Biology Study Guide Evolution Chapters 14 – 16 Test Friday April ____ Chapter 14 Oldest rocks date the earth’s age at around 4.5 billion years. Could be older. Abiogenesis – belief in spontaneous generation of some life forms from nonliving matter Biogenesis – life comes only from preexisting life Intelligent Design, or Creationism, disagrees with evolution of life forms. Scientists who helped prove biogenesis (by disproving abiogenesis): Redi: maggots on meat Spallanzani: microbes in broth Pasteur: swan-necked flasks. Life does not arise from food and air alone Oparin: hypothesized that life was synthesized on the early earth. First, inorganic chemicals formed organics, then protocells. Chemical origins of life were first tested by Miller and Urey. They made amino acids, etc. this way. Gases in early atmosphere were very different from the gases in our air today. Not much oxygen. Coacervates: collection of droplets composed of molecules of different types of organic compounds First cells were prokaryotic, anaerobic, and probably heterotrophic Microfossils of earliest cells found in 3.5 byo rock “Endosymbiosis”: 1st eukaryotic cells may have formed by large bacteria engulfing smaller aerobic or photosynthetic prokaryotes (became first organelles). Chapter 15 Evolution: life forms have changed over a long period of time. Fossils show us preexisting forms of life: remains, molds, casts, imprints. Radiometric dating; isotopes; half-life Jean LaMarck – early evolutionary theory; “acquired characteristics”, based on use or disuse Charles Darwin – traveled on the Beagle for 5 years; collected and observed “On the Origin of Species” – famous book detailing how evolution works by natural selection Alfred Russel Wallace – came up with idea of natural selection independent of Darwin Those with most favorable variations in phenotype are most likely to survive and reproduce; “survival of the fittest”. Good genes most likely to be passed to successive generations Common ancestry – modern species are related to each other; evolutionary pattern in which different species evolve from one ancestral group. Convergent evolution – similar look but totally different species (dolphins, sharks) Divergent evolution – 2 or more related populations become more dissimilar because of separation and different environmental pressures. Ex: Galapagos finches Parallel evolution (coevolution) – evolutionary changes occur because of need to survive in close proximity to another organism (flowers, pollinating animals) Homologous structures – features that are different in use, but the same in structure (evidence of common ancestry) Analogous structures – features that are used the same, but have a different structure (do not show a common ancestry) Vestigial structures – useful to ancestor but not to modern version (appendix, coccyx bone) Biochemical similarities of DNA or protein sequences can be compared/contrasted Chapter 16 Speciation – evolutionary formation of a new biological species; usually a division of a single population into 2 or more genetically distinct groups. “Allopatric speciation” – geographic barriers prevent gene flow Reproductive isolation can also cause speciation - Prezygotic and post zygotic barriers to mating. Species – a group of like organisms that are capable of producing offspring. Population – all members of the same species in one place, time. Gene pool – collection of genes for all traits in a population Gene flow – movement of alleles into or out of a population due to migration Extinction Hardy-Weinberg Principle – genetics (allele frequencies) in a population will remain in equilibrium under certain conditions. What are these conditions? Microevolution: changes in a population over time, due to: Directional selection Stabilizing selection Disruptive selection Sexual selection Macroevolution: speciation events that take place over the course of a long time. Gradualism –vs- punctuated equilibrium theory of speciation.