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Summary of Introduction to Evolutionary Biology V0.2 Summary of Introduction to Evolutionary Biology v0.2 Gleb Ebert September 27, 2017 Preface This document aims to summarize the lecture Introduction to Evolutionary Biology as it was taught in the autumn semester of 2017. Unfortunately I can’t guarantee that it is complete and free of errors. You can contact me under [email protected] if you have any suggestions for improvement. The newest version of this summary can always be found here: https://n.ethz.ch/~glebert/ 1 1 Introduction 1.4 Macroevolution 4) Survival and reproduction of individuals are not random; but individuals with the most favorable → Definition: Evolution means biological change over time indirect observation: long time-scales long-term variation given the environment are those better at Technical basis: Phenotypes of individuals that are en- changes surviving. coded by heritable genotypes vary in a population and These postulates can be tested in real world populations Evidence of Macroevolution: their frequencies change (e.g. Darwin’s finches from the Galapagos islands). One 1 ) Successions & Extinctions has to be careful to not misinterpret biasing factors. For Law of succession: pattern of correspondence be- example heritability measures can be skewed by misiden- 1.1 History tween fossile and recent forms from the same locale tified paternity, misidentified maternity, food quality or Comparative anatomy: Georges Cuvier argued maternal effects such as egg quality. Aristotle: Ladder of nature / perfection that certain species are extinct. Recent macrofauna Carl von Linn´e: Systematic classification of life is only a fraction of all that ever existed James Hutton & Charles Lyell: Gradual long-term 2) Transitional forms 2.2 Definition processes shaped earth (Uniformitarianism) Darwinian evolution predicts intermediate forms Jean-Baptiste de Lamarck: Inheritance of acquired between a species and its ancestor (e.g. Microrap- Natural selection acts on individuals (more specifically, characteristics (Lamarckian evolution) tor gui and Archaeopteryx between dinosaurs and phenotypes), its consequences occur in populations as al- Charles Darwin: Evolution is descent with modifica- modern birds lele frequency changes. tion and results in survival of the fittest 3) Homologies (Owen: ”the same organ in different animals under every variety of form and function) can be found through comparative anatomy and 2.3 Darwinian vs. Lamarckian evolution 1.2 Microevolution comparative embryology. The similarity is due to inheritance from a common ancestor. They are Different processes proposed for the same pattern. direct observation: small time-scales → short-term phenotypically and genetically defined and enable 1. No initial variation Initial variation changes the use of model organisms. 2. Individuals adapt Selection acts on Some molecular homologies are during their lifetime individuals 3. Inheritance of aquired Inheritance of Evidence of Microevolution: • the universal genetic code: bases and codons changes/characters surviving alleles if 1) Observation from natural populations • the small-subunit (SSU) ribisomal RNA genes (IAC) environment leads to • Bacterial adaptation to antibiotic stress adaptation • Soapberry bug adaptation to fruit 2 Natural selection ⇒ individuals and ⇒ populations evolve 2) Observation from living anatomy populations evolve Epigenetic modifications are attached to the genetic code Vestigal and rudimentary traits Natural selection is the process underlying adaptive evo- • and can be passed on to the offspring (up to two gener- Kiwi wings lution • Human coccyx (Steissbein) ations). Thus their evolutionary relevance is short-term. • Human arrector pili muscle (Haaraufrichter- Muskel) 2.1 Darwins postulates of evolutionary change • 2.4 Limits (Appendix might be safe house for good gut Evolutionary change over time is a deductive implication bacteria) of four postulates. • Natural selection acts on existing traits 1) All populations contain variable individuals • Natural adaptation does not lead to perfection 1.3 Speciation 2) Variation among individuals is, at least in part, her- • Natural selection is non-random, but it is not pro- itable gressive Ring species are one species splitting into two. They 3) Some individuals are more successful at surviving • Natural selection is blind to the future, but tells us provide evidence of speciation. and reproducing than others tales from the past 2.5 “Perfection” in nature William Paley argued, that the vertebrate eye is too per- fect and complicated to have resulted from natural pro- cesses. Thus it must be a creation of a conscious designer. By looking closely at eyes from various chordates one can see that there is a lot of variation in the complexity of the eye. Thus Paleys argument is wrong..
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