Mutation rate is higher at synonymous sites than at nonsynonymous sites Synonymous sites 3.0 2.0 1.0 Nonsynonymous sites 1 3 Divergence time (x 10º) FIGURE 20-8 The amount of ure of purifying selec- how that synonymous ; they show that these nutations that change o effect on the amino nucleotide divergence at synonymous sites is greater than the amount of divergence at nonsynonymous sites of the B-globin gene. Number of substitutions per nucleotide

Suppose we are sure, because of previous studies, that species 1, 2, and 3 are more closely related to each other than to species 4 (outgroup). We sequence a gene and find ten nucleotide sites that differ among the four species. Draw the most parsimonious tree and label each evolutionary change on the tree (Position – new nucleotide; Example = 8T or 6C).    *The answer is below but I do not understand where the numbers or tick marks came from? Could someone explain. For example, why is the 1A on the 2?

We talked about what makes an ideal trait for phylogenetic inference. Please match each of the following traits with the appropriate description of what makes it ideal. There are only 10 possible MHC proteins [Choose ] that an individual's cells could express [Choose ] Number of digits on the front foot of Tetrapods can only increase in number You measured the [Choose ] mutation rates among DNA bases [Choose ] transition (mutation) frequencies are estimable Number of teats can polarity of character state is known character states are continuous character states are discrete vary, but an individual female can only have an even number number of states is known < <

If you found the same gene in all organisms you test, what could this suggest about the evolution of this gene in the history of life on earth?  What if a gene is very similar in most species that you study, but quite different in a particular group?  What if it’s present in nearly everything, but the specific sequences vary quite a bit?