Study Guides for Chs. 10 & 11 – Flashcards
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Linnaeus
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contribution to evolutionary theory: developed a classification system to group organisms by their similarities that also reflect evolutionary relationships.
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Buffon
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contribution to evolutionary theory: suggested that species shared ancestors
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E. Darwin
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contribution to evolutionary theory: contended that all living things were descended from a common ancestor and that more complex forms of life arose from less complex forms.
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Lamarck
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contribution to evolutionary theory: proposed that changes in physical characteristics could be inherited and were driven by environmental changes over time.
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What two conditions must be true for a group of animals to be considered the same species?
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1. they must be able to reproduce 2. they must have fertile offspring
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Lamarck's ideas of evolution are known as the inheritance of acquired characteristics. What was incorrect about his theory of how organisms evolve?
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-he thought that greater use or disuse of a structure or organ would cause changes that could then be passed on to offspring
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In the 1700s, many people believed that species were fixed and did not change. How did plant hybridization-a type of crossing that could be observed in experiments- help change this view?
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-different species could be produced with hybridization showing that species could change
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Catastrophism
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-the theory that natural disasters, such as floods and volcanic eruptions, have happened often during earth's long history. -these events shaped land forms and caused species extinction ex: the asteroid that killed the dinosaurs
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Gradualism
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-the principle that changes observed in landforms resulted from slow changes over a long period of time
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Uniformitarianism
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-a principle that states that the geological structure of Earth resulted from cycles of observable processes and that these processes operate continuously
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What word refers to traces of an organism that existed in the past?
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-fossil
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What is the process of biological change by which descendants come to differ from their ancestors?
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-evolution
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Events such as volcanoes, floods, and earthquakes are the basis of what geological theory?
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-catastrophism
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What geological theory can be summarized by the phrase "the present is the key to the past"?
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-uniformitarianism
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E. Darwin
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Charles Darwin's poetic grandfather
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Lamarck
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Thought that a giraffe's long neck evolved from reaching high in trees
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Linnaeus
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Grouped living organisms into categories based on what they looked like
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Buffon
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Wrote *Historie Naturelle* (Natural History) in 1749
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What is variation among members of *different* species called?
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-interspecific variation
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What is variation among members of *the same* species called?
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-intraspecific variation
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What island chain in South America was the source of many of Darwin's insights?
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-the Galapagos
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Darwin saw populations of various species that seemed well-suited to their environment. What did this suggest?
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-the species may somehow be able to adapt to their surroundings
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Darwin observed fossils of huge animals such as *Glyptodon*, a giant armadillo. Why were these fossils of interest to him?
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-he thought modern animals might have some relationship to fossil forms
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Many people in the 1700s thought the Earth was only about 6000 years old. How did the fossil organisms Darwin saw lead him to think Earth must be much older than that?
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-would take much longer than 6000 years for the changes to occur between the fossil organisms he saw and their modern day relatives
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Darwin also observed fossil shells of marine organisms high up in the Andes mountains, and saw an earthquake move land that was underwater above sea level. How did he apply these insights to the evolution of organisms?
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-Darwin saw that in geologic processes great changes could occur slowly, over a long period of time. He extended this insight to the evolution of organisms.
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Look at figure 2.2 in your textbook. What differences between the two Galapagos tortoises can you identify form the two pictures?
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-shell shape -edges of the shell -lengths of the neck -lengths of their legs
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Variation
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the difference in the physical traits of an individual from those of other individuals in the group to which it belongs
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Adaptation
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a feature that allows an organism to better survive in its environment
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Adaptation
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a tortoise population lives in an area with high grass. These tortoises have longer necks than tortoises that live in other areas. The long necks are an example of this.
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Variation
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one bird in a population has a slightly thicker beak than its relatives. This thicker beak is an example of what in the population.
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Why did artificial selection interest Darwin?
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-Darwin noticed breeders could produce a great amount of diversity in species
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Why must selected traits be heritable?
