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 UNIVERSAL ANCESTOR Domain Eukarya Gram-positive bacteria Cyanobacteria Spirochetes Chlamydias Proteobacteria Nanoarchaeotes Crenarchaeotes Euryarchaeotes Korarchaeotes Eukaryotes Domain Archaea Domain Bacteria 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! DIVERSITY Many are important ocean photosynthesizers! p500 Parasitic protists Trichomonas Giardia- beavers Malaria p501

Figure Forams Ciliates Euglenozoans Diatoms COMMON ANCESTOR OF ALL LIFE Land plants Animals Amoebas Fungi Red algae Chlamydias Green algae (Mitochondria)* Methanogens Proteobacteria Nanoarchaeotes Thermophiles Domain Eukarya Gram-positive bacteria (Chloroplasts)* Spirochetes Cyanobacteria Domain Bacteria Domain Archaea

Plasma membrane Chromosomes 1. Ancestor of the eukaryotes. 2. Infoldings of plasma membrane surround the chromosomes. Endoplasmic reticulum 3. Eukaryotic cell. Nucleus ORIGIN OF THE NUCLEAR ENVELOPE Eukaryotes have a Nucleus Where did it come from?

Eukaryotes also have mitochondria and chloroplasts-Endosymbiosis! Lynn Margulis

Figure 25.3 Cytoplasm DNA Nucleus Engulfing of aerobic bacterium Engulfing of photo- synthetic bacterium Mitochondrion Mito- chondrion Plastid Plasma membrane Endoplasmic reticulum Nuclear envelope Ancestral prokaryote Ancestral heterotrophic eukaryote Ancestral photosynthetic eukaryote

Figure 25.3 Cytoplasm DNA Nucleus Engulfing of aerobic bacterium Engulfing of photo- synthetic bacterium Mitochondrion Mito- chondrion Plastid Plasma membrane Endoplasmic reticulum Nuclear envelope Ancestral prokaryote Ancestral heterotrophic eukaryote Ancestral photosynthetic eukaryote

Figure Cyanobacteria Proteobacteria Thermophiles Domain Eukarya Domain Bacteria Domain Archaea Fungi Plantae Chloroplasts Mitochondria Methanogens Ancestral cell populations How do we show endosymbiosis on a phylogenetic tree? So sometimes whole organisms were engulfed-but genes were also being swapped HOW?

Figure SECONDARY ENDOSYMBIOSIS Nucleus Predatory protist Photosynthetic protist Chloroplast Nucleus 1. Photosynthetic protist is engulfed. 2. Nucleus from photosynthetic protist is lost. Organelle with four membranes 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 Membranes are represented as dark lines in the cell. Red alga Primary endo- symbiosis Nucleus Heterotrophic eukaryote One of these membranes was lost in red and green algal descendants. Green alga Secondary endo- symbiosis Secondary endo- symbiosis Plastid Euglenids Chlorarachniophytes Stramenopiles Plastid Secondary endo- 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 25.6 Flagellum 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 Individual choanoflagellate Choano- flagellates Other animals Collar cell (choanocyte) Sponges Animals OTHER EUKARY- OTES What do we know? Multicellularity in animals…

Figure 32-11a Choanoflagellates are sessile protists; some are colonial. Choanoflagellate cell Colony Water current Food particles

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 Fruit fly

Text goes over taxonomy of protists…which we will skip. And then text goes over functional importance..

Protists-ARE ONE type of Eukaryote! DIVERSITY Many 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 legs Expression 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 6Hox gene 7Hox gene 8 About 400 mya DrosophilaArtemia 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 Chimpanzee infantChimpanzee adult Chimpanzee 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 spines No 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)