mcdb20lec9Su09

mcdb20lec9Su09 - Lecture 9 Major "breakthrough"...

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Lecture 9 Major “breakthrough” events in evolution Animal Diversity: Key differnces among major animal groups Vertebrates and hominds Invertebrate groups 1 Learning Goals ! Define an animal and the key distinctions that divide the species. ! Discuss evolutionary success. ! Define and describe vertebrates and their evolution. ! Define and describe the terrestrial vertebrates, including amphibians, birds, and mammals. Learning Goals ! Describe early human lifestyles and human evolution. ! Define and describe the invertebrates, including echinoderms, arthropods, molluscs, annelids, flatworms, cnidarians, and sponges. ! Are some animals smarter than others? Major events in the evolution of Biodiversity on Earth Origin of living cells Evolution of Photosynthesis Evolution of eukaryotic cells Evolution of sexual reproduction Evolution of multicellular life Adaptive Radiation Movement onto land 4 5 Endosymbiotic Theory 6 The Development of Multicellular Organisms Unicellular organisms aggregated to form collections of cells with no specialization, then evolved to complex arrangements in which specific cells have specific jobs. 7 Beginning of Multicellular Life Evolved ~ 650 mya (million years ago) By 600 mya, larger soft animals were present Cambrian explosion occurred 530 mya Adaptive Radiation follows mass extinctions
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Mass extinction Colonization of Land First plants ~ 500 mya Descendants of green algae Simple and non-vascular Symbiotic fungi in fossil record of earliest land plants Fossils of first land animals ~ 410 mya Spiders and millipedes Shrubs and trees 360 mya Plants developed waxy cuticles First amphibians ~ 365 mya Colonization of land by animals First reptiles ~ 265 mya First mammals ~ 220 mya Continental Drift Supercontinent Pangaea broke apart ~ 200 mya Creates geographic isolation, Promotes speciation Animal Diversity What is an animal? Three Key Characteristics What is evolutionary “success”? Extant or Extinct ! From an evolutionary perspective, all extant species are successful. ! However, some groups are represented by more species than others. ! Among the 36 animal phyla, 9 phyla account for more than 96 percent of all described animal species.
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! Animals probably originated from an ancestral protist. Four characteristics distinguish diversity in the animal kingdom 20 21 1) Does the animal have defined tissues, with specialized cells? 2) Does the animal develop with radial symmetry or bilateral symmetry? Body structured like a pie, OR Body with a left and right side, which are mirror images 22 3) During development, does the animal’s gut develop from front to back or back to front? Protostomes
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mcdb20lec9Su09 - Lecture 9 Major "breakthrough"...

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