8.8 / 8.9 magnitude earthquake

1. 8.8 / 8.9 magnitude earthquake

2. Tsunami strikes Japan - 10-meter high wave

3. Tsunami strikes Japan Hawaii orders evacuation of low-lying coastal areas after massive earthquake off Japan triggered tsunami alert Tsunami warning for all the Pacific!

4. Tsunami warnings…

5. Let’s review: Natural Diversity • By the Numbers – • Estimated 2 - 100 million species, with a best estimate of somewhere near 10 million • ~1.4 million described species • ~1 million described insects/ 350,000 described beetles • 8,800–10,200 living bird species • ~5,500 species of mammals • Great diversity exists, with each species exhibiting a considerable degree of suitability for its natural lifestyle • How? • Seems unlikely

6. What is evolution? • Broad: The gradual process by which the living world has been developing following the origin of life. • Narrow: Change in the genetic frequencies of a population.

7. Why is the theory of evolution important? • Implications for people: • Antibiotic resistance, pesticide resistance, control of disease, human epidemiology, development of new crops, medical treatments, conservation biology, etc. (not to mention the ecological implications) • Evolution provides the mechanism to address these issues.

8. Evidence for evolution • Fossil Record (The fossil record provides snapshots of the past that, when assembled, illustrate a panorama of evolutionary change over the past four billion years. The picture may be smudged in places and may have bits missing, but fossil evidence clearly shows that life is old and has changed over time.) • Morphology • Vestigial organs (A vestigial organ or structure is any organ or structure found in a species which is not being used as it is in other species. Contrary to popular belief, vestigial organs and vestigial structures aren't necessarily useless or functionless.) • Biogeography (study of the distribution of species (biology) spatially (geography) and temporally (history).) • Molecular evidence (All living things are fundamentally alike. At the cellular and molecular level living things are remarkably similar to each other. These fundamental similarities are most easily explained by evolutionary theory: life shares a common ancestor. )

9. Early fossil discoveries In the 17th century, Nicholas Steno: similarity between shark teeth and the rocks commonly known as "tongue stones". - first understanding that fossils were a record of past life. Two centuries later, Mary Ann Mantell picked up a tooth, which her husband Gideon thought to be of a large iguana, but it turned out to be the tooth of a dinosaur, Iguanodon. - many fossils represented forms of life that are no longer with us today. Nicholas Steno's anatomical drawing of an extant shark and a fossil shark tooth. Nicholas Steno's anatomical drawing of an extant shark (left) and a fossil shark tooth (right). Steno made the leap and declared that the fossil teeth indeed came from the mouths of once living sharks.

10. Transitional forms A skull of the gray whale that roams the seas today has its nostrils placed at the top of its skull. It would appear from these two specimens that the position of the nostril has changed over time and thus we would expect to see intermediate forms. Pakicetus is described as an early ancestor to modern whales. Although pakicetids were land mammals, it is clear that they are related to whales and dolphins based on a number of specializations of the ear, relating to hearing. The skull shown here displays nostrils at the front of the skull.

11. Evidence for evolution: Fossil record

12. Evidence for evolution: Fossil record • Jaw bone evolution from therapsid reptiles to mammals.

13. Evidence for evolution: Fossil record • Evolution through time: • Variation through geologic periods. • Fossils in most recent strata are often similar if not indistinguishable from living species. • The older the strata is, the more different the fossils.

14. Evidence for evolution • Morphology: • This was how species were described as “related” as far back as 18th century. • Linnaean hierarchy: • From Kingdom to sub-species

15. Evidence for evolution • Vestigial Structures: • Structures that are not fully functional or functional at all.

16. Evidence for evolution • Vestigial Structures • Blind cave dwelling animals still have eyes (that don’t work). • Why does an ostrich have wings?

17. Evidence for evolution: Biogeography • Biogeography: • the geographic distribution of organisms • those [organisms] of the Cape de Verde Islands bearing the impress of Africa, as the inhabitants of the Galapagos Archipelago are stamped with that of America.

18. Evolution through space: Evidence for evolution: Biogeography

19. Gondwana

20. Evolution through time and space EFFECTS OF CONTINENTAL DRIFT ON ECOLOGY OF EVOLUTION

21. The history of life can be gauged by the geological time scale. • Ecologists recognize key features of the geological record: • earth formed 4.5 billion years ago • life arose within the first billion years • life remained primitive for most of earth’s history • ancient physical environments were quite different from those of the present: • the early atmosphere had little oxygen and early microbes used anaerobic metabolism • increased oxygen led to diversification of complex life forms

22. The Geologic Record • About 590 Mya, most of the modern phyla of invertebrates appeared in the fossil record: • these early animals began to protect themselves with hard shells, which make excellent fossils • the Paleozoic era is thus the first of three major divisions of geologic time reflecting diversification of animals: • Paleozoic: 590 Mya to 248 Mya • Mesozoic: 248 Mya to 65 Mya • Cenozoic: 65 Mya to present

23. Continental Drift • The continents are islands of low-density rock floating on the denser material of the earth’s interior and carried along by convection currents: • the movements of the continents over time are called continental drift • These movements have two important ecological consequences: • positions of continents, ocean basins influence climate • continental drift creates and breaks barriers to dispersal

24. Continental Drift: Mesozoic to Present • In the early Mesozoic era, 200 Mya, continents formed a single giant landmass called Pangaea • By 144 Mya (beginning of the Cretaceous period) the northern continents (Laurasia) had separated from the southern continents (Gondwana) • at this time Gondwana itself was also breaking apart • By the end of the Mesozoic era (65 Mya), South America and Africa were widely separated, and many other patterns were emerging.

