DESCENT WITH MODIFICATION… A Darwinian View of Life

Learning Targets

Evolution What is evolution? Did Charles Darwin develop this notion? What is the difference between the pattern of evolution and the process of evolution? Pattern = Process =

How did each scientist influence Darwin’s thinking? 1. Linnaeus 2. Hutton 3. Lamarck 4. Malthus 5. Cuvier 6. Lyell

Lamarck and Darwin Both used the pattern of evolution to determine the process/mechanism. How are their mechanisms similar? How are they different?

Patterns; Descent with modification In your group: 1. Define what descent with modification means 2. Develop a brief explanation as to how your concept provides evidence of descent with modification: Fossil record Homologous structures Comparative embryology Vestigial structures Biogeography Molecular homologies

FIG Sugar glider Flying squirrel AUSTRALIA NORTH AMERICA

FIG Hawks and other birds Ostriches Crocodiles Lizards and snakes Amphibians Mammals Lungfishes Tetrapod limbs Amnion Feathers Homologous characteristic Branch point (common ancestor) Tetrapods Amniotes Birds

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings. Homologies and “Tree Thinking” Imagine two species that are thought to have a recent common ancestor. If this idea is correct, these two species most likely have 1. no morphological similarities. 2. few biochemical similarities. 3. identical amino acid sequences. 4. very different habits. 5. similar embryological development.

Genome sequencing What can whole genome sequence data tell us about evolution of humans?

Primate Common Ancestry? Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo)48 gorilla (Gorilla)48 chimpanzee (Pan)48 human (Homo)46 Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo)48 gorilla (Gorilla)48 chimpanzee (Pan)48 human (Homo)46 Hypothesis: What is your hypothesis? What is your prediction? Hypothesis: What is your hypothesis? What is your prediction? Could we have just lost a pair of chromosomes?

Natural Selection: Process Does resistance to DDT arise because the DDT was sprayed at these mosquitoes? OR Was this trait already present in the mosquito population before the DDT was sprayed?

4 Conditions for Natural Selection What are these conditions? How is HIV evidence for natural selection?

FIG Weeks Patient No. 3 Patient No. 2 Patient No. 1 Percent of HIV resistant to 3TC

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings. Action of Natural Selection Imagine a species of bird in which females prefer to mate with brightly colored males. However, males with bright backs are more often preyed upon by hawks. Assuming that a wide variety of genetic variation exists in the species, which do you think is the most likely evolutionary outcome? 1. Males will be selected to be brightly colored. 2. Females will be selected to choose drab males. 3. Males will be selected to have bright chests and dull backs. 4. Females will not mate. 5. The species will go extinct because the hawks catch all the males.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings. Adaptation If an adaptation is defined as a trait that promotes survival or reproduction. Indicate if the traits listed below are adaptations or not. 1. Hemoglobin is one color (bright red) when oxygenated and another color (purple-blue) when unoxygenated. 2. Humans have a “tailbone” (coccyx). 3. Young oak trees, growing in shade, have large leaves compared to older plants, growing in sun, that have smaller leaves. 4. Male elephant seals are enormous and have ferocious battles over the opportunity to mate with females. 5. The presence of sickle cell hemoglobin allele helps the holder survive malaria.

"Nothing in biology makes sense except in the light of evolution." -- Theodosius Dobzhansky March 1973 Geneticist, Columbia University ( )

-- Ernst Mayr What Evolution Is 2001 Professor Emeritus, Evolutionary Biology Harvard University ( ) Evolution is "so overwhelmingly established that it has become irrational to call it a theory."