Chapter 8 Flashcards
Apomorphy
Derived characteristic
Plesiomorphy
Preexisting/ancestral characteristic
Synapomorphy
Derived characteristic shared by multiple lineages
Paraphyletic
A common ancestor and all but one of its descendants
Polyphyletic
Some descendants (excluding more than one), but not including the common ancestor
Polytomy
Three-way split (three branches)
Convergent/Homoplasy evolution
Similar characteristics appearing in different lineages
Reversal
Loss of derived traits
Homoplasy
Similarity in character states due to convergence or reversal
Likelihood
Probability of the data given in a tree, it’s branch lengths, and a model of evolution
Molecular clock
Addressing questions about timing by analyzing molecular traits that change at a steady state
Neutral mutations
Change in an individuals DNA, but not their phenotype. Caused by genetic drift
Transitions
Evolutionary modifications
Root
The common ancestor of all descendants
Node
The common ancestor of the preceding descendants
Sister species
Each other’s closest relatives
Clade
A monophyletic group, an ancestor and all of its descendants
Explain one source of uncertainty in phylogenetic tree construction
Similar adaptations can evolve independently, known as convergent evolution.
Why are parsimonious trees not necessarily correct? Why, then, do we use parsimony?
They are not necessarily correct because evolution does not necessarily work in the fewest evolutionary changes of characteristics (Ockham’s razor). We still use it because it allows us to still make inferences when evidence is limited, and it can be justified as a statistical estimator of unknown phylogeny.
