LS2_2013_lecture3 - Life Sciences 2 September 9 2011 Embryology II Evolution Development Prof Daniel E Lieberman Office hours Tue 1-2 by appt(Peabody 53

LS2_2013_lecture3 - Life Sciences 2 September 9 2011...

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Life Sciences 2 September 9, 2011 Embryology II: Evolution & Development Prof. Daniel E. Lieberman Office hours: Tue 1-2 & by appt! (Peabody 53)
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ANNOUNCEMENTS Labs : Start THIS WEEK! (read & printout handout / wear appropriate clothes) Problems ? email Dr Carr ([email protected]) My office hours: Tuesdays 1-2 & by appt (Peabody 53)
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embryos represent basic body plan that can be widely modified ...an old idea whose origins helped Darwin formulate his theory Phylotypic stage
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Last lecture: 2. What is the basic body plan? 1. How do we go from a single cell to a whole body?
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gastrulation
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What about more complex organisms?
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1. Evolutionary changes that generate complexity occurred from many, many intermediate steps.
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2. The processes by which development occur permit & promote evolutionary change and complexity Body has many parts (modules ) that develop via hierarchical (branching) process with many interactions between modules : creates integration of many parts into a single, funtional whole Modules Genes Cells Germ layers Segments Etc Interactions Growth Movement Induction Etc.. Two solutions to the ± blind watchmaker ² problem
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An already familiar example of integration Folding of body walls to create tube-shaped embryo coelom Gut tube Neural tube Paraxial mesoderm Splanchnic mesoderm Somatic mesoderm
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AN IMPORTANT POINT: Variation happens Variation in modules Variation in how modules interact e.g. # of somites e.g. interactions among somites and other tissues NOVELTIES THAT FIT & WORK TOGETHER Genetic mutations
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An analogy Modules (different Lego™ blocks) Interactions (how you snap them together) Because Legos all share basic bits that snap together, they can be endlessly recombined in novel ways to create VARIATIONS that often fit together and ± work ² Selection can then act on this variation
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  • Fall '10
  • AndrewA.Biewener,PeterT.Ellison,andDanielE.Lieberman
  • Developmental Biology, Neural tube, Mesoderm, basic body plan

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