Science & Technology in Action

4th Edition


Department of Agriculture, Food and the Marine

Agricultural Science
Jnr Science Cert
What is biodiversity and why is it in the news? This lesson outlines the concept of biodiversity and summarises the steps that are being taken locally and globally to enhance biodiversity in rural and urban environments.
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Lesson excerpt

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.

  • Species diversity within an ecosystem: A stableecosystem must have a variety of species; these include producers, consumers and decomposers.
  • Ecosystem diversity. Different ecosystems have characteristic fauna and flora and within anecosystem there are distinct habitats and microhabitats.

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).

True or False?

  1. Biodiversity only refers to species other than humans. false
  2. Greater biodiversity in plants and animals contributes to disease control as disease-causing organisms have to adapt more in order to successfully infect them. true
  3. Irradiation of seeds is used to produce mutations which could give crops with desirable characteristics. true
  4. Oil rigs, abandoned at sea, have developed into habitats. true
  5. Nobody knows the total number of species on Earth. A very substantial percentage remains unidentified. true
  6. When planting trees, it is better for biodiversity to use native plants as they are adapted to local conditions and provide food for native organisms. true
  7. Humans are the only animals that deliberately block rivers. false
  8. Nesting in and around human habitations can often protect birds from predators. true
  9. Over-protection of a species may cause ecological problems. true
  10. Cessation of fishing has always resulted in the recovery of overfished species. false
  11. The extinction of an organism may represent the loss of millions of years of evolutionary development. true
  12. We do not know what biochemical treasures exist in the richness of the ocean’s species. true