Notes/Homework Section 1.2 Campbell Biology in Focus Ap biology 2017-2018 Notes/Homework Section 1.2 Campbell Biology in Focus

Classifying the three domains of life Analysis of form and structure has been used to classify life forms. form follows function Currently biologists use molecular comparisons as well as physical similarities to infer evolutionary relationships. We have placed all life forms into three domains: Bacteria, Archaea, and Eukarya. Bacteria and Archaea are prokaryotes. Eukarya includes the following kingdoms: plantae, fungi, animalia, and Protista.

(a) Domain Bacteria (b) Domain Archaea (c) Domain Eukarya Kingdom Figure 1.11 (a) Domain Bacteria (b) Domain Archaea 2 m 2 m (c) Domain Eukarya Kingdom Animalia 100 m Figure 1.11 The three domains of life Kingdom Plantae Kingdom Fungi Protists 3

There is a remarkable amount of unity within all this diversity DNA is the universal language – it is common to all organisms on Earth. Similarities between organisms are evident at all levels of biology. Charles Darwin is credited with developing the Theory of Evolution by Natural Selection This theory has two main points: Species show evidence of ‘descent with modification’ from common ancestors. Natural selection is the mechanism behind ‘descent with modification.’ We will study this theory in much more depth during the 3rd 9 weeks of this course.

Figure 1.13 Figure 1.13 Charles Darwin in 1840 5

Darwin’s Ideas in a nutshell… Individuals in a population vary in their traits, many of which are heritable. More offspring are produced than survive, and competition is inevitable. Species generally suit their environment. Individuals best suited to their environment are more likely to survive and reproduce. Over time, more individuals in a population will have the advantageous trait. The environment ‘selects’ for the trait(s) that ‘fit’ best. Darwin called this process natural selection.

The tree of life Darwin proposed that natural selection could cause an ancestral species to give rise to two or more descendent species. Evolutionary relationships are often illustrated with treelike diagrams that show ancestors and their descendants.

Homework Questions 1-2 (Note: You may also need to reference your textbook, pages 7-11) Name the three domains and give a brief description of each. Why is Charles Darwin’s book, On the Origin of Species by Means of Natural Selection, considered so influential? Give a specific example of natural selection in action. Explain why ‘editing’ is an appropriate metaphor for how natural selection works.