UNIT 5: Wild Species and Biodiversity Summary

Wild Species and Biodiversity

  • Geographic Focus: India, Bangladesh, Sundarbans, Bay of Bengal.

  • Key Species: Endangered Indus river dolphin in mangrove forests of Sundarbans; extinction of the Chinese river dolphin (baiji) due to human activities.

Biodiversity

  • Definition: Biological diversity includes the variety of ecosystems, species, and genetic differences among organisms.

  • Levels of Biodiversity: Genetic diversity, species diversity, ecosystem diversity (Meffe and Caroll, 1997).

Extinction Events

  • Mass Extinction: Defined as the loss of at least 75% of species within a geologically short period (≤2 million years).

  • 'Big Five' Extinctions:

    • End Ordovician: 444 Mya, 86% species lost.

    • Late Devonian: 360 Mya, 75% species lost.

    • End Permian: 250 Mya, 96% species lost.

    • End Triassic: 200 Mya, 80% species lost.

    • End Cretaceous: 65 Mya, 76% species lost.

Types of Biodiversity

  • Genetic Diversity: Vital for resilience and adaptation of species.

  • Species Diversity: Affected by species richness (number of species) and evenness (relative abundance).

  • Ecosystem Diversity: Variety of habitats supporting species diversity.

  • Functional and Structural Biodiversity: Importance in maintaining ecosystems and habitats.

Decline in Biodiversity

  • Main Reasons: Habitat destruction, invasive species, pollution, population growth, over-exploitation.

  • Examples: Habitat destruction includes land conversion and fragmentation; invasive species outcompete native species.

  • Pollution Effects: Alters habitats, affecting species health (e.g., bisphenol A in male fish).

Conservation Strategies

  • Habitat Restoration: Protecting large areas for biodiversity maintenance.

  • Captive Breeding: Zoos' role in conservation and species recovery.

  • Legislation: SARA (Species at Risk Act) and international policies like CITES.

Biodiversity

Definition: Biological diversity includes the variety of ecosystems, species, and genetic differences among organisms.

Levels of Biodiversity:

  • Genetic Diversity: Vital for resilience and adaptation of species.

  • Species Diversity:

    • Measured by:

    • Species Richness: The number of different species in a given area.

    • Species Evenness: The relative abundance of different species in an area.

  • Ecosystem Diversity: Variety of habitats supporting species diversity.

Decline in Biodiversity

Main Reasons for Decline:

  • Habitat destruction

  • Invasive species

  • Pollution

  • Population growth

  • Over-exploitation

Threats to Biodiversity:
Habitat destruction includes land conversion and fragmentation; invasive species outcompete native species. Pollution alters habitats, affecting species health (e.g., bisphenol A in male fish).

Conservation Legislation:

  • SARA (Species at Risk Act)

    • Objectives of SARA:

    1. Prevent wildlife species from becoming extinct.

    2. Provide for the recovery of endangered or threatened species.

    3. Ensure that species at risk and their habitats are protected.

Consequences of Losing Biodiversity:

  • Disruption in ecosystem services that regulate climate, water, and disease.

  • Loss of resources for food, medicine, and economic activity.

Ecosystem Goods and Services:
The benefits humans derive from ecosystems, including provisioning (foods, raw materials), regulating (climate, water), cultural (recreation, spiritual), and supporting services (nutrient cycles, soil formation).

Invasive Species:
Species that are non-native to an ecosystem and whose introduction causes or is likely to cause harm. Examples include:

  • Cane Toad (Rhinella marina): Competes with native species and is toxic.

  • Zebra Mussel (Dreissena polymorpha): Outcompetes native mussels and clogs waterways.

  • Emerald Ash Borer (Agrilus planipennis): Kills ash trees, impacting forest ecosystems.

Definitions:

  • Extirpation: Local extinction of a species in a specific area.

  • Special Concern: A species that may become threatened or endangered if factors affecting its habitat are not addressed.

  • Threatened: A species likely to become endangered if not addressed.

  • Endangered: A species in danger of extinction throughout all or a significant portion of its range.

  • Extinct: No individuals remaining of that species anywhere in the world.

Science of Conservation:
The study and practice of protecting biodiversity through various strategies, including habitat preservation, restoration, and species recovery plans.