BIOL 3040 Chapter : BIOL 3040 Ch 5 Objectives
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Selects as best the tree that is most probable given both the observed data and some prior assumptions about possible trees. To root this tree we pick another population that branched off earlier in evolutionary history from the entire clade that we are considering. We look to see how often the feature we are interested in occurs among them. But the chi-square test assumes that each sample evolved independently from one another. Another words, the test does not account for any shared evolutionary history among these species: now we can infer the evolutionary changes that gave rise to the characters that we observe. We note that the entire pattern has arisen from a single pair of evolutionary changes, one for each character. We still have evidence that nocturnal and arboreal life go hand-in- hand, because the two changes occurred on the same branch.
