2. Objectives  Summarize Darwin’s theory of natural selection  Describe the evidence for evolution  SCS: B-5

3.  Charles Darwin  1809-1882  HMS Beagle  Traveled for 5 years

4.  Gathered specimens  Made observations  Galapagos Islands  Darwin’s finches

5.  He came up with a few ideas:  Species produce a lot of offspring  Struggle for survival

6.  animals/plants are selected by nature based on their best traits to survive in that particular environment.

7. Evolution is decent with modification  Includes small scale changes  Changes in the gene frequency from 1 generation to the next  Includes large scale changes  Descent of different species from a common ancestor over many generations  Unifying concept in biology  All life shares a common ancestor  Explains diversity  Responsible for the remarkable similarities

8.  The central ideas of evolution include  that life has a history (changed over time) and  Different species share common ancestors  The process of evolution produces a pattern of relationships between species  Lineages evolve and split and modifications are inherited  We can study these relationships and reconstruct the evolutionary history of an organism  phylogeny

11.  Life began about 3.8 billion years ago  Insects diversified 290 mya  Humans and chimps diverged 5 mya  What methods do scientists use?  Radiometric dating  Stratigraphy  Sequence of events  Molecular clocks  Uses genetic divergence between organisms to extrapolate backwards

12.  Mutation  Can be beneficial, neutral, or harmful  Random mistakes in copying, environmental  Change in the genetic makeup that is passed on

13.  Migration (gene flow)  Movement into and out of population affect the gene pool

14.  Sex introduces to variations in populations

15.  Genetic drift  Chance changes that are passed on

16.  Natural selection  When organisms with adaptations survive and pass on these traits to the next generation

17.  Natural selection at work  Peppered moths in England

18.  Artificial selection  When man selection desirable traits and breeds these organisms

19.  Misconceptions about natural selection  It’s not all powerful; does not produce perfection; if it allows you to survive to pass on your genes  natural selection as a process rather than as a guiding hand.  result of variation, differential reproduction, and heredity—it is mindless and mechanistic  no goals; it’s not striving to produce “progress” or a balanced ecosystem.

20.  Fossil Evidence Examples: whale evolution

21. Horse evolution

22.  homologies  Evolutionary theory predicts that related organisms will share similarities that are derived from common ancestors.  Similar characteristics due to relatedness are known as homologies.  cellular similarities and differences,  studying embryological development, and  vestigial structures within individual organisms.

23.  Homologous structures  Similar in arrangement and function  Analogous structures  Body parts of organisms that do not have an evolutionary origin but are similar in function  Vestigial structures  A body structure that has no function in present day organism but was useful in an ancestor

25.  Cellular level similarities  Molecular level  DNA, proteins, etc.  embryology

26.  Distribution in time and space  Chronology

27.  Geography

28.  Examples of evolution today  Viruses  Bacteria  Artificial selection  agriculture

29.  Medical research  Diseases and their victims evolve  Flu, TB, HIV, and other diseases  Antibiotic resistance  Agriculture and economics  Need for diversity  Bigger, better, tastier, healthier, disease and pest resistant  conservation

30. Misconception: “Evolution is a theory about the origin of life.” Evolutionary theory deals mainly with how life changed after its origin.

31.  Misconception: “Evolution is like a climb up a ladder of progress; organisms are always getting better.” It is true that natural selection weeds out individuals that are unfit in a particular situation, but for evolution, “good enough” is good enough. No organism has to be perfect.

32.  Misconception: “Evolution means that life changed ‘by chance.’ ”  Chance is certainly a factor in evolution, but there are also non-random evolutionary mechanisms.  For example, some aquatic animals are more likely to survive and reproduce if they can move quickly through water. Speed helps them to capture prey and escape danger. Their offspring also had these traits

33.  Misconception: “Natural selection involves organisms ‘trying’ to adapt.” Organisms cannot will themselves to change

34.  Misconception: “Natural selection gives organisms what they ‘need.’ ” Mutations are random. Sometimes organisms cannot adapt fast enough to their changing environments

35.  Misconception: “Evolution is ‘just’ a theory.”

36.  Misconception: “Gaps in the fossil record disprove evolution.” Not all organisms can make fossils. Fossils are often destroyed by geologic processes. Transitional fossils have been found.

37.  Misconception: “Evolution leads to immoral behavior. If children are taught that they are animals, they will behave like animals.” Because we are animals does not mean will behave like wild animals

38.  Misconception: “Evolution and religion are incompatible.” Religion and science (evolution) are very different things. In science, only natural causes are used to explain natural phenomena, while religion deals with beliefs that are beyond the natural world.

39. Biography http://evolution.berkeley.edu/evosite/evohome.h tml