Fig. 28-03a

Gr een

algae

Am

oeb

ozo

ans

Op

istho

kon

tsA

lveolates

Stram

eno

piles

Diplomonads

Parabasalids

Euglenozoans

Dinoflagellates

Apicomplexans

Ciliates

Diatoms

Golden algae

Brown algae

OomycetesE

xcavataC

hro

malveo

lataR

hizaria

Chlorarachniophytes

Forams

Radiolarians

Arch

aeplastid

a

Red algae

Chlorophytes

Charophyceans

Land plants

Un

ikon

ta

Slime molds

Gymnamoebas

Entamoebas

Nucleariids

Fungi

Choanoflagellates

Animals

(Plantae)

the 5supergroups

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Concept 28.6: Unikonts include protists that are closely related to fungi and animals

• The supergroup Unikonta includes animals, fungi, and some protists

• This group includes two clades: the amoebozoans and the opisthokonts (animals, fungi, and related protists)

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 28-UN5

Amoebozoans

Nucleariids

Fungi

Choanoflagellates

Animals

Un

ikon

ta

Excavata

Chromalveolata

Rhizaria

Archaeplastida

Fig. 28-23

Commonancestorof alleukaryotes

DHFR-TSgenefusion

Unikonta

Excavata

Chromalveolata

Rhizaria

Archaeplastida

Choanoflagellates

Animals

Fungi

Amoebozoans

Diplomonads

Euglenozoans

Alveolates

Stramenopiles

Rhizarians

Red algae

Green algae

Plants

RESULTS

Stechman and Smith, 2002

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Amoebozoans

• Amoebozoans are amoeba that have lobe- or tube-shaped, rather than threadlike, pseudopodia

• They include gymnamoebas, entamoebas, and slime molds

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Slime Molds

• Slime molds, or mycetozoans, were once thought to be fungi

• Molecular systematics places slime molds in the clade Amoebozoa

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Plasmodial Slime Molds

• Many species of plasmodial slime molds are brightly pigmented, usually yellow or orange

Video: Plasmodial Slime Mold StreamingVideo: Plasmodial Slime Mold Streaming

Video: Plasmodial Slime MoldVideo: Plasmodial Slime Mold

Plasmodial “sporangia”

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• At one point in the life cycle, plasmodial slime molds form a mass called a plasmodium (not to be confused with malarial Plasmodium)

• The plasmodium is undivided by membranes and contains many diploid nuclei

• It extends pseudopodia through decomposing material, engulfing food by phagocytosis

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Cellular Slime Molds

• Cellular slime molds form multicellular aggregates in which cells are separated by their membranes

• Cells feed individually, but can aggregate to form a fruiting body!

• Dictyostelium discoideum is an experimental model for studying the evolution of multicellularity

Fig. 28-25-1

Spores(n)

Emergingamoeba(n)

Solitary amoebas(feeding stage)(n)

Aggregatedamoebas

Migratingaggregate

Fruitingbodies(n)

ASEXUALREPRODUCTION

600 µm

200 µm

Key

Haploid (n)

Diploid (2n)

Fig. 28-25-2

Spores(n)

Emergingamoeba(n)

Solitary amoebas(feeding stage)(n)

Aggregatedamoebas

Migratingaggregate

Fruitingbodies(n)

ASEXUALREPRODUCTION

600 µm

200 µm

Key

Haploid (n)

Diploid (2n)

Amoebas(n)

Zygote(2n)SEXUAL

REPRODUCTION

MEIOSIS

FERTILIZATION

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Gymnamoebas

• Gymnamoebas are common unicellular amoebozoans in soil as well as freshwater and marine environments

• Most gymnamoebas are heterotrophic and actively seek and consume bacteria and other protists

Video: Amoeba PseudopodiaVideo: Amoeba Pseudopodia

Video: AmoebaVideo: Amoeba

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Problem Amoebas

• Entamoebas are parasites of vertebrates and some invertebrates

• Entamoeba histolytica causes amebic dysentery in humans

• Acanthamoeba Water born eye pathogen - contact wearers beware! (spiny)

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Opisthokonts

• Opisthokonts include animals, fungi, and several groups of protists

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Choanoflagellates

Animals

Fungi

Gymnamoebas

Entamoebas

Nucleariids

Un

ikon

ta

Slime molds

Am

oeb

ozo

ans

Op

isth

ok

on

ts