Conservation Biology

Definition: Integrates ecology, physiology, molecular biology, genetics, and evolutionary biology to conserve biological diversity at all levels.

Genetic Diversity: Genetic variation within and between populations. Loss reduces adaptive potential.
Species Diversity: Number of species in an ecosystem or biosphere.
- Endangered Species: In danger of extinction.
- Threatened Species: Likely to become endangered in the future.
Ecosystem Diversity: Variety of Earth's ecosystems.

Ecosystem Services: Processes through which natural ecosystems sustain human life (e.g., purify air/water, pollinate crops, control pests, form soil).
Moral, ethical, and aesthetic reasons.
Potential for undiscovered resources (e.g., medicines from plants).

Habitat Loss: Primary threat from agriculture, urban development, pollution, and climate change. Leads to habitat fragmentation.
Introduced Species: Organisms causing ecological or economic harm in new environments, often spreading rapidly due to lack of natural controls.
Overharvesting: Harvesting wild organisms faster than populations can rebound, especially for species with restricted habitats or low reproductive rates.
Global Change: Alterations in climate, atmospheric chemistry (e.g., Acid Rain with pH < 5.2), and broad ecological systems.

Small-Population Approach: Focuses on processes (inbreeding, genetic drift) that cause extinction once a population is greatly reduced, leading to an extinction vortex.
Declining-Population Approach: Identifies and reverses the causes of population decline for threatened and endangered species, regardless of current population size.
Landscape and Regional Conservation: Aims to sustain biodiversity across entire communities, ecosystems, and landscapes.

Habitat Fragmentation: Division of habitats, creating more 'edge' areas and often reducing biodiversity.
Movement Corridors: Narrow habitat strips connecting isolated patches to promote dispersal and reduce inbreeding.
Protected Areas: Established reserves, including biodiversity hotspots (small areas with numerous endemic and threatened species) and buffer zones (protected core areas surrounded by areas managed for human use).
Species-Area Relationship: A general ecological rule describing how the number of species changes with habitat area.

Nutrient Enrichment: Human activities remove and add nutrients to the biosphere, often leading to leaching into water systems (e.g., nitrogen).
Toxins in the Environment: Release of toxic chemicals leading to biomagnification (increased toxin concentration at successive trophic levels).
Greenhouse Gases and Climate Change: Increased atmospheric $CO_2$ from fossil fuels and deforestation causes the greenhouse effect, leading to global warming, altered wind/precipitation patterns, and extreme weather events.