Classification

Concepts/ideas/notes:

Definitions:

1. Taxonomy (systematics) – science of grouping organisms according to their presumed natural relationships. 
2. Aristotle – Greek philosopher who first classified organisms as either plant or animal
3. Carolus Linnaeus (1707-1778) – first modern classification system, binomial system
4. Binomial System (scientific name) – two term name of an organism (Genus and species)
5. Subspecies (ssp) – subspecies of a species I morphologically different and often geographically separated. Ex. Northern timber wolf, Canis lupus ssp. Occidentalis
6. Variety – morphologically different but not separated geographically.  Ex peaches, Prunus persica var. persica
7. Strain – used in reference to microorganisms, it is a biochemically dissimilar group within a species.
8. Genus (Genera) – first word of an organism’s polynomial name and the “kind” of organism it is.
9. Species – the individuals name in a genus
10. Specific Epithet (species) – second part of the name of an organism in a binomial naming (nomenclature).  A specific epithet is always preceded by the genus name or initial letter and both genus and species are either printed in italic or underlined. Eg. Quercus alba (white oak)
11. Type Specimen – specimen housed in a museum (collection), which serves as a basis for comparison with other specimens in determining classifying a species.  A specific epithet is always preceded by the genus name or initial letter and both genus and species are either printed in italic or underlined. Eg. Quercus alba (white oak).
12. Dichotomous Key – written set of choices that leads to the name of the organism
13. Kingdom – most inclusive unit used in biological classification: Eubacteria, Archaebacteris, Protista, Animalia, Fungi, Plantae
14. Plant Families – names end in –aceae  (exceptions: Leguminosae, Umbelliferae, Compositae)
15. Plant Orders – end in – ales
16. Phylogeny –an evolutionary history
17. Phylogenic Tree – a visual model of the inferred evolutionary relationships among organisms.  The main branches and the trunk of the tree represent the organisms from which the recently evolved organisms arose.  The species shown at the tips of the branches represent those organisms that have evolved most recently.
18. Biosystemics – branch of taxonomy that examines reproductive compatibility and gene flow.  They assess the genetic variation in a population and among species and make inferences about ancestral history of a species.  Essentially they study speciation.

Evidence Used in Classification:

1. morphological features – physical structure of an organism
2. embryological origins – often used for larger classification categories
3. chromosomal numbers and shapes – counting chromosomes may kink species
4. biochemical – genetic similarity of amino acids, acid sequences, DNA, RNA , and proteins.
5. Physiology – the processes of how an organism metabolizes substances such as sugars

Classification Categories:

Animals:

Kingdom, phylum, class, order, family, genus, species

Plants:

Kingdom, division, class, order, family, genus, species

Classifications:

1. Eubacteria – prokaryotic bacteria
2. Archaebacteria – prokaryotic extremophile bacteria
3. Monera – made up of prokaryotic organisms, which lack nuclei and other membrane-bound organelles (basically the bacteria). Many obtain nutrients primarily through absorption while others are autotrophic, producing food either by photosynthesis or chemsynthesis.  Most reproduce asexually although some may exchange genetic material.
4. Protista – eukaryotic organisms lack specialized tissue systems but have a true nuclei and membrane bound organelles.  They live in aquatic or moist habitats and obtain their food by igestion, absorption, or photosynthesis.  They reproduce sexually or asexually.  They includes heterogeneous assemblage of unicellular, colonial, and multicellular eukaryotes that do not have the distinct characteristics of animals, plants, or fungi.  This includes protozoa (one-celled animals), all algae except cynobacteria (blue-green algae), water molds (Oomycota), chytrids (Chytridiomycota), cellular slime molds (Acrasiomycota), and the plasmodial slime molds (Myxomycota).
1. have cell division and/or sexual reproduction
2. motile by 9-plus2 flagella or cilia or non-motile
5. Animalia – the animal kingdom consists of heterotrophic, multicellular organisms with eukaryotic cells lacking cell walls, plastids, and photosynthetic pigments.
1. lack cell walls, plastids, and photosynthetic pigments
2. nutrition is primarily ingestive with digestion in an internal cavity except for some that are absorptive due to a lack of an internal digestive cavity
3. sexual reproduction
4. motile based on contractile fibrils
5. high level of cell and tissue differentiation
6. Fungi – heterotrophic, unicellular or multicellular, non-motile, filamentous eukaryotes that lack plastids and photosynthetic pigments and absorb their nutrients from either dead or living organisms.
1. sexual (spores) or asexual reproduction
2. matrix of chitin in cell walls
3. filamentous growth habit
7. Plantae – autotrophic, photosynthetic, multicellular organisms composed of vacuolated eukaryotic cells with cellulosic cell walls.
1. both sexual and asexual reproduction
2. photosynthetic meiosis results in spores not gametes
3. cellulosic cell walls
4. have vacuoles (storage organelles)