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Diversity and Unity of Life http://bio100.nicerweb.com/Locked/media/ch04/DB04030.jpg Welcome! • Clock Hours • Restrooms • Introductions Slides and resources can be found at http://lifescienceworkshop.wikispaces.com/ Schedule of Events -Evolution activities and discussion -Children’s misconceptions of evolution -Introduction and history of taxonomy -Introduction to cladistics -DNA and protein analysis -Unity and diversity in a stream ecosystem -New classification scheme Evolution To understand the unity and diversity of life, we must understand evolutionary principles bean evolution activity Evolution • What was the mechanism you observed in this scenario? • How does it work? Evolution • Natural Selection Principles – Overproduction • capable of producing huge numbers of offspring – Variation • those offspring have hereditary physical variations in phenotype – Competition • those offspring must compete for limited resources – Differential Reproduction • those whose phenotypic characters allow them to best exploit those limited resources will leave the most genes to succeeding populations. Natural Selection: Fitness does not mean strength More Fit Less Fit Evolution “Evolution is not survival of the strongest, or failure of the weakest. Evolution is not fair; it's not predictable; it's not kind. Nor is it cruel, or chaotic, or unfair, for that matter. It's what happens when environmental pressures change.” Michael Jon Jensen Children’s Misconceptions of Evolution Adaptation • Individuals adapt to their environment for survival – By need or desire • Traits are passed on to offspring • Lamarckian – Ex. Giraffes stretching neck to reach leaves Evolution Questions Q4: Cheetahs are able to run faster than 60 miles per hour when chasing prey. How would a biologist explain how the ability to run fast has evolved in cheetahs, assuming their ancestors could only run 20 miles per hour? Student answer: Because cheetahs needed to run fast for food, nature allowed them to develop faster running skills. KEY: Thinks that “need” for a trait by an individual would cause them to produce mutations that will solve the problem. This would require that mutations themselves be directed and therefore evolution is directed. Mutations are thought to occur randomly based on happenstance errors in replication, assaults on the DNA by agents such as viruses, chemicals, radiation. Bean Evolution • Scenario 2 – Randomly select 10 beans from your habitat Bean Evolution • How did the new population change in comparison to the original population? • What evolutionary mechanism is at work? • How does this mechanism differ from natural selection? Bean Evolution Suppose the beans sexually reproduce and attract mates by singing a high pitched call. Beans in the new habitat have evolved a lower frequency call that transmits better through the habitat. What would happen if these two populations (new and old) remained isolated for millions of generations and then were reunited? Would they be able to reproduce? Explain your reasoning. • What do you suppose happened to the two populations when they reunited? • Are they considered two different species? • Explain your reasoning How would a biologist explain how these two species diverged from a common ancestor through evolutionary mechanisms? Barred tiger salamander photo © user "Opencage" on Wikipedia Creative Commons Attribution ShareAlike 2.5 license Children’s Misconceptions of Evolution • Concept of species – Species is defined as a “kind” of organism and can vary in specificity (eg. Birds, ducks, mallard) – New species are derived from hybridization jack rabbit + antelope = jackelope – Few recognize or understand genetic basis of species(even at age 16). Taxonomy: Classifying Buttons • Organize all of your group’s buttons into a classification scheme within 5 minutes. • Be prepared to share your scheme Classifying Buttons • How does this activity demonstrate taxonomy? • What are the limitations? • What activities do you use in your classroom? Taxonomy & Classification: a history Aristotle first to classify as a “science” animalia and vegetebilia Classification included mobility by land, air, or water as well as reproduction mode. Led to Great Chain of Being. Similar to buttons? Aristotle’s Great Chain of Being Taxonomy & Classification: a history • Linnaeus touted “Father of Taxonomy” animalia and vegetebilia Developed bionomial nomenclature still used today Species, Genus, Class, Order, Phylum Taxonomy & Classification: a history • Small single-celled organisms recognized in 1866 (Haekel) Protista, Plantae, Animalia Taxonomy & Classification: a history Bacteria recognized • 2 empires (Chatton 1937) Prokaryota, Eukaryota • 4 kingdoms (Copeland 1956) Monera, Protista, Plantae, Animalia Taxonomy & Classification: a history • 5 kingdoms (Whittaker 1969) Fungi recognized separately from plants Taxonomy & Classification: a history • What do these schemes all have in common? phenetic (based on morphological observation) Morphology and Evolution Vertebrate Relatedness 1. Consider how these organisms are related. 2. Working in groups, arrange the images you were given. Organize them according to evolutionary relationships to the best of your ability. 3. Be prepared to share your ideas. Which is most closely related to Alligators? A. Lizard B. Bird C. Bat Which animal is most closely related to whales? A. Hippo B. Walrus C. Shark Which animal is most closely related to the wolverine? A. Tasmanian Devil B. Rhino C. Walrus Which animal is most closely related to rhinos? A. Walrus B. Hippo C. Zebra Which is most closely related to Alligators? A. Lizard B. Bird C. Bat Hippos are most closely related to whales. A. Hippo B. Walrus C. Shark Walruses are most closely related to wolverines. A. Tasmanian Devil B. Rhino C. Walrus Zebras are most closely related to rhinos. A. Zebra A. Walrus B. Hippo Cladograms • We can organize organisms while showing evolutionary relationships with a cladogram • Cladograms are a visual representation of heredity • Cladograms are a HYPOTHESIS and subject to change with new information Arrange the animals listed below on the cladogram. Alligator Shark Hippo Zebra Bird Whale Tasmanian Devil Rhino Cladogram with identified nodes Even Toes Shelled eggs Diapsid skull Odd Toes Hooves Live Birth Fur/Hair Synapsid skull Legs Pikaia Jaws DNA Analysis • Primate evolution • Explain how two species can evolve from a common ancestor (use the following words): variation, mutation, geographic isolation, natural selection, population • Why has DNA sequencing changed the way modern taxonomists classify organisms? Evidence for Speciation • • • • • Morphology & behavior Physiology Chromosomes Amino acid sequences Nucleic acid sequences (DNA, RNA) Unity and Diversity in a Stream Ecosystem • Find your organism’s CLOSEST relative • Determine what trait you have in common that no others in larger groups above you would have – Write down characteristic on a sticky on place in upper right hand corner of a baggie – Place these organisms in the baggie together Unity and Diversity in a Stream Ecosystem • Locate your sister group (closest related baggie) – Determine shared trait – Write on sticky Kingdom Animalia Kingdom Fungi Kingdom Plantae Unity of Life • Form a group with representatives from each of the 3 kingdoms we covered • Determine the unifying characteristics all of these organisms share together. – How does this also fit in with their diversity? Unifying Characteristics of Life • • • • • • • Homeostasis Complexity Continuity Development Acquiring/processing energy & matter (Evolution) (Role in ecosystem) Kingdom Protista? • Why didn’t we include them? The most current scheme has categorized previous Protista members into other categories New Classification Scheme Eukaryota Tree image © user "Vojtech.dostal" on Wikipedia Creative Commons Attribution ShareAlike 2.5 license What you are likely to see in textbooks But not entirely correct! Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)