Download Macroevolution

Phylogeny
• The evolutionary history of a group
• Systematics attempts to reconstruct
phylogeny, by analyzing evolutionary
relatedness.
–Uses morphological and biochemical
similarities
• Molecular Systematics uses DNA, RNA,
and proteins to infer evolutionary
relatedness.
Petrified Wood
Ammonites
Became
extinct at
the end of
the
Cretaceous
Period
“Sue” at the Field Museum in
Chicago – T. Rex – 67 million
years old
Barosaurus
Systematics
• Uses evidence from fossil record
and existing organisms to
reconstruct phylogeny
• Uses branching taxonomic
categories such that they reflect
phylogeny
• Binomial nomenclature (Genus
species) keeps identity of organism
universal – invented by Linnaeus
Modern Systematics
Taxonomy:
science
of
classifying
organisms
The Connection Between Classification and
Phylogeny
Cladistics
• Cladogram is a tree with two way
branch points
• Each branch point represents
divergence from common
ancestor
• Each branch is called a clade
• Clades are monophyletic
Monophyletic versus Paraphyletic
and Polyphyletic groups
Monophyletic – has the ancestral
species and all its descendants
Paraphyletic – has the ancestor
and some of the descendants
Polyphyletic – it lacks the
common ancestor of the species
in the group
Performing Outgroup Comparison
What is the shared primitive
characteristic?
Not all Similarities Represent
Common Ancestry
• Homologous structures indicate
shared common ancestry and are
therefore evidence of divergent
evolution
• Analogous structures are similar in
function but not in evolutionary
history and are evidence of
convergent evolution
How would you compare the fins in
these 2 organisms?
In what way are these organisms
displaying examples of convergent
evolution?
How do we differentiate between
homologous and analogous
structures?
• Compare embryonic development of
the structures in question
• Look for structures that are complex.
• The more complex the structures are
the more likely that they are
homologous.
• Compare macromolecules along with
anatomical features.
Molecular Clocks
• Proteins and mitochondrial
genomes have constant rate
of change over time
• Use these rates to determine
relative evolutionary
relatedness.
• Accuracy of these clocks is
still debated
• Recently used to date HIV
San Andreas Fault
Figure 25.1 A gallery of fossils
Australopithecus
Homo Erectus
Figure 34.39 Upright posture predates an enlarged brain in human evolution
Lucy
Laetoli
Footprints
Figure 34.40 Turkana boy
Lake
Turkana
Boy