Morphometric identification of individuals when there are more shape variables than reference specimens: a case study in Galápagos tortoises.

Molecular biology techniques are useful for taxonomic assignment, but they are not always accessible and can be expensive and time consuming to perform. Morphological methods to identify the origin of individuals could be valuable if they can be performed rapidly, accurately, and with minimal resources. In order to correctly assign the origin of individuals from two distinct tortoise lineages, we studied here the accuracy of shape statistics depending on the inclusion of different numbers of shape components. Misleading assignment may occur if an optimal balance between the number of shape variables and the number of sampled individuals is not respected, especially when more variables than specimens are available. Assignment of museum samples of unknown origin suggests that they mostly belong to only one of the two lineages.