More genetic data is available than ever before to help build evolutionary trees, but scientists are finding that different genes even in the same organism can tell conflicting stories.
According to a new study partly focused on yeast, the conflicting picture from individual genes is even broader than scientists suspected. “They report that every single one of the 1,070 genes conflicts somewhat,” saidMichael Donoghue, an evolutionary biologist at Yale who was not involved in the study. “We are trying to figure out the phylogenetic relationships of 1.8 million species and can’t even sort out 20 [types of] yeast,” he said.
To resolve this paradox, the researchers developed an algorithm, based on information theory, to gauge the level of certainty in specific parts of the tree. They hope the new approach will help to clarify periods of evolution that are potentially the most illuminating but also the most conflicted, such as the Cambrian explosion — the rapid diversification of animal life that occurred about 540 million years ago.
“Historically, the areas of the tree of life that have attracted a lot of attention and disagreement usually have to do with the most interesting episodes,” such as the origins of animals, vertebrates and flowering plants, said Antonis Rokas, a biologist at Vanderbilt University who led the new study.
Based on the results of the new algorithm, scientists can select only the most informative genes to build phylogenetic trees, an approach that could make the process more accurate and efficient. “I think it will help us quite a bit in speeding up the reconstruction of the tree of life,” said Khidir Hilu, a biologist at Virginia Tech in Blacksburg.