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Topic 1 Introduction to the Study of Life

Topic 1 Introduction to the Study of Life. 1.2 Diversity and Evolution Biology 1001 September 12, 2005. Diversity – THe Hallmark of Life. 1.8 million species identified & named 5200 prokaryotes 100,000 fungi 290,000 plants 52,000 vertebrates 1,000,000 insects

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Topic 1 Introduction to the Study of Life

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  1. Topic 1Introduction to the Study of Life 1.2 Diversity and Evolution Biology 1001 September 12, 2005

  2. Diversity – THe Hallmark of Life • 1.8 million species identified & named • 5200 prokaryotes • 100,000 fungi • 290,000 plants • 52,000 vertebrates • 1,000,000 insects • 10 million  200 million species in total

  3. Unity in Diversity

  4. Examples of Unity • Cells & DNA • Feedback Regulation • Correlation between structure and function • Cell ultrastructure 

  5. Evolution Accounts for BOTH THE UNITY AND THE DIVERSITY OF LIFE The unifying principle of biology: The history of life is a saga of a changing Earth billions of years old The evolutionary view of life came into sharp focus in 1859 when Charles Darwin published On the Origin of Species by Natural Selection

  6. Darwin’s First Main Point • Contemporary species arose from a succession of ancestors – Descent With Modification • DWM captures unity in kinship of species and diversity in modifications that evolve as species branch from their common ancestor

  7. Darwin’s Second Main Point Darwin’s Observations 1. Individual Variation 2. Overproduction & Competition His Inferences 1. Unequal Reproductive Success 2. Evolutionary Adaptation The Evolutionary Mechanism Responsible For Descent With Modification is Natural Selection

  8. NATURAL SELECTION

  9. Evolutionary Adaptations • The products of natural selection • Are exquisite adaptations of organisms to the special circumstances of their way of life and their environment

  10. Trees of Life • Natural selection enables an ancestral species to “split” into two or more descendant species, resulting in a “tree of life” • Trees of life encapsulate unity due to common ancestry and diversity due to modifications caused by natural selection as species evolve • Each species is one twig of a branching tree of life extending back in time through ancestral species more and more remote • All of life is connected through its long evolutionary history

  11. Darwin’s Finches

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