Biodiversity and Threats

Biodiversity is a broad term encompassing all biological variety.
It is measured at three levels:
- Ecosystem diversity: Variety of ecosystems on Earth.
- Species diversity: Variety of species within an ecosystem.
- Genetic diversity: Genetic variety within a species.

Diversity is highest near the Equator.
Reasons for high equatorial biodiversity:
- High primary productivity due to warm and wet conditions.
- Older ecosystems with less disturbance from ice age events.

34 recognized biological hotspots worldwide.
High biodiversity with a large number of endemic species.
Often islands or unique environments (e.g., Madagascar, Galapagos).
California is a hotspot, known as the California Floristic Province.
California has high species richness but also many degraded ecosystems and threatened species.

Human Health:
- Many medicines are derived from natural compounds.
- Example: Gila monster venom used to create drugs.
- Example: Madagascar Periwinkle is used for lymphoma treatment.
- Example: Fungus in yew trees used to develop multiple cancer products.
Agriculture:
- Artificial selection reduces genetic variety in crops and livestock.
- Crossbreeding with ancestral species (e.g., Teosinte for corn) can boost genetic variation.
Seed Vault:
- Goal: Preserve biodiversity by storing seeds of all plants.
- Located in permafrost to maintain seed longevity.
- Experienced flooding due to a warm year, highlighting the need for backup plans.
Wild Food Sources:
- Aquatic ecosystems provide protein sources (fish, shrimp).
- Natural populations needed for crossbreeding to maintain genetic variation.
Psychological Interactions with Nature:
- Forest bathing (Shinrin-yoku) in Japan helps replenish spirit and reduce stress.
- Research shows reduced cortisol levels with interaction in nature.
- Benefits from truly natural environments like Sequoia and Kings Canyon National Park.

Driving factor: Human population growth.
Habitat Loss:
- Number one threat to biodiversity.
- Destruction of natural habitats makes them unusable for species.
- Prevents species from adapting to climate change by moving to suitable areas.
Overharvesting:
- Concern for aquatic species (crabs, fisheries).
- Also related to the pet trade (parrots, snakes).
- Harvest rates of aquatic species are increasing, leading to population collapses.
Exotic Species:
- Introduction of species, intentionally or accidentally.
- Example: Rabbits introduced to Australia.
  Exotic vs. Invasive:
- Exotic species: A species that is not native to a specific location; an introduced species.
- Invasive species: Disrupts the natural food chain, reproduces successfully, and outcompetes native species.
Climate Change:
- Exacerbates other threats to biodiversity.
- Example: Bark beetles and coniferous forests in the Sierra Nevadas.
  - Hotter, longer summers, and droughts stress forests.
  - Stressed trees are more vulnerable to bark beetles.
  - Bark beetles reproduce more due to longer warm temperatures.
  - Leads to tree death and increased fire risk.
  - Fire suppression increases competition among trees.