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Published byClemence Elfreda Fitzgerald Modified over 9 years ago
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Nomenclature is the science of naming organisms Evolution has created an enormous diversity, so how do we deal with it? Names allow us to talk about groups of organisms. - Scientific names were originally descriptive phrases; not practical - Binomial nomenclature > Developed by Linnaeus, a Swedish naturalist > Names are in Latin, formerly the language of science > binomials - names consisting of two parts > The generic name is a noun. > The epithet is a descriptive adjective. - Thus a species' name is two words e.g. Homo sapiens Carolus Linnaeus (1707-1778) Hierarchical Classification vs. Systematics
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Taxonomy is the science of the classification (Hierarchical) of organisms Taxonomy deals with the naming and ordering of taxa. The Linnaean hierarchy: 1. Kingdom 2. Division 3. Class 4. Order 5. Family 6. Genus 7. Species Evolutionary distance
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Systematics is the science of how organisms are related and the evidence for those relationships Speciation -- the origin of new species from previously existing ones Reconstruct evolutionary history Phylogeny
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Hierarchical Classification
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Systematics
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Which pair is more closely related? A lizard/crocodile or bird/crocodile?
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Important Definitions Node: a branchpoint in a tree (a presumed ancestral OTU) Branch: defines the relationship between the taxa in terms of descent and ancestry Topology: the branching patterns of the tree Branch length (scaled trees only): represents the number of changes that have occurred in the branch Root: the common ancestor of all taxa Clade: a group of two or more taxa or DNA sequences that includes both their common ancestor and all their descendents Root Node Branch Clade
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Look at the cladogram at the right. What conclusions can be drawn about the relationship between humans and chimps?
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How to read a Cladogram This diagram shows a relationship between 4 relatives. These relatives share a common ancestor at the root of the tree. Note that this diagram is also a timeline. The older organism is at the bottom of the tree. Branches on the tree represent SPECIATION, the formation of a new species. The four descendents at the top of the tree are DIFFERENT species. This is called SPECIATION.
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How to read a Cladogram Species B and C each have characteristics that are unique only to them. But they also share some part of their history with species A. This shared history is the common ancestor
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A CLADE is a group of organisms that come from a common ancestor.
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