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Evolution, Biodiversity, and Community Processes La Cañada High School Dr. E 1 What types of Life exist on the Earth? 2 Types of Organisms • Prokaryotic Kingdom: singlecelled organisms containing no internal structures surrounded by membranes (therefore there is no nucleus) – Monera – bacteria and cyanobacteria 3 4 Endosymbiotic Theory Chloroplast Aerobic bacteria Ancient Prokaryotes Nuclear envelope evolving Photosynthetic bacteria Plants and plantlike protists Mitochondrion Primitive Photosynthetic Eukaryote Ancient Anaerobic Prokaryote Primitive Aerobic Eukaryote Animals, fungi, and non-plantlike protists 5 Types of Organisms • Eukaryotic Kingdoms: all organisms consisting of cells which contain membrane-bound nuclei – Protista - mostly one-celled organisms – have characteristics of all three other Eukaryote Kingdoms – Fungi - organisms which decompose stuff – Plantae - organisms which use photosynthesis to make their own food • Annuals complete life cycle in one season • Perennials live for more than one season – Animalia - organisms which must get organic compounds from food they eat - most are able to move • Invertebrates – no backbone • Vertebrates – Fish, Amphibians, Reptiles, Birds and Mammals 6 7 Naming Species 8 9 10 How did Life Originate? Or Chemical Evolution 11 EVOLUTION is Gradual Change 12 13 14 15 Evidence 16 Fossils 1600's - Danish scientist Nicholas Steno studied the relative positions of sedimentary rocks – Layering is the most obvious feature of sedimentary rocks • formed particle by particle and bed by bed, and the layers are piled one on top of the other • any sequence of layered rocks, a given bed must be older than any bed on top of it – Law of Superposition is fundamental to the interpretation of Earth history, because at any one location it indicates the relative ages of rock layers 17 and the fossils in them. 18 Half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo radioactive decay 19 Biological Evolution 20 Evolutionary Bush One life-form splits into two and those branches split (independently) to make more. Phenotypic ‘distance’ 21 Evolutionary Bush -thousands of earlier and later branches. 22 At any given moment (e.g. the ‘present’), all we see is current diversity… all extinct forms are gone (99.9%) 23 24 Charles Darwin • 1809-1882 • British naturalist • Proposed the idea of evolution by natural selection • Collected clear evidence to support his ideas 25 Darwin’s Observations 1. Most species produce more offspring than can be supported by the environment 2. Environmental resources are limited 3. Most populations are stable in size 4. Individuals vary greatly in their characteristics (phenotypes) 5. Variation is heritable (genotypes) 26 Darwin’s finches • 13 species of finches in the Galápagos Islands • Was puzzling since only 1 species of this bird on the mainland of South America, 600 miles to the east, where they had all presumably originated 27 Darwin’s finches • Differences in beaks – associated with eating different foods – adaptations to the foods available on their home islands • Darwin concluded that when the original South American finches reached the islands, they adapted to available food in different environments 28 29 What did Darwin say? • Organisms reproduce more than the environment can support – some offspring survive – some offspring don’t survive – competition • for food • for mates • for nesting spots • to get away from predators 30 Survival of the fittest • Who is the fittest? –traits fit the environment –the environment can change, so who is fit can change Peppered moth 31 Stephen Jay Gould (1941-2002) • Harvard paleontologist & evolutionary biologist – punctuated equilibrium – prolific author • popularized evolutionary thought 32 Punctuated Equilibrium • Rate of speciation is not constant – rapid bursts of change – long periods of little or no change – species undergo rapid change when they 1st bud from parent population Time 33 Gradualism Gradual divergence over long spans of time – assume that big changes occur as the accumulation of many small ones 34 Adaptive Radiation • When one species splits into many species to fill open habitats. – Darwin’s finches 35 Speciation • One species can evolve into two or more species • 2 step process – Geographical isolation – Reproductive isolation When a group becomes geographically isolated over time it will become reproductively isolated = new species formed. 