Chapter 12 Part Two:
Systematics: The Science of
Biological Diversity
Development of classification
• A. Until relatively recently organisms were
classified as either plants or animals and
two kingdoms were recognized.
• 1. Non-motile autotrophs were placed in the
plant kingdom
• 2. Motile heterotrophs were placed in the
animal kingdom
Many organisms didn’t fit
1. Euglena is a unicellular, motile autotroph
2. Fungi (mushrooms and molds),
traditionally classified as plants, are non-
motile heterotrophs
Technology led to better classifying
cells
1. Prokaryotes (bacteria) - lack: nuclei,
organelles, flagella, chromosomes,
multicellularity and sexuality
2. Eukaryotes (nearly all other organisms) -
have: nuclei, organelles, flagella, DNA
associated with histone proteins to form
chromatin/chromosomes, sexual
reproduction and most are multicellular
Thomas Whitaker (1969)
5 kingdom system
All Prokaryotes were placed into a single
kingdom (Monera i.e. bacteria) and the
Eukaryotes were placed into four kingdoms:
Plantae, Fungi, Animalia and Protista
(unicellular)
Three domains
A. Recent genetic and molecular
investigations have demonstrated that there
are two major groups of prokaryotes. They
differ radically in the composition of their
cell walls, membrane lipids, ribosomal
RNA, and a variety of other biochemical
features
Therefore, our text recognizes three domains
above the rank of kingdom
1. Domain Bacteria
- prokaryotes with muramic acid in cell
walls. Majority of bacteria plus
cyanobacteria ("blue green algae")
2. Domain Archaea (ancient
bacteria)
- prokaryotes that lack muramic acid in cell
walls. Many inhabit "harsh" environments.
Includes methane producers, extreme
halophiles, extreme thermophiles,
acidophiles and one group which lacks cell
walls
3. Domain Eukarya
- all eukaryotes, four kingdoms:
a) Animalia
b) Plantae
c) Fungi
d) Protista
Kingdom Animalia (Animals)
- motile, multicellular, lack plastids and cell
walls, heterotrophic via ingestion, sexual
reproduction
Kingdom Plantae (Plants)
- nonmotile, multicellular, plastids and
autotrophic via photosynthesis, cell walls
made of cellulose, adapted for life on land,
mostly sexual reproduction.
"Algae" are not included in this kingdom
Kingdom Fungi (Mushrooms and
Molds)
- nonmotile, filamentous, lack plastids, cell
walls are made of chitin, heterotrophic via
absorption of nutrients from dead
(saprophytic) or living (parasitic) matter.
Virtually all are multicellular except yeast.
Both sexual and asexual reproduction
Kingdom Protista
- lack multicellularity. Heterogeneous assemblage
of unicellular, colonial and multicellular
Eukaryotes that do not have the distinctive
characters of plants, animals or fungi.
• They have various types of reproduction from
simple cell division through sexual, and various
types of nutrition
• Includes all groups previously called protozoa as
well as all the algae except blue greens. Also
includes some organisms previously called fungi
Origin of a
Photosynthetic
eukaryotic cell
from a
heterotrophic
prokaryote
Endosymbiosis in Vorticella
Autotrophic
endosymbiotic
alga
Electron Micrograph of a
Vorticella
Fungi
• Lichen
• Fungus
• mushroom
Fungi- red blanket
lichen
Florida swamp
White coral fungus
Clavariacea
Mushrooms genus Mycena
Rainforest Peru
Earthball
Scleroderma
citrinum
Protist
• Plasmodium slime mold
• Postelsia palmiformis- “sea palm”
• Volvox- green alga
• Fauchea- red alga
• Pennate diatom
Plasmodium slime mold
Postelsia palmiformis- “sea palm”
Volvox- green alga
Fauchea- red alga
Pennate diatom
Plants
Three phyla of bryophytes
• Sphagnum (peat moss)
• Marchantia (thallose liverworts)
• Club moss
Seven phyla of vascular plants
• Wood Horsetail
• Maidenhair fern
• Dandelion Taraxacum officinale
• Strawberry cactus
• Foxtail barley
• Cymbidium orchids
• Sugar pine
Bryophytes
Sphagnum (peat moss)
Marchantia (thallose liverworts)
Club moss
Vascular plants
1. Wood Horsetail
2. Maidenhair fern
3. Dandelion Taraxacum officinale
4. Strawberry cactus
5. Foxtail barley
6. Cymbidium orchids
7. Sugar pine
The principal types of Life cycles
First eukaryotic organism probably haploid and
asexual
For plants the stage was set for diploidy
Reproduction is primarily sexual
Alternating haploid and diploid generations
Unifying character of the plantae is the presence of a
embryo during the sporophytic phase of the life
cycle-- thus “embryophyte” synonymous with
plant
• Zygotic meiosis- Fungi, some algae- two
haploid form diploid then split to form
haploid again
• Gametic meiosis
• Sporic meiosis
Give rise to
gametes by
differentiation
Divide by mitosis
4
•Zygotic meiosis
•Gametic meiosis- by “accident” some of
these cells undergo mitosis with
a “delay”meiosis
•Sporic meiosis
4 haploid
Green/brown
•Zygotic meiosis
•Gametic meiosis
•Sporic meiosis- results in the production
Of spores, not gametes, spores undergo mitosis
And produce multicellular haploid organisms these
haploid organisms can then produce gametes that in
turn fuse to form Zygote
Spores Don’t act as gametes and
Undergo Mitotic division
4 haploid produce
Differentiate to form
Sporophyte