Phylogenetics Flashcards
Synapomorphies
Shared, derived characteristic (shared due to inheritance from a common ancestor); define monophyletic groups (clades)
Phylogenetic Trees
Describe the evolutionary relationships of organisms; hypotheses based on data; illustrates ancestor-descendant relationships among organisms
Monophyletic Group
An evolutionary unit (lineage) that includes an ancestral species and all its descendants, but no others; can be inferred by parsimony; groups represent shared ancestry/evolutionary groups
Homology
Traits are similar due to shared ancestry (e.g., fruit fly Hox gene and human Hox gene)
Homoplasy
Traits are similar due to convergent evolution (e.g., dolphin vs. ichthyosaur); when species based on homoplasy (polyphyletic groups), groups do not represent shared ancestry/not evolutionary groups
Phylogeny
Evolutionary history of a group of organisms
Branch
Represents an organismal group (lineage) through time
Nodes
Time point when an ancestral species split into 2+ descendant species; ancestral species - most recent common ancestor (MRCA) of a class
Tip (Terminal Node)
Represents an extant organismal group (e.g., populations, species, family, etc.)
Root
Common ancestor of all tip species
Arbitrary Branch Length
Branch lengths are arbitrary; focus is on the branching pattern, which estimate evolutionary relationships among populations
Genetic Difference Branch Length
Horizontal branch lengths show the extent of genetic difference among populations (e.g., number of base substitutions per site)
Evolutionary Time Branch Length
Horizontal branch lengths show the extent of evolutionary time between nodes (e.g., millions of years ago)
Morphology
Anatomy; type of data used to construct phylogenetic trees
Genetic Data
RNA, DNA; type of data used to construct phylogenetic trees
