Fungi and Protists
Endosymbiotic Origin of Eukaryotes
Schimper in 1883 and
Mereschcowsky
proposed that
chloroplasts are
cyanobacteria living
inside plant cells
Andreas Franz Wilhelm
Schimper (1856-1901,
Germany)
Konstantin Sergeevich
Mereschcowsky (18551921, Russia)
Ivan Emanuel Wallin
• Rejected cytoplasmic
origin of mitochondria
• Considered them to be
microbes living in the
cytoplasm
• Claimed to have
cultured isolated
mitochondria as proof
of their microbial
nature
1883-1969, USA
Endosymbiosis
Figure from
Margulis (1970);
note the figure
illustrates
endosymbiosis and
the origin of the 5
kingdoms.
Proposed with explanation by Lynn
Margulis (1938-2011, USA) in 1967 based
on her work and drawing on the works of
Konstantin Merezhkovsky (1855-1921,
Russia) and Ivan Wallin (1883-1969, USA).
Archaezoa Hypothesis
• Autogenous theory
(Archezoa HypothesisCavalier-Smith 1983)
• Organelles evolved within
the cell by progressive
compartmentalization
• HOWEVER, Roger (1999)all extant eukaryotes have
mitochondrial genes in
their nuclear DNA
• Later, Cavalier-Smith
accepted endosymbiosis
Thomas Cavalier-Smith
(1942, Britain)
Evidence that these organelles have
prokaryotic traits:
Mitochondria and
chloroplasts
– Circular DNA
– Synthesize
proteins
– Divide by fission
– Mutate
SSU rDNA
phylogeny
a larger prokaryote (or perhaps early eukaryote) engulfed or surrounded
a smaller prokaryote (permanent resident) some 1.5 billion to 700 million
years ago
DNA
Plasma membrane
Cytoplasm
endomembrane
system evolved
from inward folds
of the plasma
membrane of a
prokaryotic cell
Ancestral
prokaryote
Endoplasmic
reticulum
Nuclear
envelope
Nucleus
Cell with nucleus and
endomembrane
system
Serial Endosymbiosis Theory
Serial endosymbiotic theory (SET (19741990)) organelles are the result of
successive engulfments…
Max F.J.R. Taylor (1939, South Africa
and Canada); eukaryote created
following endosymbiosis with
mitochondrial bacterium. Further
developed Margulis Endosymbiosis
• endosymbiosis generated mitochondria and
chloroplasts
Aerobic heterotrophic prokaryote -Proteobacteria
Photosynthetic prokaryote Cyanobacteria
(Some cells)
Chloroplast
Aerobic cells
use oxygen to release energy
from organic molecules by
cellular respiration
Mitochondrion
Photosynthetic eukaryotic cell
Eukaryotic Domains
Tree of Life generated by Sandra Baldauf of Uppsala
University using multigene analyses
Supergroup Unikonta
• A group defined by
Cavalier-Smith
• Includes Amoebozoa,
Animalia, and Fungi
• Unikonta means one to
move by. The reference
is to motile cells having
a single flagellum.
Amoebozoa
Two major groups:
1. Most free-living
amoebae
2. Slime molds
?
Amoebozoa
• Unicellular
• Heterotrophic
• Most are free-living, a few are important
parasites
Entamoeba
Physarum
Supergroup Excavata
Excavates
• Unicellular
• Most are heterotrophs, commensals, a few are
parasites
• No sexual reproduction known
• Mitochondria absent (lost them)
Euexcavata
Trichonympha is a common symbiont in
the gut of termites and is a good
representative of the upper clade.
The lower clade includes free-living cells
that typically have only 2 flagella.
Eukaryotic Domains
Discicristates
• Some photosynthetic
(secondary
endosymbiosis)
• Some are free-living
heterotrophs
• Some are important
parasites
Euglena
Trypanosoma
Supergroup Chromalveolata
Eukaryotic Domains
Supergroup Chromalveolata
• Supergroup contains
some of the most
important organisms in
the oceans
• Range in form from
simple single cells to
complex multicellular
taxa
• Vary from heterotrophs
to parasites to
autotrophs
• Includes 4 kingdoms:
–
–
–
–
Heterokontae
Alveolatae
Rhizariae
Hacrobiae
Heterokontae
• United by same type
of motile cell
• Very diverse
Phaeophyta (the Brown Algae)
Diatoms
Alveolatae
• All unicellular
• Many with complex
life histories
• Free-living and
symbionts
• Photosynthetic,
heterotrophic,
commensals,
parasitic
• United by type of
cell covering
Alveolae
Ciliata
Apicomplexa
Dinoflagellata
Rhizaria
• Usually unicellular
• When they make pseudopods, they are long and
frequently anastomose
• Taxa are free-living and symbiotic
• Many have mineralized internal cytoskeletons
Foraminifera
Radiolaria
Fungi
Fungi
• Generally multicellular
with complex life
histories
• Include: mushrooms,
molds, and yeasts
• Sister group to the
animals
• Generally are
decomposers; some are
parasitic and cause
disease, particularly in
plants
Penicillium, common mold
Mushroom Life History
Yeast
Prototaxites
Silurian to Devonian. Gigantic fungus, largest terrestrial organism until
advent of trees at the end of the Devonian. Evidence of symbiotic algae in
the trunk-like structures, making them lichens.
Honey Mushrooms
Covers 2,384 acres in Malhur National Forest of the Blue
Mountains in Eastern Oregon.
Armillaria ostoyae
2400-8650 years old
Lichens
Foliose
Fruticose
Symbiotic structures made of algae and fungi
The fungus is the primary biotic partner and
enslaves the alga.
Crustose
The lichen form is different from either the
fungus or the alga and can live in habitats that
neither one can inhabit alone.