Unit III Study Guide PART A 1 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 b Natural Theology a Essentialism Idealism Plato believed in essentialism that God created all Natural theologians were monotheistic western Christians 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 educated around 1600s and 1700s Studied the natural world to better understand God 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 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 moved in no evolution Charles Lyell who greatly influenced Darwin believed that d Uniformitarianism 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 Georges Cuvier was an early paleontologist who accepted a c Catastrophism 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 macroevolution b 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 that evolution 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 examples b 1 Organisms as dissimilar as humans and bacteria share genes inherited from a very distant common ancestor Some of these homologous genes have acquired new 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 fit and other less likely to survive This leads to evolution by natural selection because of the variation in genotypes 8 Lamarck thought that evolution was the best explanation for life s diversity as did Darwin How did Darwin s view differ from Lamarck s a
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