Lecture 1 and 2 Notes
Lecture 1 and 2 Notes Bio 152
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This 5 page Class Notes was uploaded by Lexi Kazen on Friday September 4, 2015. The Class Notes belongs to Bio 152 at University of Wisconsin - Madison taught by Dr. McCulloh in Summer 2015. Since its upload, it has received 309 views. For similar materials see Intro biology 2 in Biology at University of Wisconsin - Madison.
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Date Created: 09/04/15
0 Voyage of the Beagle ship called quotHMS Beaglequot sent by British navy to chart South American coastline 0 Since the Galapagos islands were an archipelago Darwin was able to observe populations of the same species on each island and he noticed that there were slight differences between animals of the same species that allowed them to better adapt to their unique environment ex nches with short vs long beaks homologous traits 0 From this data Darwin concluded that the populations descended from a common ancestor they evolved and are still evolving however Darwin did NOT come up with the actual idea of evolution organisms are changing and branching out in response to the environment 0 Several people in uenced Darwin s thinking including Lyell s Principles of Geology Lama rck s theory of evolution inheritance of acquired characteristics and Malthus idea of competition within species and struggle for surviva gave Darwin the idea of quotsurvival of the ttestquot o Lamarck introduced the idea of inheritance of acquired characteristics which was regarded as ridiculous at the time however today we know that due to epigenetic inheritance ie histone modi cation this phenomena is sometimes observed o Lamarck thought that the process of evolution was linear and that evolution occurred at the individual level not at the population level ex if you got a tan you could pass it on to your offspring o Lamarck s idea of adaptation did have some in uence on Darwin s thinking 0 Due to all the in uences people had on Darwin he was able to come up with the idea of evolution via natural selection 0 Idea of common descent species arise from common ancestors in a tree branching process sort of looks like a family tree 0 Gradualism determined that evolutionary changes are gradual although we now know that this isn t always the case 0 Population speciation there is a change in the proportion of individuals having a certain trait in a population leading to more favored traits to appear more frequently once again survival of the ttest o Mendel s work held part of the key to what was missing in Darwin s theory presented a mechanism of how traits got passed on a At rst Mendel and Darwin s ideas seemed incompatible o Mendel dealt with discrete traits yellow vs green wrinkled vs smooth while Darwin observed continuous traits ie beak size body length Continuous traits are traits encoded by several genes Each individual gene follows Mendelian inheritance ignoring phenomena like incomplete dominance and co dominance etc 0 At the time when Darwin proposed the idea of evolution via natural selection evolution was a widely accepted idea people just hadn t thought of a mechanism by which evolution could ve actually occurred 0 Alfred Wallace independently also developed the idea of natural selection around the same time as Darwin but Darwin got all the credit 0 During Darwin s time the concept of mutations didn t exist yet When the concept of mutations did come about people started to wonder what the point of natural selection was Why can t individuals just evolve through mutating There was a major controversy between mutationists and Darwinists o Binary thinking caused this people didn t realize that both the concepts of mutation and natural selection could go hand in hand 0 Not all mutations are favored therefore natural selection only allows favored mutations to succeed and thrive while killing off unfavored traits and mutations o The modern synthesis Encompasses both Mendel s and Darwin s ideas along with other evolutionary forces ie genetic drift recombination etc Mutation and natural selection work together