26. Continental drift

27. Consequences of Continental Drift • Details of continental drift have yet to be resolved, but implications for evolution of animals and plants are clear; for example: • the distributions of the flightless ratite birds (such as ostriches) are the results of connection between the southern continents that made up Gondwana: • these birds are descended from a common Gondwanan ancestor • splitting of a widely distributed ancestral population by continental drift is called vicariance

28. Lineages of ratite birds were separated by the fragmentation of Gondwana – 80 mya. Evolutionary relationships of these birds reconstructed from DNA sequences

29. Large flightless birds • the phylogenetic tree of the flightles birds • Ostrich (left) is African; rhea (middle) is found in similar grasslands in South America; the emu (right) in Australia

30. Analogous: similar in superficial form or function Homologous: derived from an equivalent structure in a common ancestry EVOLUTION: CONVERGENT AND PARALLELS

31. Convergence Convergence is the process whereby unrelated species living under similar ecological conditions come to resemble one another more than their ancestors did: • Analagous but not homologous • there are numerous examples of convergence: • woodpecker-like birds that fill the woodpecker niche in many systems lacking woodpeckers • similarities of plants and animals of North and South American deserts • similar body forms of dolphins and penguins, which both resemble tuna, whose swimming lifestyle they share

32. Convergent evolution Wings of bats and birds – similar in form/function but not from a common ancestry; structurally different

33. Pairs of unrelated African and South American rain forest mammals: similar lifestyles and adaptations; striking convergence

34. Parallel evolution Ancestrally related groups – then isolated from each other In contrast to convergent evolution, diversified from a common ancestral line and both inherited a common set of potentials and constraints

35. Parallel evolution of marsupial and placental mammals: Pairs of species are similar in both appearance and habit and usually (not always) in lifestyle

36. To recap Convergent Evolution • Convergent evolution takes place when species of different ancestry begin to share analogous traits because of a shared environment or other selection pressure. For example, whales and fish have some similar characteristics since both had to evolve methods of moving through the same medium: water. Parallel Evolution • Parallel evolution occurs when two species evolve independently of each other, maintaining the same level of similarity. Parallel evolution usually occurs between unrelated species that do not occupy the same or similar niches in a given habitat. • (a) divergent • (b) convergent • (c) parallel

37. Evidence for evolution • Molecular evidence • the more closely related two organisms are, the more similar are their genetic structure. • Often times, morphological traits can be ambiguous. • One of the most important sources of information on phylogenetic relationships

38. Maintaining Genetic Variation – • Without Selection: no loss or gain (random) • B. Hardy-Weinberg Theorem: constant allelic frequencies are maintained if ... • populations are large, • individuals contribute equally to genetic composition of next generation, and • matings are random • Remember: Narrow definition of evolution = change in the genetic frequency of a population.

39. Why does this matter? • If population is not at equilibrium – • There are outside forces acting on the population.

40. Outside forces that can change population genetics. • Mutations • origin of variations, and mutation increases under stress • Age, chemicals, UV-radiation • Migration • Population size • Non-Random Mating • Nonrandom Mating: ∆ gene frequencies • Environmental Variance: favor some phenotypes • Effects of Selection: stable polymorphisms • Natural Selection

41. Loss of Genetic Variation • Inbreeding: rapid loss of genes • Fixes traits quickly • Genetic Drift: random losses of genes • Neighborhoods: local breeding tendency • Races of plants and animals • Bottlenecks: low population = reduced pool, duration of the low population is critical (drift)

42. Survivors of a near-extinction resulted in close inbreeding 10,000 years ago.

43. Current Evolution • According to narrow definition: • Evolution is little more than a process that changes gene frequencies in a non-random manner; • environmental influences direct this change • What are a few examples of recent evolution of species that can be correlated to an environmental stress?

44. Examples • The evolution of pesticide resistence in pest species • The evolution of antibiotic resistence in human pathogens • note the recent discovery of plague and tuberculosis exhibiting broad-spectrum antibiotic resistence

45. Insect species resistant to pesticides

46. Strep resistance to penicillin

47. Maintenance of variation • So how is variation maintained in the face of environmental pressures and natural selection? • Ever see a constant environment? • Microenvironmental differences exist over small spatial scales. • Temporal heterogeneity is a common characteristic of physical environments.

48. “There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that whilst this planet has gone cycling on according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.” • Charles Darwin – The Origin of Species (Last sentence)

49. End of chapter 2

50. Additional information