Biology | Conservation of biodiversity

Conservation of Biodiversity: Study Notes (IB Biology - Unity and Diversity)

Welcome to the final chapter in the "Unity and Diversity" section! We've spent time understanding how life works, how organisms are classified, and how they evolve. Now, we turn our attention to the crucial importance of protecting this magnificent variety of life. This topic isn't just about memorizing terms; it's about understanding real-world impact and developing solutions to one of the biggest challenges facing our planet.

Goal: To understand what biodiversity is, why it is threatened, and what practical strategies are employed globally to conserve it.

1. Defining and Measuring Biodiversity

Biodiversity, or biological diversity, is the variety of life on Earth at all levels, from genes to ecosystems. It is typically studied at three interconnected levels:

1.1 The Three Levels of Biodiversity

• 1. Genetic Diversity: The variation of genes within a species or a population.

  Why it matters: High genetic diversity makes a population more resilient to disease or environmental change (like climate change). If all individuals are genetically similar, a single disease could wipe them all out.

• 2. Species Diversity: The number of different species present in a specific area (species richness) and the relative abundance of each species (species evenness).

  Example: A forest with 10 species, where each species has 10 individuals, has higher species evenness than a forest with 10 species where one species has 91 individuals and the other nine species have 1 each.

• 3. Ecosystem Diversity: The variety of different habitats, communities, and ecological processes within an area.

  Example: Deserts, rainforests, coral reefs, and wetlands are all different ecosystems that contribute to overall ecosystem diversity.

Did you know? (Biodiversity Hotspots)

Scientists use the term Biodiversity Hotspot to identify areas that are both highly rich in endemic species (species found nowhere else) and severely threatened by human activity. Protecting these relatively small areas can save a huge proportion of the world's species.

2. Threats to Biodiversity

The rate of species extinction today is estimated to be 100 to 1,000 times higher than the natural background rate. This accelerated loss is driven primarily by human activities. Don't worry if this list seems daunting—we can remember the main threats using a simple mnemonic.

2.1 The Major Drivers of Decline (The HIPPO Framework)

A simple way to remember the main threats is the acronym HIPPO, often adapted slightly:

• H - Habitat Loss and Fragmentation: This is the single greatest threat. When habitats (like forests or wetlands) are destroyed or divided into smaller, isolated patches, it restricts species movement, reduces population sizes, and increases extinction risk.

  Analogy: Imagine a large population living in a vast, interconnected city (the habitat). Fragmentation is like putting up huge, impassable walls between neighbourhoods. The residents in each small block can no longer access resources or find mates from other blocks.

• I - Invasive Species: Species introduced deliberately or accidentally into a new area where they are not native. They often lack natural predators and can outcompete, prey on, or cause disease in native species.

  Example: The introduction of cane toads to Australia or pythons to the Florida Everglades.

• P - Pollution: The release of harmful substances into the environment, including industrial chemicals, plastics, pesticides, and excess nutrients (like nitrates/phosphates leading to eutrophication).

  Example: Chemical runoff harming aquatic life, or bioaccumulation of toxins (like DDT) up the food chain.

• P - Population (Human Overpopulation/Overconsumption): While not a direct threat like pollution, the ever-increasing size and resource consumption of the human population underpin all other threats. More people require more land, food, water, and energy.
• O - Overexploitation: Unsustainable hunting, fishing, logging, or harvesting of resources at a rate faster than they can replenish themselves naturally.

  Example: The poaching of elephants for ivory or massive illegal fishing operations.

Climate Change is often listed as a major additional threat, as it alters global temperature and rainfall patterns, forcing species to adapt or migrate faster than their evolutionary speed allows.

3. Consequences of Biodiversity Loss

Losing biodiversity is not just aesthetically sad; it poses direct threats to human well-being because healthy ecosystems provide vital services.

3.1 Loss of Ecosystem Services

These are the processes supplied by natural ecosystems that benefit humanity:

• Provisioning Services: Resources we directly take (food, fresh water, medicines, raw materials).
• Regulating Services: Essential processes that keep the world habitable (climate regulation, pollination, pest control, water purification).

  Example: Loss of pollinating insects means catastrophic failure of many crop systems, impacting global food security.

• Supporting Services: Fundamental processes like nutrient cycling and primary production (photosynthesis).

3.2 Decreased Ecosystem Stability and Resilience

Diverse ecosystems are stable ecosystems. If an ecosystem has many species performing similar roles, it has high resilience—the ability to resist or recover quickly from disturbance (like a fire, drought, or disease). If one species is lost, others can step in to fill the gap.

Think of it like an investment portfolio: A diverse portfolio (many different stocks/bonds) is less likely to collapse entirely than one relying on a single volatile asset. A diverse ecosystem is buffered against collapse.

4. Conservation Strategies

Conservation efforts are broadly categorized into two main approaches: in situ (on-site) and ex situ (off-site).

4.1 Monitoring Ecosystem Health: Indicator Species

Before conservation can begin, we need to know where the problems are. Indicator species are organisms whose presence, absence, or abundance reflects a specific environmental condition.

• They are often highly sensitive to pollutants or habitat changes.
• Example: The presence of certain invertebrate larvae in a stream indicates water quality. The rapid global decline of amphibians is a major indicator of overall environmental stress and climate change, as their permeable skin makes them highly vulnerable to pollution and UV radiation.

4.2 In Situ Conservation (In the Habitat)

In situ conservation means protecting species in their natural environment. This is generally the preferred method because it maintains the complex ecological relationships and allows the species to continue adapting via natural selection.

• Protected Areas: Establishing National Parks, Wildlife Reserves, and Marine Protected Areas (MPAs).
• Buffer Zones: Creating transition areas around core protected zones where sustainable use (like low-impact farming) is allowed, reducing human pressure on the core habitat.
• Restoration Ecology: Actively repairing degraded or destroyed ecosystems, such as replanting native trees or restoring wetlands.

4.3 Ex Situ Conservation (Out of the Habitat)

Ex situ conservation involves removing threatened species from their habitat to protect them in a controlled, human-made environment. This is often a last resort for critically endangered species.

• Zoos and Aquariums: Used for captive breeding programs (CBP), often focusing on maximizing genetic diversity through controlled pairing.
• Botanical Gardens and Seed Banks: Gardens maintain diverse plant collections, while seed banks (like the global Svalbard vault) store seeds in controlled conditions to preserve plant genetic material.
• Gene Banks: Storing sperm, eggs, or DNA samples using cryopreservation techniques.

The Challenge of Ex Situ: While vital for genetic rescue, ex situ conservation can lead to the loss of natural behaviours necessary for survival in the wild, and is extremely expensive to maintain.

4.4 Step-by-Step Example: Captive Breeding Program (CBP)

For a critically endangered species, conservationists follow a pathway:

1. Rescue and Isolation: Individuals are captured and moved to secure facilities (zoo, sanctuary).
2. Genetic Management: Use pedigree records and genetic testing to ensure breeding pairs maximize genetic diversity (avoiding inbreeding).
3. Reintroduction Planning: Animals are often trained to relearn necessary survival skills (hunting, predator avoidance).
4. Release and Monitoring: Released into a secure, protected area of their original habitat, followed by intensive monitoring using tags or collars to assess success.