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Delve into the realm of taxonomy with Dr. Tamarkin to unravel the complexity of naming millions of organisms. Learn about Linnaeus's classification system, the evolution of kingdoms, and the role of genetic comparisons in taxonomy.
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Getting Into Diversity By Dr. Tamarkin
How Can Millions of Organisms Be Named? • Linnaeus chose to give each organism a genus and a species name • Examples: Homo sapiens, Anax junius, Canis familiaris, Escherichia coli • A species is defined by whether reproduction will lead to fertile offspring • Note that mating a horse & a donkey produces an infertile mule • Each species was put into a kingdom (at first, only plant & animal kingdoms)
Taxonomy Scheme • The taxonomic categories are each given Latin names • Example: Kingdom Animalia (not the Animal Kingdom) • We now consider the largest category to be based on cell type– it is called a domain
How many kingdoms came about • At first, only two kingdoms were recognized • Then 5 kingdoms (where protists had both plant & animal qualities) • Then there were 6 like this image • And now there many more kingdoms (since we’re splitting protists up)
The appearance of a species does not necessarily help define it • Convergent Evolution • Organisms that have to deal with the same environment may end up looking alike, even if they are not related • Divergent Evolution • Organisms that live in different environments may end up looking very different, even if they are closely related • Only genetic comparisons can help decipher details of taxonomy.
Domain Archaea Domain Bacteria Prokaryotic Domains • Unicellular organisms, but can be found stuck together • Can produce spores to withstand difficult conditions • Asexual reproduction occurs by binary fission, since they have no nuclei for mitosis to occur • Sexual reproduction occurs by conjugation • Many are heterotrophic decomposers, while some live a symbiotic existence, and others are autotrophic • Can be shaped as a rod, sphere, spiral, or filament
What about “blue-green algae” that are prokaryotic? These must be: • Protists • Bacteria • A combination
Slime Molds • Typically heterotrophic • Can be unicellular or multicellular, even if the same organism • Two types: • cellular slime molds (including Dictyostelium) • plasmodial slime molds
eukaryotic Algae • Autotrophic (usually), but may use pigments other than chlorophyll to trap the sun’s energy • Tend to be our environment’s main oxygen producers (phytoplankton) • Sometimes nonmotile, but may also be motile • Typically have a cell wall
Protozoa • Typically heterotrophic • Typically motile, but not always • Don’t usually have a real “cell wall,” but can have a protein “pellicle” surrounding them • Most are harmless, but some are parasitic • Typically aquatic (zooplankton)
What about Euglena? This organism may or may not have chloroplasts, is motile, has a simple eye, can be heterotrophic • It is a slime mold • It is an algae • It is a protozoan
Kingdom Fungi • We think of these organisms as mushrooms, but they are much more than that! • When you see one mushroom above ground, you can pretty much bet that the rest of the fungal organism, in microscopic threads, extends 10 – 50 feet (or more) around it underground. • These are excellent decomposers.
Kingdom Plantae • Land plants (and now green algae, too) • Land plants include mosses, ferns, conifers (cone-producers) and angiosperms (flower-producers) • Complex organisms built from many organ systems. • Autotrophic and nonmotile, with cell walls containing cellulose.
Kingdom Animalia • Subject of the final lab • Heterotrophic and motile, containing many organ systems • Includes the following phyla which we will address in class: Cnidaria, Platyhelminthes, Annelida and Chordata