V) Ciliates
a) Supergroup “SAR” – alveolate clade
b) move and feed by cilia
c) very diverse group
d) mostly free living
i) ex. Paramecium sp.
e) multinucleate
i) have macronucleus and micronucleus
f) cilia work synchronously
g) contractile vacuole for osmoregulation
h) usually reproduce asexually (binary fission) but
i) sexual reproduction = conjugation
i) micronuclei undergo meiosis
ii) one is traded with another paramecium
iii) fuse and give rise to new individuals
VI) Fungi-like protists
a) Considered to be fungi- like because of some shared characteristics
i) Spread by spores
ii) heterotrophic
(1) many saprobic (get nutrition from non-living organic matter and cause decay)
b) Water Molds white rusts and downy mildews
i) Supergroup “SAR” Stramenopile clade. (not actually closely related to fungi – similarities due to convergent evolution)
ii) Aquatic or on moist substrate
iii) many are decomposers - saprobic
iv) some parasitic on aquatic organisms
(1) ex. cottony stuff on aquarium fish
v) some are plant pathogens
(1) ex. mildew on grapes
vi) Irish potato famine of 1845-1860 - caused by potato late blight (Phytophthora infestans)
(1) important economically and sociologically
(2) mass emigration from Ireland (and immigration into US) in mid-19th century
c) Slime molds
i) Considered fungi-like because reproduce with fruiting bodies that produce spores
ii) 2 main types
(1) Cellular Slime Molds
(a) supergroup Unikonta - Amoebozoa clade
(b) live as amoeba-like (amoeboid) single cells
(c) prey on bacteria and yeast by phagocytosis (like amoebae)
(d) when nutrients get scarce, cells aggregate into a multicellular “slug” stage and migrate
(e) then produce a fruiting body and disperse spores
(2) Plasmodial Slime Molds
(a) Usually bright yellow or orange
(b) Can be quite large but a single multinucleated cell (syncytium) produced by mitosis without cytokinesis (technically a huge single cell).
(c) Grow and extend pseudopodia through soil and phagocytize food particles
VII) Plant-like protists = Algae
a) Former Kingdom Protista contained single-celled (phytoplankton) and simple, multicellular (sea weeds) photosynthetic aquatic Eukaryotes (algae)
b) Diatoms and brown algae (Stramenopile clade) and dinoflagellates (Alveolate clade) are currently in “SAR” supergroup.
c) Green algae share direct common ancestry with the land plants (Kingdom Plantae) and both are in the Supergroup Archaeplastida.
d) Major lineages of the algae correspond to secondary symbiotic events
i) Remember (previous lecture) that evolution of eukaryotes, originated through endosymbiosis first producing mitochondria and then plastids (chloroplasts). Major branches of algae lineages are thought to have occurred via secondary endosymbiotic events resulting in different plastids in these different groups.