A4.2 Conservation of biodiversity - UWCSEA - IB Biology 2025

A4.2.1—What is biodiversity, and what are its different levels and components?

Biodiversity is the variety of life in all its forms, levels, and combinations;

It includes ecosystem diversity, which refers to the variety of ecosystems in a given place; species diversity, meaning the variety of species within a habitat or region;

and genetic diversity, which is the variation of genes within species.

A4.2.2—How do current numbers of species on Earth compare to past levels of biodiversity?

Millions of species have been discovered, named, and described, but many more are yet to be found;

Fossil evidence suggests there are currently more species alive today than at any time in the past;

In taxonomy, "splitters" recognise more species; while "lumpers" recognise fewer;

highlighting different classification methods and disagreement over what a species is;

A4.2.3—What are the causes of anthropogenic species extinction in the current sixth mass extinction?

Anthropogenic causes are human-induced factors leading to species extinction;

Examples include overhunting and over-exploitation of species;

habitat destruction due to deforestation and land conversion;

and the introduction of invasive species that outcompete native species.

Case studies:

North Island giant moas (Dinornis novaezealandiae): Extinct due to overhunting and habitat loss.

Caribbean monk seals (Neomonachus tropicalis): Extinct because of overhunting and human activities.

An example from Singapore is the Malayan Tiger which is now extinct in Singapore due to hunting;

A4.2.4—What are the anthropogenic causes of ecosystem loss, and what are some case studies?

Ecosystem loss is primarily driven by human activities;

Causes include deforestation for agriculture, urbanization, and resource extraction;

pollution leading to habitat degradation;

and climate change affecting ecosystem stability;

Case studies:

Loss of mixed dipterocarp forests in Southeast Asia due to logging and agricultural expansion.

Another is the Great Barrier reef where climate change induced temperature increases caused mass bleaching and death of the reef in recent decades;

4.2.5—What evidence supports the existence of a biodiversity crisis?

Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) reports indicate significant declines in biodiversity;

Reliable surveys worldwide show decreases in species richness and evenness;

Simpsons diversity index can be used to quantify biodiversity;

Repeated surveys are necessary to track changes over time;

Contributions from both expert scientists and citizen scientists enhance data collection but bring methodological considerations;

A4.2.6—What are the causes of the current biodiversity crisis?

Human population growth is the overarching cause;

leading to increased resource demand;

Specific causes include:

Hunting and over-exploitation of wildlife.;

Urbanization, leading to habitat fragmentation;

Deforestation and land clearance for agriculture;

Pollution affecting air, water, and soil quality;

Spread of invasive species, pests, and diseases via global transport.

A4.2.7—Why is there a need for several approaches to conserve biodiversity, and what are these methods?

No single approach is sufficient due to the complexity of ecosystems and species needs;

Methods include in situ conservation (protecting species in their natural habitats); management of nature reserves (preserving and managing protected areas);

rewilding (restoring ecosystems to their natural, uncultivated states);

reclamation of degraded ecosystems (repairing damaged habitats);

ex situ conservation (protecting species outside their natural habitats, e.g., in zoos and botanical gardens);

and storage of germ plasm (preserving genetic material in seed banks or tissue banks).

A4.2.8—Why does the EDGE of Existence programme prioritize evolutionarily distinct and globally endangered species for conservation?

EDGE species are unique in evolutionary terms and face a high risk of extinction;

Focusing on these species preserves evolutionary history and genetic diversity;

Conservation prioritization involves ethical, environmental, political, social, cultural, and economic considerations;

Debate and discussion are necessary to address the complex implications of conservation choices.