EVOLUTION AND NATURAL SELECTION NOTES

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1 5. Evolution and Biodiversity State Frameworks Central Concepts: Evolution is the result of genetic changes that occur in constantly changing environments. Over many generations, changes in the genetic make-up of populations may affect biodiversity through speciation and extinction. 5.1 Explain how evolution is demonstrated by evidence from the fossil record, comparative anatomy, genetics, molecular biology, and examples of natural selection. 5.2 Describe species as reproductively distinct groups of organisms. Recognize that species are further classified into a hierarchical taxonomic system (kingdom, phylum, class, order, family, genus, species) based on morphological, behavioral, and molecular similarities. Describe the role that geographic isolation can play in speciation. 5.3 Explain how evolution through natural selection can result in changes in biodiversity through the increase or decrease of genetic diversity within a population.

2 Chapter 15 Darwin's Theory of Evolution Our natural world presents us with a puzzle about life's diversity. Homo sapiens share Earth with millions of other species with every imaginable shape, size, and habitat. This variety is called biological diversity. How did all these different organisms arise? How are they related? Theory- well supported testable explanation of phenomena that have occured in the natural world. Evolutionary Theory-is a collection of scientific facts, observations, and hypotheses which can account for this diversity of life. Evolution - change over time. Process by which modern organisms have descended from ancient organisms. 1700's: There is not much debate about the evidence that, based on fossil records, organisms have changed over time. The big debate is the MECHANISM for evolution. What caused organisms to evolve.

3 Jean-Baptiste Lamarck France 1809: described the 1st theory of evolution. *simplest creatures from spontaneous generation *series of transformations to more complex organisms. *his work is weakened due to lack of evidence as to a mechanism for these transformations. Lamarck suggests: *animals become more complex because they strive to be better. This desire for improvement fuels the transformations. *traits acquired during the life of an organism are passed on to the next generation.

4 Jean-Baptiste Lamarck How Lamarck explains the evolution of giraffes with longer necks. Fiddler crab example

5 Jean-Baptiste Lamarck Pro's: Removed God as the instigator of life. Animals change through time. changes make them better adapted to their environment. Lamarck is vilified in the scientific community due to his lack of evidence. Common sense should tell us that traits acquired during life are not passed down to the next generation. With a neighboring classmate, come up with an example that refutes "Lamarckism" as the mechanism for evolutionary change Weismann (Germany) Mice

6 Charles Darwin * Voyage on the HMS Beagle *His findings, collections, and experiences effect his thinking. *Has an abundance of evidence that he will use as support for his theory. Ideas that helped shape Darwin's theory: *Rich fossil record was challenging the traditional view of life. *James Hutton (1795) and Charles Lyle (1830)- Earth is many millions of years old and the processes that changed Earth (erosion, volcanism) in the past are the same processes that operate in the present. *Thomas Malthus (1798)- notes that human birth rate is faster than death rate. Reasons that if the human population continues to grow unchecked, sooner or later there would be insufficient living space and food for everyone.

7 Charles Darwin Upon his return on the Beagle, he filled notebooks with his ideas about the diversity of life and how many closely related organisms were uniquely adapted to their particular environment Darwin is convinced that Natural Selection is the mechanism for evolutionary change.

8 Charles Darwin Charles Darwin's criteria for evolution by natural selection: *Populations increase in size therefore increasing competition for resources such as food, living space, etc. *Not all organisms are equally equipped for the competition for resources *There is always variation for each trait in a population. These variations are inherited from parents. *Organisms with slightly better variations, that allow them to survive in their environment, survive and breed. Those with less beneficial variations do not survive and breed. *Useful or beneficial characteristics of survivors are passed to their offspring. *Over time, populations gradually change to better adapt to their environment.

9 How Darwin explains the evolution of giraffes with longer necks. Fiddler crab example

10 Lamarckism vs. Darwinism

11 Charles Darwin Charles Darwin is convinced that Natural Selection is the mechanism for the change in organisms over time yet he waits another 20 years before he publishes! Why? *continues to collect evidence to support and avoid Lamarck's fate. *avoid shock waves in society and religion. "God-less lanscape for life" What causes him to publish The Origin of Species by Means of Natural Selection in 1859? 502 pages of evidence.

12 Alfred Russell Wallace

13 vs. Wallace was an admirer of Darwin and was inspired by his Beagle voyage. He sent Darwin a paper detailing his idea on Evolution by Natural Selection and asked for Darwin's critique! Deal was brokered and they presented there papers together in London in The Origin of the Species by Means of Natural Selection is published in 1859 and Darwin considered the Father of Evolution. Interesting Note: Darwin cannot explain HOW traits are passed from parents to offspring. Do you know anyone at the time who could?

14 I Can Help! Gregor Mendel Who am I?

15 Mendel orders 40 reprints of his paper, Experiments in Plant Hybridization (1865), by Gregor Mendel and sends them to many famous scientists at the time. Was Darwin one of them????

16 Evidence for Evolution Evolution- Change in the genetic makeup (phenotype) of a population over time Fossils in sedimentary rock Homologous anatomy Analogous organs Vestigial structures Comparative embryology Fish Salamander Turtle Chicken Rabbit Human Biochemistry: DNA and Protein sequence similarities