Conservation Biology: Key Concepts

Conservation Biology Definition: Integrates ecology, physiology, molecular biology, genetics, and evolutionary biology to conserve biological diversity at all levels.
Current Crisis: Earth is undergoing a 6th Mass Extinction event, with current extinction rates $100-1,000x$ greater than historical background rates.

Genetic Diversity: Variation within and between populations; its loss reduces a species' adaptive potential.
Species Diversity: Variety of species in an ecosystem or biosphere.
- Endangered Species: In danger of extinction throughout all or much of its range.
- Threatened Species: Likely to become endangered in the near future.
Ecosystem Diversity: Variety of ecosystems on Earth, correlating with resource and species diversity.

Ecosystem Services: Natural ecosystem processes sustaining human life (e.g., air/water purification, waste decomposition, flood control, pollination, soil creation).
Resources: Source of medicines and genetic potential for crops.
Moral & Ethical: Responsibility to future generations; intrinsic value of life.

Habitat Loss & Fragmentation: The greatest threat, caused by agriculture, urban development, pollution, and climate change; fragments reduce population sizes and increase extinction risk.
Introduced (Invasive) Species: Non-native organisms causing ecological or economic harm, often lacking natural predators/controls.
Overharvesting: Harvesting wild organisms beyond their populations' ability to rebound, particularly affecting species with restricted habitats or low reproductive rates.
Global Change: Alterations in climate, atmospheric chemistry, and ecological systems.
- Acid Rain: Rain/snow/fog with $pH < 5.2$ due to atmospheric sulfur and nitrogen oxides from burning fossil fuels.

Small-Population Approach: Focuses on processes in small populations that lead to extinction, primarily the extinction vortex (feedback loop of inbreeding and genetic drift).
Declining-Population Approach: Focuses on diagnosing and reversing the environmental factors causing population declines, even if above minimum viable population.
Landscape and Regional Conservation: Sustains biodiversity across entire communities and ecosystems.
- Habitat Fragmentation: Can decrease biodiversity, favoring edge-adapted species.
- Wildlife Corridors: Connect isolated habitat patches to promote dispersal and reduce inbreeding.
Establishing Protected Areas: Areas like biodiversity hotspots (small areas with numerous endemic and threatened species) and buffer zones (surrounding protected areas to regulate human activity).

Nutrient Enrichment: Human activities move nutrients (e.g., nitrogen) leading to their leaching into water systems.
Toxins in the Environment: Release of toxic chemicals like pesticides (e.g., DDT) and pharmaceuticals.
- Biomagnification: Toxins become more concentrated in successively higher trophic levels of food webs.
Greenhouse Gases & Climate Change: Increased atmospheric $CO_2$ from burning fossil fuels and deforestation leads to the greenhouse effect, causing global warming, shifting weather patterns, and increased extreme weather events.