Chapter 14 The Origin of Species


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Chapter 14 The Origin of Species

  1. 1. Chapter 14 The Origin of Species 0
  2. 2. <ul><li>Mosquito Mystery </li></ul><ul><ul><li>Speciation is the emergence of new species </li></ul></ul><ul><ul><li>In England and North America </li></ul></ul><ul><ul><ul><li>Two species of mosquitoes exist and spread West Nile virus </li></ul></ul></ul>
  3. 3. <ul><li>14.1 The origin of species is the source of biological diversity </li></ul><ul><ul><li>Speciation, the origin of new species </li></ul></ul><ul><ul><ul><li>Is at the focal point of evolution </li></ul></ul></ul>Figure 14.1
  4. 4. <ul><ul><li>Earth’s incredible biological diversity is the result of macroevolution </li></ul></ul><ul><ul><ul><li>Which begins with the origin of new species </li></ul></ul></ul>
  5. 5. CONCEPTS OF SPECIES <ul><li>14.2 What is a species? </li></ul><ul><ul><li>Carolus Linnaeus, a Swedish physician and botanist </li></ul></ul><ul><ul><ul><li>Used physical characteristics to distinguish species </li></ul></ul></ul><ul><ul><ul><li>Developed the binomial system of naming organisms </li></ul></ul></ul><ul><ul><li>Linnaeus’ system established the basis for taxonomy </li></ul></ul><ul><ul><ul><li>The branch of biology concerned with naming and classifying the diverse forms of life </li></ul></ul></ul>
  6. 6. <ul><ul><li>Similarities between some species and variation within a species </li></ul></ul><ul><ul><ul><li>Can make defining species difficult </li></ul></ul></ul>Figure 14.2B Figure 14.2A
  7. 7. <ul><li>The Biological Species Concept </li></ul><ul><ul><li>The biological species concept defines a species as </li></ul></ul><ul><ul><ul><li>A population or group of populations whose members can interbreed and produce fertile offspring </li></ul></ul></ul>
  8. 8. <ul><li>Other Species Concepts </li></ul><ul><ul><li>The morphological species concept </li></ul></ul><ul><ul><ul><li>Classifies organisms based on observable phenotypic traits </li></ul></ul></ul><ul><ul><li>The ecological species concept </li></ul></ul><ul><ul><ul><li>Defines a species by its ecological role </li></ul></ul></ul><ul><ul><li>The phylogenetic species concept </li></ul></ul><ul><ul><ul><li>Defines a species as a set of organisms representing a specific evolutionary lineage </li></ul></ul></ul>
  9. 9. <ul><li>14.3 Reproductive barriers keep species separate </li></ul><ul><ul><li>Reproductive barriers </li></ul></ul><ul><ul><ul><li>Serve to isolate a species’ gene pool and prevent interbreeding </li></ul></ul></ul><ul><ul><ul><li>Are categorized as prezygotic or postzygotic </li></ul></ul></ul>Table 14.3
  10. 10. <ul><li>Prezygotic Barriers </li></ul><ul><ul><li>Prezygotic barriers </li></ul></ul><ul><ul><ul><li>Prevent mating or fertilization between species </li></ul></ul></ul>
  11. 11. <ul><ul><li>In temporal isolation </li></ul></ul><ul><ul><ul><li>Two species breed at different times </li></ul></ul></ul>Figure 14.3A
  12. 12. <ul><ul><li>In behavioral isolation </li></ul></ul><ul><ul><ul><li>There is little or no sexual attraction between species, due to specific behaviors </li></ul></ul></ul>Figure 14.3B
  13. 13. <ul><ul><li>In mechanical isolation </li></ul></ul><ul><ul><ul><li>Female and male sex organs or gametes are not compatible </li></ul></ul></ul>Figure 14.3C
  14. 14. <ul><li>Postzygotic Barriers </li></ul><ul><ul><li>Postzygotic barriers </li></ul></ul><ul><ul><ul><li>Operate after hybrid zygotes are formed </li></ul></ul></ul>
  15. 15. <ul><ul><li>One postzygotic barrier is hybrid sterility </li></ul></ul><ul><ul><ul><li>Where hybrid offspring between two species are sterile and therefore cannot mate </li></ul></ul></ul>Figure 14.3D
  16. 16. MECHANISMS OF SPECIATION <ul><li>14.4 Geographic isolation can lead to speciation </li></ul><ul><ul><li>In allopatric speciation </li></ul></ul><ul><ul><ul><li>A population is geographically divided, and new species often evolve </li></ul></ul></ul>A. harrisi A. leucurus Figure 14.4
  17. 17. <ul><li>14.5 Reproductive barriers may evolve as populations diverge </li></ul><ul><ul><li>Laboratory studies of fruit flies </li></ul></ul><ul><ul><ul><li>Have shown that changes in food sources can cause speciation </li></ul></ul></ul>Figure 14.5A Starch medium Maltose medium Initial sample of fruit flies Results of mating experiments Female Starch Maltose Female Same Different population populations Male Maltose Starch Male Different Same Mating frequencies in experimental group Mating frequencies in control group 22 9 20 8 12 18 15 15
