76 • Technologies To Maintain Biological Diversity 



Photo credit: H. Fitzhugh 



Two Sahiwal cows on a government farm in Kenya. Sahiwal were originally developed in Pakistan and then imported 

 to Kenya as an all-purpose breed (e.g., milk, meat). There is concern that inbreeding has sharply reduced the genetic 



variation in this breed, both in Pakistan and Kenya. 



dominated by a few companies (probably fewer 

 than 20 worldwide) (15). These firms typically 

 retain a number of breeds from which to make 

 selections and crosses, but they do not find it 

 cost-effective to retain stocks that might prove 

 useful more than 10 years in the future (7). Mean- 

 while, breeds adapted to traditional farm con- 

 ditions are becoming rare in industrial coun- 

 tries, because fewer farmers want them and the 

 number of small hatcheries producing them has 

 declined sharply. Poultry breeds from indus- 

 trial countries are being exported to urban mar- 

 kets in many developing countries, but no evi- 

 dence exists that these have affected the genetic 

 diversity of poultry in rural areas of develop- 

 ing countries. 



Hundreds of plant species have been domes- 

 ticated, and traditional farming systems con- 



tinue to use many species. But modern agri- 

 culture produces most human sustenance, 

 plant-derived fibers, and industrial materials 

 from only a few species. Three-quarters of hu- 

 man nutrition is provided by just seven species: 

 wheat, rice, maize, potato, barley, sweet potato, 

 and cassava (31). Within the United States, the 

 top 30 crops account for $57.7 billion in farm 

 sales and imports annually, which is 60 per- 

 cent of the combined value of all U.S. agricul- 

 tural plant resources (see table 3-5) (39). 



Within these 30 crops, modern varieties have 

 replaced traditional ones, reducing diversity 

 between and within agricultural sites and ge- 

 netic populations. The narrow species and ge- 

 netic base of modern agriculture generates two 

 distinct concerns: 1) the extinction of genes, 

 which reduces opportunities to produce new 



