1. www.cengage.com/biology/starr Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr Chapter 17 Processes of Evolution (Sections 17.11 - 17.14)

2. 17.11 Allopatric Speciation In allopatric speciation, a geographic barrier arises and ends gene flow between populations – genetic divergences then give rise to new species allopatric speciation Speciation pattern in which a physical barrier that separates members of a population ends gene flow between them

3. Barriers to Reproduction Whether a geographic barrier can block gene flow depends on whether and how an organism travels (e.g. by swimming, walking, or flying), and how it reproduces (e.g. by internal fertilization or by pollen dispersal) Example: When the Isthmus of Panama formed, it cut off gene flow among populations of aquatic organisms in the Pacific and Atlantic oceans

4. Allopatric Speciation in Snapping Shrimp

5. Fig. 17.20, p. 272 Isthmus of Panama Alpheus millsae (Pacific) Alpheus nuttingi (Atlantic) Allopatric Speciation in Snapping Shrimp

6. Fig. 17.20a, p. 272 Isthmus of Panama Columbia Atlantic Ocean Mexico Pacific Ocean Allopatric Speciation in Snapping Shrimp

7. Fig. 17.20b, p. 272 Alpheus nuttingi (Atlantic) Allopatric Speciation in Snapping Shrimp

8. Fig. 17.20b, p. 272 Alpheus millsae (Pacific) Allopatric Speciation in Snapping Shrimp

9. Speciation in Archipelagos Archipelagos are isolated island chains formed by volcanoes, such as the Hawaiian and Galápagos Islands Archipelagos were populated by a few individuals of mainland species whose descendants diverged over time Selection pressures within and between the islands can foster even more divergences

10. The Hawaiian Islands

11. Hawaiian Honeycreepers The first birds to colonize the Hawaiian Islands found a near absence of competitors and predators and an abundance of rich and vacant habitats, which encouraged rapid speciation The many species of honeycreepers, unique to the Hawaiian Islands, have specialized bills and behaviors adapted to feed on certain insects, seeds, fruits, nectar, or other foods

12. Honeycreeper Diversity

13. Fig. 17.21a, p. 273 Akepa (Loxops coccineus) Insects, spiders, nectar; high mountain rain forest Honeycreeper Diversity

14. Fig. 17.21b, p. 273 Akekee (Loxops caeruleirostris) Insects, spiders, nectar; high mountain rain forest Honeycreeper Diversity

15. Fig. 17.21c, p. 273 Nihoa finch (Telespiza ultima) Insects, buds, seeds, flowers, seabird eggs; rocky or shrubby slopes Honeycreeper Diversity

16. Fig. 17.21d, p. 273 Palila Maui (Loxioides bailleui) Mamane seeds, buds, flowers, berries, insects; high mountain dry forests Honeycreeper Diversity

17. Fig. 17.21e, p. 273 Maui parrotbill (Pseudonestor xanthophrys) Insect larvae, pupae, caterpillars; mountain forests, dense underbrush Honeycreeper Diversity

18. Fig. 17.21f, p. 273 Apapane (Himatione sanguinea) Nectar, caterpillars and other insects, spiders; high mountain forests Honeycreeper Diversity

19. Fig. 17.21g, p. 273 Poouli (Melamprosops phaeosoma) Tree snails, insects in understory; last one died in 2004 Honeycreeper Diversity

20. Fig. 17.21h, p. 273 Maui Alauahio (Paroreomyza montana) Bark or leaf insects, high mountain rain forest Honeycreeper Diversity

21. Fig. 17.21i, p. 273 Kauai Amakihi (Hemignathus kauaiensis) Bark-picker; insects, spiders, nectar; high mountain rain forest Honeycreeper Diversity

22. Fig. 17.21j, p. 273 Akiapolaau (Hemignathus munroi) Probes, digs insects from big trees; high mountain rain forest Honeycreeper Diversity

23. Fig. 17.21k, p. 273 Akohekohe (Palmeria dolei) Mostly nectar from flowering trees, some insects, pollen; high mountain rain forest Honeycreeper Diversity

24. Fig. 17.21l, p. 273 Iiwi (Vestiaria coccinea) Mostly nectar (ohia flowers, some nectar; lobelias, mints), some insects; high mountain rain forest Honeycreeper Diversity

