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Chap 27 evolution
- 1. Chapter 27: Evolution of Life 27- Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 10. Dinosaurs 27-
- 15. Bones of vertebrate forelimbs 27-
- 17. Significance of developmental similarities 27-
- 19. Significance of biochemical differences 27-
- 22. Origin of the first cell(s) 27-
- 25. Chemical evolution at hydrothermal vents 27-
- 36. Using the Hardy-Weinberg equation 27-
- 56. The Galapagos finches 27-
- 58. Phyletic gradualism versus punctuated equilibrium 27-
- 61. Five-kingdom system of classification 27-
- 63. Three-domain system of classification 27-
- 64. The three domains of life 27-
Editor's Notes
- Table 27.1 (page 541) gives the geological time scale with major events that occurred during each geological period.
- a. Archaeopteryx was a transitional link between reptiles and birds. Fossils indicate that it had feathers and wing claws. Most likely, it was a poor flier. Perhaps it ran over the ground on strong legs and climbed into trees with the assistance of these claws. b. Archaeopteryx also had a feather-covered, reptilian-type tail that shows up well in this artist’s representation.
- After 50,000 years, the amount of 14 C radioactivity is so low that is cannot be used to measure the age of a fossil accurately. Other radioactive isotopes (the ratio of potassium 40 to argon 40) can be measured in surrounding rock, thereby allowing the scientist to infer the age of the fossil.
- The mass extinction occurring now is due to human activities.
- Triceratops (left) and Tyrannosaurus rex (right) were dinosaurs of the Cretaceous period, when flowering plants were increasing in dominance.
- a. About 225 million years ago, all the continents were joined into a supercontinent called Pangaea. b. When the joined continents of Pangaea first began moving apart, there were two large continents called Laurasia and Gondwanaland. c. By 65 million years ago, all the continents had begun to separate. This process is continuing today. d. North America and Europe are presently drifting apart at a rate of about 2 cm per year.
- Although the specific details of the limbs are different, the same bones are present (they are color-coded). This unity of plan is evidence of a common ancestor.
- At this comparable developmental stage, a chick embryo and a pig embryo have many features in common, which suggests they evolved from a common ancestor.
- The branch points in this diagram tell the number of amino acids that differ between human cytochrome c and the organisms depicted. These biochemical data are consistent with that provided by a study of the fossil record and comparative anatomy. Cytochrome c is a molecule that is used in the electron transport system. Data regarding differences in the amino acid sequence of cytochrome c show that in a human it differs from that in a monkey by only one amino acid.
- There was an increase in the complexity of macromolecules leading to a self-replicating system (DNA -> RNA -> protein) enclosed by a plasma membrane. The protocell, a heterotrophic fermenter, underwent biological evolution, becoming a true cell, which then diversified.
- The same inorganic chemicals as those thought to be present in the first atmosphere were circulated past an energy source (electric spark) and cooled to produce a liquid that could be withdrawn. Upon chemical analysis, the liquid was found to contain various small organic molecules.
- Minerals (iron-nickel sulfides) found in the plume of hydrothermal vents can catalyze the formation of ammonia from N 2 and even organic molecules. Hydrothermal vents were found deep in the ocean at mid-oceanic ridges.
- a. Microspheres, which are composed only of protein, have a number of cellular characteristics and could have evolved into the protocell. b. Liposomes form automatically when phospholipid molecules are put into water. Plasma membrane may have evolved similarly.
- The heterotroph hypothesis suggests that heterotrophs evolved before aututrophs.
- Microevolution has occurred when there is a change in gene pool frequencies – in this case, due to natural selection. Far left : Birds cannot see light-colored moths on tree trunks, and therefore, the light-colored phenotype is more frequent in the population. Far right : Birds cannot see dark-colored moths on dark tree trunks, and therefore, the dark-colored phenotype is more frequent in the population. The percentage of the dark-colored phenotype has increased in the population because predatory birds can see light-colored moths against tree trunks that have become sooty due to pollution.
- Genetic drift occurs when by chance only certain members of a population (in this case, green frogs) reproduce and pass on their genes to the next generation. The allele frequencies of the next generation’s gene pool may be markedly different from those of the previous generation.
- A member of the founding population of Amish in Pennsylvania had a recessive allele for a rare kind of dwarfism. The percentage of the Amish population now carrying this allele is much higher than that of the general population.
- The Science Focus (pages 552-553) outlines how Charles Darwin, the father of evolution, explained evolution by natural selection.
- Natural selection favors the intermediate phenotype (see arrows) over the extremes. For example, most human newborns are of intermediate weight (about 3.2 kg or 7 lb), and very few babies are either very small or very large.
- Directional selection occurs when natural selection favors one extreme phenotype (see arrows), resulting in a shift in the distribution curve. Equus , the modern-day horse, which is adapted to a grassland habitat, evolved from Hyracotherium , which was adapted to a forest habitat.
- Natural selection favors two extreme phenotypes (see arrows). Today, it is observed that British land snails mainly comprise two different phenotypes, each adapted to a different habitat.
- See Table 27.2 (page 557) for a list of reproductive isolating mechanisms.
- Allopatric speciation occurs after a geographic barrier prevents gene flow between populations that originally belonged to a single species.
- Each of these finches is adapted to gathering and eating a different type of food. Tree finches have beaks largely adapted to eating insects and, at times, plants. The woodpecker-type finch, a tool-user, uses a cactus spine or twig to probe in bark of a tree for insects. Ground finches have beaks adapted to eating prickly-pear cactus or different-sized seeds.
- The differences between phyletic gradualism and punctuated equilibrium are reflected in these patterns of time versus speciation.
- All prokaryotes are in the kingdom Monera. The eukaryotes are in the kingdoms Protista, Fungi, Plantae, and Animalia. The diagram shows the lines of descent.
- Table 27.3 (page 561) gives detailed information about the differences between the three domains.
- Bacteria and archaea (both prokaryotes) are in separate domains. All eukaryotes (protists, fungi, plants, and animals) are in the domain Eukarya.
- This pictorial representation of the domains Bacteria, Archaea, and Eukarya includes an example of each of the four kingdoms in the domain Eukarya.