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Download Classification: What`s in a Name
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Classification and Beyond Chapters 19 Why do we name things? • To distinguish one thing from another • To communicate with others more effectively • It forces us to examine things more closely and make distinctions Classical Taxonomy – the Binomial System • Carl von Linné (a.k.a.) Carolus Linnaeus • Binomial nomenclature – each organism gets two names, a genus name and a species name. These are always used together. You cannot use a species name without the genus name. If you ordered americanus in a restaurant …. • Homarus americanus – lobster • Ursus americanus – black bear • Bufo americanus – American toad 3 Domains • Archaea • Eubacteria • Eukarya • Kings Play Chess On Fine Grained Sand: Kingdom Phylum Class Order Family Genus Species Taxon - a group of organisms at any particular level in this system Biological Species Concept • Biological species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups. • Reproductive unit • Genetic unit • Ecological unit Phenetics • Based on observable characteristics • Uses “yes or no” questions • “numerical taxonomists” – Choice of characteristics is subjective – Groupings unrelated to evolution – Environment affects some characteristics more than others Cladistics • Produce evolutionary trees • Groupings include the ancestral species and all its descendants – Monophyletic • Uses physical characteristics, fossil record and sequences of proteins and genes • Sometimes it agrees with classical taxonomy and sometimes it does not DNA and protein sequencing • Evolve the same way as other characteristics – homologous or analogous? • Also involves subjective choices • Noncoding DNA tends to change at a more constant rate – can be used as a “molecular clock.”
