Ch31 Lecture-Spr11

Ch31 Lecture-Spr11 - 31 Animal Origins and the Evolution of...

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Animal Origins and the Evolution of Body Plans 31
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31.1 What Evidence Indicates the Animals Are Monophyletic? Traits that distinguish animals: All are multicellular ; and undergo development from a single cell All are injestive heterotrophs – use internal digestion processes Most can move & have specialized muscle tissues www.explorebiodiversity.com/Hawaii/Shrimp-goby/general/images
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31.1 What Evidence Indicates the Animals Are Monophyletic? Animals are monophyletic – they share many derived traits (synapomorphies) Evidence: Gene sequences, such as those for rRNA, support monophyly Similar organization and function of Hox genes Regional activation (dark areas) of a regulatory region of the Mhox gene in transgenic mouse embryos.
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What are Hox genes? Conserved genes found in animal groups that specify pattern and axis formation
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31.1 What Evidence Indicates the Animals Are Monophyletic? Common Hox gene clusters in many animal phyla http://www.nature.com/hdy/journal/v97/n3/images/6800872f6.jpg
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31.1 What Evidence Indicates the Animals Are Monophyletic? Animal cells have unique junctions tight junctions, desmosomes, and gap junctions Animals have a common set of extracellular matrix molecules, including collagen and proteoglycans http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CellJunctions.gif http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-2/figure-07-30.jpg
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31.1 What Evidence Indicates the Animals Are Monophyletic? Ancestor of animal clade was probably a colonial flagellated protist Functional specialization (division of labor) of cells in colony arose – and cells continued to differentiate thru life Coordination among cells may have been improved by regulatory molecules eventually leading to larger, more complex animals http://biodidac.bio.uottawa.ca/ftp/BIODIDAC /PROTISTA/MASTIGOPH/DIAGBW Pterospongia - Hypothetical choanoflagellate ancestor to the metazoans
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31.1 What Evidence Indicates the Animals Are Monophyletic? Differences in derived traits among animal groups used to study evolutionary relationships within animal clade Derived traits are found in fossils, developmental patterns, morphology and physiology, protein structure, and genome sequences http://media.collegepublisher.com/media/paper689/stills www.llnl.gov/str/April05/gifs Morphological similarities in embryogenesis across vertebrate species at similar development stages.
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Animals: Descendants of a Common Ancestor Sponges, cnidarians, and ctenophores separated from other animal lineages early in evolutionary history Remaining animals have been divided into two major lineages: Protostomes Deuterostomes
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Figure 31.1 The Phylogeny of Animals
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Embryonic development in animals Patterns of embryonic development were traditionally used to study animal phylogeny Cleavage patterns (first few divisions of zygote) distinguish some animal groups Patterns influenced by yolk configuration
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Patterns of Cleavage in Four Model Organisms (Part 1)
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Ch31 Lecture-Spr11 - 31 Animal Origins and the Evolution of...

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