Chapter 4

1. Chapter 4 Evolution and Biodiversity

2. Evolution • Microevolution • Change over time in genetic make up of a species • Macroevolution (biological evolution) • Change over time from one organism to another • Theory of Evolution • Macroevolution • Natural selection

3. Not everything you read about Evolution is true. There is a lack of evidence to support Biological Evolution. When talking about EvolutionPlease remember

4. A belief in evolution undermines the Bible and Christianity as a whole. When talking about EvolutionPlease remember

5. Chapter 4 Natural Selection and Biodiversity

6. Why Should We Care About Biodiversity? • Biodiversity provides us with: • Natural Resources (food water, wood, energy, and medicines) • Natural Services (air and water purification, soil fertility, waste disposal, pest control) • Aesthetic pleasure

7. NATURAL SELECTION AND ADAPTATION • Natural selection involves the change in a population’s genetic makeup through successive generations. • genetic variability • Mutations: random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring.

8. I regard gene mutation as a very logical and possible occurrence but I do not think that it is, in view of the stability of the gene, as important a factor in speciation as its proponents contend. I would also like to emphasize that there are other methods of speciation such as polyploidy and hybridizationIrving W. Knobloch, Ph.D

9. "It may, in short, be stated that no mutation has ever occurred in the progress of genetic work which is fully viable and behaves as a dominant to the wild-type condition. That any have given rise to changes which could be of survival value in nature appears highly doubtful". E. B. Ford, Mendelism and Evolution, Dial Press, N. Y., 193L

10. "Mutation changes one gene at a time; simultaneous mutation of masses of genes is unknown. On the other hand, species differ from each other usually in many genes; hence, a sudden origin of a species by mutation, in one thrust, would demand a simultaneous mutation of numerous genes." Theodosius Dobzhansky, Genetics and the Origin of Species, 2nd Ed., Columbia Univ. Press, 1941

11. "Although a great many species have been studied, it must be admitted that most of them are not in a “mutating” condition. Thus if mutation is not a general phenomenon, it can have but slight significance as a means of species formation" Arthur W. Haupt,Fundamentals of Biology, McGraw Hill Book Co., N. Y., 1928.

12. Hybridization and Gene Swapping: other Ways to Exchange Genes • New species arise through hybridization. • Occurs when individuals of 2 distinct species crossbreed to produce a fertile offspring. • Some species (mostly microorganisms) can exchange genes without sexual reproduction. • Horizontal gene transfer

13. Geographic Isolation • …can lead to reproductive isolation, divergence of gene pools and speciation. Figure 4-10

14. Climate Change and Natural Selection • Changes in climate throughout the earth’s history have shifted where plants and animals can live. Figure 4-6

15. Natural Selection and Adaptation: Leaving More Offspring With Beneficial Traits • Three conditions are necessary : • Genetic variability • traits must be heritable • trait must lead to differential reproduction.

16. Natural Selection and Adaptation: Leaving More Offspring With Beneficial Traits • An adaptive trait is any heritable trait that • enables an organism to survive through natural selection and • reproduce better under prevailing environmental conditions.

17. Natural Selection: A Biological Arms Race • Interacting species can engage in a back and forth genetic contest in which each gains a temporary genetic advantage over the other. • This often happens between predators and prey species.

18. Limits on Adaptation through Natural Selection • A population’s ability to adapt to new environmental conditions through natural selection is limited by its gene pool and how fast it can reproduce. • Humans have a relatively slow generation time (decades) and output (# of young) versus some other species.

19. Common Myths about Natural Selection • Natural selection is not about survival of the fittest. • It is about the most descendants. • Organisms do not develop certain traits because they need them. • It is a completely random process. • There is no such thing as genetic perfection.

20. SPECIATION, EXTINCTION, AND BIODIVERSITY • Endemic species • Found in only one place • Vulnerable to extinction • Background extinction • Low rate of disappearance • Mass extinction • Significant rise in disappearance rate

21. Extinction: Lights Out • Extinction occurs when the population cannot adapt to changing environmental conditions. • The golden toad of Costa Rica’s Monteverde cloud forest has become extinct because of changes in climate. Figure 4-11

22. SPECIATION, EXTINCTION, AND BIODIVERSITY • Richness • Number of different species • Evenness • Relative abundance of individuals within each species

23. ECOLOGICAL NICHES AND ADAPTATION • Each species in an ecosystem has a specific role or way of life. • Fundamental niche: the full potential range of physical, chemical, and biological conditions and resources a species could theoretically use. • Realized niche: to survive and avoid competition, a species usually occupies only part of its fundamental niche.