36 Ammospermophilus spp Geographic isolation •When a population becomes divided by a natural barrier. •Mountains, river, body of water, landslides •Groups can’t interbreed or intermix •Become adapted to a different environment Harris’s antelope squirrel inhabits the canyon’s south rim (L). Just a few miles away on the north rim (R) lives the closely related white-tailed antelope squirrel 37 Reproductive Isolation • Differences in isolated groups become so great, they can no longer interbreed – Physical changes – Behavioral changes – Biochemical changes 38 Speciation Evolution of new species 39 Four causes of evolutionary change: 1. Mutation: fundamental origin of all genetic (DNA) change. 40 Four causes of evolutionary change: 1. Mutation: fundamental genetic shifts. 2. Genetic Drift: isolated populations accumulate different mutations over time. In a continuous population, genetic novelty can spread locally. 41 Four causes of evolutionary change: But in discontinuous populations, gene flow is blocked. 42 Four causes of evolutionary change 1. Mutation: fundamental genetic shifts. 2. Genetic Drift: isolation accumulate mutations 3. Founder Effect: sampling bias during immigration. When a new population is formed, its genetic composition depends largely on the gene frequencies within the group of first settlers. 43 Founder Effect.-- Human example: your tribe had to live near the Bering land bridge… 44 Founder Effect.-- …to invade & settle the ‘New World’! 45 46 Four causes of evolutionary change: 1. Mutation: fundamental genetic shifts. 2. Genetic Drift: isolation accumulation of mutations 3. Founder Effect: immigrant sampling bias. 4. Natural Selection: differential reproduction of individuals in the same population based on genetic differences among them. 47 Four causes of evolutionary change: 1. Mutation: fundamental genetic shifts. 2. Genetic Drift: isolation accumulation of mutations 3. Founder Effect: immigrant sampling bias. 4. Natural Selection: reproductive race These 4 interact synergistically 48 Modes of Action • Natural selection has three modes of action: 1. Stabilizing selection 2. Directional selection 3. Diversifying selection Number of Individuals Small Large Size of individuals 1. Stabilizing Selection Acts upon extremes and favors the intermediate Number of Individuals Small Large Size of individuals 2. Directional Selection Favors variants of one extreme Number of Individuals Small Large Size of individuals 3. Diversifying Selection Favors variants of opposite extremes Number of Individuals Small Large Size of individuals Evidence of Evolution 53 1. Biogeography: Geographical distribution of species 2. Fossil Record: Fossils and the order in which they appear in layers of sedimentary rock (strongest evidence) 3. Taxonomy: Classification of life forms. 57 4. Homologous Structures: Structures that are similar because of common ancestry Turtle Alligator Bird (comparative anatomy) Typical primitive fish Mammals 5. Comparative Embryology: Study of structures that appear during embryonic development 6. Molecular Biology: DNA and proteins (amino acids) Bibliography 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. Miller 11th Edition http://abandoncorporel.ca/medias/evolution.jpg http://www.ne.jp/asahi/clinic/yfc/fetus.html rob.ossifrage.net/images/ http://www.mun.ca/biology/scarr/Five_Kingdoms_Three_Domains.htm http://www.gpc.peachnet.edu/~ccarter/Millerlec5/Millerlec5.PPT http://www.dnr.state.md.us/education/horseshoecrab/lifecycle.html http://www.falcons.co.uk/mefrg/Falco/13/Species.htm http://www.sms.si.edu/irlspec/NamSpecies.htm http://www.falcons.co.uk/mefrg/Falco/13/Species.htm http://www.globalchange.umich.edu/globalchange1/current/lectures/complex_life/complex_life.html http://nsm1.nsm.iup.edu/rwinstea/oparin.shtm http://www.angelfire.com/on2/daviddarling/MillerUreyexp.htm http://exobiology.nasa.gov/ssx/biomod/origin_of_life_slideshow/origin_of_life_slideshow.html http://www.geo.cornell.edu/geology/classes/Geo104/HistoryofEarth.html http://astrobiology.arc.nasa.gov/roadmap/objectives/o2_cellular_components.html http://pubs.usgs.gov/gip/fossils/ http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli.html http://www.accessexcellence.org/AE/AEPC/WWC/1995/teach_rad.html http://biology.usgs.gov/s+t/SNT/noframe/pi179.htm http://www.npca.org/magazine/2001/march_april/nonnative_species.asp http://www.bagheera.com/inthewild/spot_spkey.htm Biology, 2003, Prentice Hall http://www.nearctica.com/ecology/habitats/island.htm http://www.valdosta.edu/~grissino/geog4900/lect_1.htm 61