1. Chapter 4 Evolution and Biodiversity

2. Chapter Overview Questions  How do scientists account for the development of life on earth?  What is biological evolution by natural selection, and how can it account for the current diversity of organisms on the earth?  How can geologic processes, climate change and catastrophes affect biological evolution?  What is an ecological niche, and how does it help a population adapt to changing the environmental conditions?

3. Chapter Overview Questions (cont’d)  How do extinction of species and formation of new species affect biodiversity?  What is the future of evolution, and what role should humans play in this future?  How did we become such a powerful species in a short time?

4. LIFE!!!  1 billion years of chemical change to form the first cells, followed by about 3.7 billion years of biological change.  Biological evolution – a “life-changing” experience!  Darwin and Wallace – natural selection Figure 4-2

5. Fig. 4-3, p. 84 Modern humans (Homo sapiens sapiens) appear about 2 seconds before midnight Recorded human history begins about 1/4 second before midnight Origin of life (3.6-3.8 billion years ago) Age of mammals Age of reptiles Insects and amphibians invade the land First fossil record of animals Plants begin invading land Evolution and expansion of life

6. Past life  Our knowledge about past life comes from fossils, chemical analysis, cores drilled out of buried ice, and DNA analysis.  Fossil record – what species lived when?  Very incomplete Figure 4-4

7. Mutations!  Biological evolution by natural selection involves the change in a population’s genetic makeup through successive generations. genetic variability – happens through… genetic variability – happens through… Mutations: random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring. Mutations: random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring. Happen through mutagens or random mistakes Happen through mutagens or random mistakes  Populations evolve by becoming genetically different, not individuals

9. Natural Selection and Adaptation  Three conditions are necessary for biological evolution: Genetic variability, traits must be heritable, trait must lead to differential reproduction. Genetic variability, traits must be heritable, trait must lead to differential reproduction.  An adaptive trait is any heritable trait that enables an organism to survive through natural selection and reproduce better under prevailing environmental conditions.  When things get bad, an organism can: Adapt Adapt Migrate Migrate Go extinct Go extinct  Simplified process: mutations  natural selection  populations evolve

10. Coevolution: 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. This often happens between predators and prey species. http://www.youtube.com/watch?v=CCYvPUChnIo http://www.youtube.com/watch?v=CCYvPUChnIo

11. Hybridization and Gene Swapping  New species can arise through hybridization. Occurs when individuals to two distinct species crossbreed to produce a fertile offspring. Occurs when individuals to two distinct species crossbreed to produce a fertile offspring. Killer bees! (Africanized bees = European honeybee + African honeybee) Killer bees! (Africanized bees = European honeybee + African honeybee)  Some species (mostly microorganisms) can exchange genes without sexual reproduction. Horizontal gene transfer Horizontal gene transfer Can happen with infection, interaction, or consumption Can happen with infection, interaction, or consumption

12. 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.  We also do not have unique beneficial mutations arise often.  Viruses (though not “living”) adapt quickly because of their quick and numerous “reproduction” and quick mutation rate (in some viruses)

13.  Evolution through natural selection is about the most descendants. Organisms do not develop certain traits because they need/want them. Organisms do not develop certain traits because they need/want them. There is no such thing as genetic perfection. There is no such thing as genetic perfection. Fittest ≠ Strongest Fittest ≠ Strongest

14. Plate tectonics  The movement of solid (tectonic) plates making up the earth’s surface, volcanic eruptions, and earthquakes can wipe out existing species and help form new ones. The locations of continents and oceanic basins influence climate. The locations of continents and oceanic basins influence climate. The movement of continents have allowed species to move. The movement of continents have allowed species to move. Volcanic eruptions and earthquakes disrupt environment Volcanic eruptions and earthquakes disrupt environment

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

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

17. ASTEROIDS!  Asteroids and meteorites hitting the earth and upheavals of the earth from geologic processes have wiped out large numbers of species and created evolutionary opportunities by natural selection of new species.  The four basic principles of sustainability have helped earth to adapt!