25. ANIMATION: Allopatric speciation on an archipelago To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

26. ANIMATION: Models of speciation To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

27. 17.12 Sympatric and Parapatric Speciation Populations sometimes speciate even without a physical barrier that bars gene flow between them In sympatric speciation, populations in physical contact speciate With parapatric speciation, populations in contact along a common border speciate

28. Sympatric Speciation Sympatric speciation can occur instantly with a change in chromosome number – many plants are polyploid (e.g. wheat) Sympatric speciation can also occur with no change in chromosome number (e.g. mechanically isolated sage plants) sympatric speciation Pattern in which populations inhabiting the same geographic region speciate in the absence of a physical barrier between them

29. Sympatric Speciation in Wheat

30. Fig. 17.22, p. 274 C Emmer probably hybridized with a wild goatgrass having a diploid chromosome number of 14 (two sets of 7 DD). The resulting common bread wheat has six sets of 7 chromosomes (42 AABBDD). B About 8,000 years ago, the chromo-some number of an AB hybrid plant spontaneously doubled. The resulting species, emmer, is tetraploid: it has two sets of 14 chromosomes (28 AABB). A Einkorn has a diploid chromosome number of 14 (two sets of 7, shown here as 14 AA). Wild einkorn probably hybridized with another wild species having the same chromosome number (14 BB) about 11,000 years ago. The resulting hybrid was diploid (14 AB). Triticum mono- coccum (einkorn) Unknown species of Triticum spontaneous chromosome doubling T. turgidum (emmer) T. tauschii (goatgrass) T. aestivum (common bread wheat) 42 AABBDD28 AABB14 BB14 AA14 DDX14 ABX Sympatric Speciation in Wheat

31. Examples of Sympatric Speciation Lake Victoria cichlids (sexual selection) In the same lake, female cichlids of different species visually select and mate with brightly colored males of their own species Warblers around the Tibetan plateau (behavioral isolation) Two populations overlap in range, but don’t interbreed because they don’t recognize one another’s songs

32. Male Cichlids of Lake Victoria

33. Parapatric Speciation Parapatric speciation may occur when one population extends across a broad region with diverse habitats Example: Two species of velvet walking worm with overlapping habitats in Tasmania: Where they interbreed, their hybrids are sterile parapatric speciation Speciation model in which different selection pressures lead to divergences within a single population

34. Comparing Speciation Models

35. Key Concepts How Species Arise Speciation varies in its details, but it always involves the end of gene flow between populations Microevolutionary events that occur independently lead to genetic divergences, which are reinforced by reproductive isolation

36. ANIMATION: Sympatric Speciation in Wheat To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

37. 17.13 Macroevolution A central theme of macroevolution is that major evolutionary novelties often stem from the adaptation of an existing structure for a completely different purpose (exaptation) exaptation Adaptation of an existing structure for a completely different purpose; a major evolutionary novelty

38. Patterns of Macroevolution Macroevolution includes patterns of evolution above the species level, such as one species giving rise to multiple species, origin of major groups, and major extinction events Four patterns of macroevolution: Stasis Adaptive radiation Coevolution Extinction

39. Stasis With the simplest macroevolutionary pattern, stasis, a lineage persists for millions of years with little or no change Example: Coelacanths stasis Evolutionary pattern in which a lineage persists with little or no change over evolutionary time

40. Coelacanth: Fossil and Living

41. Mass Extinctions More than 99% of all species that ever lived are now extinct There have been more than twenty mass extinctions, which are simultaneous losses of many lineages, including five catastrophic events in which the majority of species on Earth disappeared extinct Refers to a species that has been permanently lost

42. Adaptive Radiation In adaptive radiation, a lineage rapidly diversifies into several new species Adaptive radiation can occur after individuals colonize a new environment that has a variety of different habitats with few or no competitors (e.g. Hawaiian honeycreepers) adaptive radiation A burst of genetic divergences from a lineage gives rise to many new species

43. An Example of Adaptive Radiation This evolutionary tree diagram shows how one ancestral species gave rise to the Hawaiian honeycreepers Only 41 of many hundreds of species are represented here (orange are extinct)

