Lecture notes on domestication

1. SPL4563
The Dynamics of Plant Domestication

2. •How was agriculture invented?
1. Early Agriculture

3. •How was agriculture invented?
Divine gift from the gods?
1. Early Agriculture

4. •How was agriculture invented?
Divine gift from the gods?
Propinquity theory (domestication by
crowding)
1. Early Agriculture

5. •How was agriculture invented?
Divine gift from the gods?
Propinquity theory (domestication by
crowding)
Fishing link (Carl Sauer)
1. Early Agriculture

6. •How was agriculture invented?
Divine gift from the gods?
Propinquity theory (domestication by
crowding)
Fishing link (Carl Sauer)
Waste dump
Seeds were observed to germinate and grow.
1. Early Agriculture

7. •How was agriculture invented?
Divine gift from the gods?
Propinquity theory (domestication by
crowding)
Fishing link (Carl Sauer)
Waste dump
Seeds were observed to germinate and grow.
•When? About 10,000 years ago - after the Ice Age
•Agriculture spread to or was invented on several continents
within a short period
1. Early Agriculture

8. •Where and when?
1. Early Agriculture

9. •Where and when?
Mesopotamia 8,000-9,000 B.C.
Wheat, barley, lentils, chickpeas, oats, dates,
grapes, olives, almonds, figs, pomegranates
1. Early Agriculture

10. •Where and when?
Mesopotamia 8,000-9,000 B.C.
Wheat, barley, lentils, chickpeas, oats, dates,
grapes, olives, almonds, figs, pomegranates
Central Africa 4,000 B.C.
Coffee, sorghum, millet, cowpeas, yams, oil palm
1. Early Agriculture

11. •Where and when?
Mesopotamia 8,000-9,000 B.C.
Wheat, barley, lentils, chickpeas, oats, dates,
grapes, olives, almonds, figs, pomegranates
Central Africa 4,000 B.C.
Coffee, sorghum, millet, cowpeas, yams, oil palm
China 4,000 B.C.
Millet, hazelnuts, peaches, apricots, soybeans, rice,
mulberries, chestnuts
1. Early Agriculture

12. •Original idea for planting (Edgar, 1954)
Waste dump
Seeds were observed to germinate and grow.
1. Early Agriculture

13. •When and where, con’t.
Southeast Asia / Indonesia 6,000 B.C.
Rice, sugarcane, coconut, banana, mango, citrus, yams,
taro
1. Early Agriculture

14. •When and where, con’t.
Southeast Asia / Indonesia 6,000 B.C.
Rice, sugarcane, coconut, banana, mango, citrus, yams,
taro
New World (Mex. / Cen. Am.) 5,000-7,000 B.C.
Corn, sweet potato, tomato, cotton, pumpkin,
peppers, squash, beans, papaya, avocado, pineapple
1. Early Agriculture

15. •When and where, con’t.
Southeast Asia / Indonesia 6,000 B.C.
Rice, sugarcane, coconut, banana, mango, citrus, yams,
taro
New World (Mex. / Cen. Am.) 5,000-7,000 B.C.
Corn, sweet potato, tomato, cotton, pumpkin,
peppers, squash, beans, papaya, avocado, pineapple
South America 6,000 B.C. and earlier
Potato, peanut, cacao, pineapple, cashew,
Brazil nut, tobacco, guava, manioc, yam
1. Early Agriculture

16. •Shift from the hunter–gatherer strategy
•Who?
Homo erectus (Hominids)
They were collectors, who planned the use of resources
whose location was known and monitored
2. Evolution of Farming

17. •Shift from the hunter–gatherer strategy
•Who?
Homo erectus (Hominids)
They were collectors, who planned the use of resources
whose location was known and monitored
Cro-Magnon
Had considerable knowledge about how plants and
animals developed, and were returning to the same
areas year after year to harvest and hunt dependable
sources
Enhanced the productivity of native fields by weeding,
pruning and burning (became cultivators)
2. Evolution of Farming

