Lamarck and Darwin on Evolution PDF

THEORIES OF EVOLUTION Jean –Baptiste Lamarck vs Charles Robert Darwin MELC Explain the occurrence of evolution.  History of Evolutionary Thought 1. CATASTROPHISM (Werner/Cuvier) States that the Earth and geological events had formed suddenly, b...

THEORIES OF EVOLUTION Jean –Baptiste Lamarck vs Charles Robert Darwin MELC Explain the occurrence of evolution.  History of Evolutionary Thought 1. CATASTROPHISM (Werner/Cuvier) States that the Earth and geological events had formed suddenly, because of some great catastrophe.  History of Evolutionary Thought 2. Uniformitarianism (hutton/Cuvier) Idea that the Earth has always changed in uniform ways and that the present is the key to the past.  Jean-Baptiste Lamarck (1744- 1829) Developed one of the first theories on how species changed.  Theory of Need Theory of Use and Disuse Theory of Acquired Characteristics Lamarck’s Theory on Evolution  THEORY OF NEED Organisms change because they need to. For an organism to evolve a structure, it must need the structure.  THEORY OF USE & DISUSE If you don’t use it, you lose it. Organisms develop specialized characteristics by the use and disuse of organs.  THEORY OF ACQUIRED CHARACTERISTICS If a parent acquires a body structure during its lifetime, it could pass on that characteristic structure to its offspring.  Charles Robert Darwin (1809-1882) Proposed an entirely different mechanism to account for the evolution of species.  Charles Robert Darwin (1809-1882) His theory of evolution by natural selection became the foundation of modern evolutionary studies. Darwin travelled using the ship called HMS Beagle Darwin’s Finches Darwin was able to see 13 varieties of finches, which varied in size & shape from island to island, and it took him 20 THE ORIGIN OF SPECIES (1859) Darwin presented his theory of evolution based on natural Alfred Russel Wallace (1823-1913) Wallace sent a manuscript to Darwin about his studies. They have almost the same concept: natural selection.  NATURAL SELECTION Individuals within a population with the most favorable traits for an environment survive and pass those traits. In short “Survival of the Fittest”. THEORY OF NATURAL SELECTION (SPECIES OVERPRODUCTION) Organisms tend to over reproduce THEORY OF NATURAL SELECTION (COMPETITION) There is a struggle of existence and the survival of the fittest. Living space and foods are limited. THEORY OF NATURAL SELECTION (VARIATION) No two individuals are the same. Plants & animals of the same species differ in size, strength, and adaptive structures. THEORY OF NATURAL SELECTION (ADAPTATION) It is a process of becoming better suited to the environment. It improves an organism’s chance of survival. THEORY OF NATURAL SELECTION (NATURAL SELECTION) Environment selects organisms that survived to be the parents of succeeding generations. THEORY OF NATURAL SELECTION (SPECIATION) Favorable adaptions gradually accumulate in the species and unfavorable ones disappear.