• Taxonomy: grouping life
according to shared traits
– not just physical traits
anymore
• Phylogeny: Evolutionary
history of an organism
• Morphology
– Defined: studying the
form and structure of
organisms
– Comparing the
morphology (traits) of
different species
shows similarities
and/or differences
Domain Eukarya
Kingdom Animalia
Phylum Chordata
Class Mammalia
Morphology Shows Non-Relationships
Also!
• Homologous structures
– Defined: body parts that have a similar structure, but
different function
– Comparing homologous structures of different organisms
can show relationships
• Conclusion: similar structures shows relationships
• Biochemical evidence
– Comparing DNA, RNA, amino acids, & proteins
– Similarities and differences can be found
• DNA mutates at known rates
– More time that has passed = more mutations
• Conclusion: Organisms with similar DNA are more closely
related
• Chromosome Evidence
– Chromosomes of different species are examined for
similarities and differences (size, shape, gene sequences)
– Ex Above: human, orangutan, gorilla, pygmy chimp
• Conclusion: related organisms have chromosome similarities
• Embryo Development
– Blastula (ball of cells)
forms early in
development
– Blastopore (small
indentation) begins to
form digestive system
– Blastopore develops into
the anus of some animals
and mouth of others
• Conclusion: Similar
development indicates
relationship
Which two organisms are more closely
related to one another?
In both humans
and starfish, the
blastopore
becomes our
anus….
In insects, the
blastopore
becomes their
mouth.
• Defined: branching diagram used to show evolutionary
relationships
– Try to group life according to similar traits
• Shows phylogeny
• Q: List 2 characteristics of a salamander.
• Q: From the diagram, which organism is most closely
related to the Chimp?
Silly example of a cladogram
Cladogram Practice
• 1) What does an amphibian & crocodile have in common?
Vertebrae, Bony skeleton, Four limbs
• 2) List the traits of a ray-finned fish.
Bony skeleton, has vertebrae
Review
1)
2)
3)
4)
What is morphology and how can it be used to help
classify organisms?
What are homologous structures and how is it used
to help classification?
How can molecular evidence like DNA and
chromosomes be used to classify life?
What does it mean if two different organisms
develop along similar pattern? Different patterns?
Examine the cladogram to answer the questions:
5) List the traits of organism 4.
6) What does organism 2 and 5 have in common?
7) Which trait separates organism 1 from the rest?