Marine area relationships from twenty sponge phylogeneies. A comparison of methods and coding strategies

Published phylogenies of 20 marine sponge groups are used to build general area cladograms of marine areas of endemism under three different methods for which algorithms adapted for personal computers are available, viz. COMPONENT, BPA and TAS, and two different coding strategies, Assumption 0 (A0) and “no assumption” (NA). The latter is a recently proposed procedure for handling the distributions of widespread taxa by treating these as separate areas of endemism, rather than as suites of smaller constituent areas. The 20 phylogenies contained large numbers of problem data which prevented an exhaustive search for all possible equally “best” general area cladograms. The Nelson consensus trees and their equivalents in parsimony analysis for all six attempts (viz. three different methodologies under two different coding strategies) were compared using their fit with the 20 sponge phylogenies as a measure of quality. Fit was determined using the number of “cospeciations” between a general area cladogram and a taxon area cladogram computed with TreeMap 1.0. No single method or coding strategy yielded a clearly better fit, each cladogram fitting variously better or worse with various phylogenies. In general, fit with NA coding was higher than with A0 coding, but random tree tests failed to generate statistically significant support for the conclusion that NA coding improves fit. Assuming that available sponge phylogenies are representative of marine benthic groups, software and hardware limitations are serious obstacles to a successful development of marine general area cladograms under any method or coding strategy.