A Vavilov center or center of origin is a geographical area where a group of organisms, either domesticated or wild, first developed its distinctive properties. [1] They are also considered centers of diversity. Centers of origin were first identified in 1924 by Nikolai Vavilov.
Locating the origin of crop plants is basic to plant breeding. This allows one to locate wild relatives, related species, and new genes (especially dominant genes, which may provide resistance to diseases). Knowledge of the origins of crop plants is important in order to avoid genetic erosion, the loss of germplasm due to the loss of ecotypes and landraces, loss of habitat (such as rainforests), and increased urbanization. Germplasm preservation is accomplished through gene banks (largely seed collections but now frozen stem sections) and preservation of natural habitats (especially in centers of origin).
A Vavilov Center (of Diversity) is a region of the world first indicated by Nikolai Vavilov to be an original center for the domestication of plants. [3] For crop plants, Nikolai Vavilov identified differing numbers of centers: three in 1924, five in 1926, six in 1929, seven in 1931, eight in 1935 and reduced to seven again in 1940. [4] [5]
Vavilov argued that plants were not domesticated somewhere in the world at random, but that there were regions where domestication started. The center of origin is also considered the center of diversity.
Vavilov centers are regions where a high diversity of crop wild relatives can be found, representing the natural relatives of domesticated crop plants.
Cultivated plants of eight world centers of origin [6] [7]
| Center | Plants |
|---|---|
| 1) South Mexican and Central American Center | Includes southern sections of Mexico, Guatemala, El Salvador, Honduras and Costa Rica.
|
| 2) South American Center | 62 plants listed; three subcenters 2) Peruvian, Ecuadorean, Bolivian Center:
2A) Chiloé Center (Archipelago near the coast of southern Chile)
2B) Brazilian-Paraguayan Center |
| 3) Mediterranean Center | Includes all of Southern Europe and Northern Africa bordering the Mediterranean Sea. 84 listed plants
|
| 4) Middle East | Includes interior of Asia Minor, all of Transcaucasia, Iran, and the highlands of Turkmenistan. 83 species
|
| 5) Abyssinian Center | Includes Ethiopia, Eritrea, and part of Somalia. 38 species listed; rich in wheat and barley.
|
| 6) Central Asiatic Center | Includes Northwest India (Punjab, Northwest Frontier Provinces and Kashmir), Afghanistan, Tajikistan, Uzbekistan, and western Tian-Shan. 43 plants |
| 7) Indian Center | Two subcenters 7) Indo-Burma: Main Center (India): Includes Assam, Bangladesh and Burma, but not Northwest India, Punjab, nor Northwest Frontier Provinces, 117 plants
7A) Siam-Malaya-Java: statt Indo-Malayan Center: Includes Indo-China and the Malay Archipelago, 55 plants
|
| 8) Chinese Center | A total of 136 endemic plants are listed in the largest independent center
|
| Center | Plants | Years before present |
|---|---|---|
4,500–4,000 years | ||
2) Mesoamerica | 10,000 | |
9,000–7,000 | ||
2a) northern lowland neotropics | Cucurbita moschata , Ipomoea batatas , Phaseolus vulgaris , tree crops | 9,000–8,000 |
3) central mid-altitude Andes | 5,000 | |
3a) north and central Andes, mid-altitude and high altitude areas | Solanum tuberosum , Oxalis tuberosa , Chenopodium pallidicaule | 8,000 |
3b) lowland southern Amazonia | 8,000 | |
Phaseolus lunatus , Canavalia plagiosperma , and Cucurbita ecuadorensis | 10,000 | |
4) western sub-Saharan African | 4,500 | |
4a) west African savanna and woodlands | 3,700 | |
<3,000 | ||
4b) west African rainforests | poorly documented | |
>4,000? | ||
6) east African uplands | 4,000? | |
east African lowlands | poorly documented | |
7) Near East | Hordeum vulgare , Triticum spp., Lens culinaris , Pisum sativum , Cicer arietinum , Vicia faba | 13,000–10,000 |
7a) eastern Fertile Crescent | additional Hordeum vulgare | |
9,000 | ||
8a) Gujarat, India | 5,000? | |
8b) Upper Indus | 5,000 | |
8c) Ganges | 8,500–4,500 | |
8d) southern India | Brachiaria ramosa , Vigna radiata , and Macrotyloma uniflorum | 5,000–4,000 |
5,000? | ||
10) northern China | 8,000 | |
4,500? | ||
11) southern Hokkaido, Japan | 4,500 | |
12) Yangtze River Valley, China | 9,000–6,000 | |
12a) southern China | Colocasia spp., Coix lacryma-jobi | poorly documented, 4,500? |
13) New Guinea and Wallacea | Colocasia esculenta , Dioscorea esculenta , and Musa acuminata | 7,000 |
Wheat is a grass widely cultivated for its seed, a cereal grain that is a staple food around the world. The many species of wheat together make up the genus Triticum ; the most widely grown is common wheat. The archaeological record suggests that wheat was first cultivated in the regions of the Fertile Crescent around 9600 BC. Botanically, the wheat kernel is a caryopsis, a type of fruit.
