Halliday (1973) expounds the theory of metafunctions and shows the ontogenetic process in its manifestation in the language of the individual meaner.
Here, we have shown that evolutionary shifts in the reaction norm of another fundamental ontogenetic process – i.e., migration, an important life-history characteristic in salmonids – are also expected to result from elevated fishing mortality.
Concurrent appraisal of the ontogenetic processes producing variation in intestinal length, and the functional significance of these processes (i.e., associations with diet) in a phylogenetic context is similarly lacking.
Phenotypic diversity is produced by changes in ontogenetic processes occurring at earlier developmental stages.
Nonetheless, since the cranium starts to develop before birth [ 16– 18] and continues to develop until adulthood, it is fundamental to understand the ontogenetic processes, including a comparison of these processes in diverse groups of humans.
Hox genes play an important role in the specification of the primary body axis [ 56] as well as in later ontogenetic processes demanding highly specific regulation such as limb development [ 57].
Variation in AOC may also reflect early ontogenetic processes caused by maternal effects [54] [56].
An important question concerns the epigenetic mechanisms by which species differences in brain architecture arise during ontogeny, in particular the relative roles of early, genetically guided ontogenetic processes versus later processes influenced substantially by environmental input and/or hormones.
In terms of environmental contamination, these studies show that attention to ontogenetic processes, genetic background, developmental stage, timing and duration of exposure, and the interactions associated with mixtures is critical to quality risk assessment.
In addition to conceptual work on the biological bases of homology, variation, and parallel evolution, my research has focused on evolutionary changes in size and shape in mammals: the functional consequences of these changes, and the evolutionary modifications of ontogenetic processes that produce them.
