Problem
Three bivalve species (A, B, and C) occur together. The observed half-of species A is 50 years, the observed half-life of species B is 100 years, and the observed half-life of species C is 200 years. The living community in a particular spot we sample is composed of 800 individuals of species A, 150 individuals of species B, and 50 individuals of species C. Imagine we (or our descendants) come back 100 years from now and sample the fossil remains of this community.
1. About how many individuals of species A would we expect to find?
2. About how many individuals of species B would we expect to find?
3. About how many individuals of species C would we expect to find?
4. Based on your answers above, explain how time-averaging acts to alter the relative abundance structure (that is, the relative proportions of individuals of different species) in fossil assemblages compared to the living communities from which they derive.