18. Cro-Magnon as cultivators
Enhanced the productivity of native fields by weeding,
pruning and burning (became cultivators).
Began tilling with a digging stick or hoe to reduce
competition and encourage germination.
May also have discovered at an early stage that crops did
better the following year if the soil was turned after
harvest
2. Evolution of Farming

19. Cro-Magnon as cultivators
Enhanced the productivity of native fields by weeding,
pruning and burning (became cultivators).
Began tilling with a digging stick or hoe to reduce
competition and encourage germination.
May also have discovered at an early stage that crops did
better the following year if the soil was turned after
harvest
Cro-Magnon as producers
Transplanted small numbers of plants and held a few
animals captive.
2. Evolution of Farming

20. •Centres of Plant Domestication
Concept first devised by Vavilov in 1919
3. Early Stages of Plant Domestication

21. •Centres of Plant Domestication
Concept first devised by Vavilov in 1919
Archaeological evidence suggests that hunter-gatherers
independently began cultivating food plants in 24 regions,….”
(Purugannan and Fuller, 2009)
3. Early Stages of Plant Domestication

22. •Domestication
Process by which humans actively interfere with and
direct crop evolution.’
.
3. Early Stages of Plant Domestication

23. •Domestication
Process by which humans actively interfere with and
direct crop evolution.’
It involves a genetic bottleneck:
Often only few genes are actively selected and account for large
shifts in phenotype.
Crops exhibit various levels of domestication.
3. Early Stages of Plant Domestication

24. •Domestication
Process by which humans actively interfere with and
direct crop evolution.’
It involves a genetic bottleneck:
Often only few genes are actively selected and account
for large shifts in phenotype.
Crops exhibit various levels of domestication.
3. Early Stages of Plant Domestication

25. The first crops were as diverse as the people and places where
agriculture began
Middle East:
There were huge natural stands of wheat and
barley  the early farmers in this region exploited
these as their staple crops
South-East Asia:
Wheat and barley were absent, but large-grained
rice was plentiful and,  rice became one of the
crops of choice
Mesoamerica and Africa:
Wheat, barley and rice were not present.
People exploited the locally abundant
monocotyledons: sorghum in Africa and maize in
Mesoamerica
4. Origin of Crops

26. The first crops were as diverse as the people and places where
agriculture began (cont.)
South America:
No large- grained species of any kind existed.
The early farmers in this region domesticated the
tuberous species potato, sweet potato and
cassava and the pseudograins chenopod and
amaranth.
4. Origin of Crops
Amarath
Chenopod

28. •Most of the early domesticants are herbaceous annuals,
capable of selfing
Why so many of these early crop species are annual and
self- pollinating?
Some crop species are not annual selfers:
maize, quinoa, pearl millet
cassava, sugar cane
Why they were selected?
5. Characteristics of Early Domesticants

29. •Climate
Large-seeded grain and tuber crops were domesticated in
the savannah or Mediterranean climates of the Middle East,
China, Mesoamerica and South America.
- have long annual periods of drought
- favoured plants with large annual
seeds or tubers
Eastern North America were not drought adapted.
- large seeds are advantageous in areas with
periods of extreme cold
- Winter: Seeds become dormant
- Spring: Germination
5. Characteristics of Early Domesticants

30. • Increased reproductive effort
• Larger seeds and fruit
More even and rapid germination
• More uniform ripening period
• Non-dehiscent fruits and seeds
• Self-pollination
• Trend to annuality
• Increased palatability
• Colour changes
Loss of defensive structures
• Increased local adaptation
6. Changes During the Domestication Process

31. 6. Changes During the Domestication Process

32. • Many of the traits associated with plant domestication are
regulated by only a few genes, making rapid evolutionary
change possible
.
7. Genetic Regulation of Domestication Process
Shattering
Larger grains

33. 7. Genetic Regulation of Domestication Process
•Teosinte glume architechture (tga1)
Work by John Doebley and his colleagues
Regulate glume toughness, sex expression and the
number and length of internodes in both lateral branches and
inflorescences.
.

