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Chapter 26: Phylogeny
and the Tree of Life
CONT ’D
MONDAY, 9/22/2014
Warm-up
Which came first, the chicken or the egg?
Explain how you would use phylogenetics to
solve this puzzle.
Warm-up
Which came
first, the chicken
or the egg?
Explain how you
would use
phylogenetics to
solve this puzzle.
Hanken. 1998. Eggs first. Trends in Ecology and Evolution. 4: 58.
Homework
1. MasteringBiology Questions on Chapter 26: Due Wednesday, 10:45
AM
2. Short Essay: Read this short article and summarize. Instructions
posted on wiki. Due Friday, 9/26
http://evolution.berkeley.edu/evolibrary/news/080301_elephantshre
w
3. Bring your textbooks, or access to your online textbooks,
tomorrow!!!!!!!
Interactive activity with phylogenetics (useful as review):
http://www.hhmi.org/biointeractive/creating-phylogenetic-trees-dna-sequences
Homework
http://www.hhmi.org/biointeractive/creating-phylogenetic-trees-dna-sequences
http://evolution.berkeley.edu/evolibrary/news/080301_elephantshrew
Phylogenetics
Phylogenetics is the study of evolutionary relatedness among various
groups of organisms, which is discovered through molecular sequencing
and morphological data.
Tucuxi
Cladogram
Diagram that
shows
relationships
among organisms
Analogous vs. homologous structures
*Convergent evolution produces
analogous structures
◦ Convergent evolution: evolution of similar
features in independent evolutionary
lineages
◦ Homoplases (analgous features) are when
different lineages have the same solutions
to ecological problems
*Homologous structures are a
result of common ancestry
We can also use morphological differences to
deconstruct evolutionary relationships
Derived
Ancestral
Ancestral vs. derived features
Ancestral characters: a character that originated
in the ancestor of the taxon
Derived characters: character that is an
evolutionary novelty to a particular clade
◦synapomorphies: derived characters shared with
taxon (ex. Hair is a synapomorphy of mammals)
Molecular clock
Method for estimating time required for a given
amount of evolutionary change, based on the
observation that some regions of genomes (genetic
material of an organism/virus) evolve at constant
rates
The cytochrome c gene reflects
a pattern of differences in DNA
sequences due to mutations.
The changes accumulate at a
constant rate, and can be used
as a molecular clock to help
date evolutionary divergences.
Figure 26.3
Species:
Panthera pardus
Genus:
Panthera
Family:
Felidae
Order:
Carnivora
Class:
Mammalia
Phylum:
Chordata
Domain:
Bacteria
Kingdom:
Animalia
Domain:
Eukarya
Domain:
Archaea