Understanding Evolution and Biodiversity: The Diversity of Life on Earth

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

2. What types of Life exist on the Earth?

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

5. 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

6. 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

8. Naming Species

11. How did Life Originate?OrChemical Evolution

12. EVOLUTIONisGradual Change

16. Evidence

17. Fossils 1600's - Danish scientist Nicholas Steno studied the relative positions of sedimentary rocks • Layering is the most obvious feature of sedimentary rocks • formed particle by particle and bed by bed, and the layers are piled one on top of the other • any sequence of layered rocks, a given bed must be older than any bed on top of it • Law of Superposition is fundamental to the interpretation of Earth history, because at any one location it indicates the relative ages of rock layers and the fossils in them.

19. Half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo radioactive decay

20. Biological Evolution

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

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

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

24. WRONG WRONG

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

26. Darwin’s Observations • Most species produce more offspring than can be supported by the environment • Environmental resources are limited • Most populations are stable in size • Individuals vary greatly in their characteristics (phenotypes) • Variation is heritable (genotypes)

27. 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

28. 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

30. 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

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

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

33. Punctuated Equilibrium • Rate of speciation is not constant • rapid bursts of change • long periods of little or no change • species undergo rapid change when they 1st bud from parent population Time

34. Gradualism • Gradual divergence over long spans of time • assume that big changes occur as the accumulation of many small ones

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

36. 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

37. 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

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

39. Speciation Evolution of new species

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

41. 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.

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

43. 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.

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

45. Founder Effect.-- …to invade & settle the ‘New World’!

47. Four causes of evolutionary change: • Mutation: fundamental genetic shifts. • Genetic Drift: isolation  accumulation of mutations • Founder Effect: immigrant sampling bias. • Natural Selection: differential reproduction of individuals in the same population based on genetic differences among them.

48. Four causes of evolutionary change: • Mutation: fundamental genetic shifts. • Genetic Drift: isolation  accumulation of mutations • Founder Effect: immigrant sampling bias. • Natural Selection: reproductive race • These 4 interact synergistically

49. Number of Individuals Small Large Size of individuals Modes of Action • Natural selection has three modes of action: 1. Stabilizing selection 2. Directional selection 3. Diversifying selection

50. Number of Individuals Small Large Size of individuals 1. Stabilizing Selection Acts upon extremes and favors the intermediate