Evolution II 2012
Human v natural selection/evolution?
Natural v Human Selection Natural selection favors plant types which would have greatest chance of survival, reproduction, and distribution of progeny Human selection is the result of conscious decisions by the farmer or plant breeder to keep progeny from a certain parent over others
Natural Selection Greater progeny dispersal: cereals, potato, strawberry. Reduced seed/tuber dormancy: oats, rice, beans, onion, carrot. Increased spininess: pineapple, lettuce, egg plant. Increased toxicity in seeds and fruits: bean, potato, tomato.
Seed Dispersal Mechanisms
Progeny Dispersal Wild oat, awns Wild potato, stolons
Castor, ricin Potato, glycoalkoloids Tomato, atropine Rhubarb, oxalic acid
Human Selection Taller, less branched, fewer inflorescence: sunflower,maize, hemp. Reduced spininess: sisal, pineapple, lettuce, yams. Develop of attractive colors: most fruit, maize, pulses, peppers, potato. Development of quality for multiple uses: most crops incl. Wheat, barley, maize, potato, Brassica crops, linseed.
Natural & Human Selection Increased yield: all crops. Increased resistance to pests and diseases: all crops. Reduced plant size (dwarfism): sunflower, wheat, barley, banana, peach, orange, apple, etc. Shorter lifecycle (towards annual crop): Brassica crops, radish, rye, cotton, buck wheat.
Modern Plant Breeding Began Around the turn of the 20 th Century Darwin Differential breeding of better adaptation (Evolution). Mendel Inheritance of plant characters. Weissman The continuity of germplasm. Johannsen Genotype/phenotype relationships.
What contribution has modern-day plant breeders made to our present day crops
t/ha Winter wheat yield in Idaho 1920 to 2000 6 4 1920 = 1.757 Mt/ha ~ 26.8 Bu/acre 2000 = 6.895 Mt/ha ~ 105.3 Bu/acre Difference = 5.139 Mt/ha ~ 79 Bu/acre 2 0.057 Mt/ha/year 58.9 lb/acre/year 0 Year
t/ha 30 Potato yield in UK 1955 to 1987 0.2217 Mt/ha/year 487 lb/acre/year 20 10 0 1955 = 13.0 Mt/ha 1987 = 20.3 Mt/ha Diff = 7.3 Mt/ha 55 60 65 70 75 80 85 Year
t/ha 8 6 Yield of corn inbreds and hybrids 1920 to 1980 Single cross hybrids 4 Inbred lines 2 0 1930 1940 1950 1960 1970 Year
t/ha 9 8 7 6 5 4 3 2 1 0 Wheat and barley yield in UK according to year of introduction Spring wheat Spring barley 1880 1900 1905 1935 1940 1955 1960 1965 1970 1975 1980 1983 Year of Introduction
kg/plot Potato Yield in UK according to 20 18 16 14 12 10 8 6 4 2 0 year of introduction 1900 = 16.9 kg/plot 1980 = 15.2 kg/plot 1900 1910 1920 1930 1940 1950 1960 1970 1980 Year of Introduction
When did crop domestication happen? Domestication has been taking place continually for over 9000 years, at roughly constant rate Where did domestication occur? Domestication and crop evolution has occurred, and is still occurring, wherever agriculture was practiced
Who was responsible? All sorts of people, from early farmers, to modern-day farmers and plant breeders How did these crops evolve? The mechanism of crop evolution are the same as those of nature (Darwinism). Involving differentiation of populations under selection. Selection in crops has been a combination of natural and human selection
Evolution of Agriculture in the USA 1860-1870 USDA Created. Pasteurization & margarine invented. First transcontinental railroad. Mendel published his genetic theories. Division of Botany created to preserve germplasm. Farmers make up 58% of labor force.
Evolution of Agriculture in the USA 1870-1880 Navel orange introduced to California. Burbank potato released. First introduction of Turkish wheat into Kansas. First state agricultural experiment stations. Patent granted for barbed wire & automatic milking machine.
Evolution of Agriculture in the USA 1880-1890 Bacteria proven to cause disease. First successful biological control. program for crop pests (Vedalia beetle from Australia). Gas engine tractor and cotton picker invented. Insects discovered to spread diseases. First sugar beet seed produced in USA.
Evolution of Agriculture in the USA 1890-1900 Viruses discovered. First extensive table of food values published. The first US law regulating food products (tea importation act). Test to determine butter fat content of milk discovered.
Evolution of Agriculture in the USA 1900-1910 First methodical breeding of plants for disease resistance (wilt-resistance in cotton). Hybrid corn developed. Bureau of Entomology created. Airplane invented. Demonstrated that alkali soils could be reclaimed by flooding.
Evolution of Agriculture in the USA 1910-1920 Soil classification system developed. Stainless steel invented. Isotope labeling invented. Discovery of photoperiodism. Long-term study of dairy improvement started (542 lb of butter fat in 1920 ~ 720 lb today). World War I.
Evolution of Agriculture in the USA 1920-1930 Tobacco mosaic virus isolated, establish that viruses cause plant disease. Antibacterial properties of penicillin discovered by Sir Alexander Fleming. Electron microscope invented. Hydroponics invented. Farmers number 27% of labor force Great depression starts.
Evolution of Agriculture in the USA 1930-1940 Worst drought in US history, cover 75% of country agriculture. Carbon dioxide tested to reduce fresh produce decay. Methods of genetic evaluation of beef cattle pioneered. First soil conservation district in US organized. Farmers number 21.5% of labor force.
Evolution of Agriculture in the USA 1940-1950 World War II. Mass produce penicillin. Growth regulator 2,4-D discovered. Organophosphate pesticides developed. Frozen orange juice concentrate developed. Methods developed to remove offflavors in Soybean oil.
Evolution of Agriculture in the USA 1950-1960 Double helical structure of DNA described. Agricultural Research Service created Central pivot irrigation invented. Instant potato developed. First nucleotide sequence of transfer RNA isolated and characterized. National Seed Storage Laboratory set up. Farmers make up 9% of labor force.
Evolution of Agriculture in the USA 1960-1970 Silent Spring published (chemicals in the environment). First monitoring of pesticide use. First commercialization of Gaines dwarf wheat (Green Revolution starts). High-lysine corn developed. NIR developed to determine protein, oil and moisture content in grain.
Evolution of Agriculture in the USA 1970-1980 Effects of salinity on plant growth determined. Plant variety Protection Act passes. Viroids discovered. First recombinant DNA molecule synthesized, first gene spliced. Microcomputers invented. Farmers make up 5% of labor force.
Evolution of Agriculture in the USA 1980-1990 Foot & mouth vaccine developed. DNA finger printing invented. First transgenic farm animals born GRIN established. Starch encapsulation technique for pesticides developed. Water erosion prediction project model developed.
Evolution of Agriculture in the USA 1990-2000 Taxol produced in tissue culture. Bio-degradeable plastic developed. First clone of a plant-derived gene for resistance to plant virus (N gene). First genetic map of blueberry. Dolly first cloned sheep (Scotland). Farmers less than 4% of labor force.
Evolution of Agriculture in the USA 2000-2010
Modes of reproduction Types of cultivar