BIOL 1202 Dr Scott Crousillac MWF 9 30 10 20 a m 103 Williams Exam Material I will test you ONLY on material presented in class If you know and understand the lectures you will do fine on the exams Figures presented in lecture will mostly be from the textbook If they are from somewhere else I will post these slides on Moodle Descent with Modification A Darwinian View of Life Chapter 22 What is Evolution Adaptation Evolution two main ideas 1 Change over time of the genetic composition of a population not just a single organism 2 Decent of modern organisms with modification from preexisting organisms Evolutionary adaptation Accumulation of inherited characteristics that enhance organisms ability to survive in specific environments Pre Darwinian Theory of Evolution Lamarck Use disuse Bodies of living organisms are modified through the use or disuse of parts Inheritance of acquired characteristics These modifications are inherited by offspring Natural Selection The unequal survival and reproduction of organisms due to environmental forces resulting in the preservation of favorable adaptations Process selects from what is available in the gene pool New characteristics are not created on demand Catastrophism Gradualism Uniformitarianism Cuvier catastrophism Catastrophes caused extinct species strata Hutton gradualism Lyell uniformitarianism Gradualism slow natural forces wind water earthquakes volcanoes caused geological formations not catastrophes Uniformitarianism the mechanisms of change are constant over time Observations of geological formations rates processes occur Earth much older than a few thousand years Evolution in a Historical Context Linnaeus classification Hutton gradual geologic change Lamarck species can change Malthus population limits Cuvier fossils extinction Lyell modern geology Darwin evolution natural selection Mendel inheritance Wallace evolution natural selection American Revolution French Revolution U S Civil War 1750 1800 1850 1900 1795 Hutton proposes his theory of gradualism 1798 Malthus publishes Essay on the Principle of Population 1809 Lamarck publishes his theory of evolution 1830 Lyell publishes Principles of Geology 1831 1836 Darwin travels around the world on HMS Beagle 1837 Darwin begins his notebooks on the origin of species Darwin writes his essay on the origin of species 1844 1858 1859 Wallace sends his theory to Darwin The Origin of Species is published 1865 Mendel publishes inheritance papers Figure 22 2 Evolution by Natural Selection Darwin and Wallace developed the theory independently Darwin voyage of the Beagle Wallace British naturalist in Indonesia Darwin s Focus on Adaptation a Cactus eater The long sharp beak of the cactus ground finch Geospiza scandens helps it tear and eat cactus flowers and pulp c Seed eater The large ground finch Geospiza magnirostris has a large beak adapted for cracking seeds that fall from plants to the ground b Insect eater The green warbler finch Certhidea olivacea uses its narrow pointed beak to grasp insects Figure 22 6 Natural Selection The unequal survival and reproduction of organisms due to environmental forces resulting in the preservation of favorable adaptations Process selects from what is available in the gene pool New characteristics are not created on demand Mechanism Behind Natural Selection From page 458 Artificial Selection Selective breeding of organisms to encourage the occurrence of desirable traits Provides evidence for natural selection Figure 22 9 Trees vs Scala Naturae Aristotle s Scala Naturae Ladder of nature see page 453 Evolution not about climbing ladder of nature from lower to higher Evolution is a bush with lineages branching from one another Concept 22 3 Evolution is supported by an overwhelming amount of scientific evidence Within a few weeks of treatment with the drug 3TC a patient s HIV population consists almost entirely of 3TC resistant viruses How can this best be a b c d explained HIV has the ability to change its surface proteins to resist drugs The patient must have become reinfected with 3TC resistant viruses HIV began making drug resistant versions of reverse transcriptase in response to the drug A few drug resistant viruses were present at the start of treatment and natural selection increased their frequency Natural Selection HIV Resistance Homologous Analogous Structures Homologous Structures or other attributes in different species that resemble each other structurally but not necessarily functionally because of common ancestry Analogous Structures that are similar in function but NOT in structure and developmental and evolutionary origin Homologous Structures Mammalian Forelimbs Figure 22 15 Homologous Structures Vertebrate Embryos All vertebrates share similar developmental genes Differences arise by some genes being switched on or off at varying times during development Figure 22 16 Homologous Structures Biochemistry Molecular Biology DNA is universal genetic material All life forms use approximately the same 20 amino acids to make proteins All use ATP as the primary form of cellular energy All use RNA and ribosomes to make protein Convergent Evolution Convergent evolution Similarity between 2 organisms structures or molecules due to independent evolution along similar lines rather than descent from a common ancestor Analagous structures are the result of convergent evolution Examples bat wing and butterfly wing Similar in function but not in structure Analogous Homologous Structures NotNot homologous homologous analogous analogous NotNot homologous homologous notnot analogous analogous Homologous Homologous notnot analogous analogous Homologous Homologous analogous analogous Fossil Record Show change in organisms through time Change in types of organisms Past organisms differ from present day Many species have become extinct Oldest species are in the deepest layers of organisms strata
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