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Chapter 19: Evolutionary Patterns, Rates and Trends

Chapter 19: Evolutionary Patterns, Rates and Trends. Macroevolution. The large-scale patterns, trends, and rates of change among families and other more inclusive groups of species. Biological Species Concept.

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Chapter 19: Evolutionary Patterns, Rates and Trends

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  1. Chapter 19:Evolutionary Patterns, Rates and Trends

  2. Macroevolution The large-scale patterns, trends, and rates of change among families and other more inclusive groups of species

  3. Biological Species Concept “Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.” Ernst Mayr

  4. Morphology & Species • Morphological traits may not be useful in distinguishing species • Members of same species may appear different because of environmental conditions • Morphology can vary with age and sex • Different species can appear identical

  5. Morphology & Species Fig. 19-3, p.302

  6. Reproductive Isolation • Cornerstone of the biological species concept • Speciation is the attainment of reproductive isolation • Reproductive isolation arises as a by-product of genetic change

  7. Genetic Divergence • Gradual accumulation of differences in the gene pools of populations • Natural selection, genetic drift, and mutation can contribute to divergence • Gene flow counters divergence

  8. Genetic Divergence parent species daughter species time A time B time C time D

  9. Mechanisms of Speciation • Allopatric speciation • Sympatric speciation • Parapatric speciation

  10. Allopatric Speciation • Speciation in geographically isolated populations • Some sort of barrier arises and prevents gene flow • Effectiveness of barrier varies with species

  11. Allopatric Speciations Fig. 19-6a, p.304

  12. Allopatric Speciations Fig. 19-6b, p.304

  13. Allopatric Speciations Fig. 19-6d, p.304

  14. Archipelagos • Island chains some distance from continents • Galapagos Islands • Hawaiian Islands • Colonization of islands followed by genetic divergence sets the stage for speciation

  15. Speciation on an Archipelago aA few individuals of a species on the mainland reach isolated island 1. Speciation follows genetic divergence in a new habitat. Fig. 19-7a, p.305

  16. Speciation on an Archipelago bLater in time, a few individuals of the new species colonize nearby island 2. In this new habitat, speciation follows genetic divergence. b Later in time, a few individuals of the new species colonize nearby island 2. In this new habitat, speciation follows genetic divergence. Fig. 19-7b, p.305

  17. Speciation on an Archipelago cSpeciation may also follow colonization of islands 3 and 4. And it may follow invasion of island a by genetically different descendants of the ancestral species. b Later in time, a few individuals of the new species colonize nearby island 2. In this new habitat, speciation follows genetic divergence. Fig. 19-7c, p.305

  18. Case Study: Hawaiian Islands • Volcanic origins, variety of habitats • Adaptive radiations: • Honeycreepers - In absence of other bird species, they radiated to fill numerous niches • Fruit flies (Drosophila) - 40% of fruit fly species are found in Hawaii

  19. Hawaiian Honeycreepers FOUNDER SPECIES Fig.18-7, p. 297

  20. Fig. 19-7d1, p.305

  21. Fig. 19-7d2, p.305

  22. Fig. 19-7d3, p.305

  23. Fig. 19-7d5, p.305

  24. Fig. 19-7d12, p.305

  25. Speciation without a Barrier • Sympatric speciation • Species forms within the home range of the parent species • Two different species form from a similar ancestor • Parapatric speciation • Neighboring populations become distinct species while maintaining contact along a common border

  26. Sympatric Speciation in African Cichlids Fig. 19-8a, p.306

  27. Possible Evolution of Wheat Triticum monococcum (einkorn) T. turgidum (wild emmer) T. tauschii (a wild relative) T. aestivum (one of the common bread wheats) Hybridization was followed by spontaneous chromosome doubling. Unknown species of wild wheat 14AA X 14BB 14AB 28AABB X 14DD 42AABBDD Fig. 19-10, p.307

  28. Parapatric Speciation Adjacent populations evolve into distinct species while maintaining contact along a common border BULLOCK’S ORIOLE BALTIMORE ORIOLE HYBRID ZONE

  29. Parapatric Speciation T. barretti hybrid zone T. anophthalmus Fig. 19-11c, p.307

  30. extinction (branch ended before present) new species branch point (a time of divergence, speciation) a new species branch point (a time of divergence, speciation) dashed line (only sketchy evidence of presumed evolutionary relationship) a single lineage a single lineage Evolutionary Trees

  31. Evolutionary Trees species 2 species 3 species 1 suspected branching a single lineage; ancestral stock branch point (time of genetic divergence, speciation under way) Fig. 19-12, p.308

  32. Gradual Model • Speciation model in which species emerge through many small morphological changes that accumulate over a long time period

  33. Punctuation Model • Speciation model in which most changes in morphology are compressed into brief period near onset of divergence

  34. Adaptive Radiation • Burst of divergence • Single lineage gives rise to many new species • New species fill vacant adaptive zone • Adaptive zone is “way of life”

  35. Adaptive Radiation Fig. 19-14a, p.309

  36. Extinction • Irreversible loss of a species • Fossil record shows 20 or more large-scale extinctions • Reduced diversity is followed by adaptive radiation

  37. Who Survives? • Species survival is to some extent random • Asteroids have repeatedly struck Earth, destroying many lineages • Changes in global temperature favor lineages that are widely distributed

  38. Taxonomy • Field of biology concerned with identifying, naming, and classifying species • Somewhat subjective • Information about species can be interpreted differently

  39. Binomial System • Each species has a two-part Latin name • First part is generic (Genus) • Second part is specific name (Species)

  40. Higher Taxa • Kingdom • Phylum • Class • Order • Family • Genus • Species

  41. Phylogeny • The scientific study of evolutionary relationships among species • Practical applications • Allows predictions about the needs or weaknesses of one species on the basis of its known relationship to another

  42. Examples of Classification Fig. 19-15, p.310

  43. Five-Kingdom Scheme • Proposed in 1969 by Robert Whittaker Monera Protista Fungi Plantae Animalia

  44. Three-Domain Classification • Favored by microbiologists EUBACTERIA ARCHAEBACTERIA EUKARYOTES

  45. Six-Kingdom Scheme EUBACTERIA ARCHAEBACTERIA PROTISTA FUNGI PLANTAE ANIMALIA

  46. Six-Kingdom Scheme Bacteria Archaea Protists Plants Fungi Animals Fig. 19-16a, p.311

  47. Evolutionary Tree Fig. 19-17, p.311

  48. Taxon Traits (Characters) ConstructingA Cladogram Jaws Limbs Hair Lungs Tail Shell Lamprey - - - - + - Turtle + + - + + + Cat + + + + + - + + + + - - Gorilla Lungfish + - - + + - Trout + - - - + - Human + + + + - - Taxon Traits (Characters) Jaws Limbs Hair Lungs Tail Shell Lamprey 0 0 0 0 0 0 Turtle 1 1 0 1 0 1 Cat 1 1 1 1 0 0 1 1 1 1 1 0 Gorilla Lungfish 1 0 0 1 0 0 Trout 1 0 0 0 0 0 Human 1 1 1 1 1 0

  49. Fig. 19-18a,b, p.312

  50. Constructing a Cladogram trout lungfish turtle cat gorilla human lamprey tail loss hair limbs lungs jaws

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