Domestication of plants and animals.docx

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Agricultural Studies
AGST 1000
Henning Bjourlund

Domestication of plants and animals September 12, 2012 Domestication of plants - Plant domestication may be defined as growing a plant and thereby, consciously or unconsciously, causing it to change genetically from its wild ancestor in ways of making it more useful to human consumers - Many crops like almonds were originally poisonous and bitter tasting - Some were edible but had other characteristics making them unsuitable for domestication (easily scattering seeds, seed ripening not taking place uniformly) - Learning from experience it was observed that; - - seeds from gathered fruits pitted on the found at camp reproduced - - some fruit rotted on the ground and the seeds germinated - - grains dropped on the ground on the way back to camp reproduced - -seed and fruits dropped as part of human faces reproduced - Some criterion had to do with the characteristics and qualities from consumptive use: - - fruit size - - bitterness - - fleshiness - -sleedlessness - - oiliness - -fiber length Fruit size/grain numbers - Prefer large berries or fruits - Wild strawberries are miniature - Cultivated peas 10 times bigger than wild peas - Cultivated apples are 3 inches in diameter, wild are 1 - Wild corn barley hand an inch we can get them to more than a foot From wild einkorn wheat to domesticated wheat a) The ears of whild einkorn shatter at maturity b) Each spikelet leaving the stem as dispersing propagate c) Having at its base a smooth abscission scar. By contrast: d) The ears of domesticated einkorn are non-shattering and remain intact after ripening, threshing being needed to detach the spiklets which result in e) A jagged break at the base of each one Bitterness - Wild seeds are often bitter. It protects them from being eaten and enhances their chance of germinating - Wild almonds are poisonous and contain a chemical amugdalin which breaks down to cyanide - Other examples of plants which were originally bitter or poisons; watermelon, potatoes, egg plants and cabbage Fleshiness/seedlessness - We prefer fruits with lots of flesh and small seeds or thin skin - Wild varieties of fruits such as squashes and pumpkins have little or no fruit around the seeds - Cultivated bananas were selected many years ago to have all flesh and no seed Oiliness - Olives were among the first domesticated fruit trees in the Mediterranean - Cultivated for its oil - Modern scientists have now used sunflower, safflower and palm nuts for oil Fiber length - Some crops were selected for their fibers for textile - Flax was frown to make linens - Remained most important textile until cotton replaced it after the industrial revolution How did it change? - Plant occasionally produce mutation- fruits which do not have the negative characteristic or are bigger - These plants die out in nature and remain flukes - Humans might have observes these flukes and helped the plants grow - Four other types of change not involving humans making visible or taste choices to reverse the natural evolution of the plant: - - - dispersal mechanisms - - germination inhibitors - - reproductive biology - - natural selection Seed dispersal - Many plants have mechanisms which disperse seed - Prevents humands from gathering themeffectively - Peas have pods- to reproduce they must come out. Wild peas evolved a gene causing the pod to explode spreading the seeds - Some mutant plants did not do that - In nature htey would die out, however these plants were gathered and planted Germination inhibitors - Someplants develop genes which cause seeds to germinate at different times- why; if not all seeds would be lost during natural disators - Enclosed their seeds ina thick coat of armor - Cultication changed this as only those with thin armor produced when seeded and were then re- seeded gornw a
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