Chapter 22 Descent with Modification a Darwinian View of Life Chapter Learning Objectives Define evolution and adaptation o Evolution 1 The change over time of the genetic composition of a population 2 Descent of modern organisms with modification from preexisting organisms accumulation of inherited characteristics that enhance organisms ability to survive in specific environments o Adaptation Concept 22 1 The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species Describe the theories of catastrophism gradualism and uniformitarianism the principle that events in the past occurred suddenly and were o Catastrophism caused by mechanisms different from those presently operation mechanisms of change are constant over time mechanisms gradually change over time o Gradualism o Uniformitarianism Explain the mechanism for evolutionary change proposed by Jean Baptiste de Lamarck o He compared living species with fossil forms and found several lines of descent o Findings led to 2 principles bodies of living organisms are modified through the Use and disuse use or disuse of parts Inheritance of acquired characteristics inherited by offspring these modifications are Concept 22 2 Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life Explain the mechanism for evolutionary change proposed by Darwin in On the Origin of Species o Descent with Modification by Natural Selection unity in life and he attributed that to the descent of all organisms from an ancestor that lived in the remote past He believed that decent with modification led to diverse modifications adaptations Darwin believed that there was Describe the two inferences Darwin made from his observations that led him to propose natural selection as a mechanism for evolutionary change o Inference 1 Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals o Inference 2 This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations Distinguish between artificial selection and natural selection o Artificial Selection Selective breeding of organisms to encourage the occurrence of desirable traits similar to 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 o Natural Selection Explain why an individual organism cannot evolve o Individual organisms cannot evolve because natural selection occurs through interactions between individual organisms and their environment Concept 22 3 Evolution is supported by an overwhelming amount of scientific evidence Describe the observations of soapberry bugs that supported Carroll and Boyd s hypothesis that changes in a population s food source can result in evolution by natural selection o The soapberry bugs that feed on the native balloon vine had longer beaks than the soapberry bugs that fed on the introduced goldenrain tree Their beaks closely match which fruits of the seeds they eat Their beaks changed over time Explain how drug resistance develops in bacteria and viruses o It developed in bacteria and virus by being introduced to antibiotics that would not be destroyed so a resistance was built up over time Explain how the existence of homologous and vestigial structures can be explained by Darwin s theory of natural selection o Certain structures lead us to believe that natural selection occurred and favored certain structures and features Homologous There are anatomical resemblances in numerous mammals particularly the forelimb which makes it clear that it was present in their common ancestor Vestigial the organism s ancestors snakes have vestiges of pelvic and limb bones There are remnants of features that once had a function in What observations have been made regarding the fossil record What predictions can be made using evolution to account for the distribution of fossils in sediments o Some observations made include the pattern of evolution showing that past organisms differed from present day organisms and many species have become extinct o You can predict where ancestors of more recent organisms fossils will be found from the distribution of fossils in sediment Explain how biogeography is used to infer the evolution of organisms o It is used to infer the evolution of organisms because it shows the geographic distribution of species This means that starting at Pangea we can understand evolution and continental drift to predict where fossils of different groups of organisms might be Also endemic plants and animals found no where else are often found on or around islands where new species arise on mainland or a nearby island Chapter Learning Objectives Chapter 23 The Evolution of Populations Explain the statement It is the population not the individual that evolves o Concept 23 1 Genetic variation makes evolution possible Compare discrete and quantitative characters o Discrete Characters o Quantitative Characters determined by a single gene locus with different alleles that produce distinct phenotypes flower color in pea plants results from the influence of two or more genes on a single phenotypic character height weight vary along a continuum within a population and usually Describe the significance of mutation in the generation of genetic variability o The significance would be that gene duplications that do not have severe effects persist over generations allowing mutations to accumulate and result in an expanded genome with new genes that may take on new functions Explain how sexual recombination generates genetic variability o It generates genetic variability by ensuring that sexual reproduction rearranges existing alleles into fresh combinations and variation in each generation Crossing over in prophase I Independent assortment during metaphase I Concept 23 2 The Hardy Weinberg equation can be used to test whether a population is evolving Define population o Population and interbreed producing fertile offspring a group of individuals of the same species that live in the same area List the five conditions that must be met for a population to remain in Hardy Weinberg equilibrium o 1 No mutations 2 Random mating 3 No natural selection 4
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