Evolution, Biodiversity, and Community Processes

1. Evolution, Biodiversity, and Community Processes La Cañada High School Dr. E

2. Evolution – What Next?

3. What types of Life exist on the Earth?

4. Types of Organisms • Prokaryotic Kingdom: single-celled organisms containing no internal structures surrounded by membranes (therefore there is no nucleus) • Monera – bacteria and cyanobacteria

6. Endosymbiotic Theory Chloroplast Plants and plantlike protists Aerobic bacteria Ancient Prokaryotes Photosynthetic bacteria Nuclear envelope evolving Mitochondrion Primitive Photosynthetic Eukaryote Animals, fungi, and non-plantlike protists Primitive Aerobic Eukaryote Ancient Anaerobic Prokaryote

7. Types of Organisms • Eukaryotic Kingdoms: all organisms consisting of cells which contain membrane-bound nuclei • Protista - mostlyone-celled organisms – have characteristics of all three other Eukaryote Kingdoms • Fungi - organisms which decompose stuff • Plantae - organisms which use photosynthesis to make their own food • Annuals completelife cycle in one season • Perennialslive for more than one season • Animalia - organisms which must get organic compounds from food they eat - most are able to move • Invertebrates – no backbone • Vertebrates – Fish, Amphibians, Reptiles, Birds and Mammals

9. Naming Species

12. EVOLUTIONisGradual Change

13. How did Life Originate?OrChemical Evolution

28. Biological Evolution

29. Evolutionary Bush One life-form splits into two and those branches split (independently) to make more. Time   Phenotypic ‘distance’

30. Evolutionary Bush -- thousands of earlier and later branches.

31. At any given moment (e.g. the ‘present’), all we see is current diversity…all extinct forms are gone (99.9%) Time 

32. Charles Darwin • 1809-1882 • British naturalist • Proposed the idea of evolution by natural selection • Collected clear evidence to support his ideas

33. Darwin’s finches • 13 species of finches in the Galápagos Islands • Was puzzling since only 1 species of this bird on the mainland of South America, 600 miles to the east, where they had all presumably originated

34. Darwin’s finches • Differences in beaks • associated with eating different foods • adaptations to the foods available on their home islands • Darwin concluded that when the original South American finches reached the islands, they adapted to available food in different environments

36. What did Darwin say? • Organisms reproduce more than the environment can support • some offspring survive • some offspring don’t survive • competition • for food • for mates • for nesting spots • to get away from predators

37. Survival of the fittest • Who is the fittest? • traits fit the environment • the environment can change, so who is fit can change Peppered moth

38. Adaptive Radiation • When one species splits into many species to fill open habitats. • Darwin’s finches

39. Speciation When a group becomes geographically isolated over time it will become reproductively isolated = new species formed. • One species can evolve into two or more species • 2 step process • Geographical isolation • Reproductive isolation

40. Ammospermophilus spp Geographic isolation • When a population becomes divided by a natural barrier. • Mountains, river, body of water, landslides • Groups can’t interbreed or intermix • Become adapted to a different environment Harris’s antelope squirrel inhabits the canyon’s south rim (L). Just a few miles away on the north rim (R) lives the closely related white-tailed antelope squirrel

41. Reproductive Isolation • Differences in isolated groups become so great, they can no longer interbreed • Physical changes • Behavioral changes • Biochemical changes

42. Stephen Jay Gould (1941-2002) • Harvard paleontologist & evolutionary biologist • punctuated equilibrium • prolific author • popularized evolutionary thought

43. Punctuated Equilibrium

45. Speciation Evolution of new species

46. Four causes of evolutionary change: • Mutation: fundamental origin of all genetic (DNA) change.

47. Four causes of evolutionary change: • Mutation: fundamental genetic shifts. • Genetic Drift: isolated populations accumulate different mutations over time. In a continuous population, genetic novelty can spread locally.

48. Four causes of evolutionary change: But in discontinuous populations, gene flow is blocked.

49. Four causes of evolutionary change • Mutation: fundamental genetic shifts. • Genetic Drift: isolation  accumulate mutations • Founder Effect:sampling bias during immigration. When a new population is formed, its genetic composition depends largely on the gene frequencies within the group of first settlers.

50. Founder Effect.-- Human example: your tribe had to live near the Bering land bridge…