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

Electron Micrograph of a Vorticella

Autotrophic endosymbiotic alga

Fungi

• Lichen

• Fungus

• mushroom

Fungi- red blanket lichenFlorida swamp

White coral fungusClavariacea

Mushrooms genus MycenaRainforest Peru

EarthballScleroderma 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

PlantsThree phyla of bryophytes• Sphagnum (peat moss)• Marchantia (thallose liverworts)• Club mossSeven phyla of vascular plants • Wood Horsetail• Maidenhair fern• Dandelion Taraxacum officinale• Strawberry cactus• Foxtail barley• Cymbidium orchids• Sugar pine

Sphagnum (peat moss)

Bryophytes

Marchantia (thallose liverworts)

Club moss

1. Wood Horsetail

Vascular plants

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 diploidyReproduction is primarily sexual Alternating haploid and diploid generationsUnifying 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

4

Divide by mitosis

Give rise to gametes by differentiation

•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 productionOf 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

4 haploid

Spores Don’t act as gametes and Undergo Mitotic division

produce

Differentiate to formSporophyte