Download 24. Special topic: Domestication

ANNOUNCEMENTS
Open lab tomorrow (11-1)
and Thursday (11-12)
Final exam is Monday
May 9 @ 10:10 – 12:00
Inaugural Speaker:
Eugenie Scott, NCSE
4:00 in NULH
“Evolution and
Creationism”
Allison Kupar
Plant Domestication
Humans on earth for ~2 million years
- hunted and gathered plant and animal foods
Earliest domestications ~8000 - 12,000 years ago
- in areas of abundant wild food resources
How and why did agriculture happen then?
Major regions of plant domestication
Plant Domestication
Proposed explanations for the timing of agriculture
1. accidental
people saw seeds germinating in trash-heaps, caught on
2. cultural
inevitable by-product of more settled way of life
3. ecological
new conditions (ex. drought) made agriculture necessary
Plant Domestication
How does domestication happen?
• Cultivation/management of wild populations
• “Unconscious” selection through propagation
• Conscious propagation of plants with desired traits
• Now, hybridization, polyploidization, transgenics...
Plant Domestication
How does domestication happen?
• Cultivation/management of wild populations
• “Unconscious” selection through propagation
• Conscious propagation of plants with desired traits
• Now, hybridization, polyploidization, transgenics...
Alternative perspective: the plants are using us!
Wild Rice
- managed but not propagated
Cranberry bog
Huckleberry (Vaccinium)
Maize (Zea mays, Poaceae)
Maize
- modifed by selection for “domestication” traits
Changes at just a few major genes cause
most of the differences between maize and
teosinte
Maize
- further selection for increased yield etc.
Teosinte
Change in kernel
number & size over 1500 years
Later in domestication:
hybridization to introduce novel variation
Example: wheat
Banana (Musa spp) – triploid interspecific hybrids
Musa balbisiana – Wild banana
Dwarf Cavendish (3N hybrid) banana with parthenocarpy
What changes during domestication?
Traits directly related to human consumption
- seeds: oil content, protein content, size, number
- fruits: sugar content, oil content, size
- leaves: tenderness, flavor
- shoots: tenderness, flavor
Traits changed by artificial selection
Brassica oleracea
What changes during domestication?
Traits related to agricultural yield
selection for:
 annual habit (crop every year)
 lack of seed dormancy
 self-compatibility (assured seed production)
 sturdiness to withstand cultivation/harvesting
 drought tolerance
 storage
 uniformity
Transgenics: a brief history
1952-1970: Structure, replication mechanism, and proteindefining code of DNA were solved.
1972 - 1st recombinant DNA molecules made
1973 - Amplification of recombinant DNA in E. coli
1975 - Asilomar Conference set standards for regulation of
recombinant DNA technology
1985 - PCR technology published
1989 - Human Genome Project begun
1993 - FlavrSavr tomatoes (1st GMO food) in stores
What is recombinant DNA technology?
• once a major
concern, now
routine
• essential to
modern biology
• medically useful e.g. insulin
What is a transgenic organism (GMO)?
What are some common GM crops?
Round-Up (herbicide) tolerant soybeans etc.
What are some common GM crops?
Bt (Bacillus thuringensis) corn, cotton etc.
Bt
(corn-borer
resistant)
not-Bt
How widespread are GM crops?
What are concerns with GM crops?
1.
2.
3.
4.
Evolution of resistance (Bt corn)
Introgression into wild relatives (corn, canola)
Direct impacts on non-GM relatives (salmon)
Introgression into non-GM crops (corn)
5. Human health impacts?
6. General extension of agribusiness hegemony
- Loss of locally-adapted/diverse crop races
- Loss of sustainable farming practices
Major regions of plant domestication
South America
– potato (Solanaceae)
– tomato (Solanaceae)
– tomatillo (Solananceae)
– pepper (Solanaceae)
– pumpkin (Cucurbitaceae)
– cassava (Euphorbiaceae!)
– chocolate (Sterculiaceae)
Theobroma cacao
w/ fruits
Central/North America
– beans (Fabaceae)
– peanut (Fabaceae)
– chayote (Cucurbitaceae)
– hot peppers (Solanaceae)
– maize/corn (Poaceae)
– wild rice (Poaceae)
– sweet potato (Convolvulaceae)
– avocado (Lauraceae)
Ipomaea flowers
and sweet potatoes
Malaysia
– mungbeans (Fabaceae)
– blackeyed peas (Fabaceae)
– eggplant (Solanaceae)
– taro (Araceae)
– yam (Dioscoriaceae)
Dioscorea flowers
and yams
Mediterranean
– peas (Fabaceae)
– beets (Chenopodicaceae)
– cabbage (Brassicaceae)
– turnip (Brassicaceae)
– lettuce (Asteraceae)
– artichoke (Asteraceae)
– celery (Apiaceae)
– parsnip (Apiaceae)
– asparagus (Liliaceae)
Central Asia (North India, Afghanistan)
– peas (Fabaceae)
– mungbeans (Fabaceae)
– mustard (Brassicaceae)
– onion (Liliaceae)
– garlic (Liliaceae)
– spinach (Chenopodiaceae)
– carrot (Apiaceae)
– apples (Rosaceae)
– apricots (Rosaceae)
China/SE Asia
– soy bean (Fabaceae)
– Chinese cabbage (Brassicacae)
– radish (Brassicaceae)
– cucumber (Cucurbitaceae)
– Chinese yam (Dioscoriaceae)
– rice (Poaceae)
– peach (Rosaceae)
– tea (Theaceae)
Ethiopia/East Africa
–
–
–
–
cowpeas (Fabaceae)
okra (Malvaceae)
millet (Poaceae)
coffee (Rubiaceae)
okra flower and fruit
Middle East (Turkey, Jordan, Iran)
– lentils (Fabaceae)
– lupine (Fabaceae)
– barley (Poaceae)
– wheat (Poaceae)