A seed bank stores seeds to preserve genetic diversity; hence it is a type of gene bank. There are many reasons to store seeds. One is to preserve the genes that plant breeders need to increase yield, disease resistance, drought tolerance, nutritional quality, taste, etc. of crops. Another is to forestall loss of genetic diversity in rare or imperiled plant species in an effort to conserve biodiversity ex situ. Many plants that were used centuries ago by humans are used less frequently now; seed banks offer a way to preserve that historical and cultural value. Collections of seeds stored at constant low temperature and low moisture are guarded against loss of genetic resources that are otherwise maintained in situ or in field collections. These alternative "living" collections can be damaged by natural disasters, outbreaks of disease, or war. Seed banks are considered seed libraries, containing valuable information about evolved strategies to combat plant stress, and can be used to create genetically modified versions of existing seeds. The work of seed banks often span decades and even centuries. Most seed banks are publicly funded and seeds are usually available for research that benefits the public.
Domestication is a multi-generational mutualistic relationship in which an animal species, such as humans or leafcutter ants, takes over control and care of another species, such as sheep or fungi, to obtain from them a steady supply of resources, such as meat, milk, or labor. The process is gradual and geographically diffuse, based on trial and error. Domestication affected genes for behavior in animals, making them less aggressive. In plants, domestication affected genes for morphology, such as increasing seed size and stopping the shattering of cereal seedheads. Such changes both make domesticated organisms easier to handle and reduce their ability to survive in the wild.
Cucurbita pepo is a cultivated plant of the genus Cucurbita. It yields varieties of winter squash and pumpkin, but the most widespread varieties belong to the subspecies Cucurbita pepo subsp. pepo, called summer squash.
Nikolai Ivanovich Vavilov was a Russian and Soviet agronomist, botanist and geneticist who identified the centers of origin of cultivated plants. He devoted his life to the study and improvement of wheat, maize and other cereal crops that sustain the global population.
Oryza sativa, having the common name Asian cultivated rice, is the much more common of the two rice species cultivated as a cereal, the other species being O. glaberrima, African rice. It was first domesticated in the Yangtze River basin in China 13,500 to 8,200 years ago.
A landrace is a domesticated, locally adapted, often traditional variety of a species of animal or plant that has developed over time, through adaptation to its natural and cultural environment of agriculture and pastoralism, and due to isolation from other populations of the species. Landraces are distinct from cultivars and from standard breeds.
Agricultural biodiversity or agrobiodiversity is a subset of general biodiversity pertaining to agriculture. It can be defined as "the variety and variability of animals, plants and micro-organisms at the genetic, species and ecosystem levels that sustain the ecosystem structures, functions and processes in and around production systems, and that provide food and non-food agricultural products.” It is managed by farmers, pastoralists, fishers and forest dwellers, agrobiodiversity provides stability, adaptability and resilience and constitutes a key element of the livelihood strategies of rural communities throughout the world. Agrobiodiversity is central to sustainable food systems and sustainable diets. The use of agricultural biodiversity can contribute to food security, nutrition security, and livelihood security, and it is critical for climate adaptation and climate mitigation.
