Terms

• Node


  Represent taxonomic units (diverge), a speciation event from a common ancestor

  
• Taxon/ Operational taxonomic units (OTUs)


  Represents the different observed species/ genes/ population
• Branches


  Show the path of transmission of genetic information from one generation to the next (Lineages)
• Clade


  Consists of an organism and all its descendants
• Branch Length


  Indicate genetic changes (the longer the branch, the more genetic change has occurred)
• Root


  Point of origin (Common ancestor)
• Monophyletic Group


  A group composed of a collection of organisms including the most recent common ancestor of all those organisms and all the descendants
• Paraphyletic Group


  A group where all the members share a common ancestor but where not all the descendants are included
• Polyphyletic Group


  A group where the members do not have a common ancestor
• Sister groups


  Two taxa which share the same immediate ancestor
• Outgroup


  Most distantly related group of organisms that's serves as a references group
• Evolution produces a pattern of relationships among lineages that is tree-like, not ladder-like
• There is no correlation with level of "advancement" when reading phylogenies from left to right
• The choice of which lineage goes to the right and which goes to the left in a speciation event is random
• Polytomy

  Nodes degree > 3 = Polytomy (one ancestor and more than two immediate descendants)
• Polytomy

  A node in a tree where the relationships among three or more taxa cannot be resolved, indicating uncertainty or lack of information about their evolutionary branching pattern

  
• Cladogram

  Most basic tree, shows relative recency of common ancestry

  
• Phylogram

  Depicts the amount of evolutionary change along the branches

  
• Dendogram (ultrametric tree)

  The tips of the tree are all equidistant from the root of the trees, depict evolutionary time

  
• Homology

  Reflects shared ancestry among different organisms, traits with homology typically have a common underlying structure, used extensively in evolutionary biology to infer relationships between species
• Homoplasy


  Describes similarities between organisms that arise independently, without shared ancestry, often occurs due to convergent evolution, parallel evolution, or evolutionary reversals
• Convergent evolution

  When unrelated organisms evolve similar traits or characteristics due to similar selective pressures in their environments
• Parallel evolution

  Similar to convergent evolution, but occurs when closely related species independently evolve similar traits after diverging from a common ancestor
• Secondary loss

  Instances where a trait that was present in an ancestor is lost in a descendant species but then re-evolves later in a different lineage
• Phylogenies form the basis of classification
• Classification is the formal naming of groups of organisms
• Phylogenetic classification recognize only monophyletic groups or clades
• APG IV

  An international group of systematic botanists who collaborate to establish a consensus on the taxonomy of all flowering plants, reflects new knowledge about plants, plant relationships discovered through phylogenetic studies