A Level Biology 9700 Study Notes: Conservation (Topic 18.3)
Welcome to the Conservation chapter! This is one of the most real-world relevant topics in A Level Biology. We will explore why life on Earth is disappearing and what scientists and global organizations are doing to save it. Understanding conservation isn't just about passing the exam—it's about understanding our responsibility to the planet. Let's dive in!
Quick Tip for Studying: Conservation is heavy on definitions and the roles of organizations. Create flashcards for all the acronyms (IUCN, CITES, IVF, etc.) and their specific functions.
Section 1: Causes of Extinction
Extinction is a natural process, but current extinction rates are incredibly high, driven primarily by human activity. The syllabus requires us to explain four main causes of species extinction.
1.1 Degradation and Loss of Habitats
This is arguably the single greatest threat to biodiversity. Habitat loss means the natural home of an organism is destroyed or fragmented (broken up into smaller, isolated patches).
Example: Clearing tropical rainforests for farming or logging destroys the specific environments needed by thousands of specialized species. If the habitat is gone, the species is gone.
1.2 Hunting by Humans
Historically, excessive hunting or poaching has driven many species to the brink of extinction (or beyond).
Hunting directly reduces the population size, making it vulnerable to other threats (like disease or sudden environmental changes).
Did you know? The Dodo bird was driven to extinction rapidly largely due to human hunting and the introduction of new predators to its island habitat.
1.3 Competition
Competition becomes a major problem when humans introduce species outside of their native ranges. These are called invasive alien species.
The invasive species often have no natural predators in the new ecosystem and can out-compete native species for resources (food, light, space).
Think of it like this: If you introduce a strong new bully into a small classroom (the ecosystem), the original students (native species) might not be able to get enough resources to survive.
1.4 Climate Change
Climate change refers to long-term shifts in temperatures and weather patterns. These changes alter an organism's environmental conditions faster than it can adapt.
Key effects:
• Changes in rainfall patterns, leading to drought.
• Rising sea temperatures cause coral bleaching.
• Shifts in the geographical range of species, meaning they might lose access to their food sources or nesting grounds.
Key Takeaway: Extinction is accelerated by human actions leading to habitat destruction and the introduction of overwhelming competition and rapid climate shifts.
Section 2: The Importance of Maintaining Biodiversity
Biodiversity is the variety of life in the world or in a particular habitat or ecosystem. Why should we spend vast resources protecting it?
2.1 Reasons for Conservation (Outline)
We need to maintain biodiversity for several critical reasons:
1. Ecological Stability: Highly diverse ecosystems are often more resilient and stable. If one species disappears, the food web or nutrient cycle can still function because other species can take its place. Low diversity systems are fragile.
2. Economic Value (Direct): Many plants and animals provide humans with resources, such as food crops, timber, and fibers (e.g., cotton).
3. Pharmaceutical Value (Indirect): Many medicines, including powerful antibiotics and anti-cancer drugs, are derived from wild species. If we allow species to become extinct, we lose the chance to discover life-saving compounds. We need to maintain a "living library" of genetic resources.
4. Aesthetic and Ethical Reasons: Many people believe all species have an intrinsic right to exist. Biodiversity also enhances tourism and recreation (ecotourism).
Quick Review: Maintaining biodiversity protects ecosystem services (like clean water and air filtration), offers economic resources, and secures a genetic reservoir for future drugs and crops.
Section 3: Conservation Strategies (In Situ and Ex Situ)
Conservation efforts are generally split into two main approaches: keeping species where they belong (in situ) or protecting them elsewhere (ex situ).
3.1 In Situ Conservation (In the natural habitat)
This involves protecting the species within its natural environment. It protects not just the species, but the entire ecosystem and its interactions.
Roles of Conserved Areas:
• National Parks: Large areas where human activity is often highly restricted to preserve land and wildlife (e.g., Serengeti National Park).
• Marine Parks: Designated ocean areas protecting marine ecosystems (e.g., Great Barrier Reef Marine Park).
• Advantages: Maintains genetic variation, protects evolutionary processes (selection pressure remains), and is generally cheaper to maintain large numbers of individuals.
3.2 Ex Situ Conservation (Outside the natural habitat)
This involves conservation efforts away from the species’ natural environment, typically used when the wild population is too small or unstable to survive.
Roles of Ex Situ Facilities:
• Zoos and Botanic Gardens: Engage in captive breeding programs to maintain populations and eventually reintroduce them to the wild. They also serve educational purposes.
• Seed Banks: Store seeds from many plant species, acting as a genetic backup against extinction. The Svalbard Global Seed Vault is a prime example.
• 'Frozen Zoos': Cryopreservation banks that store genetic material (sperm, eggs, embryos) in liquid nitrogen. This is an insurance policy for future breeding or cloning attempts.
Analogy: In Situ is like protecting a species' original home. Ex Situ is like putting the species into intensive care or a safe deposit box until its home is safe again.
Section 4: Specialized Conservation Methods
4.1 Assisted Reproduction in Endangered Mammals (18.3.4)
When populations are critically low, traditional breeding might be too slow or dangerous. Assisted reproductive technologies offer a lifeline, specifically for mammals.
Methods include:
1. In Vitro Fertilisation (IVF): Eggs and sperm are collected from parents and fertilization occurs outside the body (in vitro), resulting in an embryo.
2. Embryo Transfer (ET): The resulting embryo from IVF is implanted into a female recipient (sometimes a closely related, non-endangered species, or a surrogate mother). This means the endangered mother can produce more eggs sooner.
3. Surrogacy: A female of a different species (the surrogate) carries the embryo of the endangered species to term. This maximizes the reproductive output of the endangered female (since she doesn't spend time pregnant) and can save critically rare embryos.
Common Mistake: Remember these techniques are limited to mammals for the syllabus, as they relate to IVF and surrogacy.
4.2 Controlling Invasive Alien Species (18.3.5)
Invasive alien species (IAS) pose a massive threat because they lack natural controls. Controlling them is a vital part of conservation.
Reasons for Control:
• IAS often out-compete native species for essential resources (e.g., invasive plants blocking light for native flora).
• They can be direct predators of native species, especially on islands where native prey have not evolved defenses.
• They can introduce new diseases or parasites to which native species have no immunity.
Control methods can range from simple removal (culling or trapping) to biological control (introducing a specific natural predator or parasite of the invasive species).
Key Takeaway: Advanced techniques like IVF rapidly increase populations, while invasive species control stabilizes the environment so native species can recover.
Section 5: Global Conservation Roles (IUCN and CITES)
Conservation requires global cooperation, managed by international bodies.
5.1 The International Union for Conservation of Nature (IUCN)
The IUCN is a global authority on the status of the natural world and the measures needed to safeguard it.
Primary Role: The IUCN maintains the Red List of Threatened Species. This list categorizes species according to their risk of extinction (e.g., Least Concern, Vulnerable, Endangered, Critically Endangered).
The Red List is crucial because it informs governments and conservation groups exactly where effort and funding should be directed.
5.2 The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)
CITES is an international agreement (a treaty) signed by governments. Its aim is to ensure that international trade in wild animals and plants does not threaten their survival.
Primary Role: CITES controls the trade (import, export, sale) of endangered species and their products (like ivory, rhino horn, or exotic hardwoods). It works by classifying species into appendices which dictate the level of protection and regulatory control over trade.
Memory Aid: CITES means Controlling International Trade in Endangered Species.
Final Key Takeaway: Conservation uses a combination of on-site habitat protection (in situ), genetic safety backups (ex situ), reproductive technology, and global legal frameworks (IUCN & CITES) to combat the threats posed by human activity.