34. 7. Genetic Regulation of Domestication Process
• Not only are there commonly major genes for the individual
traits associated with plant domestication, but in many cases
these genes have pleiotropic effects,
• affect a number of traits simultaneously.
• As a result, their selection would make change across
the whole domestication syndrome much more rapid
than if the traits were evolving separately.

35. 8. Evolution of Weeds
• As farming progressed, humans also began to inadvertently select for
weedy crop mimics through tilling, weeding and harvesting.
• Two major forms of crop mimics are generally recognized:
1. Vegetative, where the weed is similar looking to crop
seedlings and their vegetative stage
• E.g: Weedy rice, where there are numerous different
indica- and japonica-mimicking races, both where wild
species are present and where they are absent
2. Seed, where weed seeds have similar density and appearance
to those of crops, making it difficult to separate them before planting.
• E.g: Camelina sativa races, whose seeds were so similar to
those of flax that they could not be separated by
winnowing, where chaff and lighter seeds are removed by
wind from the crop’s heavy seeds

36. 9. Genetic Diversity and Domestication
• Important effect of domestication was a reduction in levels of
genetic variability in both plants and animals.
• Virtually all domesticants are less diverse due to
bottleneck.
• However, several factors had an important influence on the
amount of diversity captured during domestication:
• geographical isolation
• sexual structure and
• levels of diversity in the original species population
• Mode of planting/ reproduction (Outcrossed, planted
individually)
• Hybridizations between sexually propagated crops and
their wild progenitors

37. •5 classes of domestication patterns (Harlan, 1975,1976)
.
10. Domestication and Native Diversity Patterns

38. 10. Domestication and Native Diversity Patterns
•5 classes of domestication patterns (Harlan, 1975,1976)
1. Endemic – the domesticant occupies a well defined,
small geographical region (guinea millet)
2. Semi-endemic – the domesticant occupies a small
range with some dispersal out of it (African
rice and teff)
3. Monocentric – the domesticant has a wide distribution with a
noticeable centre of origin (the later plantation
crops, such as coffee, rubber, cacao and oil palm
4. Oligocentric – domesticant has a wide distribution and two or
more centres of diversity (major food crops, such
as wheat, barley, pea, lentil, chickpea, flax, maize and
lima bean)
5. Non-centric – domesticant has a wide distribution, but no
noticeable centres of diversity (American beans,
radish, sorghum, pearl millet, cole crops and
bottle gourd).

39. •Most people in developed countries are familiar with only a
handful of oligocentric and non-centric crops.
However, hundreds of endemic and semi-endemic crops
were domesticated
.
10. Domestication and Native Diversity Patterns

40. •Most people in developed countries are familiar with only a
handful of oligocentric and non-centric crops.
However, hundreds of endemic and semi-endemic crops
were domesticated
E.g: Ethiopia
Introduced coffee to the world
.
10. Domestication and Native Diversity Patterns

41. •Most people in developed countries are familiar with only a
handful of oligocentric and non-centric crops.
However, hundreds of endemic and semi-endemic crops
were domesticated
E.g: Ethiopia
Introduced coffee to the world
Unique assemblage of endemic crops were
domesticated:
Cereal teff
Oil crop noog
Mild narcotic chat
Enset (a relative of banana whose stem
base rather than fruit is eaten)
10. Domestication and Native Diversity Patterns

42. Assignment
•Group of 3 people
•Class Presentation
Topics:
1. Protein Plants: Phaseolus, beans, faba beans, soybean
2. Starchy Staples and Sugars I: Banana, cassava, potato, sugar cane
3. Starchy Staples and Sugars II: Sugar beet, sweet potato, taro, yam
4. Fruit: Apples, citrus, grape, peach and strawberry
5. Vegetables: Cole crops, squash and gourds
6. Oils and Fibres: cotton, groundnut, sunflower
Dateline: 19th November 2017 before 12 pm
Send the ppt files to sabrinaazmi@iium.edu.my
First presentation: 21st November 2017 during lecture (15-20
minutes presentation).