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Classification. Welcome back! Pick up the handout. With your partner, please take until 7:35 to generate a summary of the main ideas from last week, and one reasonable multiple choice test question about one of those ideas. Project. Taxonomy Poster Project due next Tuesday. Taxonomic Ranks.
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Classification • Welcome back! • Pick up the handout. • With your partner, please take until 7:35 to generate a summary of the main ideas from last week, and one reasonable multiple choice test question about one of those ideas.
Project • Taxonomy Poster Project due next Tuesday.
Taxonomic Ranks • Each pair, come up with at least one mnemonic device for the ranks (DKPCOFGS). We will vote on the best one, and that pair gets a sticker.
Back into lab group, get materials. If you didn’t read the lab packet, take a moment to skim it now. • 1. Lines on paper and cut out Caminalcules • 2. Arrange the living Caminalcules on Line 0 (present day), with the most related ones next to each other. • 3. Start placing the fossil Caminalcules on their lines, like you did with the modern day ones. (Some people like starting with 1 million years ago and working back, some like starting 19 million years ago and working forward). • 4. Use similarities to figure out out who descended from who! Draw lines connecting ancestor with descendent. (Hint: no one Caminalcule has more than 2 descendents on the next line up.)
This is what your “family tree” will look something like (though yours will have year lines, and pictures instead of names.)
Caminalcules • With your lab group, come up with a succinct explanation: What is the relationship between relatedness, last common ancestor, and taxonomic rank?
Caminalcules • The last common ancestor for any two kinds of living thing = the most recent living thing from which they are both descended. • You and your siblings have your parents as your LCA. You and your cousins have your grandparents as your LCA. You and your second cousins have your great-grandparents. Etc.
Caminalcules • The more recent the LCA for two organisms, the more closely related they are. • AND • The more closely related they are, the more taxa they share. • THEREFORE, the more recent the LCA…
Caminalcules • The more recent the LCA for two organisms, the more closely related they are. • AND • The more closely related they are, the more taxa they share. • THEREFORE, the more recent the LCA… the more taxa they share.
D H B I I A E M F J N L C G O
Caminalcules • Create a classification scheme for your Caminalcules. • Each point on the timeline is a species. Give them good hardy Latin names. • Which species are probably in the same genus? Give those genera a name; also complete the full scientific name for each species. • Which genera are probably in the same family? Label and name the family. • Which families are probably in the same order? • Which orders are probably in the same class? • (All these Caminalcules are in the imaginary phylum Caminacula, and real kingdom Animalia and domain Eukarya.)
Species • With your partner: What are the eight major taxonomic ranks, from the one with the most recent common ancestors to the one with the most distant common ancestors?
Homework • Reminder: Project
Species • What is a species?
Species • The species is the most basic unit of the taxonomic system. How scientists define species gets tricky…
Species • Consider: • Dogs (Canis familiaris) and wolves (Canis lupus) can interbreed to create viable offspring. Why are they different species? • The Lineatriton Salamander in Mexico looks identical in every way to another salamander, Oedepina, that lives several hundred miles away. Not even a herpetologist can tell them apart by looking at them. They are named as different species. • The California slender salamander (Batrachoseps attenuatus) was reclassified in the mid 1990s into more than 20 different species, after being called just one species for hundreds of years.
Species • Ensatina escholtzii, a salamander in California and Oregon, has populations that don’t look alike, and can’t breed with each other. But others can and do!
Species Concepts • There are actually many different ways that species can be defined. Different scientists have a preference for different methods, but usually, something has to be justified by several of them in order to be classified and accepted by the scientific community.
Species Concepts • Get together with another table and read through the different species concepts. Be sure that you have a handle on what each one means. • Then, try to imagine scenarios in which some living thing or things meets one or more definitions, but not others. Maybe you would consider them to be a single species, maybe not. Write their stories to be presented to another group to consider. • You’ll consider the scenarios presented by others, and must discuss and come to an evidence-based consensus as to whether or not you’d call them the same or different species.
Species • How about this one: • Now that we’ve tossed the idea of a species around a bit, how many of them do you think we have?
Species • How about this one: • Now that we’ve tossed the idea of a species around a bit, how many of them do you think we have? • If you were scientists, operating under realistic modern constraints (time, money, technology), how would you figure out the answer to that question? With your group, come up with some ideas.
Species • Why might it be important to have that measure of our biodiversity, i.e. to know how many species there are? (Besides curiosity.)
Species • Read the article (homework).
Classification • A frequently-used tool in classifying an organism that is not new to science is the use of a dichotomous key. Dichotomous keys are written devices that help you determine the classification of a living through through observation, and a series of branching pathways. • Anybody ever read “Choose Your Own Adventure” books? • http://students.ed.qut.edu.au/n2364379/mdb377/DichotomousKeyOutline.html • http://students.ed.qut.edu.au/n2364379/mdb377/DKwombat1.html • http://students.ed.qut.edu.au/n2364379/mdb377/DKredbelly1.html
Dichotomous Keys • Handout: Practice with Dichotomous Keys
Dichotomous Keys • More practice: • With your table partner, bring your notebooks and go outside. • Find three organisms that you cannot identify off the tops of your heads. • Write down a thorough description of them. If there’s a dead bit that you can take without disturbing the organism (like a dead leaf), you may. • Your assignment will be to use the internet to find a dichotomous key for our area, OR use a field guide built around a dichotomous key, identify your three organisms (common name and most specific taxon).
Useful Keys • Trees: • http://www.arborday.org/trees/whattree/WhatTree.cfm?ItemID=E6A • Arthropods: • http://www.amnh.org/learn/biodiversity_counts/ident_help/Text_Keys/text_keys_index.htm • Mushrooms: • http://www.mushroomexpert.com/major_groups.html • Lichens?
Dichotomous Keys • Echinoderm Example: Practice making a dichotomous key.
Dichotomous Keys • Split into 3 groups. • Each group gets some organisms, and . • Make a dichotomous key for those organisms. • You will then leave your key with your organisms, names concealed. Another group will step in; they should be able to correctly identify every organism using your key.