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Bio 100 Chapter 14

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  • 1. Chapter 14 Speciation and Evolution Lecture OutlineCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  • 2. 14.1 The Definition of a Species Macroevolution  Requires the origin of species  Observed best within the fossil record Speciation  Splitting of one species into two or more or the transformation of one species into a new species over time 14-2
  • 3.  Evolutionary Species Concept  Members of a species share the same distinct evolutionary pathway and that species can be recognized by diagnostic trait differences  Diagnostic traits distinguish one species from another  Assumes that the members of a species are reproductively isolated Biological Species Concept relies primarily on reproductive isolation rather than trait differences to define a species 14-3
  • 4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 14.1A Evolution of modern toothed whales No hind limbs. Orcinus orca Rodhocetus kasrani Hind limbs too reduced for walking or swimming. Ambulocetus natans Hind limbs used for walking and paddling. Pakicetus attocki Hind limbs used for walking. 14-4
  • 5. Figure 14.1B Three species of flycatchers. The call of each bird isgiven on the photograph 14-5
  • 6. Figure 14.1C The Massai of East Africa (left) and the Eskimos ofAlaska (right) belong to the same species 14-6
  • 7. 14.2 Reproductive barriers maintain genetic differences between species Reproductive isolating mechanisms  Prezygotic isolating mechanisms  Habitat isolation  Temporal isolation  Behavioral isolation  Mechanical isolation  Gamete isolation  Postzygotic isolating mechanisms  Zygote mortality  Hybrid sterility  F2 fitness 14-7
  • 8. Figure 14.2A Reproductive barriers Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. PrezygoticIsolating Mechanisms Postzygotic Isolating Mechanisms Premating Mating Fertilization Habitatisolation Zygote mortality Species at same locale Fertilization occurs, but occupy different habitats. Mechanical isolation zygote does not survive. species 1 Genitalia between species are unsuitable hybrid Temporal isolation for one another. Hybrid sterility off spring Species reproduce at Hybrid survives but is different seasons or sterile and cannot different times of day. reproduce. Gamete isolation species 2 Sperm cannot reach Behavioral isolation or fertilize egg. F2 fitness In animal species, courtship behavior differs, Hybrid is fertile, but F2 hybrid or individuals respond to has reduced fitness. different songs,calls, pheromones,or other signals. 14-8
  • 9. Figure 14.2B Mating activity peaks at different times of the year forthese species of frogs Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. high g g fro ro g g ro ro f g rel rd fro f f en od pa ke Mating Activity ll gre pic leo wo bu low March 1 April 1 May 1 June 1 July 1 14-9
  • 10. Figure 14.2C Male blue-footed boobie doing a courtship dance fora female 14-10
  • 11. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Parents Figure 14.2D Mules cannot reproduce due to chromosome noncompatibility horse mating donkey 64 chromosomes 62 chromosomes fertilization mule (hybrid) 63 chromosomes Usually mules cannot reproduce. If an offspring does result, it cannot reproduce. 14-11 Offspring(donkey): © Robert J. Erwin/Photo Researchers, Inc.; (offspring): © Jorg & Petra Wegner/AnimalsAnimals
  • 12. 14.3 Allopatric speciation utilizes a geographic barrier Allopatric speciation  Requires that the subpopulations be separated by a geographic barrier  Ex: Ensantina salamanders in California  Distinct forms no longer interbreed  Ex: Sockeye Salmon in Washington State  Some introduced to Lake Washington  Colonized different habitats and different traits favored 14-12
  • 13. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ensatina eschscholtzi picta Figure 14.3A Allopatric 1 Members of a northern ancestral population migrated southward. speciation among Ensatina salamanders Ensatina eschscholtzi oregonensis 2 Subspecies are separated by California’s Central Valley. Some interbreeding between populations does occur. Central Valley Ensatina eschscholtzi platensisEnsatina eschscholtzixanthoptica Ensatina eschscholtzi croceaterEnsatina eschscholtzieschscholtzii 3 Evolution has occurred, and in the south, subspecies do not interbreed Ensatina eschscholtzi 14-13 even though they live in the same klauberi environment.
