Contains the full lesson along with a supporting toolkit, including teachers’ notes.
What is Biodiversity?
Biodiversity refers to the variety of life. This variety is expressed in different ways:
Genetic diversity within a species. All individuals of a particular species have common features but they are not all identical. In general each individual has a unique set of genes. In a large population there is typically more variation than in a small population with a limited gene pool.
Biodiversity on Earth has varied historically due to natural variations in climate, impact events, geological activity and other factors. Mass extinctions have occurred many times in the Earth’s history. Less dramatically, unknown numbers of species have disappeared through the long process of evolution andnatural selection. Scientists agree that species extinctions have accelerated in recent decades however.
Reasons for Biodiversity Loss
Rising human population has meant increased demand for space and resources. Pollution and habitat loss have led to extinctionof some species and endangerment of others. Unsustainable activities such as over–fishing and rainforest clearance exemplify these problems. Some reports predict that Climate Change may also result in biodiversity loss.
Worldwide, exotic species introduction reduces the overall biodiversity in favour of fewer species. If an introduced species survives, it may be because of the absence of the predators and competitors that would normally limit its numbers. As a result, these non-native species can become invasive and can transform ecosystems and threaten native and endangered species (e.g. Grey Squirrel in Ireland).