Evolution

1. Evolution

2. Chemical Evolution • Dust cloud condenses to form molten Earth (4.7 bya) • Earth cools sufficiently to form crust (3.8 bya) • a) volcanic eruptions, meteorites allow water vapor to escape inner earth • b) vapor cools ---> rain ---> dissolved minerals ---> oceans, mud ponds

3. Miller’s primordial soup • CO2, N2, H2O, CH4, etc exposed to lightning and UV form organic molecules, including amino acids

4. Biological Evolution • 1st prokaryotic cells (bacteria) (3.5 bya) • a) no ozone so lived 10m below sea surface • 1st photosynthesis: cyanobacteria (2.3-2.5 bya) • (Gaia hypothesis) • O2 levels increase (2 bya)

5. Biological Evolution • O2 at current levels (1.5 bya) • 1st eukaryotic cells (1.2 bya) • h) O3 formed and UV levels were low enough for life (plants) on land (400-500 mya)

6. Natural Selection • mutations (alleles) ---> envircond change + • adaptation (adaptive trait: must be heritable)---> differential reproduction = natural selection

7. 1) environmental cond. change---> adaption, migration, extinction 2) artificial selection ( selective breeding)

8. Three types of natural selection 1) directional natural selection low frequency alleles --> high frequency (resistance to pesticides) 2) stabilizing natural selection high freq alleles dominate (no envir change) 3) diversifying natural selection low freq alleles at either end become favorable (new food supply)

9. Lamark’s Theory • How did giraffes get long necks?

10. Coevolution (pos feedback loop) • change in one population makes a certain trait more favorable in another species • (e.g owls and mice: Drought--> loss of food for mice--> mouse pop declines. Certain owls become better hunters, then certain mice survive (faster, better hider). As population of mice decreases, owls must be faster, have better eyesight to survive. (adaptation)

11. Niche vs habitat • 1) fundamental niche vs realized niche -niche overlap leads to competition • 2) generalist vs specialist species (cockroaches vs giant panda, spotted owl) • 3) convergent evolution -similar niches lead to similar traits in otherwise unrelated species that are geographically isolated

12. 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

13. Plate Tectonics • 225 mya: Pangaea (N.A. at equator) • 180 mya: continents separate • 65 mya: Indian plate seperate

14. 225 million years ago 225 million years ago 135 million years ago 65 million years ago Present Fig. 4-5, p. 88

15. Speciation • Geographic isolation • Plate movement (Madagascar) • Long migration (Galapagos, Hawaii)

16. Artic vs Gray • Adapted to cold through heavier fur,short ears, short legs,short nose. White fur matches snow for camouflage. • Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat.

17. Speciation 2. reproductive isolation a. mutations and natural selection occur independently in 2 populations that are geographically isolated b. eventually 2 pop cannot reproduce - different breeding times, etc

18. Arctic Fox Northern population Different environmental conditions lead to different selective pressures and evolution into two different species. Early fox Population Spreads northward and southward and separates Southern Population Gray Fox Fig. 4-10, p. 92

19. Insect and nectar eaters Fruit and seed eaters Greater Koa-finch Kuai Akialaoa Amakihi Kona Grosbeak Crested Honeycreeper Akiapolaau Maui Parrotbill Apapane Unknown finch ancestor Fig. 4-9, p. 91

20. Macroevolution • gradualist model vs punctuated equilibrium hypothesis

21. Extinction • Due to changing environmental conditions • Can be caused by 1) plate movement 2) gradual climate change 3) abrupt, catastrophic climate change

22. Extinction • All species become extinct (4-22 million years); mammals (2-5 million years) • Endemic species are vulnerable to extinction (Madagascar) • Mass extinction vs background extinction

23. Species Diversity • Species richness (nunber of species) • Species Evenness (pop of each species

24. Theory of Island Biogeography • Big vs Small • Close vs far from mainland • Application to national parks • With road vs roadless

25. Species Roles Generalist vs Specialist • Advantage? • Native • Nonnative (alien, invasive, exotic) a) no predators? b) killer bees 4. Indicator species

26. 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

27. Species Roles • Keystone species • Foundation Species

28. Disappearing Amphibians Vulnerable because: • No shell on eggs • Permeable skin

29. Disappearing Amphibians Human related Causes? • Pesticides on insects • Habitat loss • Pollution • Increase in UV • Climate change • Overharvesting

30. Disappearing Amphibians • Downside • Indicator species • Niche: eat insects, place in food chain • Pharmaceutical possibilities