  • 14. Figure 14.3B: Sockeye salmon at Pleasure Point Beach, Lake WashingtonC: Sockeye salmon in Cedar River. The river connects with Lake Washington Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. River male Lake male River female Lake female B C 14-14
  • 15. 14.4 Adaptive radiation produces many related species Adaptive radiation  Single ancestral species gives rise to a variety of species, each adapted to a specific environment  An ecological niche is where a species lives and how it interacts with other species Ex: Common goldfinch-like ancestor arrived in Hawaii from Asia or North America about 5 mya  Today honeycreepers have a range of beak sizes and shapes for feeding on various food sources, including seeds, fruits, flowers, and insects 14-15
  • 16. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. *Lesser Koa finch Palila Figure 14.4 Adaptive Laysan finch radiation in Hawaiian *Greater Koa finch honeycreepers Ge nu sP sit Ou tir os tra Maui parrot bill *Kona finch Akiapolaau *Kauai akialoa Nukupuu *Akialoa Genu s Hem ignath amakihi us (green solitaire) *Extinct species or subspecies Anianiau (lesser amakihi)Alauwahio(Hawaiiancreeper) Akepa Amakihi 14-16
  • 17.  Sympatric speciation  Speciation without the presence of a geographic barrier  More common in flowering plants than in animals due to self-pollination Polyploidy – chromosome number beyond the diploid (2n) number 14-17
  • 18. Figure 14.5A Autoploidy: The small, diploid-seeded banana is contrastedwith the large, polyploid banana that produces no seeds Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. no seeds seeds diploid polyploid banana (2n) banana (diploid): © Randy C. Ploetz 14-18
  • 19. HOW BIOLOGY IMOPACTS OUR LIVES 14A The Many Uses of Corn, an Allotetraploid Modern corn’s (Zea mays) ancient ancestor was teosinte from southern Mexico Between 4000 and 3000 B.C., the hand of artificial selection began to shape the evolution of corn Corn is an allotetraploid – it is 4n  Hybridization between 2 related species followed by doubling of the chromosomes Corn is America’s number-one field crop, yielding 9.5 billion bushels yearly 14-19
  • 20. Macroevolution Involves Changes at the Species Level and Beyond 14-20
  • 21. 14.6 Speciation occurs at different tempos  Many evolutionists accept a gradualistic model evolution which proposes that speciation occurs after populations become isolated  Some paleontologists think that species appear suddenly, and then they remain essentially unchanged phenotypically until they undergo extinction  Based on these findings, other evolutionists developed a punctuated equilibrium model to explain the pace of evolution 14-21
  • 22. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 14.6A Gradualistic model New species Gradual change as time passes.Time ancestral species 14-22
  • 23. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 14.6B Punctuated equilibrium model no change no change no change new speciesTime new species no change ancestral species 14-23
  • 24. HOW SCIENCE PROGRESSES 14B The Burgess Shale Hosts a Diversity of Life Burgess Shale contains fossils of marine life some 540 mya Many of the fossils are remains of soft-bodied invertebrates Fossils tell us that the ancient seas were teeming with weird-looking, mostly invertebrate animals All of today’s groups of animals can trace their ancestry to one of these strange-looking forms 14-24
  • 25. Figure 14BBurgess Shale quarry where many ancient fossils have been found 14-25
  • 26. Figure 14B cont’dAn artist’s depiction of the variety of fossils is accompanied by photos of theactual fossilized remains 14-26
  • 27. Figure 14B cont’dAn artist’s depiction of the variety of fossils is accompanied by photos of theactual fossilized remains. 14-27
  • 28. 14.7 Development plays a role in speciation Investigators have discovered genes whose differential expression can bring about changes in body shapes These regulatory genes found in all organisms Genes must date back to a common ancestor that lived more than 600 MYA 14-28
  • 29. Figure 14.7A Differential expression of regulatory genes during development can account for differences in vertebrate limbs Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.The limbs of these ferrestrial mammals are shaped for running (or walking). The limbs of birds are shaped for flight. (boy, dog, bird): © Corbis RF 14-29
  • 30. Figure 14.7B Differential expression of a Hox genes causes (a) a chick to havefewer vertebrae than (b) a snake in a particular region (colored pink) of the spine 14-30
  • 31. 14.8 Speciation is not goal- oriented Modern horses evolved about 4 mya  Have features adaptive for living on an open plain: large size long legs, hoofed feet, and strong teeth Family tree of Equus tells us once more that speciation, diversification, and extinction are common occurrences in the fossil record 14-31
  • 32. Figure 14.8 Simplified family tree of Equus. Every dot is a genus. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2 MYA 4 MYA Equus Neohipparion Hipparion 12 MYA Dinohippus 15 MYA Megahippus Merychippus 17 MYA 23 MYA 25 MYA 35 MYA Miohippus 40 MYA Palaeotherium 45 MYA 50 MYA Hyracotherium 55 MYA 14-32
  • 33. Connecting the Concepts: Chapter 14 Macroevolution is the study of the origin and history of species on Earth Speciation usually occurs by allopatric speciation but can occur after sympatric speciation Gradualistic vs punctuated equilibrium model for speed of speciation Ancient regulatory genes can bring about changes in body shape and organs Evolution is not goal-oriented 14-33