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-if a trait is not heritable it won't be passed down to offspring
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In natural selection, what must be true of traits that are passed down through generations?
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-the traits are selected only if they give advantages to individuals in their present environment
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What important idea from Thomas Malthus inspired Darwin?
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-human populations would grow geometrically if resources were unlimited. Instead, disease and a limited food supply kept the population smaller.
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Overproduction
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producing many offspring, some of which may not survive
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Variation
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individual differences that may be heritable
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Adaptation
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a structure well-suited for the environment
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Dissent with modification
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a heritable trait becoming common in a population
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*Humans* are the selective agent in which type of process, artificial or natural selection?
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-artificial selection
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*The Environment* is the selective agent in which type of process, artificial or natural selection?
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-natural selection
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What is the measure of the ability to survive and produce offspring relative to other members of the population called?
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-fitness
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What is the ability of a trait to be passed down from one generation to the next called?
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-heritability
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What are all the individuals of a species that live in an area called?
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-population
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Vestigial structures
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-seem to lack any useful function, or are at least no longer used for their original purpose. List three examples.
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Many modern whale species have vestigial pelvic and leg bones. What does this suggest about the ancestry of modern whale?
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-that they lived on land
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Homologous structure
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feature that is similar in structure in different organisms but has different functions -human arm and horse leg
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Analogous structure
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feature that performs a similar function in different organisms but is not similar in origin -example insect wing, bird wing
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Analogous structure
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-is *not* evidence of a common ancestor
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Vestigial structure
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remnant of an organ or structure that had a function in an early ancestor
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Homologous structure
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examples include the wing of a bat and the hand of a human
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Analogous structure
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examples include the wing of a bird and wing of an insect
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Vestigial structure
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examples include the wing of an ostrich and appendix of a human, the tiny pelvic bones and hind limbs in many snakes
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What are two reasons that the fossil record is not complete?
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1. most living things do not form into fossils after they die 2. fossils have not been looked for in many areas of the world
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What is one example of a transitional fossil that has been found?
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-basilosaurus isis
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Why are transitional fossils important?
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-demonstrate the evolution of traits within groups as well as the common ancestors between groups
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DNA sequence analysis
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contribution to evolutionary theory: -the more related two organisms are the more similar their DNA will be. -Because there are 1000s of genes in even simple organisms, DNA contains a huge amount of information on evolutionary history.
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Pseudogenes
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contribution to evolutionary theory: -they no longer function but can change as they are carried along with functional DNA through generations. -Similarities between pseudogenes must come from a common ancestor
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Homeobox Genes
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contribution to evolutionary theory: -homeobox genes control the development of specific structures. -similar homeobox gene clusters are evidence of a common ancestor
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Protein comparisons
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contribution to evolutionary theory: -similarities of proteins across organisms can be revealed by molecular fingerprinting and are evidence of a common ancestor.
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What two things combine to make up our modern evolutionary theory?
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-the theory of natural selection combined with genetics
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How has molecular evidence helped support fossil evidence in determining the early ancestor of our modern-day whales?
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-comparison of milk protein genes confirmed the fossil evidence that modern day whales descended from land mammals
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What is meant by the phrase "Evolution unites all fields of biology"?
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-the basic principles of evolution are used in all fields of biology
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How does paleontology contribute to evolutionary biology?
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-the study of fossils can provide new information and support hypotheses about how evolution occurs
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What kind of variation must exist in a population that has a wide range of phenotypes?
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-genetic variation
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How can a wide range of phenotypes increase the chance that some individuals will survive in a changing environment?
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-some individuals will have traits that allow them to survive in a new environmental condition
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Mutation
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How it provides genetic variation: -can produce new alleles -mutations in reproductive cells can be passed on to offspring
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Recombination
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How it provides genetic variation: -forms new genetic combinations that are passed on to offspring
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Hybridization
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How it provides genetic variation: -new genetic information can be introduced into populations when species mate with other closely related species
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How is a gene pool like a pool of genes?
