Imagine you have 100 related organisms in a bag with PRO written on it. You take 10 and put them in a bag with EUC written on it. Then you sequence everything—and calculate what fraction of the total number of genes are found in both bags—and you come back with 64%.
That this is less than 100% doesn’t represent the genomes in the EUC bag changing. It just means that you selected a small sample from the PRO bag. Choose 5 and the figure would have been smaller. Choose 50 and the figure would have been bigger.
Imagine you have 100 related organisms in a bag with PRO written on it. You take 10 and put them in a bag with EUC written on it. Then you sequence everything—and calculate what fraction of the total number of genes are found in both bags—and you come back with 64%.
That this is less than 100% doesn’t represent the genomes in the EUC bag changing. It just means that you selected a small sample from the PRO bag. Choose 5 and the figure would have been smaller. Choose 50 and the figure would have been bigger.