1. Chapter 26.5: Horizontal Gene Transfer
By Maria Waterhouse

2. Horizontal Gene transfer
Before, vertical evolution has been thought as the normal way
Now, horizontal gene transfer has come into play
Any process by which an organism incorporates genetic material from another organism without being the offspring of that organism.

3. Genomes and proteomes Connection
Horizontal gene transfer helps species evolve
“Tree of life” becomes “web of life”
Traits transfer through conjugation, transformation, transduction
May encode proteins that provide survival advantage
Common among unicellular eukaryotes
Frequency and importance in multicellular eukaryotes are remains difficult to evaluate

4. In the Beginning Was it in the earliest stages of evolution?
Three domains of life arose from prokaryotic cell.
Bacteria
Archaea
Eukarya
Horizontal gene transfer may have been common during those stages
Could be that the universal ancestor was actually an ancestral community of cell lineages that evolved as a whole.
We wouldn’t be able to trace back to a single ancestor
Was a prominent way to foster evolutionary change

5. In the Beginning Was it in the earliest stages of evolution?
Three domains of life arose from prokaryotic cell.
Bacteria
Archaea
Eukarya
Horizontal gene transfer may have been common during those stages
Could be that the universal ancestor was actually an ancestral community of cell lineages that evolved as a whole.
We wouldn’t be able to trace back to a single ancestor
Was a prominent way to foster evolutionary change

7. Where is It Now? Eukaryotic cells
Multicellularity and sexual reproduction presented barriers to horizontal gene transfer
In those organisms, web is more treelike in structure.
Have to be transferred when the eukaryotic cell is a gamete, or is a cell that gives rise to gametes.