14
2 Genetic Resources: Status, Development, Losses, and Conservation
Table 2.2. Examples of important secondary centers of diversity
Crop
Primary center of diversity
Secondary center of
diversity
Finger millet"
East Africa
South Asia
Sorghums
b
Africa
South Asia and Latin America
Beans and groundnut
Latin America
Sub-Saharan Africa
Maize and cassava
<
Latin America
Indochinese-Indonesian area
Barley
Fertile Crescent of the Middle East Ethiopia
Rye
Near East and Mediterranean
Introduced as weeds in
northern European fields
Oats
Near East and Mediterranean
Introduced as weeds in
northern European fields
Rubber d
Latin America
Indochinese-Indonesian area
Source:
FAO, 1996a;": Engels et aI., 1991; b: Kloppenburg and Kleinman, 1987; <: Plucknett
et aI., 1987; d Wood, 1988a
Although the biodiversity declined over time because of human interaction, the
level of agrobiodiversity increased at the same time due to human activities.
Agricultural domestication, breeding, and trading of crop species increased the
genetic diversity as well as the diversity of varieties and - to a certain extent - the
diversity of crop species over the past 10,000 years (McKelvy Bird, 1996). While
the number of crop species utilized in agriculture is relatively small, the diversity
within such species is often immense. For instance, there are an estimated 130,000
distinct varieties within the rice species Oryza sativa (Chang, 1992). With
modern, scientific breeding emerging, the expansion process changed its trend:
the main objective for exchange of varieties changed from adapting an imported
crop or variety to local conditions to incorporating only some traits of a foreign
variety into existing, local or modern varieties. These modern-bred varieties
include genetic resources from completely different sites and are spread over a
larger area than were the former local varieties, thus reducing the local intra-crop
diversity and the inter-crop diversity.
2.1.3
The Interdependence of Countries on PGRFA
The centers of origin often differ, however, from today's important areas of
production. Secondary centers of diversity were established in some areas.
Consequently, over two thirds of developing countries acquire more than half of
their crop production from crops domesticated in other regions (Wood, 1988a).
The impact of species originating from other regions on local food production for
major crops can be seen in Fig. 2.1. Only South Asia, South East Asia, and West
Central Asia depend on food crops originated from other countries for less than
50% of their food production. In all other regions over 50% of the food
2 Genetic Resources: Status, Development, Losses, and Conservation
Table 2.2. Examples of important secondary centers of diversity
Crop
Primary center of diversity
Secondary center of
diversity
Finger millet"
East Africa
South Asia
Sorghums
b
Africa
South Asia and Latin America
Beans and groundnut
Latin America
Sub-Saharan Africa
Maize and cassava
<
Latin America
Indochinese-Indonesian area
Barley
Fertile Crescent of the Middle East Ethiopia
Rye
Near East and Mediterranean
Introduced as weeds in
northern European fields
Oats
Near East and Mediterranean
Introduced as weeds in
northern European fields
Rubber d
Latin America
Indochinese-Indonesian area
Source:
FAO, 1996a;": Engels et aI., 1991; b: Kloppenburg and Kleinman, 1987; <: Plucknett
et aI., 1987; d Wood, 1988a
Although the biodiversity declined over time because of human interaction, the
level of agrobiodiversity increased at the same time due to human activities.
Agricultural domestication, breeding, and trading of crop species increased the
genetic diversity as well as the diversity of varieties and - to a certain extent - the
diversity of crop species over the past 10,000 years (McKelvy Bird, 1996). While
the number of crop species utilized in agriculture is relatively small, the diversity
within such species is often immense. For instance, there are an estimated 130,000
distinct varieties within the rice species Oryza sativa (Chang, 1992). With
modern, scientific breeding emerging, the expansion process changed its trend:
the main objective for exchange of varieties changed from adapting an imported
crop or variety to local conditions to incorporating only some traits of a foreign
variety into existing, local or modern varieties. These modern-bred varieties
include genetic resources from completely different sites and are spread over a
larger area than were the former local varieties, thus reducing the local intra-crop
diversity and the inter-crop diversity.
2.1.3
The Interdependence of Countries on PGRFA
The centers of origin often differ, however, from today's important areas of
production. Secondary centers of diversity were established in some areas.
Consequently, over two thirds of developing countries acquire more than half of
their crop production from crops domesticated in other regions (Wood, 1988a).
The impact of species originating from other regions on local food production for
major crops can be seen in Fig. 2.1. Only South Asia, South East Asia, and West
Central Asia depend on food crops originated from other countries for less than
50% of their food production. In all other regions over 50% of the food