18. Niches  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. 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. Realized niche: to survive and avoid competition, a species usually occupies only part of its fundamental niche.

19. 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.  Specialists have less competition, but generalists survive better under rapidly changing environmental conditions.  Natural selection can lead to an increase in specialized species.

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

21. Evolutionary Divergence  Each species has a beak specialized to take advantage of certain types of food resource. Figure 4-9

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

23. SPOTLIGHT Cockroaches: Nature’s Ultimate Survivors  350 million years old  3,500 different species  Ultimate generalist Can eat almost anything. Can eat almost anything. Can live and breed almost anywhere. Can live and breed almost anywhere. Can withstand massive radiation. Can withstand massive radiation. Figure 4-A

24. Speciation  Speciation: A new species can arise when member of a population become isolated for a long period of time.  Genetic makeup changes, preventing them from producing fertile offspring with the original population if reunited.  Geographic isolation: different groups of same population of species becoming geographically isolated for a long time.  Reproductive isolation: mutation and change by natural selection occurs independently in each isolated population.  Can take different amounts of time depending on the species

25. Fig. 4-10, p. 92 Different environmental conditions lead to different selective pressures and evolution into two different species. Southern Population Northern population Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Adapted to cold through heavier fur,short ears, short legs,short nose. White fur matches snow for camouflage. Gray Fox Arctic Fox Spreads northward and southward and separates Early fox Population

26. Extinction  Extinction occurs when the population cannot adapt to changing environmental conditions.  Endemic species: only lives in one area  The golden toad of Costa Rica’s Monteverde cloud forest has become extinct because of changes in climate. Figure 4-11

27. Fig. 4-12, p. 93 Tertiary Bar width represents relative number of living species EraPeriod Species and families experiencing mass extinction Millions of years ago Ordovician: 50% of animal families, including many trilobites. Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites. 500 345 Cambrian Ordovician Silurian Devonian Extinction Paleozoic Mesozoic Cenozoic Triassic: 35% of animal families, including many reptiles and marine mollusks. Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites. Carboniferous Permian Current extinction crisis caused by human activities. Many species are expected to become extinct within the next 50–100 years. Cretaceous: up to 80% of ruling reptiles (dinosaurs); many marine species including many foraminiferans and mollusks. Extinction Triassic Jurassic Cretaceous 250 180 65 Extinction QuaternaryToday

28. More extinction!  Background extinction: a certain number of species disappear at a low rate as local environmental conditions change. Scientists estimate average background extinction is 1-5 species per million species. Scientists estimate average background extinction is 1-5 species per million species.  Mass extinction: significant rise in extinction rates above background level. Usually catastrophic and widespread, with 25-70% of existing species wiped out in up to 5 million years. Usually catastrophic and widespread, with 25-70% of existing species wiped out in up to 5 million years. We have had 5 mass extinctions We have had 5 mass extinctions  Mass depletion: somewhere in between.

29. Effects of Humans on Biodiversity  The scientific consensus is that human activities are decreasing the earth’s biodiversity. Figure 4-13

30. 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

31. Genetic Engineering: Genetically Modified Organisms (GMO) AKA Transgenic Organisms  GMOs use recombinant DNA genes or portions of genes from different organisms. genes or portions of genes from different organisms. Figure 4-14

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

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

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

35. THE FUTURE OF EVOLUTION  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. 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. Do not know where the new gene will be located in the DNA molecule’s structure and how that will affect the organism.

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. Case Study: How Did We Become Such a Powerful Species so Quickly?  We lack: strength, speed, agility. strength, speed, agility. weapons (claws, fangs), protection (shell). weapons (claws, fangs), protection (shell). poor hearing and vision. poor hearing and vision.  We have thrived as a species because of our: opposable thumbs, ability to walk upright, complex brains (problem solving). opposable thumbs, ability to walk upright, complex brains (problem solving).