Lecture 5 Biodiversity and Evolution

Amphibians: Frogs, toads, salamanders
- First vertebrates to live on land; adapted to both aquatic and terrestrial environments.
- Survivability through various environmental changes.
Population Declines (circa 1980s):
- Causes:
  - Pollution: Pesticides and fertilizers affecting habitats.
  - Excess UV Radiation: Resulting from ozone layer depletion.
  - Climate Change: Temperature sensitivity leading to stress.
  - Diseases: Parasites and fungal infections (e.g., Chytrid fungus).
  - Non-native Species: Predators and competitors impacting ecosystem balance.
- Approximately 33% of known amphibian species face extinction.
- Minnesota example: Observations of wide-scale deformities in frogs (extra/missing limbs).
Importance of Amphibians:
- Indicator species reflecting ecosystem health.
- Vital for insect control, impacting local ecosystems (e.g., mosquito population).

Definition: Biodiversity refers to the variety of life on Earth, crucial for sustaining life.
Components of Biodiversity:
- Species Diversity: Variety and number of species.
- Genetic Diversity: Variety of genes within a species.
- Ecosystem Diversity: Different biological communities (deserts, forests, etc.).
- Functional Diversity: Variety of processes such as energy flow and nutrient cycling.

Species Diversity: Variety of species in a community.
- Defined by the ability to mate and produce fertile offspring.
Genetic Diversity: Range of genes within a population/species.
Ecosystem Diversity: Variation of biological communities across environments.
- Includes biomes such as lakes, forests, etc.
Functional Diversity: Processes occurring within ecosystems such as energy flow and nutrient cycling.

Each species has a specific ecological role known as its niche.
Types of Roles:
- Native: Flourishes in its ecosystem.
- Nonnative: Introduced species that can disrupt local ecosystems (invasive species).
- Indicator: Sensitive to changes, providing early warning signs of ecological shifts.
- Keystone: Critical species that significantly influence abundance and diversity of other species.
Habitat: The environment that supports a species.
Species can be generalists (broad niches) or specialists (narrow niches).

Generalist Species:
- Adaptable to various environments; less risk of extinction.
Specialist Species:
- Limited to specific habitats; more vulnerable to extinction.

Definition: Species that play a pivotal role in maintaining the ecosystem balance.
E.g., Sea otters in kelp forests
- Control sea urchin populations, preserving kelp habitats.
- Conservation efforts aim to restore sea otter populations due to their endangered status.

Theory of Evolution: Describes changing life on Earth through natural selection.
- Genetic variation enables adaptation; traits favorable for survival are passed to offspring.
Speciation: Process of forming new species when populations become isolated and diverge over time.
- Type of isolation:
  - Geographic Isolation: Physical separation by features like mountains, leading to distinct species.
  - Reproductive Isolation: Genetic divergence prohibits interbreeding upon reconnection.

Human-induced changes in species traits through:
- Artificial Selection: Breeding for desirable traits.
- Genetic Engineering: Altering genes for specific outcomes, including synthetic biology.
Harmful actions can lead to extinction:
- Habitat destruction, overfishing, and pollution contribute to biodiversity loss.

Definitions:
- Extinction: Complete loss of species.
- Endemic Species: Highly vulnerable, found in specific locations.
Types of Extinction:
- Background Extinction: Ongoing low-rate extinction.
- Mass Extinction: Significant global extinction events often caused by environmental changes.
Current observation suggests a sixth mass extinction largely driven by human activities.