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-it contains all of the genes or alleles of all the individuals in a poulation
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What does an allele frequency measure?
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-how common a certain allele is in a gene pool
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What is a phenotypic distribution?
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-the distribution of different physical traits
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What can you learn from looking at a phenotypic distribution?
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-how common each phenotype is in the population
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In a population that is not undergoing natural selection for a certain trait, what does the phenotypic distribution look like?
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-a normal distribution
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Directional Selection
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How it works: -favors phenotype at one extreme of a trait's range
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Stabilizing selection
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-the intermediate phenotype is favored - selects against phenotypes at both extremes
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Disruptive selection
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-favors phenotypes at both extremes of a trait's range
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How is genetic drift different from natural selection?
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-changes in allele frequencies through genetic drift are due to chance alone -changes through natural selection are result of specific environmental pressures
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Why is genetic drift more likely to occur in smaller populations?
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-there are less variety of alleles
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What are some problems that can result from genetic drift?
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-loss of genetic diversity decreases the chance that some individuals will be able to survive new environmental conditions -genetically harmful alleles can build up in the population due to chance alone
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Why is the cost of reproduction different for males and females?
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-males produce many sperm continuously -females are much more limited in the number of offspring they can produce in each reproductive cycle
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What is sexual selection?
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-occurs when certain traits increase mating success
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What variable remains constant, or in equilibrium, in the Hardy-Weinberg model?
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-allele frequencies
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Name the 5 conditions required for a population to be in Hardy-Weinberg equilibrium.
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-no genetic drift -no gene flow -no mutations -no sexual selection -no natural selection
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Name two ways that population biologists can use Hardy-Weinberg equilibrium.
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1. study the degree in which real populations are evolving 2. better understand the five factors that can lead to evolution
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Write the Hardy-Weinberg equation.
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p²+2pq+q²=1
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p²
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-frequency of dominant homozygous genotype
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2pq
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-frequency of heterozygous genotype
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q²
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-frequency of recessive homozygous genotype
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p
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-frequency of dominant allele
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q
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-frequency of recessive allele
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In what types of systems can the Hardy-Weinberg equation be used?
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-single gene traits in simple, dominant-recessive systems
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What variables must be known in order to use the Hardy-Weinberg equation?
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-the phenotype and allele frequencies
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What can be concluded if real genetic data do not match the frequencies predicted by the equation?
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-the population is evolving
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Genetic drift
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How it can lead to evolution: -alleles change due to chance
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Gene flow
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How it can lead to evolution: -gene flow changes allele frequencies
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Mutation
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How it can lead to evolution: -new alleles created
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Sexual selection
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How it can lead to evolution: -traits favored for mating
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Natural selection
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How it can lead to evolution: -traits favored for survival
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Behavioral isolation
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How it works: -changes in behavior between two populations can act as barriers that prevent mating
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Geographic isolation
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How it works: -physical barriers that can divide populations
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Temporal isolation
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-differences in mating periods or times of day when individuals are active can prevent mating between populations
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What is speciation?
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-the rise of two or more species out of an existing species
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Convergent evolution
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-distantly related species can evolve similar traits while adapting to similar environments
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Divergent Evolution
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-closely related species can evolve different traits while adapting to different enviornments
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Beneficial relationship
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How it works: -two or more species evolve in a beneficial way -it's a plus, plus -each involving characteristics that are beneficial to the other
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Evolutionary arms race
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How it works: -two or more species evolve in a competitive way, each evolving characteristics that put some type of evolutionary pressure on the other ex: crab (pincers) and snail (harder shell)
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Background extinction
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Possible causes: -local changes in environment such as changes in food supply Outcome: -a few species may go extinct in localized area (slow extinction)
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Mass extinction
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Possible causes: -catastrophic event on a global level, ex: ice age Outcome: -many species go extinct around the world in a relatively short period of time (quick extinction)
