Artificial Selection PDF

Theory of Natural Selection Individuals with heritable, favorable traits results in a population that is better adapted to its current environment. Galapagos finches show diversity in bill size and...

Theory of Natural Selection Individuals with heritable, favorable traits results in a population that is better adapted to its current environment. Galapagos finches show diversity in bill size and shape. Each species has adapted to a specific type of food. The ground finch has a thick beak for eating seeds, while the warbler finch has a slender, pointy bill for catching insects. Huskies - what are they bred for? 2 Bred for dog sleds - strength & endurance 3 Greyhounds - what are they bred for? 4 Bred for racing 5 Artificial Selection The Origin of Dogs 7 Remember any genetic reproductive technologies? IVF (In-Vitro Fertilization) Cloning Artificial Insemination How do these relate to artificial selection? We can use these technologies to artificially “select” traits that we deem favourable 8 9 Artificial Selection The intentional reproduction of individuals that have desirable traits. Best understood as a contrast to natural selection Natural selection: environment determines which traits are advantageous and passed on Artificial selection: humans determine which traits are advantageous and passed on Both natural & artificial selection change the genotype and phenotype of future generations (evolution) Artificial Selection process : 🡪 domestication or artificial selection (creating desired combination of traits via selective and cross breeding) selected traits selected Less Fur colour aggressive Friendliness Fluffy fur, Grey wolf speed Golden retriever Husky Canis lupus Cold Canis lupus familiaris Canis lupus familiaris endurance a faster & directive process, results in a wide range of phenotypic change generates variations within a species population and given enough time, it can lead to the creation of new species in less time Consequences of Artificial Selection Can create a monoculture: the same varieties of species over a large expanse of land Organisms which are artificially selected (selectively bred) can be susceptible to changes in the environment or disease Inbreeding (mating of closely related individuals) has lead to health issues in dogs (decreased life span to hip dysplasia)  Biotechnology: the use of technology and organisms to artificially select for traits Much of what we eat (milk, vegetables, grains, and fruits) comes from artificial selection and biotechnology 5  What’s the fruit? 17th-century painting by Giovanni Stanchi depicts a watermelon that looks strikingly different from modern melons (Christie's) 1 https://www.sciencealert.com/fruits-vegetables-before-domestication-photos-genetically-modified-food-natural 4  (Genetic Literacy Project) The first bananas may have been cultivated at least 7,000 years ago – and possibly as early as 10,000 years ago – in what is now Papua New Guinea. They were also grown in Southeast Asia. Modern 1 bananas came from two wild varieties, Musa acuminata and Musa balbisiana, which had large, hard5 seeds, like the ones in this photo.  (Genetic Literacy Program) The earliest known carrots were grown in the 10th century in Persia and Asia Minor. These were thought to originally be purple or white with a thin, forked root – like those shown here – but they lost their purple pigment and became a yellow colour. 1 6  (livingcropmuseum.info) Perhaps the most iconic example of selective breeding is North American sweetcorn, which was bred from the barely edible teosinte plant. Natural corn, shown here, was first domesticated in 7,000 BC and was dry like a raw potato.Today, corn is 1,000 times larger than it was 9,000 years ago and much easier to peel and grow. Also, 6.6 percent of it is made up of sugar, compared with just 1.9 percent in natural corn. 1 7 The Power of Artificial Selection Unexpected results; exhibit traits far beyond natural variability Breeders CANNOT create traits that do not already exist in some form within the population – E.g. no gene for blue roses BUT, new mutations can arise and give new material for breeder to work with Artificial Selection can reduce overall genetic diversity of population and contribute to loss of biodiversity Selective Breeding Artificial Selection in Plants A group activity Several thousands of years ago the wild mustard plant (Brassica oleracea) was domesticated. Now, there are a wide variety of vegetables descended from this single plant! Differences in taste & appearance of these vegetables are the result of artificial selection over thousands of generations. Artificial Selection of Wild Mustard Plant Cauliflower, broccoli, cabbage, kale, kohlrabi, bare little superficial resemblance to their wild mustard relative Yet, through many generations of artificial selection, these five distinct crops were intentionally evolved from this wild weedy ancestor = wild mustard plant 2 0 Copy this in your notes: Morphology Trait selected from Description Wild Mustard plant Wild Mustard plant Kale Brussels sprouts Broccoli Cabbage Cauliflower Kohlrabi 2 1 2 2 Domesticated Varieties of Wild Mustard Plant  Natural vs. Artificial Mechanisms