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Taxonomy and Systematics

Humans have named things of importance to us since the dawn of communication (eat this, run from that...) But how do scientists organize living things and what are the levels of organization they use to describe relationships between groups? Aristotle and Linnaeus take starring roles here, but there's a lot they got wrong. Want more? Subscribe:    / thepenguinprof   FB Page:   / thepenguinprof   Twitter:   / penguinprof   Web: http://www.penguinprof.com/ -------------------------------------------------------------------------------------------------------------------- VIDEO DETAILS Taxonomy and Systematics Taxonomy (G taxis: arrangement; nomia: method) is the discipline of defining groups of biological organisms on the basis of shared characteristics Hierarchical groups help us to identify related organisms and also describe evolutionary relationships Aristotle To understand anything, one must classify it according to it's parts Classified all animals into two groups: blooded and bloodless Pliny the Elder Carl Linnaeus Systema Naturae 10th ed. in 1758 Binomial Nomenclature Where do the Names Come From? Latin (Classical or Medieval) Classical Greek Names of People Names of Places Other Languages What's In a Name? Morphologic Characters General external morphology Special structures Internal morphology Embryology Karyology and other cytological factors Physiological Factors Metabolic factors Body secretions Genic sterility factors Molecular Characters Immunological distance Electrophoretic differences Protein sequences DNA hybridization DNA and RNA sequences Restriction endonuclease analyses Other molecular differences Behavioral Characters Courtship and other ethological isolating mechanisms Other behavior patterns Ecological Characters Habitats and hosts Food Seasonal variations Parasites Host reactions Geographic Characters General biogeographic distribution Sympatric-allopatric relationship of populations Levels of Organization Linnaeus' Domains Linnaeus Described Six Classes of Animals Heart with 2 auricles, 2 ventricles. Warm, red blood Viviparous: Mammalia Oviparous: Aves Six Classes of Animals Heart with 1 auricle, 0 ventricles. Cold, puss-like blood Have antennae: Insecta Have tentacles: Vermes Hierarchy of Similarities Modern 3-Domain System Domain Kingdom Phylum (= Divisions in Botany) Class Order Family Genus Species Example: The Dog Problems... Linnaeus (and everyone else) wondered about where these species came from and how to define a species Linnaeus treated species as immutable Georges-Louis Leclerc, Comte de Buffon Compared living and fossil mammals (elephants and mammoths) He did not see how organisms could cross inhospitable boundaries to reach suitable environments He found different kinds of animals and plants in very similar, but completely isolated environments Age of Enlightenment Paleontology and the discovery of extinct species in the fossil record began to undermine the static view of nature which had persisted since Aristotle Species are NOT Fixed Entities Taxonomy and systematics is a dynamic science