Wrapping Up Evolution

Gene Pool

• The total number of genes that are present in a population

Genetic Drift

• Any change in the allele frequency in a population that is due to chance

Mutations

• Random change in genetic material

Natural Selection

• Selects the individuals that are best adapted for survival and reproduction

Stabilizing Selection

• Favors the average individuals in a population

• Example: average birth weights

Directional Selection

• Favors the extreme versions of a trait

• Example: Peppered Moth

Disruptive Selection

• Weeds out the average: half the population goes toward one extreme and half goes toward the other

• Example: mottled brown snakes on grassland and gray snakes on rocky shores

Comparing Selection

Speciation

• Formation of a new species

Adaptive Radiation/Divergent Evolution

• One species gives rise to many species in response to the creation of a new habitat or environment

Co-evolution

• Species evolve in close relationship with another species

• Example: Comit orchids (foot long flowers) and moths (foot long tongue)

The end

• Or is it really? • Does evolution ever

end?