NR 509 Unit 1 Exam study guide (spring 2020) - Chamberlain College
Biology II - Unit 1 Study Guide
CH 22: Descent with Modification – A Darwinian View of Life
• What is the simplest definition of evolution?
o Descen
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NR 509 Unit 1 Exam study guide (spring 2020) - Chamberlain College
Biology II - Unit 1 Study Guide
CH 22: Descent with Modification – A Darwinian View of Life
• What is the simplest definition of evolution?
o Descent with modification
o Change in the population gene frequencies over time
• What does evolution help us explain?
o The adaptations of organisms
o The unity and diversity of life
• What are the major points of evolution?
o Species change over time
o All organisms share common ancestors with other organisms
o Evolutionary change is gradual and slow
• What are the assumptions of natural selection?
o Variation- Members of a population exhibit variation in appearance and behavior
o Inheritance- Some traits are consistently passed on from parent to offspring; heritable
o Overproduction - More offspring are produced than the environment can support; creates struggle to survive
o Differential survival and reproduction- Individuals possessing traits well-suited to environment (adaptations) will contribute more offspring to the next generation
• Why are the assumptions of natural selection important?
o Natural selection is the primary mechanism of evolution; it causes changes in the traits of organisms within a population from generation to generation
o If one of the assumptions does not occur, then the trait does not experience natural selection
• What does descent with modification by natural selection explain?
o The adaptations of organisms
o The unity and diversity of life
o All species are descended from one or a few original forms of life, closely related species diverged from ancestors by accumulation of slightly different traits over time
• What ideas pre-dated Darwin’s? Explain them
o Aristotle- “The Great Chain of Being” (scala naturae): static universe where living organisms were created initially and then remained essentially unchanged, these ideal species were arranged hierarchically, higher to lower forms of being
o Traditional Judeo-Christian- Species were designed by God and therefore perfect
o Carolus Linnaeus- Systema Naturae: developed binomial nomenclature and taxonomic classification, described life in nested system grouped by similarities, unchanging order of life, each species designed for a specific purpose
o Georges Cuvier- Catastrophism: first to recognize extinction, different strata – different fossils (strata represent time), catastrophes altered landscape and killed off life, repopulated by immigration from other areas
o James Hutton- Gradualism: change occurs through slow but continuous cumulative effect; change over time
o Charles Lyell- Uniformitarianism: processes operating in the past are the same as those in the present
o Robert Malthus- “An Essay on the Principle of Population”: overproduction – plants and animals produce more offspring than can survive, struggle to survive – population growth will outstrip food supply
o Jean-Baptiste Lamarck- first real theory on how life changes over time: use and disuse, inheritance of acquired traits
• Who influenced Darwin’s thought processes as he developed his theory?
o Robert Malthus- “An Essay on the Principle of Population”: overproduction – plants and animals produce more offspring than can survive, struggle to survive – population growth will outstrip food supply
o James Hutton- Gradualism: change occurs through slow but continuous cumulative effect; change over time
• What factors promote selection in populations?
o Variation among individuals of the same population
o Adaptation among related species
• How do we synthesize evolution today?
o Populations evolve, not individuals
o Natural selection can only increase or decrease traits that vary in a population
o Accumulation of small changes over long periods of time
• What evidence do we have for evolution’s occurrence?
o Direct observation: antibiotic resistance in bacteria
o Homology:
♣ Homologous structures: similar structures in related organisms, inherited from a common ancestor
♣ Vestigial structures: remnant structures that were of some value to ancestor’s
♣ Molecular homologies: similarity in amino acids among vertebrate hemoglobin
♣ Analogous structures: similar structures in unrelated organisms, not inherited from common ancestor but evolved to do the same job
o Fossil record: transitional fossil forms consistent with major branches of descent in tree of life
o Biogeography: geographic distribution of species, different species in different regions exhibit similar adaptations to local environments, influenced by continental drift and plate tectonics
CH 23 Evolution of Populations
• What is a population?
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-What is taxonomy?
o The principles of classification
o How organisms are named and classified
• Why is taxonomy important?
o The classification of organisms shows the relationship between the organism and its contemporaries
o Each species is assigned a unique name
o Systematists can easily specify the closest relatives of any species
o Each species has a universal name regardless of language barriers among scientists
• How does taxonomy work?
o Binomial nomenclature: 2-part Latin name, genus (capitalized) and species (lowercase) written in italics
o Hierarchical classification: group of related species nested together into same genus, related genera, into families, etc. (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species)
• How would you write the scientific name of a particular organism? How would you type it?
o Written: Genus (capitalized) and species (lowercase), underlined
o Typed: Genus (capitalized) and species (lowercase), italicized
• What is hierarchical classification, and why do we use it?
o Group of related species nested together (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species)
o Categories within taxonomic classification are arranged in increasing specificity
o Illustrates patterns of descent and shared characteristics
• How do we use phylogenetic trees? What use do they have?
o Focus on shared features from common ancestry
♣ Homologies: phenotypic and genotypic similarities due to shared common ancestry
o Cladistics: groups organism by common descent, ancestral species, and all its descendants
• What are ways in which phylogenetic trees can be constructed and read?
o Identify characters that are newly evolved (derived) and shared among groups
o Use shared derived characters (synapomorphies) to identify clades (an ancestor and all its descendants; they share characters due to shared ancestry)
o Use clades to create a phylogeny (shows pattern of descent not phenotypic similarity)
o Phylogenetic trees can be read like a map of evolutionary history
• How could you use one of these trees to find a common ancestor for two species?
o Look for homologies: shared features from common ancestor
o Follow tree back to a point where they both diverge from
• What are sister and basal taxa?
o Sister taxa: share immediate common ancestor
o Basal taxa: lineage that diverged early in group history
• What is a clade?
o Specific group that includes a common ancestor and all of its descendants
o Monophyletic clade: valid clade that consists of ancestor species and all its descendants
o Paraphyletic clade: ancestral species and some, but not all of the descendants
o Polyphyletic clade: includes closely related species but doesn’t include their most recent common ancestor
• How are cladograms used?
o Diagram used in cladistics which shows relations among organisms
o Cladograms show the characteristics that the organisms have acquired or lost throughout time that gave rise to different species
• What are homologous and analogous structures? What insight do they give us?
o Homologous structures: similar structures in related organisms, inherited from common ancestor
o Analogous structures: similar structures in unrelated organisms, not inherited from common ancestor but evolved to do the same job, example of convergent evolution
o Evidence of natural selection in action
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