microbial diversity chapt. 28 – the origins of eukaryotic diversity

Microbial Diversity

Chapt. 28 – The Origins of Eukaryotic Diversity

What are microbes?

Single-celled organisms and some non-cellular parasites

Kinds of microbes

Non-cellular, parasitic moleculesViruses ViroidsPrions

ProkaryotesDomain BacteriaDomain Archaea

EukaryotesSeveral Kingdoms in Domain Eukarya

Carl Woese’s 3 Domains of Life

Based primarily on genetic sequence data;

e.g., small subunit ribosomal RNA – present in all

organisms

EukaryotesEukaryotesKingdoms of Protists within the

Domain Eukarya

EukaryotesEukaryotesProtists

Complex cellular structure – cells with nucleus and other organelles

Eukaryotic cellMany membranous organelles…

including mitochondria,which arecommon to all eukaryotes…

and chloroplasts (found only in photosynthesizers)


Complex cellular structure – cells with nucleus and other organellesE.g., cilia & flagella aid motility; these cytoplasmic extensions are

not homologous with pili or flagella of prokaryotes


Complex cellular structure – cells with

nucleus and other organelles

Nutrition – Absorption, Photosynthesis, or Ingestion


Complex cellular structure – cells with

nucleus and other organelles


Reproduction – mostly asexual, but some exchange genetic material

Asexual cell

division(mitosis)

Conjugation:exchange of

some genetic material across a

cytoplasmic bridge

Sexual reproduction via

the formation and union of gametes or other haploid cells(requires meiosis)

Sexual, spore-forming cells of a

slime mold:


Complex cellular structure – cells with nucleus and other organelles


Reproduction – mostly asexual, but some reproduce sexually

Cysts – resting stages through harsh conditions


Arose from endosymbiosis

Compelling evidence for Lynn Margulis’ theory is found in the genetic material of mitochondria & plastids

EukaryotesEukaryotes

Macroevolutionary timeline

Figure 26.13

Ancestralprokaryote



Figure 26.13

Ancestralprokaryote

Infolding of plasmamembrane to form

endoplasmic reticulum and nuclear envelope



Figure 26.13

Ancestralprokaryote



Engulfing of heterotrophic

prokaryote



Figure 26.13

Ancestralprokaryote




prokaryote

Mitochondrion



Figure 26.13

Ancestralprokaryote




prokaryote

Mitochondrion

Engulfing of photosynthetic

prokaryote

Plastid


Cyanobacterium

Heterotrophiceukaryote

Primaryendosymbiosis

Red algae

Green algae

Secondaryendosymbiosis


Dinoflagellates

Apicomplexans

Ciliates

Stramenopiles

Euglenids

Plastid

Figure 28.3


Cyanobacterium



Green algae



Dinoflagellates

Apicomplexans

Ciliates

Euglenids

Plastid

Figure 28.3

Stramenopiles

Red algae


Cyanobacterium



Red algae

Green algae



Dinoflagellates

Apicomplexans

Ciliates

Euglenids

Plastid

Figure 28.3

Stramenopiles

Plastid


Cyanobacterium



Red algae

Green algae



Plastid

Dinoflagellates

Apicomplexans

Ciliates

Euglenids

Plastid

Figure 28.3

Stramenopiles


Cyanobacterium



Red algae

Green algae



Plastid

Dinoflagellates

Apicomplexans

Ciliates

Stramenopiles

Euglenids

Chlorarachniophytes

Plastid

Figure 28.3


Arose from endosymbiosis

Various lineages gave rise to all modern unicellular & colonial protists, as well as all

multicellular organisms (some protists, as well as all plants, fungi, and animals)

Paraphyletic distribution of protists within a tentative phylogeny of Eukarya

An ancestor and only some of its

descendents

Ch

loro

ph

yta

Pla

nta

e

Ancestral eukaryote

Rh

od

op

hyt

a

Fu

ng

i

Dip

lom

on

ad

ida

Par

aba

sal

a

Eu

gle

no

zoa

Alveolata Stramenopila Ce

rco

zoa

Ra

dio

lari

a

Amoebozoa An

ima

lia

Ch

oan

ofl

ag

ella

tes

Figure 28.4

“Last Universal Common Ancestor”

Hypotheses for the earliest stages of biological diversification:

Hypotheses for the earliest stages of biological diversification:


Highly diverse genetically and

phenotypically



phenotypically

“Fungus-like” protists

Heterotrophic

Absorption



phenotypically


Heterotrophic

Decomposers

E.g., slime molds



phenotypically


Heterotrophic

Parasitic

E.g., water molds



phenotypically

“Plant-like” protists

Autotrophic

Photosynthesis



phenotypically


Autotrophic

Unicelluar

E.g., EuglenaPhytoplankton (unicellular algae & cyanobacteria [prokaryotes] ~ 70% of all photosynthesis)



phenotypically


Autotrophic

Multicelluar

E.g., Many

seaweeds



phenotypically

“Animal-like” protists

Heterotrophic

Ingestion



phenotypically


Heterotrophic

Free-living

E.g., Some amoebae



phenotypically


Heterotrophic

Parasitic

symbionts

E.g., Giardia



phenotypically


Heterotrophic

Mutualistic symbionts

E.g., protistsof termite guts



phenotypically


Heterotrophic

Exhibit slightly more complex behavior than prokaryotes…

Predator-prey interaction between ciliates:Didinium preys upon Paramecium

microbial diversity chapt. 28 – the origins of eukaryotic diversity

Documents

endoplasmic reticulum

organellesnutrition

genetic sequence data

cytoplasmic extensions

domain eukaryacarl woeses

cilia flagella aid motility

domains of lifebased

slime mold