Download cladograms molecular

Phylogenetic Trees/Cladistics
Sticker:
1. If two species share many similar structures, this
indicates that they are more (closely/distantly)
related and have a more (recent/distant) last
common ancestor.
2. A _________ structure, like the appendix, has lost
most or all of its original function over evolutionary
time.
3. If two species share a homologous skull ridge, this
indicates what about shape of their last common
ancestor’s skull?
Homework
Recap
 Variation + Inheritance + Overreproduction + Limited
Resources = Reproductive advantage = more babies = natural
selection. Change in allele frequencies over time = evolution.
 Can increase OR decrease biodiversity, complexity
 Cumulative effects of natural selection over many generations
+ barrier that limits gene flow -> Speciation
 More recent last common ancestor = more related = more
similar
 Scientists can determine common ancestry by comparing
morphology. They can use this information to make a
cladogram, or diagram of common ancestry.
 Identical structures
 Homologous structures
 Adult homologous structures
 Adult vestigial structures
 Embryo structures
Objectives
 Learn how to make and read a
phylogenetic tree (or cladogram)
 Learn how to put together cladograms
and anatomy (homologous structures,
vestigial structures, etc.) to determine
descent
“What Did T. Rex Taste Like?”
 You’ll proceed through an online tutorial
that will teach you what a phylogenetic
tree is, how to read one, and how to
make one.
 Work two per laptop
 Remember, this is how you’re going to
learn this concept, I’m not going to stand
up and give notes on it. Don’t click “Next”
if you don’t understand what the screen is
teaching you.
 Concepts from before to remember:
Instructions
 Go to
http://www.ucmp.berkeley.edu/education/exp
lorations/tours/Trex/navigation.html
 Click “Go To Beginning”
 Go through each of the folders in order.
 Complete the handout, take any notes you’d
care to on the main ideas.
 THINK AND UNDERSTAND! ASK QUESTIONS
WHEN CONFUSED!
Cladograms
 (Not for a sticker, required) There is a cladogram on
the board. Please write your answers in your
notebook:
 Which number marks the last common ancestor for:
 1. A and D?
 2. C and H?
 3. H and G?
 Which symbol marks the point where a skull ridge
feature arose, if these species have a skull ridge:
 4. Only I?
 5. B, E, C, H, G, I?
 6. If I and G both have a feature, does that mean
that H must have it too?
 What are
the
essential
cladogram
ideas?
 Lineage
 Last
Common
Ancestor
 Why
Related
= Similar
QuickTime™ and a
decompressor
are needed to see this picture.
Cladograms
Molecular Similarities
 We can research ancestry by analyzing
molecular similarities just like we could
by analyzing anatomical similarities.
 Similar molecular (DNA, RNA, and
amino acid) sequences = more recent
common ancestor = more closely
related
Molecular Similarities
 Demonstration
 Whiteboards
Molecular Similarities
QuickTime™ and a
decompressor
are needed to see this picture.
 Molecular evidence is extremely
powerful in studying evolution.
 In modern-day science, we study
molecular similarities more often and with
more power than we study fossils!
 Many scientists argue that this is now the
most powerful tool in our research arsenal.
QuickTime™ and a
decompressor
are needed to see this picture.
Whale Evolution
 Online activity
 First, use a highlighter to make a
cladogram the “old fashioned way” from
amino acid sequences
 Then, you will use the National Center for
Biotechnology’s real software and protein
sequences to analyze the ancestry of
whales