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.)
QuickTime™ and a
decompressor
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 greatgrandparents. 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
A
I
E
F
J
L
C
M
N
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!
QuickTime™ and a
decompressor
are needed to see this picture.
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
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/ide
nt_help/Text_Keys/text_keys_index.htm
Mushrooms:
http://www.mushroomexpert.com/major_groups.ht
ml
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.