EXAM 3 STUDY GUIDE CHAPTER 22 Evolution Predarwinian ideas on creation of species James Hutton Charles Lyell Jean Baptiste de Lamarck Mechanism for evolution Thomas Malthus Elements of Darwin s theory of natural selection Descent with modification a change in genetic composition of a population from generation to generation Aristotle No evolution each organism on ladder of nature is perfect but there is spontaneous generation of lowest organisms Judeo Christian culture special creation by a god Georges Cuvier catastrophism and paleontology Linnaeus created a classification system but still had belief of god creation Gradualism Geological change is the result of a slow continuous process Uniformitarianism mechanisms of change are constant over time Catastrophic discontinuities in the geological record are the exception Geological changes are shaped by the same forces that are at work today No need to invoke supernatural forces to explain geology of fossil record the earth is very old Inheritance of Acquired Characteristics Proposes that organisms not created perfect but evolve toward greater and greater complexity perfection Microorganisms created by spontaneous generation and evolve towards greater complexity moving up the ladder of life Sees an elaborate branching tree of life organisms acquire new characteristics as they strive to adapt to their environment These acquired characteristics are passed on to their offspring The fate of the poor is inescapable because their reproductive powers will always exceed their means of sustenance Makes Darwin see the conflict between resources and reproduction Individuals better able to use limited resources will have more progeny Characteristics of the population will change from one generation to the next Natural Selection Darwin and Alfred Wallace s idea 1 Within a population more offspring are produced than can survive Leads to competition for limited resources 2 Variability exists in all organisms and much of this variability is heritable 3 Some of this variability affects survival rates Those that are better adapted have a better chance of survival Survival of the Fittest 4 Individuals that are more fit will leave more offspring Natural Selection 5 Survival of the fittest will lead to changes in the population with favorable characteristics accumulating with time EXAM 3 STUDY GUIDE Darwin s theory has 2 parts Natural selection Influence over Darwin into thinking that populations inevitably grow faster than their food supply Biogeography Endemic Artificial selection Evidence for evolution Evolution and natural selection are blind processes Populations evolve not individuals Natural selection can amplify only heritable variations Evolution modern species evolved from ancestral forms Natural Selection the mechanism for evolution Process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits If an environment changes or if individuals move to a new environment natural selection may result in adaptation to these new conditions sometimes giving rise to new species individuals do not evolve populations evolve over time Thomas Malthus study of the geographic distributions of organisms evidence for evolution Influenced by many factors including continental drift the slow movement of Earth s continent over time Species that are found nowhere else in the world ties in with biogeography ex islands tend to have many species of plants animals that are endemic Process of selecting and breeding individuals that possess a desired trait Galapagos Finches represent an adaptive radiation 14 species Some islands have only one Each species is adapted to a local food supply by differences in their beaks Closest relative is a finch living in costal South America Australian marsupials compared with placental mammals Convergent Evolution Unrelated species adapt similar forms when living in similar environments demonstrates progression from ancestral forms to modern ones Fossil record shows close relationships between extinct species and living ones from the same geographical area evidence of evolution Evolution does not follow a straight path species respond to changing Conditions The fossil record Evolution straight path EXAM 3 STUDY GUIDE Comparative anatomy Homology Homologous structures Vestigial structures Molecular biology Phylogeny Artificial selection Implication Evolutionary tree Convergent evolution Analogous supports the idea of descent with modification from a common ancestor related species share many common structures similar structures resulting from common ancestry evidence for evolution Represent variations on a structural theme that was present in their common ancestor Ex arrangement of forelimbs in a human arm and bat wing structures with little or no function that are remnants of ancestral structures with important functions Ex hip bone in a whale appendix in humans comparison of DNA or protein sequences provides a measure of relatedness of organisms and confirms family trees based on morphology anatomy The evolutionary history of a species can produce new forms of plants and animals including new species Great genetic variability exists within species and new forms can be selected for A diagram that reflects evolutionary relationships among groups of organisms The independent evolution of similar features in different lineages Ex marsupials vs mammals Species that share features because of convergence the resemblance is said to be analogous instead of homologous The Modern Synthesis merging Darwinian evolution with genetics 1 mutation constantly creates new alleles and genes therefore individuals in populations are genetically variable for nearly all traits 2 3 Individuals pass their alleles on to their offspring intact In most generations more offspring are produced than Key ideas for natural selection can survive 4 Individuals that survive and reproduce or reproduce the most are those with alleles that best adapt them to their environment As a result alleles associated with higher fitness increase in frequency from one generation to the next Natural selection acts on individuals but populations evolve Natural selection can only modify existing traits but this can result in new traits Natural selection is backward looking not forward looking Evolution and natural selection are blind processes Natural selection is nonrandom but it is not directed
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