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  1. Evolution Chapter 16

  2. Early Theory of Evolution • Lamarck, a French biologist, proposed: • That body structures could change according to the actions of the organism. • Acquired characteristics could be passed on to any offspring. • He was incorrect, but paved the way for Darwin.

  3. Developing the Modern Theory of Evolution • @Charles Darwin published ideas on how species evolved and they became the basis of modern evolutionary theory@; • He took a job as a naturalist on the HMS Beagle where he traveled to South America and the Galapagos Islands collecting samples of specimens • He made many observation and after further experimentation he proposed the process of natural selection.

  4. Darwin’s observations: • Finches and tortoises had different beaks and shells/necks depending on diet. • However, all the finches and all the tortoises have many similar physical characteristics suggesting a common ancestor for each. • The differences in the finches and tortoises was due to adaptation to the food source.

  5. Natural Selection • @Survival of the fittest, those individuals better suited to survive@ • Darwin wrote “ On the Origin of Species by means of Natural Selection”, after years of observations and studying evidence he collected on the mechanism of change. • 4 principles of Natural Selection: • Variation • Heritability • Overproduction • Reproductive advantage

  6. Evolution • @Is cumulative changes in groups of organisms through time.@ • Natural selection is not evolution but it is the mechanism by which it occurs.

  7. 5 Types of Evidences of Evolution • Fossils - Recorded for Earth’s history.

  8. 5 Types of Evidences of Evolution • Anatomy • Homologous structures – Similar structures, Different use or function. • Analogous structures – different structure but are similar in function. • Vestigial structures – a body part structure that has no function in a present day organism but was useful to an ancestor. (ex human appendix)

  9. 5 Types of Evidences of Evolution • Chemistry – reveals relationships between organisms, species, and individuals. • Using RNA and DNA.

  10. 5 Types of Evidences of Evolution • Embryology – through development of a tail and gill silts can be seen in embryos of birds, reptiles, and mammals.

  11. 5 Types of Evidences of Evolution • Distribution – geographical distribution

  12. Extra Credit Question What is this fish’s name and what TV show is it from? Blinky. The Simpsons

  13. Adaptation • @A trait shaped by natural selection that increases an organisms reproductive success.@ • Mimicry – is a structural adaptation that enables one species to resemble another; predator may avoid them if they look harmful. • Camouflage – an adaptation that enables species to blend with their surroundings.

  14. Population Genetics • Populations evolve not individuals. • Natural selection acts on poor phenotypes that will not benefit the survival of the organism. • Genes in the population are called gene pool.

  15. 5 Mechanisms of Evolution

  16. 5 Mechanisms of Evolution • Genetic drift – change in frequency of gene variations in a population. • Founder’s effect reduction in alleles resulting from a small group settling in a separate location away from the rest of the population. • Bottleneck effect is a reduction in alleles resulting from a chance event that drastically decreases population size.

  17. 5 Mechanisms of Evolution • Genetic flow – migrating individuals transport genes.

  18. 5 Mechanisms of Evolution • Non-random mating – organism mate with individuals in close proximity. • Mutation – change in genetic material.

  19. Extra Credit Quote Mutation, it is the key to our evolution. It has enabled us to evolve from a single-celled organism into the dominant species on the planet. This process is slow, and normally taking thousands and thousands of years. But every few hundred millennia, evolution leaps forward. –Professor X (X-Men 1) Or -Dr. Jean Gray (X-Men 2)

  20. 5 Mechanisms of Evolution • Natural Selection acts on variation – “Survival of the fittest” • Types of Natural selection • Stabilizing selection – favors average individuals. • Directional selection – favors one extreme or the other, example very large or very small. • Disruptive selection – favors individuals of both extremes. • Sexual selection – changes in frequencies of traits based on ability to attract mates.

  21. Speciation • Speciation – evolution of new species. • Allopatric speciation – physical barrier divides a population into 2 or more population. • Sympatric Speciation – a species evolves into a new species without physical barriers.

  22. Reproductive isolation occurs when formerly interbreeding organisms can no longer mate and produce fertile offspring. • Prezygotic isolation – prevent fertilization • Geography • Behavioral • Mating time • Physical differences • Postzygotic isolation – when fertilization occurs, prevent hybrid organism from reproducing. (sterility)

  23. Patterns of Evolution • Adaptive radiation (Divergent evolution) – when ancestral species evolve into an array of species to fit number of diverse habitats. • patterns in which similar species become increasingly different.

  24. Patterns of Evolution • Convergent evolution – patterns of evolution in which distantly related organisms evolve similar traits. • Due similar environmental pressures.

  25. Gradualism is the idea of that species originating through a gradual change of adaptation. Punctuated equilibrium is rapid speciation, in burst with long periods of genetic equilibrium in between. Rate of Speciation