Agrobiodiversität in Deutschland - Genres

20 | Johannes Engels
From the earliest conservation and use activities
of genetic resources until today
activities of von Humboldt and Vavilov, will be explored. The importance of
(plant) breeding and genetic resources is another important dimension that
needs to be dealt with as well, before moving to questions and issues related
to access and benefit sharing, genetic resources and politics. Some concluding
remarks will be made at the end of the presentation.
Farmers, domestication and agriculture
The domestication of crops and animals is a key factor in the development
of agriculture and an integral part of human evolution and civilization.
Recent archaeological findings suggest that the process of domestication,
and thus the origin of agriculture, date back to approximately 11.000 years.
The earliest well-documented domesticates occurred around that time in
the Near East (Iran/Iraq area, i.e. the Fertile Crescent) with wheat and barley
along with goats and sheep as the main domesticates (http://courses.washington.edu/anth457/agorigin.htm,
consulted on 11.12.2011) and that there
are a number of independent regions of the world where this has happened
since then. Farmers are key players in the domestication process, they select
plant types of a given species consciously or sometimes just by chance
that respond to their criteria and subsequently conserve those types from
one season to another. Depending on the crop and the prevailing genetic
diversity this selection process can be more or less directional and the domestication
process might take in some cases many years, sometimes many
generations of farmers. The reproductive isolation of the material under
domestication, i.e. non-domesticated population(s), is an important factor
that influences the progress of the domestication in terms of changes and
time. It can take millennia of years before a wild plant or population has
been fully domesticated!
Besides the aforementioned reproductive isolation also the ‘unrestricted’
movement of the material with neighbours and other villages in a region is
an important factor with a bearing on the success of the domestication. It
has been observed that traditionally farmers do care about their planting
material and sometimes they even develop a sense of ‘ownership’ over the
material that they cultivate/domesticate. However, with the spread of the
human race around the world planting material has been carried along and/
or the knowledge of domesticating wild plants was carried along and thus,
the genetic resources and the related domestication knowledge have spread
to other regions and continents! It is the migration of people that made it
possible to spread agriculture, the corresponding crops and the cultivation/
domestication knowledge from a few centres of origin to the rest of the
world. This movement of people and plants had a further and direct impact
on agriculture as new crop introductions usually do well in ‘new regions’,
especially during the initial stages after introduction as in general the traditional
natural enemies of the crops in question do not migrate along with
the planting material and thus, newly introduced crops tended to be more
productive in their new environment.
Region of crop domestication and of diversity
The origin of crop plants is rather dispersed and somewhat erratic, although
a clear concentration of domestication events in a limited number of regions
or centres around the world have been observed and reported. Vavilov (1926)
postulated eight centres of plant diversity and origin of agriculture plus
one smaller sub-centre in South America. It should be mentioned that these
areas of crop domestication or origin of agriculture are largely confined to
the tropical and sub-tropical belts of the world (see also Fig. 1) and generally
located in mountainous areas. However, with increasing information on
the origin of crops and their respective centres of diversity it became clear
that numerous crops had their origin outside these centres of agriculture
origin. Scientists like Jack Harlan suggested that it would be more correct to
speak of centres and non-centres of agricultural origins (Harlan 1975). Also
Vavilov had realized that sometimes actually more genetic diversity for a
given crop occurs in the so-called secondary centre of genetic diversity than
in the actual centre of domestication. Even if centres of domestication and
agriculture origin do not have to coincide with centres of diversity of our
crop plants it can be stated that the mere concept that some regions in the
world harbor more genetic diversity for crops than others this concept has
been very important and useful in the conservation of PGRFA.
Johannes Engels | 21