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