You are interested in finding out how the budding yeast Saccharomyces cerevisiae is so good for making bread and have collected five new related species from the wild.You sequence the genomes of all of these new species and also consult with a fungal biologist to help you construct the phylogenetic tree shown in Figure 9-19.You find that species V, W, and X make pretty good bread whereas species Y and Z do not, suggesting that the last common ancestor of species X and S.cerevisiae may have the genes necessary for making good bread.You compare the gene sequences of species X and S.cerevisiae and find many identical coding sequences, but you also identify nucleotides that differ between the two species.Which species would be the best to examine to determine what the sequence was in the last common ancestor of species X and S.cerevisiae? 
Figure 9-19
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