diversity and unity of life
TRANSCRIPT
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• 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.
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
• 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
Barred tiger salamander photo © user "Opencage" on Wikipedia -Creative Commons Attribution ShareAlike 2.5 license
How would a biologist explain how these two species diverged from a common ancestor
through evolutionary mechanisms?
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 hybridizationjack 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?
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 EvolutionVertebrate 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.
Walruses are most closely related to wolverines.
A. Tasmanian Devil
B. Rhino
C. Walrus
Placental c
arnivores
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.
AlligatorSharkHippoZebraBirdWhaleTasmanian DevilRhino
Alli
gato
r
Shar
k
Wha
le
Hip
po
Zeb
ra
Rhi
no
Bird
T. D
evil
Pikaia Jaws
Legs
Live BirthFur/HairSynapsid skull
Hooves
EvenToes
OddToes
Shelled eggsDiapsid skull
Cladogram with identified nodes
• Explain how two species can evolve from a common ancestor (use the following words):variation, mutation, geographic isolation, natural selection, population
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
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
Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)
What you are likely to see in textbooks
But not entirely correct!