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Lecture 4

BIOL 111 Lecture Notes - Lecture 4: Binomial Nomenclature, Homo Sapiens, Endoplasmic Reticulum


Department
Biology (Sci)
Course Code
BIOL 111
Professor
Irene Gregory- Eaves
Lecture
4

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Biology Lecture 4 Phylogeny, origin and diversity of
eukaryotes 9/13/2011 6:43:00 AM
Pre-lecture vocabulary
Taxon/taxa
Taxonomy
Phylogeny
Mitosis
Meiosis
Haploid
Diploid
Taxonomy
The classification of life forms
Two key ideas:
1. binomial nomenclature (two names)
- genus species (a group of closely related species)
- Example: homo sapiens
- when writing we use italics or underlined
2. Hierarchy Kingdom, phylum, class, order, family, genus, species
“Kings Play Chess On Finely Grained Sand”
- Example of hierarchy of Humans:
Animalia, Chordata, Mammalia, Primate, Hominidae, Homo, sapiens
Today we use a 3 domain system: Bacteria, Archaea, Eukarya
How to read a phylogenetic tree (Vocabulary)

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

The position of the branches could be rotated around the node and won’t change the
meaning of the tree
Analogy vs. homology
Homology: similarity due to common ancestor
- Example: Bat wing and human armsimilar because the bone structure evolved in a common
ancestor
Analogy: similarity due to common environment (convergent evolution)
- Example: Bird wing and insect wingsimilar because each evolved wings from different
wingless ancestors to solve the problem of flight
Bird wing and bat wing however are both: the bones are homologous and the wings are
analogous
How to build a phylogeny
Step 1: get a list of observable “traits” or “characters” for each taxon (genetic data)
Step 2 (optional): identify order of progression on traits (jaw came after no jaw) and need to
be looking at homologous traits
Step 3: let a computer find groupings, trying to find monophyletic groupingsthe most
parsimonious tree (simplest)
Taxon vs. Clade: FIND DEFINITIONS
A monophyletic group: ancestor and all its descendants

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Derived Trait: trait shared by the group but not found in their ancestor
This means that they evolved to get that trait
Taxonomy and Phylogeny summary:
As we learn more, ideas about taxonomy have changed, but still use binomial nomenclature
system
Phylogenies are based on evolutionary history and strive to form monophyletic groups
Similarities in morphology are not necessarily due to a common ancestornot always
homologous
Still in a state of flux
Which event preceded the origin of eukaryotes? The formation of oxygen availability in the
atmosphere
18
Phylogeny, origin and
diversity of eukaryotes
lecture outline
1. Taxonomy & phylogeny
2. Origin of eukaryotes
3. Diversity of “protists”
35
Which event preceded
the origin of eukaryotes?
43
%
43
%
A. origin of
14%
multicellularity
B. formation of O2
atmosphere
C. A & B
36
origin of mult...
formation of O...
A & B
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