The historical proliferation of terms discussed in Chapter 1 created a formidable obstacle to the study of heterochrony for many years. It was in Gould’s (1977) Ontogeny and Phylogeny that the first successful simplification was achieved with the establishment of the “clock model.” Shortly thereafter, this semiquantitative scheme was modified in a widely cited paper by Alberch et al. (1979). Since then, McNamara (1986a) and McKinney (1986) have presented schemes based on allometry alone, with only partial success. More recently, McKinney (1988a) has attempted to present a simplified version of the Alberch et al. (1979) scheme. Each of these will be reviewed briefly because all are in use. However, lest the reader despair of a tyranny of schemes replacing the tyranny of terms, be aware that all schemes are very similar, with concepts and terms that deviate little from the original presentation of Gould (1977). The process has been mainly one of theoretical refinement and methodological simplification.
KeywordsBody Size Specific Growth Rate Shape Change Sexual Maturation Growth Field
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