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 1001
• September 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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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
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Darwins 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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Darwins Second Main Point
The Evolutionary Mechanism Responsible For
Descent With Modification is Natural Selection

• Darwins Observations
• 1. Individual Variation
• 2. Overproduction Competition
• His Inferences
• 1. Unequal Reproductive Success
• 2. Evolutionary Adaptation

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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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Darwins Finches