IB Biology HL Protecting Biodiversity Paper 1 & 2 ~13 min read

Preserving Biodiversity

There is no single fix. Conservation splits into protecting species where they live and protecting them somewhere else, and both are needed — along with a way of deciding who gets saved first when the money runs out.

📚 What you need to know

Why there is no single solution

As human activities continue to cause a decline in biodiversity, the need for solutions increases. But the problem is complex and there is no one simple answer, so a mixture of different approaches is needed.

The complexity usually comes from conflicts between the needs of the natural world and the needs of humans — and those conflicts are not always easy to resolve. Land that would make a good nature reserve is often also land that people farm, live on or need for work.

Two places to protect a species in the wild, or away from it IN SITU protected where it lives EX SITU protected away from the wildProtected areas national parks and nature reserves Rewilding restoring it until it sustains itself Reclamation repairing land damaged by peopleZoos captive breeding and research Botanic gardens and seed banks plants and seeds kept alive off site Tissue banks frozen sperm, eggs and body cellsIn situ keeps the whole ecosystem; ex situ keeps the species only. Ex situ is a backup, not a replacement: most species can only recover in the wild.
The Latin does the work here. In situ means “in position”; ex situ means “out of position”.

In situ conservation

Protected areas

A protected area is a defined geographical space, such as a national park or nature reserve, that is managed and protected for the purposes of conservation.

TypeWhat it is
National parksGovernment-controlled areas within countries where the wildlife and environment are protected
Nature reservesSmaller regions than national parks, which can be on privately or publicly owned land

Restrictions inside a protected area could include:

Rewilding

Rewilding is the restoration of ecosystems to a point at which they can sustain themselves. Such sustainable ecosystems are, by their nature, biodiverse habitats. Rewilding can happen on privately or publicly owned land, and it can be active or passive.

TypeWhat is doneExample
Active rewildingHumans intervene to speed up or steer the recoveryRemoving human features such as roads, and reintroducing locally extinct species
Passive rewildingAn area is left alone so ecological processes gradually restore themselvesStopping the management of land to allow natural succession to occur
Passive rewilding will not work for every habitat. Grassland often needs grazing to stop tree species taking over — leave a meadow completely alone and it slowly turns into woodland, and the grassland species disappear. Some habitats only exist because something keeps eating them.

Reclamation

Reclamation is the reclaiming and restoration of areas that have been damaged by human activities — abandoned quarries, or areas where deforestation has taken place. Such projects aim to restore previously existing ecosystems.

Ex situ conservation

Zoos

Botanic gardens

Seed banks

Tissue banks

Tissue banks, also called frozen zoos, store genetic material from animals at very low temperatures. Properly frozen tissue samples are thought to last indefinitely. Ideally, samples come from different individuals of the same species, again to maintain genetic diversity.

Type of tissueWhat it isWhat it could be used for
GermplasmReproductive tissue: sperm cells, egg cells and embryosUsed by zoos in captive breeding programmes; in theory, IVF with a suitable surrogate species could bring back an extinct species
Somatic tissueNon-reproductive tissue, i.e. body cellsContains the full genome, so it can be used for DNA research and possibly for cloning extinct species in future
🧠

The thread running through ex situ

Every ex situ method has the same worry attached: genetic diversity. Artificial insemination between zoos, seeds from different sites, tissue from different individuals — all three exist to stop the rescued population becoming inbred.

Choosing which species to save

So many species need protection that deciding where to put limited resources can seem impossible. The Evolutionarily Distinct and Globally Endangered (EDGE) programme works with the Zoological Society of London (ZSL) to carry out research and highlight the needs of certain species.

How the EDGE programme picks a species it has to score high on both axesevolutionarily distinct ↑ distinct but not at risk EDGE PRIORITY distinct and endangered common and widespread endangered but has close relativesglobally endangered → examples: Chinese giant salamander, purple frog, largetooth sawfishA species must be BOTH evolutionarily distinct AND globally endangered. EDGE does not decide policy; it gives the evidence to the people who do.
Three of the four boxes get no EDGE priority. A rare species with many close relatives loses less of the tree of life than a rare species with none.
CriterionWhat it means
Evolutionarily distinctThe species has few close evolutionary relatives, is unusual in appearance, behaviour and DNA, and represents a part of Earth’s evolutionary tree that is not represented anywhere else
Globally endangeredThe IUCN red list is used to give the threat level. The species must be threatened globally, not just on a local level

A species must be both to be prioritised. Priority EDGE species include the largetooth sawfish, the Chinese giant salamander and the purple frog. The programme highlights their needs to local, government and international conservation organisations, so that such species are not lost before their plight is even recognised.

NOS: these decisions have to be debated

The EDGE criteria are useful, but choosing priority species also involves complex ethical, environmental, political, social, cultural and economic issues.

For this reason, EDGE does not make conservation decisions. It passes important information to stakeholders, allowing a range of people to be involved in the debate.

Worked examples

WE 1

In situ or ex situ?

Distinguish between in situ and ex situ conservation, giving one example of each. (3 marks)

Point 1: in situ In situ conservation protects a species in its natural habitat, e.g. a national park or a rewilding project. Point 2: ex situ Ex situ conservation protects it away from its natural habitat, e.g. captive breeding in a zoo or seeds in a seed bank. Point 3: the key difference In situ conserves the whole ecosystem and its interactions; ex situ conserves the species alone, as a backup. In position, or out of position “distinguish” needs both sides and a clear contrast, not two separate descriptions
WE 2

Genetic diversity in a seed bank

Explain why seeds of the same species are collected from several different sites. (3 marks)

Point 1: populations differ Populations in different areas experience different selection pressures, so they have different allele frequencies. Point 2: what is preserved Collecting from several sites captures more of the species’ alleles, so genetic diversity is maintained. Point 3: why that matters A population grown from those seeds can adapt to and survive environmental change, whereas a genetically uniform one may not. More sites, more alleles, better chance of adapting later the same argument works for tissue banks and for artificial insemination between zoos
WE 3

EDGE priorities

Explain why a critically endangered species may not be prioritised by the EDGE programme. (3 marks)

Point 1: two criteria, not one EDGE requires a species to be both evolutionarily distinct and globally endangered. Point 2: the missing half A critically endangered species with many close evolutionary relatives is not evolutionarily distinct, so it is not an EDGE priority. Point 3: the reasoning Losing it would remove less unique evolutionary history than losing a species that represents a part of the tree of life found nowhere else. Endangered alone is only half the requirement add that EDGE only advises — other ethical, cultural and political factors still feed into real decisions

💡 Exam tips

⚠ Common mistakes

That completes Protecting Biodiversity. The five notes run in one line of argument: biodiversity is measured at three levels, human activity is removing it species by species and habitat by habitat, careful evidence shows how fast, and conservation works either in the wild or as a backup outside it — with hard choices about what to save first.

Want this explained one-to-one?

Book a free session with an experienced IB Biology tutor and get your trickiest topics made simple.

Book a Free Session →