Chapter 28: Protists - structure, function, diversity, evolution, impact

1. Chapter 28: Protists - structure, function, diversity, evolution, impact Protists (Chapter 28) 1. More structural and functional diversity than any other group of organisms… 2. Most are unicellular, some colonial and multicellular… 3. Most nutritionally diverse eukaryotes A. photoautotrophs B. heterotrophs C. mixotrophs – combine photosyn with hetertrophic nutrition

2. Chapter 28: Protists - structure, function, diversity, evolution, impact Protists Broken into three general categories based on ecological context: 1. Photosynthetic (plant-like) protists - algae 2. Ingestive (animal-like) protists - protozoans 3. Absorptive (fungus-like) protists

3. Chapter 28: Protists - structure, function, diversity, evolution, impact Protists How did such incredible diversity arise? Many species resulted from two rounds of endosymbiosis…

4. Chapter 28: Protists - structure, function, diversity, evolution, impact Phylogeny of protists Fig. 28.4 Phylogenetic tree showing the major clades of protists.

5. Chapter 28: Protists - structure, function, diversity, evolution, impact Phylogeny of protists Fig. 28.4 What’s a clade? A complete branch of a phylogenetic tree. Above how many clades are highlighted? Two, the blue and the red because these are complete branches. The green is not complete.

6. Chapter 28: Protists - structure, function, diversity, evolution, impact Phylogeny of protists Fig. 28.4 Let’s examine a handful of these clades…

7. Chapter 28: Protists - structure, function, diversity, evolution, impact Fig. 28.8 Kingdom Euglenozoa Characterized by spiral or crystalline rod within flagella in addition to 9+2 arrangement of microtubules. Cyrstalline structure has unknown function.

8. Chapter 28: Protists - structure, function, diversity, evolution, impact Fig. 28.8 Kingdom Euglenozoa Phylum kinetoplastid Ex. Genus Trypanosoma - Causes sleeping sickness - Spread by African tsetse fly - Fatal if untreated - Evade immune system by repeatedly changing the proteins on the surface of the cell

9. Chapter 28: Protists - structure, function, diversity, evolution, impact Fig. 28.8 Kingdom Euglenozoa Phylum euglenid Ex. Euglena - Found in freshwater - Photoautotroph if sunlight available otherwise heterotroph by absorbing nutrients from environment (mixotroph)

10. Chapter 28: Protists - structure, function, diversity, evolution, impact Phylogeny of protists Fig. 28.4 Let’s examine a handful of these clades…

11. Chapter 28: Protists - structure, function, diversity, evolution, impact Fig. 28.8 Kingdom Alveolata Characterized by sacs below membrane called alveoli having yet unknown function

12. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Alveolata Phylum dinoflagellates - Abundant as both marine and freshwater phytoplankton Phytoplankton – phyto = photosynthetic, plankton = “free-drifting” - free-drifting photosynthetic organisms (cyanobacteria is also a large part of phytoplankton) - Bloom (explosion of growth) can cause “red tide” - Secrete toxins that bioaccumulate in molluscs making them dangerous to eat - Have internal “plates” of cellulose giving its characteristic shape…

13. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Alveolata Phylum Ciliates - Obviously use cilia to move and feed Ex) Paramecium Two types of nuclei - Large (macro) nucleus - Smaller (micro) nucleus - Can have more than one of each

14. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Alveolata Phylum Ciliates Macronucleus - Contains dozens of copies of genome - Genes are not on chromosomes (they don’t have chromosome) - Arranged in small units each having many duplicates of a single gene - The gene products (i.e. proteins) control daily functions like feeding, waste removal, etc…

15. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Alveolata Phylum Ciliates Feeding - Mainly on bacteria, which are moved through oral groove and phagocytosed at “cell mouth” into food vacuoles. - Food vacuoles fuse with lysosomes - Undigestable material is egested when lysosomes fuse with cell membrane

16. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Alveolata Phylum Ciliates Reproduction - Mostly asexually by “binary fission” Conjugation - Genetic diversity, NOT REPRODUCTION - two organisms exchange haploid micronuclei (see fig 28.12b above and use book for more detail)

17. Chapter 28: Protists - structure, function, diversity, evolution, impact Phylogeny of protists Fig. 28.4 Let’s examine a handful of these clades…

18. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Stramenopila Phylum Diatom (Bacillariophytes) - Unicellular Algae - glass-like silica based cell wall as shown in figure - Protection from predators - Withstand pressures up to 1.4 million kg/m2 (pressure applied by the leg of a table with an elephant standing upon it)

19. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Stramenopila Phylum Diatom (Bacillariophytes) Reproduction - Usually asexually by mitosis - Sexual reproduction is not common, but does occur Diversity - Estimated 100,000 species - Major component of phytoplankton in oceans and lakes

20. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Stramenopila Phylum Golden Algae (chrysophytes) (chrysos = golden) Dinobryon - Contain yellow/brown cartenoid pigments - Freshwater and marine plankton - All obviously photosynthetic, some species mixotrophs - Most unicellular, but some, as shown, are colonial

21. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Stramenopila Phylum Brown Algae (phaeophytes – guess what phaeo means…) Kelp - Largest and most complex algae (its what you call seaweed) - All are multicellular and most are marine (salt water – ocean) - Common along temperate costs like ours

22. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Stramenopila Sea palm (Postelsia) Phylum Brown Algae Kelp Thallus - The body of the seaweed that is plant-like - Basically, the holdfast, stipe (stem-like) and blades (leaf-like) (see above) Holdfast - root-like structure at base solely for anchoring, not absorption like roots of plants

23. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Stramenopila Phylum Brown Algae Life-cycle: Alternation of Generations This is important to understand because as you might guess, since plants evolved from multicellular algae, they also do this. Heteromorphic - The two generations are structurally different as opposed to being isomorphic Laminaria (a brown algae)

24. Chapter 28: Protists - structure, function, diversity, evolution, impact Phylogeny of protists Fig. 28.4 Let’s examine a handful of these clades…

25. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Cercozoans and Radiolarians - Amoeba with threadlike pseudopods - Amoeba is a general term for a protist that uses pseudopodia to move and feed. There is no one clade or kingdom that consists of amoebas

26. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Cercozoans and Radiolarians Radiolarian Foraminiferans (Forams) - Tests made of silica - Foramen means “little hole” - Pseudopodia called axopodia - Named for porous shells called tests - Organic molecules hardened with CaCO3 - Pseudopodia extend through pores of shell and fx in test formation, swimming and feeding Both of these phyla consist of amoebas because…

27. Chapter 28: Protists - structure, function, diversity, evolution, impact Phylogeny of protists Fig. 28.4 Let’s examine a handful of these clades…

28. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Amoebozoans - Amoeba with lobe shaped rather than threadlike pseudopods belong to this clade: Now this amoeba belongs to the above kingdom…

29. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Amoebozoans Phyla: Gymnamoeba Phagocytosis of a ciliate:

30. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Amoebozoans Phyla: Slime Molds (mycetozoans) Were once thought to be fungus hence the name, but molecular evidence has revealed convergent evolution Two major types: 1. Plasmodial Slime Molds 2. Cellular Slime Molds They in part by their life cycles…

31. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Amoebozoans Phyla: Slime Molds (mycetozoans) Plasmodial Slime Mold Life Cycle

32. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Amoebozoans Phyla: Slime Molds (mycetozoans) Cellular Slime Mold Life Cycle

33. Chapter 28: Protists - structure, function, diversity, evolution, impact Phylogeny of protists Fig. 28.4 Let’s examine a handful of these clades…

34. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Rhodophyta Rhodo = red Red Algae Red due to pigment known as phycoerythrin, which masks chlorophyll Most large and multicellular, living in tropical waters Alternation of Generations

35. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Chlorophyta Chloro = green Green Algae Much like plants, systematics has shown close relationship b/w green algae and plants as you would expect… - Chlorophytes and Charophyceans Two groups 1. Chlorophytes - More than 7,000 species, most in fresh water - Simplest are unicellular - These are the ones that live in mutualism with fungus to form lichen Watermelon snow showing the incredible diversity of chlorophytes *Charophyceans and most related to land plants and are discussed at beginning of Ch. 29 with plants

36. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Chlorophyta Chloro = green Green Algae Larger size and complexity arose via: 1. Colony formation (ex. Volvox) and multicellular filament formation. 2. Repeated division of nuclei without cytoplasmic division (ex. Caulerpa) 3. True multicellular forms with cell division and differentiation (Ex. Ulva)

37. Chapter 28: Protists - structure, function, diversity, evolution, impact Kingdom Chlorophyta Syngamy = fusion of gametes, aka fertilization/conception Chloro = green Green Algae Complicated life cycle of asexual and sexual stages:

38. Chapter 28: Protists - structure, function, diversity, evolution, impact