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Micro- to Macro-evolution. Mechanisms of genetic variations: Natural vs. Artificial Random mutations S elective breeding Artificial Selection in Plants- Group Activity. Review Natural vs. Artificial Mechanisms. Changes to the genetic sequences can occur through two (2) ways:
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Micro- to Macro-evolution Mechanisms of genetic variations: Natural vs. Artificial Random mutations Selective breeding Artificial Selection in Plants- Group Activity
ReviewNatural vs. Artificial Mechanisms Changes to the genetic sequences can occur through two (2) ways: a) natural processb) artificial (unnatural) process Natural process: mutation(changing the base-pairing of the DNA sequence) e.g. CCTAGACCATG CCGAGACCATG [point mutation] CCTAGACCATG CCTAAGACCATG [insertion] CCTAGACCATG CCAGACCATG [deletion] CCTAGACCATG CCTAGTAGCCATG [duplication] CCTAGACCATG CCCAGATCATG [inversion] a slow & random process that results in subtle changes to traits e.g. errors during DNA replication, uptake of bacterial/viral DNA sequence generates variation withina species population - Microevolution
Review Natural vs. Artificial Mechanisms Artificial process: domesticationor artificial selection (creating desired combination of traits via selective and cross breeding) traits selected selected Less aggressive Fluffy fur, speed Cold endurance Fur colour Friendliness Grey wolf Canis lupus Husky Canis lupus familiaris Golden retriever Canis lupus familiaris • 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 • (note: different species cannot produce fertile offsprings)
Artificial Selection in PlantsA group activity Several thousands of years ago the wild sea cabbage (Brassicaoleracea) 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. Get into groups of 4-5 people. Visit all of the “veggie stations” At each station: (a) analyze the morphology of the vegetable (b) predict what trait was selected for
Micro- vs. Macroevolution • Artificial process: • When mutations cause small changes to the phenotype: Microevolution • changes that still enable you to recognize variants as the same species • When mutations accumulate and a new species is formed: Macroevolution
Micro- vs. Macroevolution • Artificial process: • When mutations cause small changes to the phenotype: Microevolution • changes that still enable you to recognize variants as the same species • When mutations accumulate and a new species is formed: Macroevolution cabbage cauliflower broccoli Brussel’s sprout selected for sterile flowers selected for terminal buds selected for stems & flowers ornamental cabbage selected for lateral buds selected for colour & terminal buds selected for stem kale selected for large leaves kohlrabi