por K, pero nuestra población global ha crecido más rápido que casi cualquier otro animal grande. ¿Qué eliminó nuestros factores limitantes habituales?