2. Bellwork: What are the six kingdoms of life
Bellwork: What are the six kingdoms of life? Give examples of organisms that live in each of the six kingdoms…

3. Building the tree of life
Section 18.3

4. Naming organisms isn’t the biggest challenge..
It is one thing to name an organism, but the real challenge is to group everything together in a way that reflects their evolutionary relationships
These have produced a number of major changes from Linnaeus’s original scheme

5. Kingdoms of life through time
Linnaeus divided the world into two kingdoms – Animalia and Plantae
This did not reflect the full diversity of life
Classification systems have changed dramatically over the last few hundred years to reflect advances in understanding
Relationships among organisms are still changing today as new data is gathered

6. Five kingdoms
As biology developed, researchers realized that single celled organisms are significantly different from plants and animals
Originally all micro-organisms were placed in their own kingdom – Protista
Yeast, molds and mushrooms were placed in their own kingdom – fungi
Prokaryotic bacteria placed in their own kingdom – Monera
Single celled eukaryotic organisms placed in the kingdom Protista

7. Six kingdoms Monera was divided in to two distinct groups
Eubacteria and Archabacteria
This division was on the basis of knowledge over the genetics and biochemistry of bacteria
Occurred in the 1990s

8. Three domains
Genomic analysis shows that the two main prokaryotic groups are even more different from each other, and from eukaryotes than previously thought
Domains are a new form of taxonomic category
Larger, more inclusive than a kingdom
Three distinct kingdoms
Bacteria – corresponds to Eubacteria
Archea – archaebacteria
Euakarya – (Fungi, plantae, animalia and “protista”
Protista not a true clade as no single common ancestor for all

9. What does the tree of life show?
Currently the tree of life shows hypotheses regarding evolutionary relationships among the taxa within the three domains of life
But modern evolutionary science is constantly evolving
Cladograms are not hard facts, but instead are visual representations of hypotheses

10. Domain bacteria Unicellular and prokaryotic
Cells have thick rigid walls that surround a cell membrane
Cell wall contains peptidoglycan
Ecologically diverse, ranging from free living soil organisms to deadly organisms
Some photosynthesize, others don’t
Some need oxygen, others don’t
Corresponds to kingdom Eubacteria

11. Domain Archaea Unicellular and prokaryotic
Live in extreme harsh environments
Volcanic hot springs
Brine pools
Black organic mud devoid of oxygen
Many can only survive without oxygen
Cell walls do not contain peptidoglycan
Cell membranes contain lipids often not found in other organisms
Corresponds to kingdom Archaebacteria

12. Domain Eukarya All organisms that have a nucleus
Four remaining groups of the six kingdom system
Protista, fungi, plantae and animalia
”Protista”
Do not form a valid clade
Most are unicellular, with the exception of brown algae group
Some are photosynthetic, others are heterotrophic
Fungi
Heterotrophs
Cell walls contain chitin
Feed on dead or decaying organic matter
Secrete digestive enzymes into their food source
Fungi can then absorb small molecules
Both single (yeast) and multi cellular (mushrooms)

13. Domain Eukarya cont… Plantae - Animalia Autotrophs
Cell walls contain cellulose
Carry out photosynthesis using chlorophyll
Non-motile (cannot move from place to place)
Includes green algae, mosses, ferns, cone bearing plants and flowering plants
Animalia
Multicellular and heterotrophic
No cell walls
Most can move about
A large amount of diversity