Agriculture - Genetic erosion
March 2004, Rome Conference on Animal Genetic Resources –
The FAO warned that the loss of domestic animal breeds around the world is continuing at an alarming rate.
The World Watch List has shown that of the 6300 breeds registered by the FAO, 1350 are threatened by extinction.
Natural and Artificial Selection:
- Natural Selection acts on the available variation within a gene pool. Changes in the gene pool of a population constitute the basic process of evolution.
- In the wild, a population with a small gene pool is unlikely to survive for long since it lacks the ability to make evolutionary adjustments to changing conditions.
- Artificial Selection (plant and animal breeding) in agriculture cannot select for new varieties if the gene pool is too small.
Importance of Genetic variability and indigenous (specific to one place) wild populations:
1. Biological – ensures the survival of a species
2. Agricultural –
- Ensures continued development of new varieties to cope with environmental and farming demands e.g. climate change.
According to one agricultural scientist (Irene Hoffman of the Animal Production Service - FAO) –
"Genetic diversity is an insurance against future threats such as famine, droughts and epidemics".
- Increase yields by crossing with wild types.
- Indigenous species represent a potential new crop – at present only about 30 plants account for 95% of human nutrition.
- Just 14 out of 30 domesticated mammal and bird species provide 90% of human food supply from animals.
Genetic erosion is now so rapid that within 50 years natural habitats will have little to offer plant breeders searching for genetic variability. So far scientists have only looked at about 10% of the earth’s species.
Causes of this erosion are:
- A narrowing of variation within breeds - breeders require uniformity within a breed e.g. the amount of genetic variability within a popular breed of dairy cow (Holstein-Friesian) is very low. The number of breeds used in intensive agriculture is low and only a few popular breeds are used.
- Farming trends – There has been a loss of genetic variation as farmers plough up old less productive varieties and replace with ‘improved’ and ‘more uniform’ varieties.
- Population increase and habitat loss due to the need for more agricultural land.
- Loss of rare breeds – farmers cannot afford to keep commercially unviable older breeds e.g. Dexter cattle.
Gene Banks for plants and animals
(Zoos and Gene banks are discussed in more detail in
the Conservation section)
- Botanical solutions –
- Zoological solutions –
- Rare Breeds animal centres.
- Zoos and modern breeding technology (genetic fingerprinting).
- Reintroduction ‘back into the wild’ programmes.
- Sperm banks