Evolution and Biodiversity Laboratory Systematics and Taxonomy I ...

The hypothetical animals used in this exercise are called Caminalcules and werecreated and "evolved" by J. H. Camin, Professor of Biology at the University of Kansasin the 1960's. They have served as test material for a number of experimentsconcerning systematics, its theory and practice. Use of imaginary organisms for suchstudies offers a distinct advantage over using real groups, because preconceivednotions and biases about classifications and evolutionary relationships can beeliminated.Figure ST-4. A variety of Caminalcules, arranged in no particular order.Cladistics: Synapomorphies and CladogramsCarefully examine the eight Caminalcules illustrated in Figure ST-4. These will beyour Operational Taxonomic Units (OTUs)--a name we use to avoid assigning them toany particular taxonomic rank (such as “species”). You may think of them as biologicalspecies, and refer to them by number.Cladistic methods provide an objective and suitable way of inferring evolutionaryrelationships. Cladistics is sometimes known as quantitative phyletics. Rather thangrouping organisms on the basis of overall similarity, as in numerical taxonomy, theinvestigator using this method groups OTUs together on the basis of shared, derivedcharacters (synapomorphies)--characters whose presence or absence in two or moreOTUs is inferred to be the result of inheritance from their common ancestor.Results of a cladistic analysis are usually summarized in a phylogenetic tree called acladogram (from the Greek clad meaning "branch"), an explicit hypothesis ofevolutionary relationships.systematics-15