Stem cells: Rare species can be cloned to protect from extinction.

The idea

Cloning produces genetically identical offspring from a single parent, so it can preserve the genes of a rare species. In conservation, adult cell cloning or embryo cloning may be used when few individuals remain. For example, a tissue sample from a rare animal can provide a nucleus that is placed into an egg cell with its nucleus removed; the resulting embryo is implanted into a surrogate. This creates a new individual without needing a mate. The method protects the species from extinction because it maintains a breeding population and preserves genetic material. However, cloned populations have low genetic variation, so they may be vulnerable to the same disease or environmental change. Cloning is therefore one conservation tool among others, such as habitat protection and captive breeding.

What earns the marks

• Cloning produces genetically identical offspring, so the genome of a rare species can be preserved even when few individuals remain.
• Adult cell cloning involves removing the nucleus from a body cell of the rare species and inserting it into an egg cell whose nucleus has been removed.
• The cloned embryo is implanted into a surrogate mother, allowing offspring to be produced without a mate of the rare species.
• Protection from extinction means maintaining a viable population and preserving genetic material for future breeding programmes.
• A limitation is that cloned individuals have identical genes, so the population lacks genetic variation and may be vulnerable to disease or environmental change.
• Cloning supports conservation but does not replace habitat protection, which addresses the cause of endangerment.

Common mistakes and how to put them right

• Thinking cloning creates genetic variation.

  Put it right: Cloning produces genetically identical offspring, so it reduces variation rather than increasing it.

• Confusing cloning with natural sexual reproduction.

  Put it right: Cloning does not require fertilisation and does not mix genes from two parents.

• Assuming cloning alone prevents extinction.

  Put it right: Cloning can help preserve a species, but habitat loss, disease and low variation must also be managed.

Exam tips

• Link the method to the purpose: state that the nucleus comes from the rare species and the egg cell is from a surrogate, then explain how this preserves the species.
• Use the phrase genetically identical when describing clones, and contrast this with the genetic variation produced by sexual reproduction.
• When asked to evaluate, give one benefit and one limitation of cloning for conservation, such as preserving genes but reducing variation.