Figure 20.UN01

A

B

C

D

(a)

D

C

B

A

(c)

B

D

C

A

(b)

Which of these trees is not like the others…..

Figure 24.18

UNIVERSALANCESTOR

Do

main

Eu

karya

Gram-positivebacteria

Cyanobacteria

Spirochetes

Chlamydias

Proteobacteria

Nanoarchaeotes

Crenarchaeotes

Euryarchaeotes

Korarchaeotes

Eukaryotes

Do

main

Arch

aeaD

om

ain B

acteria

Archaea

Bacteria

Prokaryotes

Who are the Eukaryotes?

How do they get their energy?

Which lineages are good monophyletic groups?

When did they evolve? GO back to your timeline….

Fossils 1.8bya (but lipids made by Euk. around 2.7 bya)

Multicellularity?

600mya

Protists-ARE ONE type of Eukaryote!DIVERSITYMany are important ocean photosynthesizers! p500

Parasitic protists

•Trichomonas•Giardia- beavers•Malaria p501

Figure 20.20

Forams

Ciliates

Euglenozoans

Diatoms

COMMONANCESTOR OF ALL LIFE

Land plants

Animals

Amoebas

Fungi

Red algae

Chlamydias

Green algae

(Mitochondria)*

Methanogens

Proteobacteria

Nanoarchaeotes

Thermophiles

Do

ma

in E

uk

arya

Gram-positivebacteria

(Chloroplasts)*

Spirochetes

Cyanobacteria

Do

ma

in B

acteria

Do

ma

inA

rch

aea

Plasma membrane

Chromosomes

1. Ancestor of theeukaryotes.

2. Infoldings ofplasma membranesurround thechromosomes.

Endoplasmicreticulum

3. Eukaryotic cell.

Nucleus

ORIGIN OF THE NUCLEAR ENVELOPEEukaryotes have a Nucleus

Where did it come from?

Eukaryotes also have mitochondria and chloroplasts-Endosymbiosis!

Lynn Margulis

Figure 25.3

CytoplasmDNA

Nucleus

Engulfingof aerobicbacterium

Engulfingof photo-syntheticbacterium

Mitochondrion

Mito-chondrion

Plastid

Plasmamembrane

Endoplasmicreticulum

Nuclearenvelope

Ancestralprokaryote

Ancestralheterotrophiceukaryote

Ancestralphotosyntheticeukaryote

Figure 25.3

CytoplasmDNA

Nucleus

Engulfingof aerobicbacterium

Engulfingof photo-syntheticbacterium

Mitochondrion

Mito-chondrion

Plastid

Plasmamembrane

Endoplasmicreticulum

Nuclearenvelope

Ancestralprokaryote

Ancestralheterotrophiceukaryote

Ancestralphotosyntheticeukaryote

Figure 20.21

Cyanobacteria

Proteobacteria

Thermophiles

Do

main

Eu

karyaD

om

ain B

acteriaD

om

ainA

rchaea

Fungi

Plantae

Ch

loro

plasts

Mito

cho

nd

ria

MethanogensAncestral cellpopulations

How do we show endosymbiosis on a phylogenetic tree?

So sometimes whole organisms were engulfed-but genes were also being swapped

HOW?

Figure 29-16SECONDARY ENDOSYMBIOSIS

Nucleus

Predatory protist

Photosynthetic protist

Chloroplast

Nucleus

1. Photosynthetic protist is engulfed.

2. Nucleus from photosynthetic protist is lost.

Organelle with four membranes

1 23 4

Engulfing of a protist that already engulfed a photosynthetic prokaryote

Some ate a green algae and some ate a red algae.

Figure 25.4

Cyano-bacterium

Membranesare representedas dark lines inthe cell.

Red alga

Primaryendo-

symbiosis

1 2 3

NucleusHeterotrophiceukaryote

One of thesemembraneswas lost inred andgreen algaldescendants.

Greenalga

Secondaryendo-

symbiosis

Secondaryendo-

symbiosis

Plastid

Euglenids

Chlorarachniophytes

Stramenopiles

Plastid

Secondaryendo-

symbiosis

Dinoflagellates

Figure 25.5

When did multicellularity evolve?What traits would need to evolve in order to be a multicellular organism? What would you have to be able to do?

Many protists are multicellular!This is a colonial protist with rigid cell walls-what do we mean by colonial?

More on multicellularity…integration!

•Stick together

•Communicate

•Ways of moving materials around

•Germ vs Soma-controls on mitosis and meiosis

•Differentiated cells are arranged in tissues

•Genes regulated so that even though all cells contain all the animals genes, particular genes are active only in particular cells at certain times during a lifetime

•These things require changes in controls over developmental processes and changes in gene expression rather than new cellular structures or genes not present in unicellular organisms!

Multicellularity evolved many times

Ex Algae (“protists”), Plants, Fungi and Animals

Figure 25.6Flagellum

Cytoplasm

Outer cell wall

Inner cell wall

Outer cell wall

Cytoplasm

Extracellular matrix (ECM)

Chlamydomonas

Gonium

Pandorina

Volvox

Few totally new genes…..

Figure 25.7

Individualchoanoflagellate

Choano-flagellates

Otheranimals

Collar cell(choanocyte)

Sponges

An

imals

OTHEREUKARY-OTES

What do we know? Multicellularity in animals…

Figure 32-11a

Choanoflagellates are sessile protists; some are colonial.

Choanoflagellate cell

Colony

Water current

Foodparticles

Genome of a single celled choanoflagellate vs animals

Many protein domains in common (domain is a key part or functional region of a protein)

Choanoflagellate had the same domains that in animals are important in cell adhesion and signaling.

So evolution of multicellularity involved the “co-opting” of existing genes that had been used for other purposes

As well as one small new piece the CCD domain in the cadherin protein

Figure 25.8

Hydra

Mouse

“CCD” domain

Choano-flagellate

Fruitfly

Text goes over taxonomy of protists…which we will skip.

And then text goes over functional importance..

Protists-ARE ONE type of Eukaryote!DIVERSITYMany are important ocean photosynthesizers! p500

Parasitic protists

•Trichomonas•Giardia- beavers•Malaria p501

Development is obviously only important in multicellular organisms

How do we get such diversity of morphology?

Small changes in development can yield big differences in shape or morphology. See P 449-CH23

Two kinds of developmental changes

1. Homeotic mutations affect placement and number of body parts

(typically Hox mutations)

Numbers of legsExpression of a particular Hox gene suppresses the formation of legs in fruit flies (and presumably all insects) but not brine shrimp(Pinpointed the exact amino acid changes)

Hox gene 6 Hox gene 7 Hox gene 8

About 400 mya

Drosophila Artemia

Ubx

What is going on here?

2. Heterochronic (allometric) changes or mutations

These affect the timing or rate of development of different body parts (rate of mitosis)

parts pulled and stretched at different rates to make “new” morphologies…

Figure 23.16

Chimpanzee infant Chimpanzee adult

Chimpanzee adultChimpanzee fetus

Human adultHuman fetus

Heterochrony…paedomorphosis..Some species of salamander retain juvenile characteristics (external gills) into sexual maturity

Sticklebacks-Ex from text…

Lakes with predators-make spinesNo predators-no spines

What is genetic basis of this evolutionary change?

Change in nucleotide sequence OR change in how the gene is expressed or regulated

Thoughts on which is more risky?? Easier??

Change in way gene is regulated…

Pleiotropic effects of gene can be controlled (turn off spine production but other functions of gene on other parts of body retained)