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Lovaye Kajiura

WEEK 10: MONDAY, NOVEMBER 4TH TO FRIDAY, NOVEMBER 8TH, 2013 CHAPTER 14: PRINCIPLES OF EVOLUTION & SUPPLEMENTARY INFORMATION Early Biological thought did not include the concept of evolution. ESSENTIALISM (Plato) * - Two Worlds: 1. An ideal world 2. Illusionary world, which is perceived by the senses Plants and animal variations were simply imperfect representations of ideal forms Only perfect ideal forms were real Fig. 14-1 Aristotle’s Ladder of Nature LADDER OF NATURE (Aristotle) * Species are fixed on a continuum from simple designs to more complex designs All living forms could be arranged on this ladder -Each group of organisms was fixed, permanent, and did not change Fig. 14-2 A timeline of the roots of evolutionary thought GEORGES-LOUIS LECLERC (Comte De Buffon) Believed that species were created then evolved NATURAL THEOLOGY (PALEY) Discovery of the Creator’s (God’s plan) through the study of nature LINNAEUS Developed taxonomy (classification hierarchy for naming organisms) Binomial system of naming organisms (genus species) GRADUAL GEOLOGICAL CHANGE (Hutton) Profound change is the cumulative product of slow continuous processes INHERITANCE OF ACQUIRED CHARACTERISTICS (Lamarck) inheritance of acquired characteristics use or disuse of body parts lead to their development or their deterioration Ex. Giraffes having longer necks over time because of having to stretch their necks CATASTROPHISM (Cuvier) Differences between older and modern forms Earth’s history is marked by local catastrophic events, not from gradual processes of change Example – floods and droughts led to extinctions FOSSIL DISCOVERIES SHOWED THAT LIFE HAS CHANGED OVER TIME (Smith) Fig. 14-3 Types of fossils SEQUENCE OF FOSSILS (SMITH)******** Fig. 14-4 Different fossils are found in different rock layers FOSSIL RECORD there is a gradual transition with the layers of sediment with respect to the depth of the sediments there is a relationship between the sediment layers and the fossils present in those layers older fossils are found in the deep sediments, whereas the more recent fossils are found in the sediments in the upper layers UNIFORMITARIANISM (Lyell) Geological processes have constant (uniform) rates, which balance out over time Earth is very old Some areas had more rapid change vice versa DARWIN AND WALLACE PROPOSED A MECHANISM OF EVOLUTION Darwin's Voyage of the Beagle Father wanted him to be doctor, went to school and did not enjoy it (physician) Galapagos Islands; Mendell vs Darwin – ability to observe and describe his observations Figure 14-.5 Darwin’s finches, residents of the Galapagos Islands *** adaptations to different conditions Different types of finches with different beaks CHARLES DARWIN • 1859, Darwin published "On the Origin of Species by means of Natural Selection", which was the 1st convincing • case supporting evolution (shook the world) • the theory of evolution suggests that all organisms on Earth are related by common ancestry and have changed over time, primarily by natural selection • evolutionary processes have changed life on Earth from early beginnings to the present diversity of organisms • Darwin's Theory was originally considered "radical", since it went against prevailing scientific and world views held for centuries • however, most biologists accepted the idea of evolution • but, there was still some resistance to the idea that natural selection was a mechanism of evolution • things adapt and change because of different conditions (observing plants on the islands) • Alfred Wallace – shared an essay; Charles Darwin has similar perspective Why did Darwin have great difficulty convincing that natural selection was the mechanism of evolution? • It was difficult since there was no detailed knowledge of genetics and the chromosomal basis of inheritance • Some species were not there any more; just bones & fossils (Bias) NATURAL SELECTION (Charles Darwin & Alfred Wallace) - Is the mechanism of evolution - microevolutionary changes that increase survival and reproduction -time scale* Darwin and Wallace’s Theory Rests on Four Postulates: 1. Individuals in a population vary 2. Traits are passed from parent to offspring 3. Some individuals fail to survive & reproduced 4. Survival & reproduction are not determined by chance (conditions) OBSERVATION 1 individual variation exists OBSERVATION 2 any population has the potential to produce more offspring than the environment can support this leads to a struggle for existence INFERENCE DIFFERENTIAL REPRODUCTIVE SUCCESS - those with genetic traits best suited to their environment will generally leave disproportionately large numbers of surviving/fertile offspring (large representation) displaying those traits in the future generations. - selective reproduction favours the representation of certain heritable variations in the next generation resulting in evolution. DARWIN'S 2 CLAIMS 1. Modern species evolved from ancestral forms 2. Mechanism of evolution is natural selection Natural Selection Modifies Populations over Time What does “DESCENT WITH MODIFICATION” mean? • Darwin viewed all organisms as being related through descent from a common ancestor over millions of year, adaptions or modifications accumulated as descendants from the common ancestor moved into diverse habitats COMPARATIVE ANATOMY GIVES EVIDENCE OF DESCENT WITH MODIFICATION *** STRUCTURAL HOMOLOGIES*** • Homologous structures provide evidence of common ancestry Figure 14-8 Homologous structures HOMOLOGOUS structures *** • appear to have similar structural skeletal elements but different functions • suggests support for a common ancestor Figure 14-9 Vestigial structures
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