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SBI3UE Chapter 5.3 Classification of Biodiversity (Three domains…
SBI3UE Chapter 5.3
Classification of Biodiversity
Hierarchy of Taxa
Binomial system: genus name (upper-case) + species name (lower-case), underlined or italics in printed text → abbreviation for genus name allowed after it has been used once
Three domains
Bacteria (no histones associated w/ DNA, rare presence of introns, peptidoglycan cell walls)
Archaea (proteins similar to histones bound to DNA, introns present in some genes, not peptidoglycan cell walls): found in broad/extreme range of habitats
Eukaryota (histones associated w/ DNA, frequent introns, not peptidoglycan cell walls/cell walls not always present)
Hierarchy: kingdom → phylum (division) → class → order → family → genus → species
Natural classification: molecule methods that show all members of genus/higher taxon have common ancestor
Advantages
Easier identification: assigning unknown organism through the hierarchy makes it easy + use of dichotomous keys
Dichotomous key: division into two (one is a clear match; other is wrong) → each of the pair leads to another of the numbered pairs of descriptions or to identification
Similar characteristics inherited/allows prediction of characteristics of species
Reclassification: new evidence shows that members of group do not share common ancestor → group split up into 2+ taxa, and vice versa
Disadvantages
Convergent evolution can make distantly related organisms appear similar
Adaptive radiation can make closely related organisms appear different
Phyla
Animal
Porifera: internal needles (spicules), pores for filter feeding
Cnidaria: radial, mostly soft, tentacles around mouth
Platyhelminthes: soft (no skeleton), flat and thin
Mollusk: obvious CaCO3 shell, mantle secretes shell
Annelida: segmented, bristles, visible blood vessels
Arthropod: external chitin exoskeleton, jointed legs
Chordata
Vertebrates
Bony fish: bony plates/scales, gills, fins
Amphibian: moist permeable skin
Reptilia: impermeable skin/keratin scales, four legs, one tpe of teeth
Aves/birds: skin made of keratin-rich feathers, 2 legs and 2 wings, beaks
Mammalia: skin w/ follicles, sweat glands, alveoli, most have live birth and feed w/ mammary glands, have molars
Plant
Bryophyte: no vascular tissue (true roots/leaves), spores
Filicinophyte: spores
Coniferophyte: male gametes in cones, ovule in female cones
Angiospermophyte: fruits, protected seeds, ovules within ovaries of flowers; male gametes in anthers of flowers