Unit III Study Guide: PART A1. Discuss the following various views people held about life’s diversity (how it arose) and the age of the earth (old? young?) before evolution was suggested:a. Essentialism/Idealism : Plato believed in “essentialism” – that God created all things; that all things have a constant, perfect “essence” or an “ideal form;” that variation is an imperfect reflection of the inner essence; species don’t change, no new species. b. Natural Theology : Natural theologians were monotheistic western Christians, educated, around 1600s and 1700s. Studied the natural world to better understandGod’s plan; believed that species are divinely created as perfect all at the same time (about 6000 years ago: Judeo-Christian biblical Old Testament story in Genesis). Carolus Linnaeus was a natural theologian who organized life into a nested classification system based on similar appearance. Each “type” of organism has a 2-part binomial scientific name consisting of its genus and species: Homo (genus) sapiens (species).c. Catastrophism : Georges Cuvier was an early paleontologist who accepted a divine creation, believed in a relatively young age for the earth, and that sporadic catastrophes caused the appearance and disappearance of organisms in the fossil record (ex: local floods wiped out existing species and neighboring species movedin – no evolution).d. Uniformitarianism : Charles Lyell (who greatly influenced Darwin) believed that mechanisms of geologic change are constant (“uniform”) over time, that the same processes are operating today as in the past and at the same rate (“uniform”), therefore: the earth must be very old to have accumulated all the changes evident in the geological record.2. What is the biological meaning of the term “evolution”a. Species change over time and new species arise by the modification of earlier species (“descent with modification”).Contrast microevolution with macroevolutionb. Microevolution is the gradual evolution of traits within a population of a species over time: populations evolve, not individuals. Macroevolution, on the other hand, is the evolution of an entirely new species.3. Describe/explain how each of the following served as evidence at the time of Darwin thatevolution could be a means by which life’s diversity arose:a. Artificial Selection: If new species could be “created” artificially by selective breeding by humans, it could surely happen naturally.b. Comparative Anatomy: The similarity in the anatomy of different organisms supports the idea of descent with modification from a common ancestor.c. Geology: Fossil records reveal intermediate species leading to the modern one along with other related lineages that are extinct. Hence, evolution is not “goal oriented”d. Paleontology: Reveals mostly macro evolutionary changes over time; fossils also reveal intermediate species leading to the modern species.e. Comparative Embryology: Early embryos of different vertebrates share many “general” features; as development proceeds, similarity persists only among more closely related vertebrates.4. How can molecular biology provide evidence for evolution?a. By comparing protein and DNA sequences of different species, one can see that the more recently two species shared a common ancestor, the more similar their proteins and DNA.Provide two examplesb. 1. Organisms as dissimilar as humans and bacteria share genes inherited from a very distant common ancestor. Some of these homologous genes have acquirednew functions, while others, such as those coding for the ribosomal subunits used in protein synthesis, have retained their original functions.2. It is common for organisms to have genes that have lost their function, even though the homologous genes in related species may be fully functional. Such inactive genes may be present simply because a common ancestor had them.5. Distinguish between:a. Homologous Structures: Share common ancestry, but not necessarily similar function. For example, a human arm and cat leg are homologous.b. Analogous Structures: Share similar function, but not common ancestry. For example, an insect wing and a bird wing are analogous.c. Vestigial Structures: These are “remnants” of once-functional ancestral structures.For example, the hind limbs in whales and snakes are vestigial and indicate common ancestry with other vertebrates.6. What did Darwin find intriguing about the finches on the Galapagos Islands?a. Darwin found it intriguing that there were 14 endemic species of finches (found nowhere else) on this one island. The different finches evolved from a common mainland ancestor, and each was adapted to suit the conditions of their various islands. Darwin found it interesting that similarities and differences between species were determined more by relative location of species than by simply how well each species was suited to their environment.Explain why/how the Galapagos finches might have helped Darwin formulate his hypothesis of evolution by natural selection:b. Darwin saw that the finches’ various beaks and behaviors were adapted to the specific foods available on their islands. He realized that explaining such adaptations was essential to understanding evolution. His explanation of how adaptations arose centered on natural selection.7. Describe the process by which populations evolve via natural selection:a. In a population, more offspring are produced than can survive. This leads to competition for limited resources and a struggle for existence. Random variation exists in all organisms and much of this variation is heritable (genetic). Some of the variation affects fitness, so the ability to survive and reproduce is not random. Better adapted individuals survive and produce more offspring, passing their “adaptive” genes on to the next generation. This results in a change in the gene composition form one generation to the next, with adaptive characteristics accumulating over time. This change in the gene composition of a population over time is the basic definition of evolution by natural selection.Why is it said that genetic variation is a prerequisite (is required) for evolution by natural selection?b. Darwin observed that individuals differed in their inherited traits and that selection acted on such differences, leading to evolutionary change. Due to the genetic variation, certain characteristics are more
View Full Document
Unlocking...