Download Cladogram Lab

Name: ______________________________________________ Date: _____________________ Period: _____
Make a Cladogram Lab
Background: Cladistics is the study of evolutionary classification. A cladogram, or a branching tree, shows
evolutionary relationships among organisms. Comparative morphology (physical traits) investigates
characteristics to determine which organisms share a recent common ancestor. A cladogram will begin by
grouping organisms based on a characteristics displayed by ALL the members of the group. Subsequently, the
larger group will contain increasingly smaller groups that share the traits of the groups before them. However,
they also exhibit distinct changes as the new species evolve. Further, molecular evidence from genes which
rarely mutate can provide molecular clocks that tell us how long ago organisms diverged, unlocking the secrets
of organisms that may have similar morphology (physical traits) but do not share a recent common ancestor.
Pre-Lab Questions:
Fig. 1 Sample Cladogram
1. Which organisms in the cladogram in figure 1 have fur and mammary glands?
2. Which organisms in the cladogram in figure 1 have jaws?
3. Based on the cladogram in figure 1, which shared a common ancestor most recently – a mouse and a
lizard or a mouse and a perch?
4. Which two organisms would you expect to have a closer matching DNA sequence for a gene that
doesn’t matter in terms of natural selection – Hagfish and Pigeon or Hagfish and Salamander?
5. Using the species listed in Table 1 and Table 2, hypothesize and list the species in order of evolutionary
relationships beginning with Amoeba.
Procedure:
Part I - Morphological (physical) Evidence: Using any means of research, determine the morphological
characteristics of the organisms in table 1. For every characteristic the organism possesses, put a check in that
box.
Table 1: Comparative Morphology Data
Organism Multicellular Segmented body
Amoeba
Sponge
Earthworm
Shark
Lizard
Dolphin
Cat
Jaws
Has bone
Limbs
Hair
Part II: Molecular (DNA) Evidence: Cytochrome c is a protein located in the mitochondria of cells involved
with cellular respiration. Compare each organism’s Cytochrome c DNA sequences with the common ancestor
cell and each other. Circle or highlight the differences (mutations) present in the cytochrome c DNA sequences
from ancestor cell. If multiple organisms have the same number of mutations from the common ancestor,
differentiate them by looking at the nucleotide differences between each other.
Table 2: Cytochrome c DNA Sequence Data
Organism
DNA Sequence
Ancestor Cell A T T A G C G A C C A G T A T A T C C T A C A A T C C G T C T A C T T C A T T
ATTAGCGACCAGTTTATCCTACAATCCCGTCTACTTCAT
Amoeba
ATTATCGACCAGTTTATCCTACATTCCCGTCTACTTCGT
Sponge
CTTATCGACCCGTTTATCCTACATTCCCGTCTACTTCGT
Earthworm
CTTATCCCCCCGTTTATCCTACTTTCCCGTCTACTTCGT
Shark
CTAATCCCCCCGTTTATCCTACTTTCCCGTCTACTTCGT
Lizard
CTAATCCCCCCGTTTATCCTACTTTCCCATGTAGTAAGT
Dolphin
TTAATCCCCCCGTTTATCCTACTTTCCCATCTACTAAGT
Cat
# mutations
0
Part III – Analyze the data in both tables. Create a cladogram based on the morphological (physical) and
molecular (DNA) evidence.
Post Lab Discussion Questions:
1. Does your cladogram support or reject your hypothesis?
2. If your two pieces of evidence don’t support each other, what more should you do to determine the correct
relationships?
3. Which type of evidence for evolution is most accurate in determining evolutionary relationships –
morphology or molecular and why?
4. Cladograms show divergent evolution (species becoming more and more different), but they can also show
convergent evolution. Research the term, convergent evolution. Define the term and identify the two
organisms in the cladogram that show convergent evolution. Are they closely related?
5. Research and provide another example of convergent evolution and explain with details.