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Speciation - Macroevolution
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What is a Species?
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Morphological species Problems?
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Variable Morphology Grown in water Grown on land
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Figure 14.3a
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What is a Species? Biological Species Concept –Population –Interbreed –Fertile offspring –Reproductive isolation
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Reproductive Isolation
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Isolating Mechanisms Prezygotic isolation Postzygotic isolation
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Figure 14.4
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Prezygotic Isolation Behavioral Isolation
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Prezygotic Isolation Temporal Isolation
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Prezygotic Isolation Ecological Isolation
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Prezygotic Isolation Mechanical Isolation
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Prezygotic Isolation Gametic Mortality
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Postzygotic Mechanisms Hybrid inviability Hybrid sterility Hybrid breakdown
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Figure 14.3D
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Mechanisms of Speciation Allopatric speciation –Barrier prevents gene flow Sympatric speciation –W/in home range
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Figure 14.7
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Allopatric Speciation A. harrisiA. leucurus Figure 14.4
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–Isolation in Death Valley New species of pupfish Figure 14.5B A pupfish Allopatric Speciation
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Figure 14.9
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Sympatric Speciation Polyploidy Change in chromosome number (3n, 4n, etc.) Parent species Meiotic error Self- fertilization Offspring may be viable and self-fertile Zygote Unreduced diploid gametes 2n = 6 Diploid 4n = 12 Tetraploid O. gigas O. lamarckiana
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AABB AB AA BB DD ABD AA BB DD Triticum monococcum (14 chromosomes) Wild Triticum (14 chromosomes) Sterile hybrid (14 chromosomes) Meiotic error and self-fertilization T.turgidum Emmer wheat (28 chromosomes) T.tauschii (wild) (14 chromosomes) Sterile hybrid (21 chromosomes) Meiotic error and self-fertilization T.aestivum Bread wheat (42 chromosomes) Possible Evolution of Wheat Figure 14.7B
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Models for Speciation Gradual change model –Small changes over time Punctuation model –Brief period near divergence
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Figure 14.12
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How have complex structures evolved? Many stages From simpler versions w/ the same basic function Figure 14.11 Light-sensitive cells Light-sensitive cells Fluid-filled cavity Transparent protective tissue (cornea) Cornea Layer of light-sensitive cells (retina) Nerve fibers Nerve fibers Optic nerve Optic nerve Optic nerve Eyecup Retina Lens Patch of light- sensitive cells Eyecup Simple pinhole camera-type eye Eye with primitive lens Complex camera-type eye LimpetAbaloneNautilusMarine snailSquid
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Changes in development Timing and rate of growth How? Figure 14.12A
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Figure 14.12B Chimpanzee fetusChimpanzee adult Human fetusHuman adult
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Stephen Jay Gould (evolutionary biologist) Mickey Mouse “evolved” Copyright Disney Enterprises, Inc. Mickey?
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Evolutionary trends do not mean that evolution is goal directed Figure 14.13 Hippidion and other genera Nannippus Neohipparion Hipparion Sinohippus Megahippus Archaeohippus Callippus Hypohippus Anchitherium Miohippus Parahippus Paleotherium Propalaeotherium Pachynolophus Orohippus Epihippus Equus Pliohippus Merychippus Mesohippus Hyracotherium Grazers Browsers EOCENE OLIGOCENE MIOCENE PLIOCENE E RECENT PLEISTOCEN End Goal? No!
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Rocks and fossils –Radiometric dating radioactive isotopes Geologic Record
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Figure 14.17
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Figure 14.16
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Table 15.1
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Impact on macroevolution? Edge of one plate being pushed over edge of neighboring plate (zones of violent geologic events) Antarctic Plate Australian Plate Split developing Indian Plate Eurasian Plate North American Plate South American Plate Nazca Plate Pacific Plate Arabian Plate African Plate Figure 15.3A Continental drift Figure 15.3B 0 65 135 245 Millions of years ago Paleozoic Mesozoic Cenozoic North America Eurasia Africa South America India Antarctica Australia Laurasia Gondwana Pangaea
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Continental drift Volcanoes and earthquakes San Andreas Fault North American Plate San Francisco Santa Cruz Los Angeles Pacific Plate California Figure 15.4A, B
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Figure 14.18
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Permian and Cretaceous periods –Dinosaurs? Mass extinctions
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Adaptive Radiation Burst of divergence Single lineage gives rise to many new species New species fill vacant adaptive zone
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Hawaiian Islands Adaptive radiations: –Honeycreepers –Fruit flies (Drosophila) - 40% of fruit fly species are found in Hawaii
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Hawaiian Honeycreepers FOUNDER SPECIES Figure 18.7 Page 297
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Classifying Diversity Taxonomy Phylogeny –Homologous structures and molecular sequences –Evidence of common ancestry
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Figure 15.6 Ancestry? Or Convergent evolution? PHYLOGENY
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Systematics –Connects classification w/ evolution Binomial –Genus –Species Phylogeny Species Genus Family Order Class Phylum Kingdom Domain Felis catus Felis Felidae Carnivora Mammalia Chordata Animalia Eukarya
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Species Felis catus (domestic cat) Mephitis mephitis (striped skunk) Lutra lutra (European otter) Canis familiaris (domestic dog) Canis lupus (wolf) Genus Family Order Felis Felidae Carnivora Mustelidae Mephitis Lutra Canis Canidae Figure 15.7B Phylogenetic tree PHYLOGENY
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Figure 14.24
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–The simplest (most parsimonious) hypothesis Figure 15.8B Lizards Snakes CrocodilesBirds Common reptilian ancestor CLADOGRAMS
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