44. Adaptive Radiation (cont.) Adaptive radiations also occur after geologic or climatic events eliminate some species from a habitat Example: Mammals were able to undergo an adaptive radiation after the dinosaurs disappeared

45. Adaptive Radiation (cont.) A key innovation can result in an adaptive radiation, or rapid diversification into new species Example: evolution of lungs opened the way for an adaptive radiation of vertebrates on land key innovation An evolutionary adaptation that gives its bearer the opportunity to exploit a particular environment more efficiently or in a new way

46. Coevolution In coevolution, close ecological interactions between two species cause them to evolve jointly Over evolutionary time, two species may become so interdependent that they can no longer survive without one another (e.g. the large blue butterfly (Maculinea arion) and red ant (Myrmica sabuleti)) coevolution Joint evolution of two closely interacting species Each species is a selective agent for traits of the other Each adapts to changes in the other

47. Coevolved Species The ant eats honey exuded by the butterfly larva and carries it to its nest The caterpillar lives in the ant nest and eats ant larvae until it pupates

48. Evolutionary Theory Many biologists disagree about how macroevolution occurs Dramatic jumps in morphology may be the result of mutations in homeotic or other regulatory genes Macroevolution may be an accumulation of many microevolutionary events, or it may be an entirely different process

49. Key Concepts Macroevolution Patterns of genetic change that involve more than one species are called macroevolution Recurring patterns of macroevolution include the origin of major groups, one species giving rise to many, and mass extinction

50. ANIMATION: Adaptation to What? To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

51. ANIMATION: Animal evolution in Phyla To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

52. ANIMATION: Evolution of Horses To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

53. 17.14 Phylogeny Instead of trying to divide the diversity of living organisms into a series of taxonomic ranks, most biologists are now focusing on evolutionary connections Cladistics allows us to reconstruct evolutionary history (phylogeny) by grouping species on the basis of their shared characters

54. Key Terms phylogeny Evolutionary history of a species or group of species cladistics Method of determining evolutionary relationships by grouping species into clades based on shared characters character Quantifiable, heritable characteristic—any physical, behavioral, physiological, or molecular trait of a species

55. Examples of Characters

56. Ranking Versus Grouping The result of a cladistic analysis is a cladogram, a type of evolutionary tree used to visualize evolutionary patterns Each line represents a lineage, which may branch into two sister groups at a node, which represents a shared ancestor Every branch ends with a clade, a species or group based on a set of shares characters Ideally, each clade is a monophyletic group that comprises an ancestor and all of its descendants

57. Key Terms evolutionary tree Type of diagram that summarizes evolutionary relationships among a group of species cladogram Evolutionary tree that shows a network of evolutionary relationships among clades clade A species or group of species that share a set of characters

58. Key Terms sister groups The two lineages that emerge from a node on a cladogram monophyletic group An ancestor and all of its descendants

59. Cladograms

60. Fig. 17.27, p. 278 earthworm multicellular with a backbone, legs, and fur or hair multicellular with a backbone and legs multicellular with a backbone multicellular A human mouse lizard tuna B earthworm human mouse lizard tuna Cladograms

61. ANIMATION: Interpreting a cladogram To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

62. How We Use Evolutionary Biology Hawaiian honeycreepers illustrate how evolution works: Isolation that spurred honeycreepers’ adaptive radiations also ensured they had no built-in defenses against predators or diseases from the mainland Specializations became hindrances when habitats suddenly changed or disappeared At least 43 species of honeycreeper that thrived on the islands before humans arrived were extinct by 1778 -- today, 32 of the remaining 71 species are endangered, and 26 are extinct

63. Going, Going, and Gone Destruction of food sources and avian malaria decimated the palila and akekee The poouli is probably now extinct

64. Key Concepts Cladistics Evolutionary tree diagrams are based on the premise that all species interconnect through shared ancestors Grouping species by shared ancestry better reflects evolutionary history than do traditional ranking systems

65. Rise of the Super Rats (revisited) The allele that makes rats resistant to warfarin is adaptive when warfarin is present, and maladaptive when it is not Periodic exposure to warfarin maintains a balanced polymorphism of the resistance gene in rat populations