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 ( ) Hierarchical Classification vs. Systematics

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

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

Hierarchical Classification

Systematics

Which pair is more closely related? A lizard/crocodile or bird/crocodile?

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

Look at the cladogram at the right. What conclusions can be drawn about the relationship between humans and chimps?

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.

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

A CLADE is a group of organisms that come from a common ancestor.