Is morphology still relevant?

Summary

The utility of morphological data in modern systematics has recently been challenged because strong selection pressures are thought to create widespread patterns of convergent evolution at this level. This concern has led to suggestions that morphological data should be excluded either from all analyses or at least from analyses where there is conflict with molecular data. These concerns, however, are generally unwarranted and excluding data is not a defensible strategy for dealing with problems that do exist. We emphasize the importance of empirical responses, such as collecting additional and diverse data and exploring taxa and data set interactions, rather than the implementation of a priori assumptions, to overcoming many of the concerns associated with combining morphological and molecular data. Numerous factors may create biases in both molecules and morphology. While these biases are prevalent enough to cause widespread incongruence, they highlight the importance of combining, rather than separating, data. Morphological data also offer distinct advantages over molecular data, such as the inclusion of fossil taxa, cost-effectiveness and the presence of biases different from those in molecular data.