Module 4: Biodiversity, Conservation, and Evolution

1. Biodiversity has three levels: genetic diversity (variation within a species), species diversity (variety of species in an area), and ecosystem diversity (variety of habitat types on Earth).
2. Ecosystem services fall into four categories: provisioning (food, water, medicine), regulating (climate, flood, disease control), cultural (recreation, spiritual value), and supporting (nutrient cycling, soil formation).
3. Natural selection requires three conditions: variation (individuals differ in traits), heritability (traits are passed to offspring), and differential reproduction (some traits improve survival and reproduction more than others).
4. Adaptations are heritable traits that increase an organism's fitness (reproductive success) in its environment. They evolve over many generations — no individual evolves.
5. Speciation occurs when populations become reproductively isolated. Over time, accumulated genetic differences produce new species.
6. Background extinction rate: species go extinct at a low baseline rate throughout life's history. Mass extinctions are sudden, catastrophic events that eliminate more than 75% of species.
7. The IUCN Red List classifies species by extinction risk: Least Concern → Near Threatened → Vulnerable → Endangered → Critically Endangered → Extinct in the Wild → Extinct.
8. Keystone species have a disproportionately large effect on ecosystem structure relative to their abundance. Removing them triggers trophic cascades (e.g., sea otters → sea urchins → kelp forests).

Netiquette from the syllabus: address ideas, not people. Complete sentences, correct spelling. Personal matters go to email, never the board.

Ask at home: If you had to choose one keystone species to protect in your local area, what would it be and why?

En español: Si tuvieras que elegir una especie clave para proteger en tu área local, ¿cuál sería y por qué?