Cladistics 13,1–20 (1997) WWW http://www.apnet.com Marine Area Relationships from Twenty Sponge Phylogenies. A Comparison of Methods and Coding Strategies Rob W. M. van Soest1 and Eduardo Hajdu1,2 1Institute for Systematics and Population Biology (Zoölogisch Museum), University of Amsterdam, P.O. Box 94766, 1090 GT Amsterdam, The Netherlands and 2Departamento de Invertebrados, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta de Boa Vista, 20940–040, Rio de Janeiro, RJ, Brazil and Centro de Biologia Marinha, Cx. Postal 83, 11600–970, São Sebastião, SP, Brazil Accepted 6 March 1997 Published phylogenies of 20 marine sponge groups are available sponge phylogenies are representative of used to build general area cladograms of marine areas of marine benthic groups, software and hardware limita- endemism under three different methods for which algo- tions are serious obstacles to a successful development rithms adapted for personal computers are available, viz. of marine general area cladograms under any method or COMPONENT, BPA and TAS, and two different coding coding strategy. © 1997 The Willi Hennig Society 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 INTRODUCTION contained large numbers of problem data which pre- vented an exhaustive search for all possible equally “best” general area cladograms. The Nelson consensus Marine sponges are organisms fixed on a firm sub- trees and their equivalents in parsimony analysis for all strate and possessing a free swimming larva capable of six attempts (viz. three different methodologies under limited propagation (Bergquist, 1978). Sea water tem- two different coding strategies) were compared using perature limits reproductive activity and growth (e.g. their fit with the 20 sponge phylogenies as a measure of Vethaak et al., 1982; Wapstra and van Soest, 1987). quality. Fit was determined using the number of “cospe- Sponge distributions reflect these life history traits. ciations” between a general area cladogram and a taxon area cladogram computed with TreeMap 1.0. No single Barriers between areas of endemism are land masses, method or coding strategy yielded a clearly better fit, oceanic depths and isotherms (van Soest, 1994). Still, each cladogram fitting variously better or worse with var- over geological time, adaptation to almost any marine ious phylogenies. In general, fit with NA coding was habitat has occurred resulting in cosmopolitan distri- higher than with A0 coding, but random tree tests failed butions of higher taxa. At lower taxonomic levels to generate statistically significant support for the con- (genera and species groups) four clearly demarcated clusion that NA coding improves fit. Assuming that patterns are found: cosmopolitan warm water 0748-3007/97/010001+20/$25.00/0/cl970035 Copyright © 1997 by The Willi Hennig Society All rights of reproduction in any form reserved 1 2 van Soest and Hajdu (tropical/subtropical); restricted Indo-Australian; Arc- Indo-West Pacific), numbers of phylogenies (van Soest, tic-Boreal; and Antarctic-Antiboreal (van Soest, 1994). 1993: four; Hooper and Lévi, 1994: three, Hajdu, 1995: Information on distributions of individual species is seven), and analytical methods (De Weerdt, 1989) and still incomplete and it is estimated that only about half van Soest (1993): Component Compatibility (Zandee the number of species are known to science (Hooper and Roos, 1987); Hooper and Lévi (1994): BPA (Wiley, and Wiedenmayer, 1994). Nevertheless, patterns of 1988). Hajdu (1995) was the first among sponge bioge- species distributions are emerging (van Soest, 1994) ographers to use several alternative methods: and they seem to conform largely to schemes formu- Component Analysis (Nelson and Platnick, 1981; Page, lated by Ekman (1953) and Briggs (1974). At the 1990), BPA, and Panbiogeography (Craw, 1988). In present time, about 35 areas of endemism may be rec- other marine benthic groups attempts at cladistic bio- ognized (van Soest, 1994), defined by the presence of at geography have also been made (e.g. molluscs: Reid, least several, and in many cases large numbers of, 1990). The results of these attempts give conflicting endemic sponge species. There are also many species answers, probably because numbers of phylogenies which have wider distributions covering several of the were inadequate, and no results comparable to those of 35 areas of endemism, for example the Mediterranean– land organisms have so far been obtained (e.g. Crisci et Atlantic distribution which involves the Eastern and al., 1991; Oosterbroek and Arntzen, 1992). However, Western Mediterranean, North-East Atlantic and West whereas marine cladistic