PART THREE THE EVOLUTION OF DIVERSITY Section A The History of Diversity The Tree of Life 10 27 I The Sweep of History Life on Earth A Establishing Time Scales using half life metamorphic igneous rocks 1 Radiometric dating K Ar younger U pb older 2 Radiocarbon dating n14 c14 reverse process when organism dies up to 50k yrs B Overview of Evolutionary History 1 Life is ancient 4 5 billion yrs look at chart 2 Complex life is relatively recent eukar 1bya humans 2 5 mya II The Major Branches of the Tree of Life A Establishing Archaea Bacteria and Eukarya 1 Clear delineation of three groups bacteria Eukarya archaea 2 Difficulty in rooting the deepest tree of life lateral gene transfer B The Role of Lateral Gene Transfer 1 Mechanisms of lateral gene transfer transduction virus takes host dna conjugation of plasmids transformation cell takes up dna endosymbiotic 2 Diagnosing lateral gene transfer distinctive gene tree proportions of GC vs AT pairs genes w codons producing AA are distinct from codons used in other genes relics of transposase viral insertion sequence C The Major Innovations Within the Tree of Life 1 From promiscuous horizontal transfer to vertical transfer restricted asexual reproduction genes passed to children 2 The origin of eukaryotic cells begins the stop of horizontal 3 Multicellularity makes it hard to do horizontal gene transfer 4 The evolution of sex meiosis and outcrossing recombination III The Endosymbiotic Origin of Eukaryotes A Hypothesis and Evidence 1 Evidence for endosymbiosis circular chromosomes w supercoiled DNA absence of Of chromosomal proteins DNA synthesis in organelles are continuous not Steplike antibiotics bacterial mutagens affect MTdna but not nuclear DNA Organelles enclosed by double membrane diff in codon usage in AA coding identify strong similarity in DNA sequences of same gene 2 Evidence for cooperation and gene transfer benefit of endosymbiosis ribosomes have rRNA coded in MT proteins coded in nucleus large subunit coded in chloroplast but small subunit coded in nucleus gene content of MT chloroplasts is similar among eukaryotes B Evidence for the Multiple Origin of Eukaryotes 1 Differences between animals and plants MTdna diff mechanisms of inheritance Contribute to diff ribosome structures 2 Multiple origins of plants 2 origins of photosynthesis chloroplasts chlorophytes prochlorophyte bacteria chromophytes purple bacteria via 2ndary tertiary endosymbiosis 2 diff chloroplasts w diff sequence structure PART THREE THE EVOLUTION OF DIVERSITY Section A The History of Diversity The Major Radiations 10 29 I Dynamism of History life of diversity is accelerating A Clades Emerge Diversity and Disappear major groups B Turnover of Dominant Forms within Enduring Clades changes in fish over time phenotypes II Adaptive Radiations A What Are Radiations major sudden expansion of species and of phenotypes 1 Fossil record Sudden profusions of new taxa from a common ancestor with some rapid continued proliferation 2 Extant taxa Many closely related species with diverse features occupying a circumscribed area apparently a result of rapid recent evolution B Examples from the History of Life 1 Dinosaurs birds are sister taxa still exist diversity of time shape tropical climate 2 Mammals diversity like dinosaurs apical group of larger group but diversifying 3 Snakes reptile expansion occupy all niches closely track radiation of birds C Correlates of Radiations 1 Phenotypic novelty promote success rapid speciation geographic spread 2 The empty niche new niche opened up by opportunity in geography extinction of previous occupants or new feature competitive replacements 1 replaces other vs incumbent replacement extinction of 1 clade allows another to diversify D Examples of Radiations in Historical Time 1 Darwin s finches common ancestor diverse to many species phenotypes locations No fossil record of new species on mainland 2 Hawaiian Drosophilids newest species on newest islands 3 Cichlids of the African Rift Lakes post transcription editing of same gene diff colors E Comparing Rates of Radiation of species formed per million yrs know history of habitats More species in less amount of time more recent origin more species PART THREE THE EVOLUTION OF DIVERSITY Section A The History of Diversity Patterns in the Rise and Fall of Clades 10 31 I The Life History of Clades A Rates of Lineage Formation 1 Rates vary among clades at all hierarchical levels some faster than others 2 Rates vary over time within a clade can be stable then rapid mammals B Duration of Taxa 1 Average duration varies among clades at all hierarchical Levels some last longer than others dinosaurs 2 Average duration varies over time lung fish 3 Average duration can vary with geography location and Range protozoans bigger range longer time C The Shapes of Lineages 1 Lineages tend to be bottom heavy with high rates of taxon emergence early in history contract as time goes on 2 Degree of bottom heaviness decreases in lineages emerging later in time earlier appearance more bottom heavy later they emerge more top heavy II Extinctions 99 species are extinct A Patterns in Extinction Rates 1 Background rates vs periodic pulses of extinctions 2 Patterns in marine and terrestrial regularity organisms 3 Are extinctions selective among species depends on suitability to environment Some are selective but some are not B Mass Extinctions large taxa based on features NOT due to asteroids or volcanos 1 The end Permian extinctions extinct of marine insects plants diversity climate change low O2 in water but no constistent differences btwn those who survived or died in marine species 2 The K T Cretaceous Tertiary extinctions dinosaurs body size marine range marsupials less land cooler temps no extinction of freshwater species ONLY extinction w evidence of asteroid giant volcanic provinces 3 The Pleistocene extinctions body size reproductive rate megafauna human hunted out PART THREE THE EVOLUTION OF DIVERSITY Section A The History of Diversity The Intertwined History of Places and Clades 11 3 I Tectonic Movement Continental Drift A Process of Tectonic Movement 1 Mantle and lithosphere long solid plates that move due to currents in mantle 2 Consequences of collisions and sideswipes 1 plate below another subduction Mountains volcanoes crust moves down at ocean trenches B Evidence for Tectonic Movement 1 Patterns of age of material on ocean floor younger than continents 2 Patterns of magnetic field orientation near