13/09/11
Phylogeny:
1.7 million species
Taxonomy:
- binomial nomenclature: Genus species, or Genus species
- Carolus Linnaeus (1758)
Then: Kingdom, phylum, class, order, family, genus, species
Now: 3 domians – Bacteria, Archaea, Eukarya
Reading Phylogenies:
Root: common ancestor
Node: where branches are started, order around node has no significance
Clade: ancestor and all its decendants
Sister group: closely related pairs of taxa (generally species) with recent
common ancestors
Outgroup: closely related taxon outside of the group of interest (clade)
- At the end of a tree: species, populations, genetics - alleles
Homology: similarity due to common ancestor (eg. bat wing/human arm)
Analogy: similarity arose through different, independent events (eg. wings of
bird/insect)
(eg. bat/bird wings – bones evolved homologously, wings themselves
analagous)
= Convergent evolution
Building a phylogeny:
1. list traits/characters for taxons
2. identify order of progression of traits only looking at homologous traits
3. let computer find groupings trying to find monophyletic groupings
a. monophyletic group = ancestor + all descendents
b. paraphyletic group = missing descendent
c. polyphyletic group = more than one chain involved (things don’t
belong)
Derived trait: distinguishing trait shared by a group that was not found in their
ancestor
Origin of eukaryotes:
Eu – True
Karyon – Kernal (nucleus)
- formation of O2 preceded eukaryotes
- differ from prokaryotes: membrane bound organelles (eg. mitochondria, nucleus,
chloroplast), larger ribosomes (80s)
1. loss of cell wall
2. infolding of membrane = increased surface area
3. pinching of membrane = vacuoles with DNA/ribosomes attached form
nucleus, further infolding form endoplasmic reticulum 13/09/11
4. building of cytoskeleton
5. extension of cytoskeleton = flagellum for motion
6. development of phagocytosis
7. swallow proteobacteria mitchodria
8. swallow cyanobacteria chloroplast
Endosymbiosis: internal & living together (eg. Mitochodira)
- one cell swallows another and lives inside without being digested
- over long time living together genome of endosymbiote reduces or may
move to the nuclear genome
- Evidence: - double membrane
- reproduce with binary fission, like bacteria
- bacterial genes found in mitochondria
Diversity of Protists:
- Eukaryotes: monophyletic, are not just plants, fungi, and animals
- Protists: not a taxanomic group, used to describes eukaryotes that do not fit into
other defined taxa
Size: microscopic meters longs
Trophy: photoautotrophs and (chemo)heterotrophs
Niches: free-living, endosymbiotes, parasites
Diverse methods of locomotion
1. Unikonts: single cone
- refers to optional single flagella
- Close to root of eukaryotic tree
a) Amoebas (loboseans): unicellular
- move with pseudopods, extensions of cytoplasm
- may have a “test” = shell
- nom with phagocytosis
- some are pathenogenic = amoebic dysentery
b) Slime molds: like amoebas
- move by cytoplastic streaming
- eat by phagocytosis
- form large aggregate = slug
- create fruiting structures with spores for reproduction
c) Choanoflagellates = collar
- sister group to animals
- colonial
- use flagella to capture prey
2. Rhizaria: Typically have long thins pseudopods
a) Foraminiferans:
- Marine primarily
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