Origins of Evolution • Jean Baptiste de Lamarck and Acquired Characteristics • Charles Darwin • Charles Lyell’s Principles of Geology • Thomas Malthus called The Principles of Population • 40,000-mile trip on the Beagle
Galapagos Islands • What did he find there? • Aquatic iguanas • Giant Tortoises • Species of finches
2 Themes Emerged • Variations within a species were dependent on the environment. • Organisms on the Galapagos Islands had become geographically separated resulting in reproductive isolationwhich leads to speciation.
Natural Selection • Changes in a population that occur when organisms with favorable variations for that particular environment survive, reproduce and pass these variations on to the next generation.
Darwin’s Theory • Decent with modification through natural selection. • Environmental Challenges result in certain traits increasing the reproductive fitness of certain individuals within a species.
History of Life • Types of Evolution • Divergent (Adaptive Radiation) • Convergent • Rates of Evolution • Gradualism • Punctuated Equilibrium
Types of Natural Selection • Stabilizing Selection • Directional Selection • Diversifying Selection • Disruptive Selection • Balancing Selection
Diversifying Selection When a population is faced with conditions so diverse that no single phenotype is more successful that any other, genetic and phenotypic variability allow different selective pressures to operate at the same time.
Balancing Selection operates to counteract the loss of variant alleles in a population. • Two forms of : heterozygote advantage and frequency-dependent selection.
Biodiversity • Resulted from divergent evolution.
Lines of Evidence • Incomplete Fossil Record >Relative Dating >Time Averaging >Radioisotope Dating • Building a Phylogeny >Phylogenetic Tree
Mass Extinctions • Were catastrophic events the cause of mass extinctions, did they happen quickly or did they occur over a long period of time?
If they occurred over a long period of time, why did the species not adapt to their changing environment in order to survive?
Biological Resistance • Oysters in Malpeque Bay • Insect Resistance to Insecticides • Viruses • Gene Amplification