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Concept 14.1 Darwin Developed a Theory of Evolution I. Idea’s From Darwin’s Time A. Evolution is all of the changes that have transformed life over time B. In the mid 1700’s Charles Buffon suggested that the Earth is older than 10,000 years old C. In the early 1800’s Jean Baptiste Lamarck developed the idea of Inheritance of Acquired Characteristics II. The Voyage of the Beagle A. In 1831 The HMS Beagle left England for a five year voyage around the world B. Darwin studied the geology, plants, and animals he encountered III. Darwin’s Observations A. Darwin maintained extensive journals of his observations, studies and thoughts B. Darwin noticed the animals and plants he observed were uniquely South American C. Darwin was especially intrigued by the Galapagos Islands because of their diversity IV. Ideas from Geology A. Darwin read books from Charles Lyell that proposed Earth’s features today could be explained by geological processes B. From this Darwin made two conclusions 1. The Earth must be very old 2. Slow and gradual processes occurring over vast amounts of time could cause tremendous change V. Darwin Publishes His Theory A. Over many years after his return, Darwin developed his theory based on observations, inferences and ideas B. In 1844 Darwin wrote a 200 page essay that outlined his idea C. In 1856 Darwin released his findings to the public in the book The Origin of Species VI. Darwin’s Two Main Points A. Darwin’s first point was that the species of organisms living on Earth today descended from ancestral species, Descent with Modification B. Darwin’s second main point was that Natural Selection is the mechanism for evolution Concept 14.2 Evolution has left much evidence I. The Fossil Record A. Preserved remains or markings left by organisms that lived in the past are called fossils B. The positions of fossils in the rock strata can reveal relative age C. The fossil record is this chronological collection of life’s remains in the rock layers II. Geographic Distribution A. The differences and similarities between organisms and different parts of the world shows how species today evolved from ancestral forms B. Geographic distribution gives clues as to how modern species evolved III. Similarities in Structure A. Similar structures in species sharing a common ancestor are called homologous structures B. Vestigial structures are remnants of structures that may have had important functions in an ancestral species, but have no clear function today IV. Similarities in Development A. Embryos of closely related organisms often have similar stages in development B. Comparing the development of organisms supports other evidence of homologous structures V. Molecular Biology A. The closer two organisms DNA sequence match, the closer the relationship B. DNA and protein analysis are new tools for testing hypothesis about evolution C. There is molecular evidence that there are common genetic codes shared by all species Concept 14.3 Darwin proposed natural selection as the mechanism of evolution I. Darwin’s Theory of Natural Selection A. A population is a group of individuals of the same species in the same area at the same time B. Populations in different areas become more and more different, leading to new species II. Observations Lead to A Question A. There are 13 species of finches unique to the Galápagos Islands B. They most closely resemble one finch species living on the South American mainland III. More Observations Lead to an Idea A. Darwin recognized that all species tend to produce excessive numbers of offspring B. Darwin also recognized there was variation among the individuals of a population IV. Artificial Selection A. Artificial selection is the selective breeding of domesticated plants and animals to produce offspring with traits that humans value B. You see this change in Dog’s over the last 500 years V. Pesticides-Natural Selection in Action A. When a new pesticide is sprayed it will kill about 99% of the insects targeted B. As time goes on, more insects are resistant to the pesticide C. This illustrates two key points about natural selection 1. natural selection is a “screening” of the traits available 2. natural selection favors those characteristics in a varying population that fit the specific current, local environment Concept 14.4 Microevolution is a change in a population’s gene pool I. Populations and Their Gene Pools A. A population is the smallest level at which evolution can occur B. The gene pool consists of all the alleles in all the individuals in a population II. Changes in Gene Pools A. Natural selection is not random B. Microevolution is a change in the frequencies of alleles from generation to generation C. The Hardy-Weinberg Equilibrium is when a populations gene frequencies are not changing, i.e. not evolving III. Genetic Drift A. A change in the gene pool due to chance is called genetic drift B. The smaller the population the greater the impact C. The Bottleneck Effect is when a disaster reduces the size of a gene pool D. The Founder Effect is when a few individuals colonize a new habitat IV. Gene Flow and Mutation A. The exchange of genes with another population is called gene flow B. A mutation is a change in an organism’s DNA V. Natural Selection and Darwinian Fitness A. Natural Selection is a blend of chance and sorting B. Darwinian Fitness is the contribution of one individual to the gene pool compared to others VII. A Return to the Galapagos A. Peter and Rosemary Grant have studied finches on Daphne Major in the Galapagos B. Their data has provided clear evidence of natural selection Concept 14.5 Evolutionary Biology is important in health science I. Natural Selection and Sickle Cell Disease A. Sickle Cell disease is a recessive disorder which affects the shape of red blood cells at a ate of 1 out of 25 people in some African populations B. Individuals with one copy of the allele are resistant to developing malaria C. Natural Selection has selected for those individuals which are resistant even with the negative affects of the sickle cell allele II. Evolution of Antibiotic Resistance in Bacteria A. Antibiotics kill or slow the growth of bacteria B. An antibiotic will kill most of the bacteria in a population but leave those which are resistant behind soon a greater percentage of the bacteria is resistant to the antibiotic C. In New York City, there are strains of the bacteria which causes Tuberculosis which are resistant to all three antibiotics used to treat the disease D. The overuse of antibiotics is the speeding up the evolution of these strains Concept Check 14.1 1. How did the work of Lyell and Malthus influence Darwin as he developed his theory of evolution? 2. What characteristics of the Galápagos Islands were particularly important for Darwin? 3. What is natural selection? 4. Which of the following is an adaptation: the sharp teeth of a house cat, or a scar on the cat's ear? Explain. Concept Check 14.2 1. Why are older fossils generally in deeper rock layers than younger fossils? 2. How can evolutionary theory explain why Australia is home to relatively few native placental mammals? 3. What are homologous structures? 4. What can you infer about species that differ significantly in their DNA sequences? Concept Check 14.3 1. In Darwin's view, what conditions lead to a struggle for existence among individuals in a population? 2. What is the goal of artificial selection? 3. Why does a specific pesticide become less effective over time? Concept Check 14.4 1. What is a gene pool? 2. How has genetic drift affected the world's populations of cheetahs? 3. Describe what is meant by a "biologically fit" organism. 4. Describe the Grants' hypothesis about how environmental conditions led to microevolution among the finches of Daphne Major. 5. What are the two main forces of evolutionary change in gene pools? Concept Check 14.5 1. Under what conditions is the sickle cell allele beneficial to a heterozygous individual? 2. Identify a possible risk of overuse of antibiotics.