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 Caminalcules2. 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.)

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are needed to see this picture.

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.

A

B

C

D

E

F

G

H

I

J

LN

I

O

M

CaminalculesCreate 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…

SpeciesConsider:

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.

SpeciesEnsatina 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!

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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

ClassificationA 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.htmlhttp://students.ed.qut.edu.au/n2364379/mdb377/DKwombat1.htmlhttp://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

Homework

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.