COMPARATIVE PATTERNS OF GROWTH AND DEVELOPMENT IN CRICETINE RODENTS AND THE EVOLUTION OF ONTOGENY

The quantitative description of growth curves for morphometric traits provides a basis for assessing the ontogenetic patterns underlying differences in morphological structure, as demonstrated with comparisons among neotomine-peromyscine rodents. Morphometric differences among contemporary rodent species are shown to result from relatively simple changes in relative growth rates and timing. Quantitative ontogenetic studies add a dynamic component to the assessment of morphological similarity, thus providing a more robust procedure for detecting homoplasy than static comparison of adult morphology. Applying the principles of phylogenetic systematics to studies of developmental timing among closely related taxa may be a useful and informative complement to studies based on molecular similarity or static comparison of adult morphology. Interspecific and intraspecific differences in allometric scaling of anatomical structures may reflect differences in growth patterns among the taxa compared; caution is warranted in inferring patterns of genetic correlation from data on phenotypic scaling.