  At Alife VI, Mark Bedau proposed some evolutionary statistics as a means of
classifying different evolutionary systems. Ecolab, whilst not an artificial
life system, is a model of an evolving ecology that has advantages of
mathematical tractability and computational simplicity. The Bedau statistics
are well defined for Ecolab, and this paper reports statistics measured for
typical Ecolab runs, as a function of mutation rate. The behaviour ranges from
class 1 (when mutation is switched off), through class 3 at intermediate
mutation rates (corresponding to scale free dynamics) to class 2 at high
mutation rates. The class 3/class 2 transition corresponds to an error
threshold. Class 4 behaviour, which is typified by the Biosphere, is
characterised by unbounded growth in diversity. It turns out that Ecolab is
governed by an inverse relationship between diversity and connectivity, which
also seems likely of the Biosphere. In Ecolab, the mutation operator is
conservative with respect to connectivity, which explains the boundedness of
diversity. The only way to get class 4 behaviour in Ecolab is to develop an
evolutionary dynamics that reduces connectivity of time.
