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? • Strong opposable thumbs • Walk upright • Intelligence

4. Origin & Evolution of Life • Chemical evolution - 1st billion yrsorganic molecules, biopolymers & chemical rxns needed for formation of first cells (Age of Earth = 4.6 billion years) • Biological evolution - first life 3.7 bya (prokaryotes)“Populations - not individuals - evolve by becoming genetically different.”

5. Animation- Chemical Evolution Stanley Miller's experiment animation

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. How Do We Know Which Organisms Lived in the Past? • Fossil record • Radiometric dating • Ice cores • DNA studies

8. Biological Evolution • Evolution= change in populations genetic makeup over time (“Populations - not individuals - evolve by becoming genetically different.”) • “Theory” of evolution= All species descended from earlier, ancestral species • Microevolution= small genetic changes in a population • Macroevolution= long-term, large scale evolutionary changes (speciation, extinction)

9. Natural Selection • Definition: Process where particular beneficial trait is reproduced in succeeding generations more than other traits • Three Conditions:1. Genetic Variability2. Trait must be inherited3. Differential Reproduction - individuals w/ trait have more offspring

10. Adaptations • Structural- coloration, mimicry, protective, gripping • Physiological - hibernate, chemical • Behavioral - ability to fly, migrate

11. Animation Change in moth population animation “Genes mutate, individuals are selected, and populations evolve.”

12. Animation Adaptive trait interaction

13. Ecological Niches and Adaptation • Ecological niche = occupation (role) • Habitats = address • Fundamental niche = no competition • Realized niche = with competition

14. Broad and Narrow Niches and Limits of Adaptation • Generalist species - broad niche • Specialist species - narrow niche, more extinction-prone under changing environmental conditions. Which is better? • Limits of adaptation- gene pool & reproductive capacity Refer to Spotlight, p. 72- cockroaches

15. 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

16. Animation Stabilizing selection animation.

17. Animation Disruptive selection animation.

18. 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

19. Cockroaches: Nature’s Ultimate Survivors Fig. 4-11, p. 72

20. 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

21. Misconceptions of Evolution • “Survival of the fittest”Fitness = reproductive success ≠ strongest • “Progress to perfection”

22. Speciation • What is speciation? • Geographic isolation • Reproduction isolationmutation & natural selection operate independently in gene pools of geographically isolated populationsoriginal populations become genetically distinct- unable to produce live, fertile offspring

23. 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. 4-8, p. 68

24. Animation Speciation on archipelago animation

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

26. Extinctions • Background extinctions= 1-5 species per million • Mass extinctions- five previous mass extinctions: 25% - 75% species go • Mass depletions- > background, but < mass • Human impacts - 6th major mass extinction???

27. 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. 4-6, p. 66

28. Mass Extinctions of the Earth’s Past

29. 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

30. Genetically Engineered Mouse Mouse on right has human growth hormone gene- grows 3x faster and 2x larger Fig. 4-B, p. 69