BIOLOGY 112 NOTES Chapter 22 Decent with Modification Cosmology is the study of the origins and biology is more related to it than other sciences Misconceptions o Species are always evolving into higher or better beings False o Evolution creates new forms of life by dramatic mutations False o An organism can evolve during its lifetime False o An organism can influence the evolution of it s own structures in response to its environment False o Evolution is a random process False Yes evolution is random in the sense of mutations but not entirely a random process Evolution is the change in organisms throughout earth s history o Today s life is different from and descended from earlier life decent with modification proposed by Charles Darwin Views of life before Darwin o Antiquity thru 1600 s Plato and Aristotle were very important Aristotle believed in fixed ideal species All the best characteristics became into one representative individual species Scale naturae the ladder of nature Biblical creation and young earth fixed creation of life o Age of Reason 1700 s 1800 s Linnaeus s nested classification system Domain Kingdom Phylum Class Order Family Genus Species The more similar characteristics shared the smaller the groups became o Cuvier s interpretation of fossils a record of change over time The first person to interpret the layers and conclude they are a record of change over time Realized a connection between the organisms and the environment they were in Rock strata reveal relative age Lower strata older fossils and upper strata newer fossils Believed that catastrophic events caused extinctions followed by recolonization o Hutton slow and gradual change gradualism Slow continuous processes in the past produced big geological features Ex Rivers cause gradual erosion of canyons to form valleys o Lyell and uniformitarianism Expanded on Hutton s ideas processes were both slow and gradual change at a constant rate same rate as today thus earth is extremely old Lyell wrote Principles of Geology that was read by Darwin o Erasmus Darwin Charles Darwin s grandfather philosophized on evolution Ideas that minute forms improved over time gaining Charles Darwin and his theory complexity Wrote a poem called Zoonomia that discussed the idea of life forms leaving the ocean o Lamarck tied evolution to adaptation extinct species replaced by descendants that are better adapted to their environment Adaptation the process of adapting as well as inherited feature that enhances survival reproduction in an environment He proposed a mechanism for evolution such that features are modified by use and disuse Organisms were making an effort to be better so they would inherit acquire characteristics and pass them on to offspring Lamarckism is wrong Ex A giraffe ancestor stretched it s neck then passed it on to offspring o Darwin s voyage Born in a respectable family the same day as Abraham Lincoln Naturalist who went to medical school then dropped out and studied to be a clergyman Goes on the HMS Beagle to survey all the lands around South America for the British to colonize On this five year trip he collected plants wildlife and fossils He observed species geographic locales and adaptations He studied local geology and saw evidence for Lyell s uniformitarianism that concluded maybe earth could be a million years old An earthquake caused many organisms to surface and supplied evidence for uniformitarianism o Darwin s life work Marriage and family gave time for research She had money and he had ten children in which most died but some went on to be really respected scientists in London He developed his theory by 1844 and wrote his theory and held off publishing because he wanted more evidence because he knew it would cause controversy Alfred Wallace sent a letter to Darwin with the same ideas as Darwin in 1858 Darwin respected Lyell s opinion to present both papers of the men in 1859 Darwin s book of Origin of Species 1859 Wrote and researched until he died at age 73 Darwin ridiculed until the day he died because of his theory o Darwin s theory Part 1 Evolution All present life is related thru descent with modification from a common ancestor in past evolution First to put this idea into the tree diagram form Part 2 natural selection is the mechanism for evolution Artificial Selection breeding shows that even small heritable variations can be chosen and enhanced Darwin derived this idea from Malthus essay on human populations that said population constraint is based on resources Observation 1 In most species there is some variation among individuals that is heritable Once you start choosing characteristics artificial selection brings about more variation Observation 2 All species produce more offspring than the environment can support Potential for human population growth is exponential Resources grow at a much slower rate than the growth of the population so growth is restrained by limiting resources and the weakest poorest people were the ones that didn t survive or reproduce as often He thought that since this applied to humans that it must also be common in nature Inference 1 Individuals with traits that help them survive and reproduce in their environment leave more offspring than other individuals Unequal reproductive success Once past on to offspring these adaptations would accumulate over time Inference 2 Heritable favorable traits ultimately leading to new species Adaptations would lead to new species Artificial selection led to different varieties Natural selection with different environments and natural consequence would also lead to new species o What s not in Darwin s theory Origin of life Had nothing to say about the first organism How variation arises Didn t know about genes DNA mutations or inheritance How inheritance works He believed in blended inheritance but this wouldn t work because eventually everything would look the same Why variation still exists Thought everything would eventually look the same once desired traits continue to be passed on Sudden changes in fossil record Source of totally new characters o Fossil Record Ex Soapberry bug pokes it s beak into the middle of the fruit This may have been a random result because the sample could be skewed or too small this is why we do many trials The nutrition of the bugs may be the reason to this and it may have nothing to do with the length of the beaks The difference actually had to do with the beak length so it was not a random
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