* Any views expressed in this opinion piece are those of the author and not of Thomson Reuters Foundation.
What's the impact of losing variety in global food supplies and what can we do about it?
Much of the food produced today is grown in monocultures - vast fields of a single crop - that make it easier to mechanise planting and harvesting, while meeting imperatives to maximise profits in competitive markets. Supermarket demands for standardisation in shipping, packaging and display put a premium on produce that is uniform in shape and appearance. Producers are under pressure to focus on a small number of crop varieties that meet these criteria - those that do not are rejected.
The fruit market epitomises the dominance of a small number of varieties, favoured for their appearance and ability to withstand long distance shipping. There are over 1,000 banana varieties in the world, but just one variety - the Cavendish - accounts for 95 percent of the global banana export market. Only four commercial varieties of apples - Golden Delicious, Red Delicious, Gala and Granny Smith - currently make up 90 percent of the world market. Of the 2,500 types of pears that were grown in the past, just two account for 96 percent of the market.
The same trends are operating in animal husbandry. A small number of high-performance breeds have spread throughout the world since the mid-twentieth century, in many cases replacing local breeds. These include Rhode Island Red and Leghorn chickens, Large White, Duroc and Landrace pigs, Saanen goats and Holstein Friesian and Jersey cattle.
The result is that the many local varieties and breeds - plants and animals well-adapted to their local conditions and therefore less reliant on chemical fertilisers, pesticides and antibiotics - have been replaced by a small number of "improved" ones.
This is not just a rich world phenomenon. While the developing world has until recently preserved a large number of local breeds, today an increasing number are at risk. Globally, nearly 17 percent of livestock breeds are at risk of extinction. Many of these are indigenous breeds that are well adapted to local conditions and are an important part of agricultural and pastoral traditions, even if they are not as productive under favourable circumstances as exotic breeds. Local breeds tend to be less costly to raise than exotic breeds, and are more able to survive and reproduce in harsh climates.
Monocultures and the increased reliance on a narrow range of crop varieties pose a significant threat to our food supply, increasing vulnerability to threats such as drought, pests and diseases, all of which are likely to intensify due to climate change. They sacrifice diversity, and in some cases taste as well.
Furthermore, relying on a small number of animal breeds and crop varieties is risky. For instance, the Cavendish banana variety is susceptible to the TR4 virus, which has ravaged plantations in much of Southeast Asia and now threatens plantations worldwide. An estimated 80-90 percent of wheat varieties grown worldwide are susceptible to the Ug99 race of stem rust - considered a significant threat to global wheat production.
In order to safeguard against pest and disease outbreaks, as well as the threat that climatic change poses to agriculture, greater efforts are needed by governments, consumers and farmers around the world to preserve agricultural biodiversity. While seed banks such as the Svalbard Global Seed Vault are an essential insurance policy against the loss of crop varieties and as a resource for plant breeders, they are not sufficient in themselves. The only way to ensure that our wealth of plants and animals and their wild relatives continue to adapt to changes in the environment and pressures from pests and diseases, and act as a living genetic reservoir to meet future needs, is to maintain them in the fields. This is a far more challenging endeavour.
Farmers need incentives to preserve thousands of crop varieties that are in danger of being lost, which in turn entails improving market access for them. Farm-to-plate restaurants have a vital role here, as do farmers markets, box schemes and food hubs. In the battle to preserve diverse foods, consumers need to vote with their fork.
Seth Cook is a senior researcher in agroecology and China teams at the International Institute for Environment and Development (IIED)