At both locations, the log gill-to-palp mass ratios of
bivalves fall along a gradient from small values typical
of deposit-feeding species to large values typical of
suspension-feeding species (Beesley et al. 1998). This
indicates the use of a wide spectrum of feeding modes
at each location. However, within the Roebuck Bay
assemblage, the log gill-to palp mass ratios displayed a
striking amount of morphological overlap within the
larger total morphospace occupied. Part of the high
morphological overlap is correlated with phylogeny,
e.g. members of the family Tellinidae show considerable
overlap in log gill-to-palp mass ratios typical of
deposit feeders. Phylogeny plays an important role in
morphospace occupation, as genetic relatedness is an
inherent property of the natural systems that we investigate;
however, it is not solely responsible for the
morphological overlap, as the taxonomic distinctness
values indicated no correlation with morphological