3.1 Biodiversity and evolution

Biodiversity

Biodiversity is the variety of life on Earth, including the diversity of species, ecosystems, and genetic variation within species.

Levels of Biodiversity:

• Species Diversity: Variety of species within a habitat or ecosystem.
• Genetic Diversity: Variation of genes within a species.
• Ecosystem Diversity: Variety of ecosystems within a region.

How Biodiversity Contributes to Ecosystem Resilience

• Ecosystem Stability: Biodiverse ecosystems are better able to withstand and recover from disturbances (e.g., climate change, and natural disasters).
• Redundancy and Adaptation: More species mean that if one species declines, others can take over its role, ensuring the ecosystem continues functioning.
• Nutrient Cycling and Productivity: A diverse range of species contributes to more efficient nutrient cycling and overall higher productivity.

How Biodiversity Arises from Evolutionary Processes

• Evolution by Natural Selection:
  • Individuals with traits better suited for survival reproduce more successfully, passing those traits on to their offspring.
  • Over time, this leads to adaptations and the emergence of new traits within populations.
• Speciation:
  • Definition: The process by which new species form from existing ones, leading to an increase in biodiversity.
  • Types:
    • Allopatric Speciation: Occurs when a population is geographically separated, leading to different selective pressures.
    • Sympatric Speciation: Occurs without geographic separation, often due to ecological or reproductive isolation.

Simpson's Reciprocal Index

• Simpson’s reciprocal index is used to provide a quantitative measure of species diversity, allowing different ecosystems to be compared and for change in a specific ecosystem over time to be monitored

Where N is the total number of species in the population and n is the number of individuals of a single species

• Interpretation: Higher values indicate greater biodiversity; a value of 1 means no diversity and higher values indicate greater diversity.

How Knowledge of Biodiversity Helps Develop Management Strategies

• Conservation Planning: Identifying and prioritizing areas that need protection to preserve biodiversity hotspots.
• Sustainable Resource Use: Managing natural resources in a way that maintains biodiversity and ecosystem services.
• Ecosystem Restoration: Using biodiversity data to guide reforestation, habitat restoration, and wildlife management.

Biodiversity Hotspots (HL)

• Definition: Areas that are rich in endemic species and have experienced significant habitat loss.
• Importance: Protecting these areas is crucial for conserving global biodiversity.

Human Activities Impacting Biodiversity

• Deforestation: Loss of habitats and decreased species diversity.
• Pollution: Toxic chemicals and waste harm ecosystems and wildlife.
• Overexploitation: Overfishing, hunting, and harvesting reduce populations.
• Climate Change: Shifts in temperature and weather patterns affect species distribution and survival.
• Habitat Fragmentation: Splitting of ecosystems into smaller, isolated patches, making it harder for species to thrive.