An Introduction to Geometric Morphometrics and Intraspecific Variation

Abstract

It is quite peculiar that since its renaissance, geometric morphometries has been little associated with the study of variation among closely related taxa. This is true despite the fact that the potential oflandmark-based morphometries has been widely explored during earlier morphometric workshops (see Rohlf and Bookstein, 1990; Marcus et al., 1993), where they proved to be powerful tools for investigations in systematics (for example, Loy et al., 1993). One important contribution from this NATO Advanced Study Institute volume is the relatively large number of papers addressing intraspecific variation, the subject of this section. These papers confirm that geometric morphometries is maturing as one of the more powerful techniques for the description and interpretation of patterns of variation below the species level. The analysis of closely related groups, such as populations, demes and subspecies, often implies the comparison of very similar shapes, differing only in slight relative displacements of landmarks. This means that landmarks are more likely to be homologues when comparing different shapes. The absence of homology among landmarks for more distantly related taxa is a major problem for landmark morphometries.