BIOL 220 Lecture Notes - Lecture 15: Choanocyte, Heterotroph, Phytoplankton
Lecture 15
BIO 220
Genome Evolution
Eukaryotes
Microbial Ecology
The Black Queen Hypothesis
oReductive evolution is driven not by genetic drift but by natural selection; so long as the
benefit gained by losing a gene outweighs the cost of no longer having it, the loss og
that gene will continue to spread throughout the population
Endosymbiosis
oSymbiosis is the intimate association of two unrelated species
Mutualism is when both partner benefit
Parasitism is when one partner benefits, while the other is harmed
oSymbiosis leads to coevolution
Evolution of two species in response to each other, showing parallel phylogeny
oThe most intimate kind is when one partner grows within the body of the other
Margulis and Mitochondria and Chloroplasts
oObserved that they share several traits with free-living bacteria
DNA
Ribosomes
Size
Mechanism of division
Microbial Eukaryotes
oWith all their diversity, eukaryotic cells share a common structure defined by the
presence of the nucleus and other membrane-enclosed organelles
oFungi were considered a form of plant
oAnimal like organisms were called protozoa
oSingle celled phototrophs such as diatoms and dinoflagellates were called algae
oProtists refers to single celled and colonial eukaryotes other than fungi
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Document Summary
Endosymbiosis: symbiosis is the intimate association of two unrelated species. Parasitism is when one partner benefits, while the other is harmed: symbiosis leads to coevolution. Evolution of two species in response to each other, showing parallel phylogeny: the most intimate kind is when one partner grows within the body of the other. Margulis and mitochondria and chloroplasts: observed that they share several traits with free-living bacteria. Complex eukaryotic cells frequently lose structures through reductive evolution. Superficially similar forms of organisms have evolved idependently in distantly relaxed taxa. The evolution of eukaryotes includes multiple events of endosymbiosis. Genetic studies have revealed several genes found only in animals. Collared cells closely resemble the choanocyte cells of colonial sponges. Fungi: provide essential support for all communities of multicellular organisms. Fungi recycle the biomass of wood and leaves which other organisms may be unable to digest. Underground fungal filaments called mycorrhizae extend the root systems of most plants.
