Principles of Biology II
Principles of Biology II BIOL 2108
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Date Created: 10/12/15
Chapter 22 Descent with Modification o Themes of Biology Diversity and Evolution o Dazzling diversity o 18 million species described o 10100 million present 0 Evolution decent with modi cation o Link between unity and diversity o Why study evolution o Species diversity o Adaptations for survival o Similarities and differences among species o Patterns in fossil record o Geographic distribution of species o All these patterns are explained by evolution o Many practical applications 0 Evolution change in genetic makeup ofa population over time o How does evolutionary change take place o Mechanism of evolution 2 step process o Heritable variation in population o Differential reproductive success o Heritable variation in population o Variation among individuals can represents o Direct response to environment during organism s lifetime 0 not heritable o Genetic variation heritable o How can we tell these apart o Differential reproductive success 0 Artificial selection Fig 229 We choose who is successful o Artificial selection activity for homework on Mastering Biology part of Ch 22 homework Due Jan 19 o Natural Selection o Environment chooses which individuals will be successful o Evolution accounts for life s unity and diversity o Charles Darwin proposed Descent with Modification in 1859 with publication of The Orgn 0f Speces o Descent o Common ancestors unity o with Modification o Changes over time diversity o Descent with Modification unity of life all organisms are related through descent from an ancestor o history of life tree where branch tips present day diversity 0 forks ancestors of all lines that follow o Darwin Introduces a Revolutionary Theory o Challenged young earth and unchanging species ideas o Darwin made two major points in his book 0 Many current species are descendanm of ancestral species 0 a1 selection is a mechanism for this evolutionary process 0 Historical Timeline Fig 222 standing on the shoulders ofgianm o Fossils Guvier and Catastrophism Paleontology study of fossils laid groundwork for Darwin s ideas Fossils found in layers or strata ofsedimentary rock o George Guvier 17691832 catastrophism each boundary between strata represents a catastroth Comment 1 o Theories of Gradualism Uniformitarianism TEST o Gradualism profound change through cumulative effect of slow continuous processes beologists Hutton 1795 and Lyell changes inEarth s surface result from slow continuous actions still operating today 0 strongly influenced Darwin s thinking challenged the young Earth perceptioni w o iLamarck s Theory of Evolution TEST o Lamarck hypothesized that species evolve published in 1809 year Darwin was born only one of Darwin s predecessors who proposed a mechanism for how life changes over time o Mechanisms he proposed are unsupported by evidence 0 Use and disuse the idea that parts of the body that are used extensively become larger and stronger while those that are not used deteriorate o Inheritance of acquired characteristics stated that an organism could pass these modifications to its offspring 0 Today our understanding of genetics refutes this mechanism There is no evidence that acquired characteristics can be inherited in the way proposed by Lamark Comment 3 o Darwin s background TEST o 22 years old when departed on the Beage o Influences from Darwin s Trave s o Voyage of the Beage18311836 Fig 225 o Influences from Darwin s Travels o South America o Temperate and tropical species similar in appearance and similarto fossils o Earthquake in Chile caused coastline to rise 0 Hypothesis fossils in Andes got there by series of earthquakes o Galapagos o Found several similar finches that seemed to be different species 0 Hypothesis Islands colonized by species from mainland then diversified o Galapagos Finches Fig 226 o Darwin s Writings o 1844 essay on the origin of species and natural selection but did not introduce theory publicly anticipated an uproar o June 1858 received manuscript from Alfred Russell Wallace that developed a theory of natural selection similar to Darwin s o Darwin quickly finished The Orgn ofSpeces and published it the next year Darwin s Logic pg 458 o Observation 1 Members of a population often vary in their traits o Observation 2 Traits are passed from parents to offspring o Observation 3 All species produce more offspring than environment can support o Observation 4 Many offspring do not survive due to limited resources o lnference 1 Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring Differential Reproductive Success o lnference 2 The unequal ability of individuals to survive and reproduce leads to the accumulation of favorable traits in the population over generations o Evolution Change in genetic makeup of a population over time Natural Selection A Summary 0 Natural selection is a process in which individuals that have certain heritable characteristics survive and reproduce at a higher rate than other individuals Over time natural selection can increase the match between organisms and their environment 0 If an environment changes or if individuals move to a new environmth natural selection may result in adaptation to these new conditions sometimes giving rise to new species in the process 0 Change environmental factors vary from place to place and over time A trait that is favorable in one place or time may be uselessor even detrimentalin other places or times 0 Genetic makeup natural selection can only amplify or diminish heritable traits 0 Population Individuals do not evolve Only populations do over time 0 Time natural selection takes a long time o Evolution supported by much scientific evidence o Direct Observations of Evolutionary Change o Effect ofdifferential predation on guppy populations Read and understand pp 460461 It was observed that the color patters of male guppies appeared to correspond to the intensity of predation In pools that had few predator species male guppies tended to be brightly colored whereas in pools that had many predators males were less brightly 0 Evolution of drugresistant HIV p 461 Researchers have made numerous drugs to combat this pathogen but using these medications selecm for viruses resistant to the drugs 0 Evolution of Roundup resistant weeds 2 when weeds are sprayed with Roundup there may be a few individuals who live through the extermination They will reproduce and the longer this cycle goes on the more resistant to Roundup these weeds evolve to be o Crops genetically modified to tolerate weed killer scientists have artificially selected crops that have genetic resistance to weed killer to reproduce Over time all of the crop was resistant to the weed killer o Roundup sprayed on fields to control weeds Many weeds becoming resistant to Roundup i m o The Fossil Record TEST o Provides evidence of species extinctions origin of new groups and changes within groups over time o Trilobites Fig 2215 o Evolution of whales from land mammals Fig 2216 o GSU museum houses Georgacetus vogtenss