biogeographical data in most Africa. Seven of these “wide” distributions have been groups are still scarce and apparently do not show recognized as recurring frequently in distantly related much congruence, there are currently 20 published sponge groups (van Soest, 1994). It is also possible that area cladograms of sponge groups available, together finer patterns of endemism may need to be recognized covering most of the 35 areas of endemism. Although in the future (suggested by Hooper and Lévi, 1994), but this data set is far from perfect—the clades are of so far evidence is lacking. widely different sizes and may cover considerably dif- The large areas of endemism and the nature of the ferent sets of areas of endemism—it prompted us to abiotic barriers indicate that most marine sponges have make the first serious attempt to find general patterns diverged in a process of slow allopatric speciation in of marine area relationships. Because many of the areas the sense of Palumbi (1992). Under this paradigm of of endemism considered are also recognized in other geographical speciation, several attempts have been marine benthic groups, the results presented here may made to analyse marine sponge distributions to find be of wider interest. out whether they can be correlated with present-day distributions of abiotic parameters and with the pro- posed history of the ocean basins. Methodologies for CLADISTIC BIOGEOGRAPHY these studies varied from comparing lists of species occurring in various areas (Boury-Esnault and Lopes, 1985; van Soest, 1993; Desqueyroux-Faúndez, 1994), The aim of cladistic biogeography is here understood numbers of species of genera occurring in various as the reconstruction of the history of areas of ende- areas (van Soest, 1989, 1993, 1994), and phylogenies of mism (not geographical areas, although these may sponge groups (De Weerdt, 1989; van Soest, 1993; coincide), using phylogenies of organisms as input Hooper and Lévi, 1994; Hajdu, 1995). data (see also Morrone and Crisci, 1995: figure 5). This The latter method, cladistic biogeography (Hum- history of areas of endemism takes the form of a gen- phries and Parenti, 1986), is superior over other eral area cladogram and from this scenarios of analytical methods such as determining degrees of diversification of individual organism groups may be area similarity because it uses phylogenies as building derived in an objective manner. blocks for general area cladogram construction, ensur- Cladistic biogeography methods are still under ing that historical events are not obliterated by development, and several competing approaches have present-day ecogeography. The attempts cited above appeared in the literature. Relatively established, rival were limited in areas (De Weerdt, 1989: only the North methodologies are Component Analysis (Nelson Atlantic considered; Hooper and Lévi, 1994: only the and Platnick, 1981; Humphries and Parenti, 1986; Copyright © 1997 by The Willi Hennig Society All rights of reproduction in any form reserved Marine Area Relationships 3 Page, 1990), and Brooks’ Parsimony Analysis (Brooks, cladograms by employing different coding for the 1981; Wiley, 1988), with its sibling “Component Com- same area in different positions in the cladogram. patibility Analysis” (Zandee and Roos, 1987). A Thus, they potentially solved both the problem of method recently formulated is “Three-Area State- redundant distributions and the single presence of ments” Analysis (TAS) (Nelson and Ladiges, 1991, areas in the general area cladogram. A similar solution 1996). Component Analysis attempts to find general is available for the presence of “wide” distributions in patterns by seeking the congruent parts of individual taxon area cladograms: “no assumption” recoding. taxon area cladograms; BPA and TAS use Wagner Tree parsimony (Farris, 1983) to solve conflicting area rela- tionships. BPA converts all taxon area cladograms into “WIDE” DISTRIBUTIONS AND “NO a combined matrix of areas and taxa, whereas TAS con- ASSUMPTION” RECODING verts the area relationships of all nodes occurring in the taxon area cladogram into suites of three-area relation- ships, which are subsequently put into a matrix of In line with Brooks’ (1990) proposal, van Soest (1996) areas and “statements” (columns, each of which con- suggested a similar solution for the coding of distribu- tains a three-area relationship). tions of widespread taxa. Different groups have Despite claims of proficiency by its proponents, no different methods of dispersal (range extension with- method has been demonstrated to have a clear advan- out crossing barriers) and are affected differently by tage