Evolution and Biodiversity

1. Evolution and Biodiversity Chapter 4

2. Key Concepts • Origins of life • Evolution and evolutionary processes • Ecological niches • Species formation • Species extinction

3. How Did We Become Such a Powerful Species So Quickly? • Adaptive traits • Human weaknesses • Opposable thumbs • Walk upright • Intelligence • Environmental impacts p. 67

4. Origins of Life • Chemical evolution • Biological evolution

5. How Do We Know Which Organisms Lived in the Past? • Fossil record • Radiometric dating • Ice cores • DNA studies Fig. 4-2, p. 65

6. Biological Evolution of Life Modern humans (Homo sapiens) appear about 2 seconds before midnight Recorded human history begins 1/4 second before midnight Origin of life (3.6–3.8 billion years ago) Fig. 4-3, p. 66

7. Biological Evolution • Evolution • Theory of evolution • Microevolution • Macroevolution

8. Microevolution • Gene pool • Genetic variability • Mutations • Mutagens • Natural selection

9. A human body contains trillions of cells, each with an identical set of genes. Genetic Materials There is a nucleus inside each human cell (except red blood cells). Each cell nucleus has an identical set of chromosomes, which are found in pairs. A specific pair of chromosomes contains one chromosome from each parent. Each chromosome contains a long DNA molecule in the form of a coiled double helix. Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks of life. The genes in each cell are coded by sequences of nucleotides in their DNA molecules. Fig. 2-5 p. 33

10. Natural Selection • Differential reproduction • Adaptation (adaptive trait) • Coevolution

11. Ecological Niches and Adaptation • Ecological niche • Habitats • Fundamental niche • Realized niche

12. Specialized Feeding Niches for Birds Herring gull is a tireless scavenger Brown pelican dives for fish, which it locates from the air Black skimmer seizes small fish at water surface Ruddy turnstone searches under shells and pebbles for small invertebrates Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds 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 Flamingo feeds on minute organisms in mud Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Piping plover feeds on insects and tiny crustaceans on sandy beaches Louisiana heron wades into water to seize small fish Fig. 4-10, p. 72

13. Broad and Narrow Niches and Limits of Adaptation • Generalist species • Specialist species • Limits of adaptation

14. Niches of Specialist and Generalist Species 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. 4-4, p. 68

15. Cockroaches: Nature’s Ultimate Survivors Fig. 4-A, p. 69

16. Insect and nectar eaters Fruit and seed eaters Greater Koa-finch Kuai Akialaoa Amakihi Kona Grosbeak Crested Honeycreeper Akiapolaau Apapane Maui Parrotbill Unknown finch ancestor Evolutionary Divergence of Honeycreepers Fig. 4-6, p. 70

17. Misconceptions of Evolution • “Survival of the fittest” • “Progress to perfection”

18. Speciation • What is speciation? • Geographic isolation • Reproduction isolation

19. Geographic Isolation can Lead to Speciation Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage. Arctic Fox Northern population Spreads northward and southward and separates Early fox population Different environmental conditions lead to different selective pressures and evolution into two different species. Gray Fox Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Southern population Fig. 4-9, p. 70

20. Factors Leading to Extinction • Plate tectonics • Climatic changes over time • Natural catastrophes • Human impacts

21. Extinctions • Background extinctions • Mass extinctions • Mass depletions • Human impacts

22. LAURASIA PANGAEA GONDWANALAND 225 million years ago 135 million years ago NORTH AMERICA EURASIA AFRICA INDIA SOUTH AMERICA MADA GASCAR AUSTRALIA ANTARTICA 65 million years ago Present “Continental Drift” (Plate Tectonics): The Breakup of Pangaea Fig. 4-8, 4-9 p. 69

23. Mass Extinctions of the Earth’s Past Fig. 4-9, p. 73

24. Changes in Biodiversity over Geologic Time 1600 Terrestrialorganisms Silurian Triassic Permian Jurassic Devonian Cambrian Ordovician 1200 Cretaceous Marineorganisms Pre-cambrain Carboniferous Number of families 800 Tertiary Quaternary 400 0 3500 545 500 440 410 355 290 250 205 145 65 1.8 0 Millions of years ago Fig. 4-10, p. 74

25. Future of Evolution • Artificial selection • Genetic engineering (gene splicing) • Genetic modified organisms (GMOs) • Cloning • Ethical concerns

26. Genetic Engineering Phase 1 Make Modified Gene E. coli Cell Genetically modified plasmid Extract plasmid Extract DNA plasmid DNA Gene of interest Identify and extract gene with desired trait Identify and remove portion of DNA with desired trait Remove plasmid from DNA of E. coli Insert extracted DNA (step 2) into plasmid (step3) Insert modified plasmid into E. coli Grow in tissue culture to make copies Fig. 4-11, p. 75

27. Genetic Engineering Phase 2 Make Transgenic Cell A. tumefaciens (agrobacterium) Foreign DNA E. coli Host DNA Nucleus Transfer plasmid copies to a carrier agrobacterium Agrobacterium inserts foreign DNA into plant cell to yield transgenic cell Transfer plasmid to surface microscopic metal particle Use gene gun to inject DNA into plant cell Fig. 4-11, p. 75

28. Genetic Engineering 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. 4-11, p. 75

29. Genetically Engineered Mouse p. 71