Chapter 15

1. Chapter 15 Theory of Evolution

2. Section 1 History of Evolutionary Thought: Objectives • Define the biological process of evolution • Summarize the history of scientific ideas about evolution • Describe Charles Darwin’s contribution to scientific thinking about evolution • Analyze the reasoning in Darwin’s theory of evolution by natural selection • Relate the concepts of adaptation and fitness to the theory of natural selection

3. The Idea of Evolution • Charles Darwin was one of the first people to study evolution of different species. He came up with one of the most important theories in biology with his work. • Evolution is the process of change in inherited characteristics within populations over generations such that new types of organisms develop from pre-existing types. • Or simply: the change in a population’s allele frequencies over time

4. The Idea of Evolution • Ideas of Darwin’s Time • Scientific understanding of evolution began to develop in the 17th and 18th centuries as geologists and naturalists compared geologic processes and living and fossil organisms around the world

5. Darwin’s Ideas • 1859 – Darwin published On the Origin of Species by Means of Natural Selection • Darwin had two main goals writing this book: • Wanted to present the large amount of evidence that evolution occurs • Wanted to explain the variety and distribution of organisms on Earth in terms of natural processes that are observable • Darwin’s book pointed out many different ideas like the following: • Species change slowly over time • Some organisms reproduce at different rates than other • Some species become better suited to their environment than others

6. Darwin’s Voyage

7. Darwin’s Ideas • Descent with Modification • Darwin argued in On the Origin of Species: • That descent with modificationoccurs • That all species descended from common ancestors • And that natural selection is the mechanism for evolution Charles Darwin's 1837 sketch, his first diagram of an evolutionary tree (1837)

8. Darwin’s Ideas • Natural Selection • A population adapts to their environment as the proportion of individuals with genes for favorable traits increases • Those individuals that pass on more genes are considered to have greater fitness • Fitness is a measure of an individual’s hereditary contribution to the next generation

9. Section 2 Evidence of Evolution: Objectives • Relate several inferences about the history of life that are supported by evidence from fossils and rocks • Explain how biogeography provides evidence that species evolve adaptations to their environments • Explain how the anatomy and development of organisms provide evidence of share ancestry • Compare the use of biological molecules with other types of analysis of evolutionary relationships • Describe the ongoing development of evolutionary theory

10. Support for the Theory of Evolution • Evidence of evolution can be found by comparing several kinds of data, including the fossil record, biogeography, anatomy and development, and biological molecules • Evolutionary theories are supported when several kinds of evidence support similar conclusions

11. The Fossil Record • A fossil is the remains of an organism that lived long ago • Geologic evidence supports theories about the age and development of Earth • 1669 – Danish scientist Nicolaus Steno proposed the idea of superposition • “If a rock strata at a location haven’t been disturbed, the lowest stratum was formed before the strata above it” Younger Rock Old Rock

12. The fossil record • Absolute Age v. Relative Age • Absolute age is the exact age of rock layers or fossils using techniques like radiometric dating • Relative age is an age that is a comparison, by comparing fossils or rock layers to one another “The trilobite fossil is 300 million years old” “The trilobite fossil is older than the T. rexfossil”

13. The Fossil Record • Distribution of Fossils: the fossil record shows that the types and distribution of organisms have changed over time • Transitional Species: Fossils of transitional species show evidence of descent with modification • EX: evolutionary scientists have hypothesized that modern marine mammals like whales evolved from early mammals that walked with four legs on land based on fossil skeletons that show a sequence of transitional forms

14. Biogeography • Biogeography, the study of locations of organisms around the world, provides evidence of descent with modification Map from Alfred Russel Wallace’s book, The Geographical Distribution of Animals

15. Anatomy and Physiology • In organisms, analogous structures are similar in function but have different evolutionary origins • EX: Bird beak and giant squid beak; both beaks, but evolved independently • EX: Insect v. bid wings; both for flight, but evolved independently (and from entirely different organs!) • Homologous structures have a common evolutionary origin • EX: Vertebrate forelimbs

16. Anatomy and Physiology • A species with a vestigial structure probably shares ancestry with a species that has a functional form of the structure • EX: human tailbone, human appendix, pelvic bones of modern whales, and the eyes of a blind mole rate

17. Anatomy and Physiology • Related species show similarities in embryological development Hoxc-6 gene controls vertebrae development (in purple) in animals including chicks (left) and garter snakes. Photo courtesy of Ann Burke and Brian McOmber. (http://www.hawaii.edu/malamalama/2009/02/development-returns-to-evolution-theory/)

18. Biological Molecules • Similarity in the subunit sequences of biological molecules such as RNA, DNA, and proteins indicates a common evolutionary history

19. Developing Theory • Hypotheses about evolution continue to be proposed and investigated • Modern scientists have integrated Darwin’s theory with other advances in biological knowledge: • Not until the mid-1900s did scientists begin to integrate the theory of natural selection with new understandings of genetics. This blending is called the modern synthesis of evolutionary theory (MSOET) • The MSOET predicts: • Closely related species will show similarities in DNA sequences • If species have changed over time, their genes should have changed • Closely related species will show similarities in amino acid sequences

20. Section 3 Evolution in Action: Objectives • Compare artificial selection and natural selection • Explain how organisms can undergo coevolution

21. Artificial Selection • The great variety of dog breeds is an example of artificial selection • Artificial selection, a type of biotechnology, has been used by humans to speed up the process of divergent evolution by allowing them to pick specific traits and blend them together Saint Berdoodle St. Bernard / Poodle Hybrid LabradoodleLabrador Retriever / Poodle Hybrid ChugChihuahua / Pug Hybrid Credit: John Doebley

22. Coevolution • Coevolutionis the process in which two or more species become more adapted over time to each other’s presence • EX: Plants and their pollinators Bees can see UV light and are attracted to darker colors. For a bee, this flower guides them right to the pollination center (right), even though it just looks yellow to humans (left)

23. Homework Pp 301 #1, 5-7 Pp 307 #1-6 Pp 310 #2-3