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Evolution and Biogeograhy

Evolution and Biogeograhy. June 20, 2006 Lecturer: Meg Grantham. Adaptive Features of Organisms. Ancestral descent with modification – something arises that makes organism better equipped to survive. Natural Selection – features allow organism to survive to reproduce.

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Evolution and Biogeograhy

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  1. Evolution and Biogeograhy June 20, 2006 Lecturer: Meg Grantham

  2. Adaptive Features of Organisms • Ancestral descent with modification – something arises that makes organism better equipped to survive. • Natural Selection – features allow organism to survive to reproduce.

  3. Macroevolution: the origin of new taxonomic groups • Speciation: the origin of new species • 1- Anagenesis (phyletic evolution): accumulation of heritable changes • 2- Cladogenesis (branching evolution): budding of new species from a parent species that continues to exist (basis of biological diversity)

  4. What is a species? • Biological species concept (Mayr):a population or group of populations whose members have the potential to interbreed and produce viable, fertile offspring (genetic exchange is possible and that is genetically isolated from other populations)

  5. Speciation • Morphological species – determined by appearance • Biological species – the largest unit of a population in which gene flow is possible without artificial means

  6. Reproductive Isolation (isolation of gene pools), I • Prezygotic barriers:impede mating between species or hinder the fertilization of the ova • Habitat (snakes; water/terrestrial) • Behavioral (fireflies; mate signaling) • Temporal (salmon; seasonal mating) • Mechanical (flowers; pollination anatomy) • Gametic (frogs; egg coat receptors)

  7. Reproductive Isolation, II • Postzygotic barriers: fertilization occurs, but the hybrid zygote does not develop into a viable, fertile adult • Reduced hybrid viability (frogs; zygotes fail to develop or reach sexual maturity) • Reduced hybrid fertility (mule; horse x donkey; cannot backbreed) • Hybrid breakdown (cotton; 2nd generation hybrids are sterile)

  8. Mechanisms for the origin of reproductive isolation • Geographic Barriers • Small populations become separated • Fringe populations become segregated from smaller population • Adaptive radiations • Gene pools become segregated by adaptations to different habitats

  9. Mechanisms for the origin of reproductive isolation • Genetic Barriers • Can be gradual or sudden. • Speciation by diverengence – isolation is secondary consequence between already separated populations. • Separated populations accumulate mutations over time • Barrier produced by prezygotic or postzygotic mechanisms.

  10. Resources to investigate evolution • List of resource material from PBS. • http://www.pbs.org/wgbh/nova/link/resources.html

  11. Evidence for assessing historical population shifts • Paleontology • Phylogenetic systematics • Interplay between dispersal and continental drift • Example: S. America had distinct populations until continental collisions about 3 MYA, when Panamanian uplift connected N. and S. America.

  12. Introduction of Population Biology:Biogeographic Distributions • Cosmopolitan – everywhere • Endemic – restricted to specific regions • Disjunct – separated • Caused by • Dispersal • Vicariance – i. e. continental drift

  13. Biogeography Resources • An excellent online textbook to investigate biomes: • http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/biogeography/outline.html

  14. Biogeographical Heirarchy • Realm – Geographical Distinction • Ecoregion – Function of Climate • Biome – Function of Rainfall • Community – Function of other physical parameters • Ecotone – intermediate plant distribution; characteristics of 2 different communities

  15. Energy Transfer in the Environment • Photosynthesis 6CO2+12H2O + (Solar Energy) ---> C6H12O6+6O2+6H2O • RespirationC6H12O6+6O2---> 6CO2+6H2O+2830 kj • Simplified CO2+H2O + (Solar Energy) ---> CO2+ CH2O

  16. Biomes • Five Principal Biomes – based on unique plant and animal communities. • Forest • Savannah • Grassland • Desert • Tundra

  17. Comparison between a food chain and a food web

  18. Ecology – Trophic Levels • Primary Producers – plants • Consumers – live plants or prey • Decomposers – use energy stored in dead plants or animals

  19. Ecology – Trophic Levels • First Law of Thermodynamics - states that energy cannot be created or destroyed; it can only be changed from one form to another. • Second Law of Thermodynamics - states that whenever energy is transformed, there is a loss energy through the release of heat. This occurs when energy is transferred between trophic levels

  20. Ecology – Trophic Levels

  21. Ecology – Trophic Levels

  22. Pond Ecology Resources • Microscopic Pond Life http://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org.uk/ponddip/index.html • Virtual Pond http://www.uen.org/utahlink/pond/virtpond2.cgi • Pond Life Game http://www.nalms.org/games/pondgame/plgame.htm#002 • Create a Pond Activity http://www.geocities.com/sseagraves/createapond.htm • Center for Global Environmental Education http://cgee.hamline.edu/ http://cgee.hamline.edu/frogs/teachers/index.html

  23. Difference between lake and pond • Lakes are statified by temp and oxygen • Ponds are not for the most part • Can get an estimate by the use of a Secchi Disk.

  24. Other Resources • Find an activity- http://www.accessexcellence.org/AE/ATG/

  25. Schematic for Virtual Pond

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