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Evolution
• Process where a species may change over time
• Individuals w/traits better suited for their
environment are more likely to survive
– Organisms better suited tend to pass on traits
– Survival of species and inherited traits are result of
natural selection
Darwin’s Travels
Decent with modification
Theory of Evolution by Natural Selection
• Number of individuals that have “strong” traits
will increase in a population
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Overproduction (more offspring than will survive)
Variation (more than one form of trait)
Selection (trait increase/decrease survival rate)
Adaptation (trait increase survival will be more
common) (txt uses differential reproduction)
Natural Selection
What Darwin Explained
• Fossils
– Pattern of gradual change from past to present
• Biogeography
– Similar environments shape organisms in
similar ways
• Developmental Biology
– Development of embryos
• Biochemistry and Anatomy
Evidence of Whale Evolution
transitional species
Forelimbs of Vertebrates
Homologous (same) and Analogous Structures (different)
Darwin’s Strengths
• Lots of data
• Testable material
• Showed that organisms changed
– Evidence
– Mechanism
– Variation
Darwin’s Theory Updated
• Can an individual evolve?
– Populations evolve when natural selection act
on genes
• Is evolution the survival of the fittest?
– The “fittest” is not always formed, just those
that “fit” well enough to have offspring
• Is evolution predictable?
– We cannot predict the exact path that evolution
will take
Natural Selection of Anole Lizard
Adaptive Radiation
Evolution at ALL Scales
• Speciation (formation of new species)
– Natural population that can interbreed and
produce healthy fertile offspring
– Also classified by their physical features,
ecological roles, and genetic relationships
• Microevolution
• Macroevolution
Microevolution
• Inherited traits over time in a population
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Natural selection
Migration
Mate choice
Mutation
Genetic drift
• Hardy – Weinberg Principal (Genetic Change)
Macroevolution
• Patterns in which new species evolve
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Convergent evolution (strongly directed)
Coevolution (organism involved)
Adaptive Radiation (split into lineages)
Extinction (fail to reproduce, die off)
Gradualism
Punctuated Equilibrium
Natural Selection of Anole Lizard
Adaptive Radiation
Species Formation
• Geography
• Niche
• Behavior and Timing of Mating
• Hybridization
• Polyploidy