24. Generalist and Specialist Species: Broad and Narrow Niches • Generalist species tolerate a wide range of conditions. • Specialist species can only tolerate a narrow range of conditions. Figure 4-7

25. Specialist species with a narrow niche Generalist species with a broad niche Niche separation Number of individuals Niche breadth Region of niche overlap Resource use Fig. 4-7, p. 91

26. SPOTLIGHTCockroaches: Nature’s Ultimate Survivors • 3,500 different species • Ultimate generalist • Can eat almost anything. • Can live and breed almost anywhere. • Can withstand massive radiation. Figure 4-A

27. ECOLOGICAL NICHES AND ADAPTATION • Native species • Normally live in the environment • Non native species • Accidentally introduced to the environment • Invasive or alien species • Indicator species • Provide an early warning of damage

28. ECOLOGICAL NICHES AND ADAPTATION • Keystone species • Have a large effect on types and abundance of other organisms • Have critical roles in the environment • Foundation species • Shape communities by creating & enhancing habitats

29. Specialized Feeding Niches • No two organisms can share the exact same Niche in the exact same place • Resource partitioning reduces competition and allows sharing of limited resources. Figure 4-8

30. Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds Ruddy turnstone searches under shells and pebbles for small invertebrates Herring gull is a tireless scavenger Brown pelican dives for fish, which it locates from the air Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Black skimmer seizes small fish at water surface Louisiana heron wades into water to seize small fish Piping plover feeds on insects and tiny crustaceans on sandy beaches Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Flamingo feeds on minute organisms in mud Scaup and other diving ducks feed on mollusks, crustaceans,and aquatic vegetation Knot (a sandpiper) picks up worms and small crustaceans left by receding tide (Birds not drawn to scale) Fig. 4-8, pp. 90-91

31. GENETIC ENGINEERING AND THE FUTURE OF EVOLUTION • We have used artificial selection to change the genetic characteristics of populations with similar genes through selective breeding. • We have used genetic engineering to transfer genes from one species to another. Figure 4-15

32. Genetic Engineering:Genetically Modified Organisms (GMO) • GMOsuserecombinant DNA • genes or portions of genes from different organisms. Figure 4-14

33. Phase 1 Make Modified Gene E. coli Genetically modified plasmid Insert modified plasmid into E. coli Cell Extract Plasmid Extract DNA Plasmid Gene of interest DNA Remove plasmid from DNA of E. coli Identify and remove portion of DNA with desired trait Insert extracted (step 2) into plasmid (step 3) Identify and extract gene with desired trait Grow in tissue culture to make copies Fig. 4-14, p. 95

34. Phase 2 Make Transgenic Cell A. tumefaciens (agrobacterium) Foreign DNA E. Coli Host DNA Plant cell Nucleus Transfer plasmid copies to a carrier agrobacterium Agrobacterium inserts foreign DNA into plant cell to yield transgenic cell Transfer plasmid to surface of microscopic metal particle Use gene gun to inject DNA into plant cell Fig. 4-14, p. 95

35. Phase 3 Grow Genetically Engineered Plant Transgenic cell from Phase 2 Cell division of transgenic cells Culture cells to form plantlets Transfer to soil Transgenic plants with new traits Fig. 4-14, p. 95

36. Controversy Over Genetic Engineering • There are a number of privacy, ethical, legal and environmental issues. • Should genetic engineering and development be regulated? • What are the long-term environmental consequences?

37. THE FUTURE • Biologists are learning to rebuild organisms from their cell components and to clone organisms. • Cloning has lead to high miscarriage rates, rapid aging, organ defects. • Genetic engineering can help improve human condition, but results are not always predictable. • Do not know where the new gene will be located in the DNA molecule’s structure and how that will affect the organism.

38. How Would You Vote? • Should we legalize the production of human clones if a reasonably safe technology for doing so becomes available? • a. No. Human cloning will lead to widespread human rights abuses and further overpopulation. • b. Yes. People would benefit with longer and healthier lives.