  18. 18. <ul><ul><li>Geographic isolation in Death Valley </li></ul></ul><ul><ul><ul><li>Has led to the evolution of new species of pupfish </li></ul></ul></ul>Figure 14.5B A pupfish
  19. 19. <ul><li>14.6 New species can also arise within the same geographic area as the parent species </li></ul><ul><ul><li>In sympatric speciation </li></ul></ul><ul><ul><ul><li>New species may arise without geographic isolation </li></ul></ul></ul>
  20. 20. <ul><ul><li>Many plant species have evolved by polyploidy </li></ul></ul><ul><ul><ul><li>Multiplication of the chromosome number due to errors in cell division </li></ul></ul></ul>Figure 14.6B Parent species Meiotic error Self-fertilization Offspring may be viable and self-fertile Zygote Unreduced diploid gametes 2 n = 6 Diploid 4 n = 12 Tetraploid O . gigas O . lamarckiana Figure 14.6A
  21. 21. CONNECTION <ul><li>14.7 Polyploid plants clothe and feed us </li></ul><ul><ul><li>Many plants, including food plants such as bread wheat </li></ul></ul><ul><ul><ul><li>Are the result of hybridization and polyploidy </li></ul></ul></ul>  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) Figure 14.7A Figure 14.7B AA BB AB AA BB DD ABD AA BB DD
  22. 22. <ul><li>14.8 Adaptive radiation may occur in new or newly vacated habitats </li></ul><ul><ul><li>In adaptive radiation, the evolution of new species </li></ul></ul><ul><ul><ul><li>Occurs when mass extinctions or colonization provide organisms with new environments </li></ul></ul></ul>
  23. 23. <ul><ul><li>Island chains </li></ul></ul><ul><ul><ul><li>Provide examples of adaptive radiation </li></ul></ul></ul>Figure 14.8B Figure 14.8A Cactus-seed-eater (cactus finch) Seed-eater (medium ground finch) Tool-using insect-eater (woodpecker finch) 1 2 3 4 5 A B B B C C C B C C D D D
  24. 24. TALKING ABOUT SCIENCE <ul><li>14.9 Peter and Rosemary Grant study the evolution of Darwin’s finches </li></ul><ul><ul><li>Peter and Rosemary Grant </li></ul></ul><ul><ul><ul><li>Have documented natural selection acting on populations of Galápagos finches </li></ul></ul></ul>Figure 14.9
  25. 25. <ul><ul><li>The occasional hybridization of finch species </li></ul></ul><ul><ul><ul><li>May also have been important in their adaptive radiation </li></ul></ul></ul>
  26. 26. <ul><li>14.10 The tempo of speciation can appear steady or jumpy </li></ul><ul><ul><li>According to the gradualism model </li></ul></ul><ul><ul><ul><li>New species evolve by the gradual accumulation of changes brought about by natural selection </li></ul></ul></ul>Figure 14.10A Time
  27. 27. <ul><ul><li>The punctuated equilibrium model draws on the fossil record </li></ul></ul><ul><ul><ul><li>Where species change the most as they arise from an ancestral species and then change relatively little for the rest of their existence </li></ul></ul></ul>Time Figure 14.10B
  28. 28. MACROEVOLUTION <ul><li>14.11 Evolutionary novelties may arise in several ways </li></ul><ul><ul><li>Many complex structures evolve in many stages </li></ul></ul><ul><ul><ul><li>From simpler versions having the same basic function </li></ul></ul></ul>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 Limpet Abalone Nautilus Marine snail Squid
  29. 29. <ul><ul><li>Other novel structures result from exaptation </li></ul></ul><ul><ul><ul><li>The gradual adaptation of existing structures to new functions </li></ul></ul></ul>
  30. 30. <ul><li>14.12 Genes that control development are important in evolution </li></ul><ul><ul><li>“ Evo-devo” </li></ul></ul><ul><ul><ul><li>Is a field that combines evolutionary and developmental biology </li></ul></ul></ul>
  31. 31. <ul><ul><li>Many striking evolutionary transformations </li></ul></ul><ul><ul><ul><li>Are the result of a change in the rate or timing of developmental changes </li></ul></ul></ul>Figure 14.12A
  32. 32. <ul><ul><li>Changes in the timing and rate of growth </li></ul></ul><ul><ul><ul><li>Have also been important in human evolution </li></ul></ul></ul>Figure 14.12B Chimpanzee fetus Chimpanzee adult Human fetus Human adult
  33. 33. <ul><ul><li>Stephen Jay Gould, an evolutionary biologist </li></ul></ul><ul><ul><ul><li>Contended that Mickey Mouse “evolved” </li></ul></ul></ul>Figure 14.12C <ul><li>Copyright Disney </li></ul><ul><li>Enterprises, Inc. </li></ul>
  34. 34. <ul><li>14.13 Evolutionary trends do not mean that evolution is goal directed </li></ul><ul><ul><li>Evolutionary trends reflect species selection </li></ul></ul><ul><ul><ul><li>The unequal speciation or unequal survival of species on a branching evolutionary tree </li></ul></ul></ul>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