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Chapter 24

Biology 1M03 Ch. 24 Textbook Notes

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Department
Biology
Course
BIOLOGY 1M03
Professor
Ben Evans
Semester
Winter

Description
Saturday, January 11, 2014 Biology 1M03 Chapter 24 Notes The Evolution of Evolutionary Thought • Typological thinking is based on the idea that species are unchanging types and  that variations within species are unimportant or even misleading • Aristotle’s ideas o Species are fixed types o Some species are higher­ in the sense of being more complex or “better”­  than others • Lamarck claimed that simple organisms originate at the base of the chain by  spontaneous generation and then evolve by moving up the chain over time • He also thought that species changed through time by the inheritance of acquired  characteristics • Darwin and Wallace claimed that instead of being unimportant or an illusion,  variation among individuals in a population was the key to understanding the  nature of species. Biologists refer to this view as population thinking • The theory for evolution by natural selection was revolutionary o It overturned the idea that species are static and unchanging o It replaced typological thinking with population thinking o It was scientific. It proposed a mechanism that could account for change  through time and made predictions that could be tested through  observation and experimentation The Pattern of Evolution: Have Species Changed Through Time? • Descent with modification­ he meant that species that lived in the past are the  ancestors of the species existing today, and that species and their descendant  species change through time • The theory of evolution by natural selection makes two statements about the  nature of species o Species change through time o Species are related by common ancestry • Fossil­ any trace of an organism that lived in the past • Fossil record­ consists of all the fossils that have been found and described in the  scientific literature • Extant species­ those living today • Geologic time scale­ a sequence of named intervals called eons, eras, and periods  that represented the major events in Earth’s history • Transitional feature­ is a trait in a fossil species that is intermediate between those  of older and younger species • Vestigial traits­ is a reduced or incompletely developed structure that has no  function or reduced function but is clearly similar to functioning organs or  structures in closely related species • Similar species are found in the same geographic area • Homology can be studied at 3 levels Saturday, January 11, 2014 o Genetic homology o Developmental homology o Structural homology • The three levels of homology interact. Genetic homologies cause the  developmental homologies observed in embryos, which then lead to the structural  homologies recognized in adults The Process of Evolution: How Does Natural Selection Work? • Darwin’s four postulates o The individual organism that ma
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