Lecture #14—Acquired Characteristics and Epigenetics Soon after Darwin published his books, most scientists accepted that evolution had occurred. But there were two major mechanisms explaining how that change through time had of Acquired Characteristics occurred: Lamarck’s Principle (characteristics acquired during an organism’s lifetime could be passed on to its offspring; Darwin and Principle of Natural Selection (organisms with Wallace’s the most favorable characteristics would survive and they would pass on their traits to their offspring). This argument has lasted over and hundred years and still continues. This lecture highlights major experiments that shed light on the debate. Note that in view the environment can directly affect the heredity of the Lamarck’s organism. That is not true in affect the heredity Darwin’s model. Instead, 3 factors in provides new genes, and Mutation crossover sexual reproduction today’s model: mixes all alleles into new combinations, i.e. produces variations among individuals. The environment plays a role by selecting out some organisms (most fit) and not others by natural selection. If this process goes on for a long time the species will gradually change. Here are the key experiments that we describe in the lecture. Can you describe them? Sexual Selection Experiments on giraffes. August Weisman’s rat experiments. Experiments on midwife toads Paul Kammerer’s experiments on wheat in Russia Trofim Lysenko’s Epigenetics studies Terms/Concepts to Define Jean-Baptiste Lamarck Acquired characteristics Sexual selection August Weismann Natural Selection Paul Kammerer Midwife toad
Lecture #14—Acquired Characteristics and Epigenetics Soon after Darwin published his books, most scientists accepted that evolution had occurred. But there were two major mechanisms explaining how that change through time had occurred: Lamarck’s Principle of Acquired Characteristics (characteristics acquired during an organism’s lifetime could be passed on to its offspring; Darwin and Wallace’s Principle of Natural Selection (organisms with the most favorable characteristics would survive and they would pass on their traits to their offspring). This argument has lasted over and hundred years and still continues. This lecture highlights major experiments that shed light on the debate. Note that in Lamarck’s view the environment can directly affect the heredity of the organism. That is not true in Darwin’s model. Instead, 3 factors affect the heredity in today’s model: Mutation provides new genes, crossover and sexual reproduction mixes all alleles into new combinations, i.e. produces variations among individuals. The environment plays a role by selecting out some organisms (most fit) and not others by natural selection. If this process goes on for a long time the species will gradually change. Here are the key experiments that we describe in the lecture. Can you describe them? Sexual Selection Experiments on giraffes. August Weisman’s rat experiments. Paul Kammerer’s Experiments on midwife toads Trofim Lysenko’s experiments on wheat in Russia Epigenetics studies Terms/Concepts to Define Jean-Baptiste Lamarck Acquired characteristics Sexual selection August Weismann Natural Selection Paul Kammerer Midwife toad