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Biology and Evolution
 What is Evolution?
 What are the forces responsible for Evolution?
 What are the moral and social implications of the
theory of evolution?
 HMS Beagle
 2 year voyage to chart the coastline of S.America
 Took 5 years
 Galapagos Island discoveries
 Minor differences (island to island) in birds, turtles
 Significance?
 Natural selection
Based on two observations:
 All organisms display a range of variation.
 All organisms have the ability to expand beyond
their means of subsistence.
 Translation?
 All organisms that survive have adapted to their
environment
 Occurs as genetic variants in the gene pool of a
population change in frequency.
 Genes, the units of heredity, are segments of molecules
of DNA (deoxyribonucleic acid).
 Provides the instructions for the thousands of proteins
that keep us alive and healthy.
 Molecules are able to produce exact copies of
themselves.
 DNA molecules are located on chromosomes,
structures found in the nucleus of each cell.
 Each organism has a
characteristic number of
chromosomes, usually found
in pairs.
 Humans have 23 pairs.
 Genes located on paired
chromosomes and coded for
different versions of the same
trait are called alleles.
 Dominant alleles are able to mask the presence of
recessive alleles.
 Example: The allele for type A blood in humans, is
dominant to the allele for type O blood.
Punnett
Square
 Mutation - happens when copying mistakes are made
during cell division.
 Genetic drift - the effect of chance events on the gene
pool of small populations.
 Gene flow - the introduction of new alleles from
nearby populations.
 Variation
 Every species has individuals that are better adapted to
their environment than others
 Heritability
 Offspring inherit traits from their parents
 Differential reproductive success
 Better adapted individuals produce more offspring
 Frequency of good adaptations increases in successive
generations
 How can we prove that natural selection exists?
 Can you think of any examples? Turn to the person next
to you and discuss an example of natural selection
 Thoughts?
 Bacteria – certain strains become resistant to antibiotics
 Fruit flies – those that survive DDT exposure reproduce
Bacteria
“Gone
Bad.” Ha!
 Implications?
 Social Darwinism (survival of the fittest)
 Eugenics = only allowing certain people to reproduce
 How did we explain the world
before Darwin?
 Answer: God
 Creationism and Evolution don’t
jive too well
 Scientific creationists = evolution can
only account for change, NOT the
creation of organisms
 An evolutionists response – look
at the fossil record!
 Evolutionists claim that the fossil record
clearly shows speciation meaning the
creation of entirely new species