Phylogenetic Vocab

• Synapomorphy 


  A Charater/trait that is present in the recent ancestor AND is shared by two or more organisms exclusive to that ancestor's decendants.
• Apomorphy


  A shared characteristic/trait between two or more groups of organisms but isn't found in the common ancestor.
• An apomorphy becomes a synapomorphy if they find that shared characteristic in their ancestor too.
• Symplesiomorphy

  An ancestral character state/trait shared by two or more taxa. These organisms may have very different derived characters, but you are looking back at the earliest ancestor and seeing the trait shared between that and the new descendants.
• The difference between symplesiomorphy and Synapomorphy is that the synapomorphy is referring to a derived trait shared between most recent common ancestor and its descendants--where as symplesiomorphy is looking at ANCESTRIAL traits that have been shared between EARLIEST common ancestor and its descendants.
• Monophyletic groups


  a Set of species that have a common ancestor and includes all of its descendants. AKA a complete clade.
• Mono refers to "same & All":


  Same shared ancestor and ALL descendants of that ancestor
• Paraphyletic Groups

  Ancestral species that include some, but not all descendants.
• Polyphyletic Group


  A set of species that descended from more than one common ancestor. Ultimate ancestor is NOT included.
• Para=Some descendants are included but not all. Same Ancestor. Not a complete clade
• Poly = more than one common ancestor is shared by different species.
• Phylogenetic trees tell us a story
• Nodes are points at the end of the tree's branches and represent divergences between species. They branch off to form tips.
• Character reversal is the reappearance of an old ancestral trait.
• Character reversal is like reverting back to an ancestral trait.
• Parsimony is when the simplest explanation is the correct one. Its to seek the simplest route
• A tree is considered parsimonious if it has the fewest number of evolutionary steps
• An example of autapomorphy is the presence of feathers on birds when comparing them to reptiles and mammals.
• Homoplasy, aka convergence, is a derived character trait that is common in different lineages but have evolved independently.
• An example of homoplasy is the evolution of wings among bats and birds. They both evolved a similar trait but don't even share a common ancestor.
• An example of convergent evolution is when arctic foxes and arctic birds both evolve to have a white phenotype but aren't even closely related to each other.