Reproduction with heritable variation is at the heart of any Darwinian evolutionary process. Through the inevitable collision between Malthusian growth and limited resources, it establishes the conditions for natural selection--quasi-deterministic displacements of one lineage by another. But more importantly for our purposes here, the patterns of variation establish the potential for continuing innovation, and ultimately, continuing growth of complexity.
Maynard Smith (1999, pp. 7-9) make a useful distinction between ``limited'' and ``unlimited'' heredity. The former exhibits heritable variation, but the total number of distinct reproductive variants is finite and rather small; the latter encompasses an indefinitely large number of distinct reproductive variants. We will be concerned throughout with evolutionary systems having unlimited heredity.
We know of just two clearly distinguished modes or processes for achieving reproduction with (unlimited) heritable variation. Many different terms have been coined for these; we will use ``template'' and ``genetic'' reproduction. Genetic reproduction is the more complicated--not least in the sense that it relies on already having a subsidiary template reproduction process at its disposal. Genetic reproduction also seems to be the more ``powerful'', in several distinct ways. Our primary purpose in this paper is to distinguish and elucidate these as clearly as possible.
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