Figure 20.UN01

Which of these trees is not like the others….. B A D Figure 20.UN01 B C D C C B A A D (a) (c) (b)

Figure 24.18 Domain Eukarya Eukaryotes Korarchaeotes Euryarchaeotes Archaea Domain Archaea Crenarchaeotes UNIVERSAL ANCESTOR Nanoarchaeotes Prokaryotes Proteobacteria Chlamydias Bacteria Spirochetes Domain Bacteria Cyanobacteria Gram-positive bacteria

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

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

Eukaryotes also have mitochondria and chloroplasts-Endosymbiosis! Lynn Margulis

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

Figure 20.21 How do we show endosymbiosis on a phylogenetic tree? So sometimes whole organisms were engulfed-but genes were also being swapped HOW? Fungi Domain Eukarya Plantae Chloroplasts Methanogens Domain Archaea Mitochondria Ancestral cell populations Thermophiles Cyanobacteria Proteobacteria Domain Bacteria

Figure 29-16 SECONDARY ENDOSYMBIOSIS Engulfing of a protist that already engulfed a photosynthetic prokaryote Some ate a green algae and some ate a red algae. Predatory protist Photosynthetic protist Nucleus Chloroplast Nucleus 1. Photosynthetic protist is engulfed. 2. Nucleus from photosynthetic protist is lost. Organelle with four membranes 4 3 2 1

Figure 25.4 Secondary endosymbiosis Dinoflagellates Membranes are represented as dark lines in the cell. Red alga Cyano- bacterium Plastid 2 1 3 Primary endosymbiosis Stramenopiles Secondary endosymbiosis Plastid Nucleus Heterotrophic eukaryote One of these membranes was lost in red and green algal descendants. Euglenids Secondary endosymbiosis Green alga Chlorarachniophytes

Figure 25.5 Many protists are multicellular! This is a colonial protist with rigid cell walls-what do we mean by colonial? 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?

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 Chlamydomonas Outer cell wall Inner cell wall Few totally new genes….. Gonium Pandorina Outer cell wall Cytoplasm Volvox Extracellular matrix (ECM)

Figure 25.7 What do we know? Multicellularity in animals… Individual choanoflagellate Choano- flagellates OTHER EUKARY- OTES Sponges Animals Collar cell (choanocyte) Other animals

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

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 Choano- flagellate Hydra Fruit fly “CCD” domain Mouse

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 6 Hox gene 7 Hox gene 8 Ubx About 400 mya Drosophila Artemia

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 fetus Chimpanzee adult Human fetus Human adult

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)

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Figure 20.UN01

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