Topic 1 Introduction to the Study of Life
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Transcript of Topic 1 Introduction to the Study of Life
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Topic 1Introduction to the Study of Life
1.2 Diversity and Evolution
Biology 1001September 12, 2005
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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
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Unity in Diversity
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Examples of Unity
Cells & DNA
Feedback Regulation
Correlation between structure and function
Cell ultrastructure
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EvolutionEvolution Accounts for BOTH THE Accounts for BOTH THE UNITYUNITY AND AND THE THE DIVERSITYDIVERSITY OF OF LIFELIFE
The unifying principle of biology:
The evolutionary view of life came into sharp focus in 1859 when Charles Darwin published On the Origin of Species by Natural Selection
The history of life is a saga of a changing Earth billions of years old
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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
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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
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NATURAL SELECTION
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Evolutionary Adaptations
• The products of natural selection
– Are exquisite adaptations of organisms to the special circumstances of their way of life and their environment
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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
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Darwin’s Finches