BIS 2C Lecture Notes - Lecture 4: Pyrimidine, Purine, Synapomorphy
29 Aug 2016
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There are three informative characters: c1, c6, c7. There are three uninformative characters: c2, c3, c4, but they still add length (1 step) It"s only 1 step bc all the way through there"s only 1 step, but if there"s 2 steps for all the trees, then add 2 steps. There is one invariant character: c5 b/c it is all the same character state. Sowhen calculating the number of evolutionary steps of all the possible unrooted trees, make sure to add length for uninformative characters. Clicker question: we use unrooted trees b/c it makes it easier to discover synapomorphies. False b/c we don"t know where the root is situated so we don"t know which taxon is monophyletic to each other. Most data sets have more than four taxa. The number of possible trees increases very fast, so it is impossible to evaluate every tree.
