What is Evolution?What is Evolution?• Variation exists in all populations• Variation is inherited

• Evolution is heritable changes in a population over many generations.

• Descent with modification • Evolution is change in allelic frequency

• Variation exists in all populations• Variation is inherited

• Evolution is heritable changes in a population over many generations.

• Descent with modification • Evolution is change in allelic frequency

Mechanisms of EvolutionMechanisms of Evolution• Natural Selection (Darwinism)

• individuals with favorable variations (traits) better survive and reproduce.

• The genes (inherited variation) of the successful individuals increase in frequency in subsequent generations.

Survival of the fittest

• Genetic Drift

• Natural Selection (Darwinism) • individuals with favorable variations (traits) better

survive and reproduce.• The genes (inherited variation) of the successful

individuals increase in frequency in subsequent generations.

Survival of the fittest

• Genetic Drift

Evolutionary Theory does not:

Evolutionary Theory does not:

• Propose the origin of life.“There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.”

• Charles Darwin, 1859, The Origin of Species

• Specify a rate of evolution

• Propose the origin of life.“There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.”

• Charles Darwin, 1859, The Origin of Species

• Specify a rate of evolution

Points to RememberPoints to Remember

• Populations Evolve• Individuals do not

• Mutations are random, selection is not

• Populations adapt to new environments

• Individuals acclimate

• Populations Evolve• Individuals do not

• Mutations are random, selection is not

• Populations adapt to new environments

• Individuals acclimate

SahiwalSahiwal

TharparkarTharparkar

Genotypic Frequencies of Indian Dairy Cattle

Genotypic Frequencies of Indian Dairy Cattle

AA = 0.031AB = 0.276BB = 0.693

AA = 0.023AB = 0.733BB = 0.244

What are the allelic frequencies of each breed?

Allelic Frequencies of Indian Dairy Cattle

Allelic Frequencies of Indian Dairy Cattle

A = 0.17B = 0.83

A = 0.39B = 0.61

What are the expected genotypic frequencies of each breed?

Expected Genotypic Frequencies of Indian Dairy Cattle

Expected Genotypic Frequencies of Indian Dairy Cattle

ExpectedAA = 0.029AB = 0.282BB = 0.689

How do you interpret these results?

ExpectedAA = 0.152AB = 0.476BB = 0.372

ObservedAA = 0.031AB = 0.276BB = 0.693

ObservedAA = 0.023AB = 0.733BB = 0.244

How would test for significance?

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χ 2 =∑Observed − Expected( )

2

Expected