Natural Artificial Differences Similarities  Natural Artificial 1. Random 1. Directive (by humans) Differences Similarities  Natural Artificial 1. Random 1. Directive 2. Changes to DNA 2. Selects for specific trait Differences Similarities  Natural Artificial 1. Random 1. Directive 2. Changes to DNA 2. Selects for specific trait 3. Slow process because the 3. Faster process (100s of years) rate of mutation is low (1000s to millions of years) or it may not happen Differences Similarities  Natural Artificial 1. Random 1. Directive 2. Changes to DNA 2. Selects specific trait 3. Slow process because the combination rate of mutation is low (1000s 3. Faster process (100s of years) to millions of years) or it may not happen Differences 4. New species arises due to the accumulation of mutations 4. New species arises when cross from many generations breeding two organisms lead to sterile offsprings Similarities  Natural Artificial 1. Random 1. Directive 2. Changes to DNA base-pairings 2. Selects specific trait 3. Slow process to achieve combination certain phenotype because the 3. Faster process (100s of years) rate of mutation is low (1000s to millions of years) or it may not happen Differences 4. A new species arises due to the 4. A new species arises when accumulation of mutations from cross breeding two organisms many generations lead to sterile offsprings 5. New species is gradual, occurs 5. New species is not gradual, can over many generations occur immediately after 1 generation Similarities  Natural Artificial 1. Random 1. Directive 2. Changes to DNA 2. Selects specific trait 3. Slow process to achieve combination certain phenotype because the 3. Faster process (100s of years) rate of mutation is low (1000s to millions of years) or it may not happen Differences 4. A new species arises due to the 4. A new species arises when accumulation of mutations from cross breeding two organisms many generations lead to sterile offsprings 5. Process of achieving a new 5. Process of achieving a new species is gradual, occurs over species is not gradual, can many generations occur immediately after 1 generation 1. Cannot change/alter the phenotypes of the organism during its lifetime Similarities  Natural Artificial 1. Random 1. Directive 2. Changes to DNA base-pairings 2. Selects specific trait 3. Slow process to achieve combination certain phenotype because the 3. Faster process (100s of years) rate of mutation is low (1000s to millions of years) or it may not happen Differences 4. A new species arises due to the 4. A new species arises when accumulation of mutations from cross breeding two organisms many generations lead to sterile offsprings 5. Process of achieving a new 5. Process of achieving a new species is gradual, occurs over species is not gradual, can many generations occur immediately after 1 generation 1. Cannot change/alter the phenotypes of the organism during its lifetime 2. Can only change/alter the phenotypes of the offspring yet to be born by manipulating the parental genotypes Similarities  Natural Artificial 1. Random 1. Directive 2. Changes to DNA base-pairings 2. Selects specific trait combination 3. Slow process to achieve certain 3. Faster process (100s of years) phenotype because the rate of mutation is low (1000s to millions of years) or it may not happen 4. A new species arises due to the 4. A new species arises when cross Differences accumulation of mutations from breeding two organisms lead to many generations sterile offsprings 5. Process of achieving a new 5. Process of achieving a new species is gradual, occurs over species is not gradual, can occur many generations immediately after 1 generation 1. Cannot change/alter the phenotypes of the organism during its lifetime 2. Can only change/alter the phenotypes of the offspring yet to be born by manipulating the parental genotypes Similarities 3. Required time to achieve offsprings with desired traits 4. Varies gene pool within a species population  Natural Artificial 1. Random 1. Directive 2. Changes to DNA base-pairings 2. Selects specific trait combination 3. Slow process to achieve 3. Faster process (100s of years) certain phenotype because the rate of mutation is low (1000s to millions of years) or it may not happen 4. A new species arises when cross Differences 4. A new species arises due to breeding two organisms lead to the accumulation of mutations sterile offsprings from many generations 5. Process of achieving a new 5. Process of achieving a new species is not gradual, can occur species is gradual, occurs over immediately after 1 generation many generations 1. Cannot change/alter the phenotypes of the organism during its lifetime 2. Can only change/alter the phenotypes of the offspring yet to be born by manipulating the parental genotypes Similarities 3. Required time to achieve offsprings with desired traits 4. Can varies gene pool within a species population 5. Can lead to the formation of a new species Gizmo Time! 1. Go to www.gizmo.explorelearning.com. 2. Launch the Natural and Artificial Selection Gizmo and follow the instructions on your student worksheet (see D2L) to complete the Gizmo and answer the questions. Submit your worksheet to D2L when finished. 3 5