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Bio 7: General Biology II Evolutionary, Organismal, & Ecological Biology

Bio 7: General Biology II Evolutionary, Organismal, & Ecological Biology. Dr. Diane Livio liviodl@lamission.edu CANVAS: ilearn.instructure.com CMS 229 (in the 221 suite) M 4:00-6:00pm W 12:30-2:30pm T/Th 10:30-11:30am. About this course.

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Bio 7: General Biology II Evolutionary, Organismal, & Ecological Biology

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  1. Bio 7: General Biology IIEvolutionary, Organismal, & Ecological Biology Dr. Diane Livio liviodl@lamission.eduCANVAS: ilearn.instructure.com CMS 229 (in the 221 suite) M 4:00-6:00pm W 12:30-2:30pm T/Th 10:30-11:30am

  2. About this course • Majors course – rigorous and challenging, designed to be rewarding • Student responsibilities • Review the syllabus • Check CANVAS regularly

  3. Expectations & Goals • What is expected of you? • What do you expect of me? Or your class mates?Of the course? • First module on CANVAS has help! • “Learn How You Learn” www.vark-learn.com

  4. Evolutionary Processes "Nothing in biology makes sense except in the light of evolution" - Theodosius Dobzhansky

  5. Scientific Theory • Def: a proposed explanation for a very general class of phenomena, supported by a large body of evidence • Possesses both pattern and process components

  6. Theory of Evolution • On the Origin of Species (1859) • All life evolved gradually from one primitive species [lived 3.5 bya] • Split off into many diverse species over time • Mainly by natural selection

  7. Pattern of Evolution • Descent with modification • Inherited characteristics in a population of a species change over time • Sometimes population changes over time to form a new species • Newer species descend from older species

  8. Macroevolution • Pattern of evolution over large scales • Larger than the species level • Over geologic time scale How old is the Earth? How old is life?

  9. Earth’s Early History • Estimates of Age of Earth/Solar System -- Current estimate: 4.54 by • Oceans formed by 3.8 bya • No O2, much solar radiation

  10. Life – 3.6 to 3.8 bya Oldest fossils: 3.5 by Most history of “higher” organisms in most recent 500 million years…

  11. Macro- vs Micro-

  12. Process of Evolution Microevolution: the change in allele frequencies in a population over time Population: a group of individuals of one species living in a particular place

  13. DNA • Genetic info – heritable • Genes: code for proteins to make and maintain organisms • Allele: form of a gene

  14. GENOME CHROMOSOMES NUCLEOTIDES GENOTYPE vs PHENOTYPE

  15. Process of Evolution Microevolution: the change in allele frequencies in a population over time Mechanisms of Evolution: Mutation Genetic Drift Gene Flow Natural Selection

  16. Mutation in DNA • Def: change to the nucleotide bases (adds variation to the population)

  17. Mutation = Source of DNA Variation DNA Replication = Potential MISTAKES

  18. Genetic Drift • Def: any change in allele frequencies in a population that is due to chance • Random with respect to fitness

  19. More pronounced in small populations • Drifting allele frequency could lead to loss of allele or fixation (100% frequency) Fig. 23.4

  20. Genetic Drift - how it occurs: • Genetic bottleneck – sudden reduction in # of alleles in a population

  21. Conservation biologists manage “gene pool” of species with small population sizes to prevent loss of alleles through drift.

  22. Genetic Drift - how it occurs: • Founder’s effect – change occurs when a new population is established • Small subset does not represent allele frequencies of source population

  23. Gene Flow • Def: change in allele frequency due to migration between populations

  24. Gene Flow: movement of alleles from one population to another • Tends to make one or both populations look more like the other

  25. Charles Darwin: The Origin of Species (1859) • Identified natural selection as the major mechanism of adaptive evolution • Much focus on survival aspect of reproduction  “survival of the fittest”

  26. Adaptive Evolution Adaptation = a heritable trait that increases an individual’s ability to produce offspring (its fitness) in a particular environment relative to individuals lacking the trait

  27. Natural Selection • Process by which heritable variation leads to differential success in survival and reproduction • Differential reproductive success can result from differences in survival, fecundity, and mating success.

  28. Artificial selection – deliberate manipulation by humans

  29. Summary • Natural selection adapts a population to its environment. • Selection operates on individuals. Evolution occurs in populations and species. • Other mechanisms of evolution: mutation, drift, gene flow.

  30. Speciation • Species: “an evolutionarily independent population or group of populations” • Reproductive compatibility • Similar physical appearance • Shared, unique genetic history • Allopatric vs sympatric speciation • Physically separated populations vs “living together”

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