The Fascinating World of Taxonomy: Exploring Organism Diversity

1. Getting Into Diversity By Dr. Tamarkin

2. 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)

3. 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

4. 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)

5. 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.

6. 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

7. Domain Eukaryaprotist groups

8. What about “blue-green algae” that are prokaryotic? These must be: • Protists • Bacteria • A combination

9. Slime Molds • Typically heterotrophic • Can be unicellular or multicellular, even if the same organism • Two types: • cellular slime molds (including Dictyostelium) • plasmodial slime molds

10. 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

11. 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)

12. 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

13. 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.

14. 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.

15. 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