ISB 202 1nd Edition Lecture 9Outline of Last Lecture I. Biogeochemical CyclesOutline of Current Lecture II. EvolutionIII. Charles DarwinIV. Natural SelectionCurrent LectureContinuity Through Evolution• Epigenetics: environmental factors like diet, stress and prenatal nutrition can make an imprint ongenes that are passed from one generation to the next. o Epigenetic changes represent a biological response to an environmental stressor• Biological Diversity: The variety of living thingsEvolution (change over time): is the process by which modern organisms have descended from ancient organisms. • A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world. Sexual Selection• Mate Choice: maximizing reproductive potentialo Strength, territory, ornaments, etc.Survival of the Fittest• Coined by Philosopher Herbert Spencer• It is not the survival of the strongest, but the environmental sorting of heredityCharles Darwin• Came up with the theory of evolution based on his observations while voyaging on HMS Beagle These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.• Tried to explain similarities between animals and plants of arid Galápagos Islands and humid South American mainland• Darwin: A Short history• Born February 12, 1809• 1831 Voyage of the Beagle• 1859 Published On Origin of the Species• 1871 The Descent of ManOn the voyage• Collected plants & animals on land• At sea – studied specimens, read, recorded observations• Saw great diversity in the organisms – enormous numbers of species!• Patterns of Diversity • Plants and animals seemed so well suited to their environments• Impressed by the many ways organisms survive and reproduce• Similar areas on different continents were inhabited by very different animals.o Ex: why are there no rabbits on the Australian grasslands? No kangaroos in England?The Journey Home• Darwin began to wonder if animals living on different islands had once been members of the same species. • These separate species would have evolved from an original South American ancestor species after becoming isolated from one another • Massive, rich fossil record – much older than the current age of the earth beliefs.• James Hutton (1795) – old earth – great earth changes take time• Charles Lyell (1831) – the processes shaping the Earth now are the same ones that shaped the earth in the pasto Could life change as earth has changed?Thomas Malthus-The Malthusian Catastrophe (1798)• Population growth (if gone unchecked) would quickly over run the earth• Why don’t maple trees cover the earth since they each release 1000s of seeds?• Darwin’s questions:o What causes the deaths of so many?o What factors determine which survive and reproduce?• This led him to the idea of natural selection.Natural selection rests on three indisputable facts:1. Organisms produce more offspring than can survive.2. Individuals vary in their characteristics.3. Many characteristics are inherited by offspring from their parents.Vestigial Organs: organ that serves no useful function in an organism• Why would an organism possess organs with little or no function? o Presence of a vestigial organ may not affect an organism's ability to survive and reproduce, so natural selection would not cause the elimination of that organ. Natural Selection • Mechanism of evolution in which individuals with inherited characteristics well suited to the environment leave more offspring than do individuals that are less suited to the environment Descent with Modification• Over large amounts of time natural selection produces organisms: o with different structureso establishes different nicheso occupies different habitatso organisms look different than their ancestorso Descent with modification: each living thing has descended with changes, from other species over
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