The founder crops or primary domesticates are a group of flowering plants that were domesticated by early farming communities in Southwest Asia and went on to form the basis of agricultural economies across Eurasia. As originally defined by Daniel Zohary and Maria Hopf, they consisted of three cereals, four pulses, and flax. Subsequent research has indicated that many other species could be considered founder crops. These species were amongst the first domesticated plants in the world.
Germplasm refers to genetic resources such as seeds, tissues, and DNA sequences that are maintained for the purpose of animal and plant breeding, conservation efforts, agriculture, and other research uses. These resources may take the form of seed collections stored in seed banks, trees growing in nurseries, animal breeding lines maintained in animal breeding programs or gene banks. Germplasm collections can range from collections of wild species to elite, domesticated breeding lines that have undergone extensive human selection. Germplasm collection is important for the maintenance of biological diversity, food security, and conservation efforts.
During 10,000 years of cultivation, numerous forms of wheat, many of them hybrids, have developed under a combination of artificial and natural selection. This diversity has led to much confusion in the naming of wheats. Genetic and morphological characteristics of wheat influence its classification; many common and botanical names of wheat are in current use.
Chenopodium berlandieri, also known by the common names pitseed goosefoot, lamb's quarters, and huauzontle (Nahuatl) is an annual herbaceous plant in the family Amaranthaceae.
Genetic pollution is a term for uncontrolled gene flow into wild populations. It is defined as "the dispersal of contaminated altered genes from genetically engineered organisms to natural organisms, esp. by cross-pollination", but has come to be used in some broader ways. It is related to the population genetics concept of gene flow, and genetic rescue, which is genetic material intentionally introduced to increase the fitness of a population. It is called genetic pollution when it negatively impacts the fitness of a population, such as through outbreeding depression and the introduction of unwanted phenotypes which can lead to extinction.
Genetic erosion is a process where the limited gene pool of an endangered species diminishes even more when reproductive individuals die off before reproducing with others in their endangered low population. The term is sometimes used in a narrow sense, such as when describing the loss of particular alleles or genes, as well as being used more broadly, as when referring to the loss of a phenotype or whole species.
A crop wild relative (CWR) is a wild plant closely related to a domesticated plant. It may be a wild ancestor of the domesticated (cultivated) plant or another closely related taxon.
Crop diversity or crop biodiversity is the variety and variability of crops, plants used in agriculture, including their genetic and phenotypic characteristics. It is a subset of a specific element of agricultural biodiversity. Over the past 50 years, there has been a major decline in two components of crop diversity; genetic diversity within each crop and the number of species commonly grown.
Plant breeding started with sedentary agriculture, particularly the domestication of the first agricultural plants, a practice which is estimated to date back 9,000 to 11,000 years. Initially, early human farmers selected food plants with particular desirable characteristics and used these as a seed source for subsequent generations, resulting in an accumulation of characteristics over time. In time however, experiments began with deliberate hybridization, the science and understanding of which was greatly enhanced by the work of Gregor Mendel. Mendel's work ultimately led to the new science of genetics. Modern plant breeding is applied genetics, but its scientific basis is broader, covering molecular biology, cytology, systematics, physiology, pathology, entomology, chemistry, and statistics (biometrics). It has also developed its own technology. Plant breeding efforts are divided into a number of different historical landmarks.
Plant genetic resources describe the variability within plants that comes from human and natural selection over millennia. Their intrinsic value mainly concerns agricultural crops.
Elena Ivanovna Barulina was a Russian and Soviet botanist and geneticist who conducted pioneering research on lentils and their wild relatives. In 1930, she published the first map of their international distribution, in a 317-page monograph that became the standard reference for researchers. The standard author abbreviation Barulina is used to indicate this person as the author when citing a botanical name.
Genetic resources means genetic material of actual or potential value where genetic material means any material of plant, animal, microbial or other origin containing functional units of heredity... Genetic resources thus refer to the part of genetic diversity that has or could have practical use, such as in plant breeding. The term was introduced by Otto Frankel and Erna Bennett for a technical conference on the exploration, utilization and conservation of plant genetic resources, organized by the Food and Agriculture Organisation (FAO) and the International Biological Program (IBP), held in Rome, Italy, 18–26 September 1967.