ECOL 182R 1st Edition Lecture 7 Outline of Last Lecture I Major divisions of life a Prokaryotes vs eukaryotes b five kingdoms c 3 domains II Ecological roles of bacteria III Metabolic not morphological diversity IV Bacteria V Archaea Outline of Current Lecture I Protists are a paraphyletic group II Importance of protists III Morphological features IV Feeding V Movement VI Sex VII Key lineages Current Lecture Monophyletic all descendants of a single common ancestor Paraphyletic some but NOT all descendants of a single common ancestor Protists aren t a natural group Protists all eukaryotes except green plants animals fungi They re a grouping of convenience NOT a natural evolutionary grouping No single synapomorphy shared derived trait unites all protists Examples of synapomorphy Mammals having hair Chocolate shakes have ice cream and milk Deep branching eukaryotes Those that diverged shortly after the split of the major domains of life They re protists These are key lineages in our understanding of how the eukaryotic genome evolved Protists are particularly abundant in the aquatic environments Open ocean Shallow coastal waters Intertidal habitats Important agents of disease Irish potato famine phytophthora infestans Malaria plasmodium Red Tides Montezuma s Revenge Sleeping sickness Giardia Irish Potato Famine Over 1 million deaths 50 crop loss then 75 loss Agent of blight was Phytophthora infestans Malaria Kills over 1 million each year mostly kids India alone 30 million cases per year Potential to affect 40 of world population Agent was plasmodium Over vertebrates get malaria lizard malaria in the southwest Controls strategies target mosquitoes Red Tides Massive blooms of dinoflagellates High concentration of red pigments ocean can turn red Dinoflagellates produce a toxin to defend against copepod predators Paralytic shellfish poisoning Ecological Importance of Protists Phytoplankton are the foundation of most aquatic ecosystems By fixing carbon these generate the food energy upon which the rest of the food chain depends They re the base of the food chain Key Morphological Features Nuclear membrane Organelles Mitochondria Chloroplast Coverings shells tests Multicellularity Key innovation of Eukaryotes is the nuclear membrane Separates DNA replication repair from translation Allows for RNA processing Where d they come from One hypothesis derived from unfolding of the plasma membrane Key innovation 2 Organelles The mitochondrion the chloroplast genomes are bacterial in structure Endosymbiosis hypothesis Both derived originally from bacteria engulfed by a primate eukaryote DNA sequence based phylogeny support endosymbiont origin of mitochondrial genome Chloroplasts Again genomic sequencing fully supports bacterial origin Some lineages have chloroplasts with four membranes as opposed to two Supports a secondary endosymbiosis Structure Protection Silicon oxide glass tests for diatoms Cellulose based structures for dinoflagellites Calcium carbonate tests for some foraminifera Feeding Photosynthesis make your own Ingestive feeding pseudopodia to engulf food Or ciliary currents to sweep food into mouth Absorptive feeding take food through membranes sit on it Secrete something out to dissolve it Important for decomposers parasites Movement Amoeboid motion via pseudopodia crawling Swimming via flagella whip like structures Swimming via cilia basically ores Sex Is a major innovation of eukaryotes The genomes of 2 individuals are used to make their offspring Sexual meiosis vs asexual mitosis reproduction Real advantage of sex you can make many more variations Protists can have both extensive haploid diploid life cycle phases Alternations of generations Haploid reproduction is asexual Diploid reproduction can be sexual or asexual
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