Phylogenetic rate

Table 1.1). Out of the 400 distinct bacterial species in the colon, 30% of fecal isolates are of the genus Bacteroides. This phylogenetic group is characterized by a relatively high growth yield even at low rates, which enables it to compete successfully in this region of the intestine... 

Yokokawa, T., Nagata, T., Cottrell, M.T., and Kirchman, D.L. (2004) Growth rate of the major phylogenetic bacterial groups in the Delaware estuary. Limnol. Oceanogr. 49, 1620-1629. 

They found that prohibiting crossover between parents that are too close in ancestry improves the outcome of the search. The benefit of preventing phylogenetic incest is high for low mutation rates and then, at a critical mutation rate, reverses so incest prevention is deleterious. Because mutation is explorative, a low mutation rate was required to balance the extra exploration caused by incest prevention. 

Another way of obtaining indirect information on molecular evolution was offered by the study of phylogenetic trees. A typical example, in this field, is the comparison between amphibians and mammals. Both groups derived from a common aquatic ancestor, but amphibians evolved much more slowly. They share so many anatomical characters that a single order comprises most of them, while mammals differentiated into as many as sixteen distinct orders. Mammals clearly underwent a much faster phenotypic evolution than amphibians, and it seemed logical to conclude that, at the molecular level, the mutation rate has been much faster in mammals than in amphibians. 

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