Contributions to Zoology, 81 (4) 199-221 (2012) Evolutionary trends in onshore-offshore distribution patterns of mushroom coral species (Scleractinia: Fungiidae) Bert W. Hoeksema1, 2 1 Department of Marine Zoology, Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, The Netherlands 2 E-mail: [email protected] Key words: competitive exclusion, ecophylogenetics, environmental gradients, habitat partitioning, niche differen- tiation, phylogenetic ecology Abstract Species co-occurrences based on abundance and incidence data ............................................................... 209 A phylogenetically based comparative analysis of onshore-off- Ordination of species co-occurrences ............................. 209 shore distribution patterns of mushroom coral species (Sclerac- Discussion ...................................................................................... 214 tinia: Fungiidae) was made to reconstruct an evolutionary sce- Onshore-offshore patterns ................................................. 214 nario for differentiation in fungiid shelf habitats. This phylo- Spatial partitioning and co-existence ............................. 214 ecological study integrates data on fungiid distribution patterns Phylogenetic ecology ........................................................... 215 along environmental gradients on the Spermonde Shelf, SW Acknowledgements ...................................................................... 217 Sulawesi, with a recently published phylogeny reconstruction of References ...................................................................................... 217 the Fungiidae. A mushroom coral fauna of 34 species was used to compare their distributions by use of 50-m2 belt quadrats in transects (1) from the mainland to the shelf edge, (2) around reefs with regard to predominant wind directions, and (3) over Introduction bathymetrical reef zones. Species association ordinations were made for each of the four shelf zones using both abundance and Most studies on biotic changes of marine faunas along incidence data to examine whether closely related species co- onshore-offshore gradients concern the evolution and occurred. Some closely related species or even sister species extinction of taxa as represented in the fossil record. appeared to show very similar distribution patterns and to co- exist in high abundances. These results indicate that there may The general scenario is that marine faunas in the Phan- not be community saturation and competitive exclusion among erozoic originated in shallow coastal seas and expanded mushroom corals species, most of which are free-living. In re- from there into deep offshore ecosystems, but also that constructions of fungiid habitat evolution, offshore reef slopes some of the younger lineages may have originated in appear to be original (ancestral), whereas onshore habitats, less stable nearshore environments (Jablonski and Val- shallow reef flats, and deep sandy reef bases seem to be derived. The latter is in contrast with an earlier hypothesis, in which entine, 1981; Jablonski et al., 1983; Valentine and Ja- deep sandy substrates were considered ancestral mushroom blonski, 1983; Jablonski and Bottjer, 1988, 1990; Sepko- coral habitats. ski, 1991; Jacobs and Lindberg, 1998). With an increas- ing availability of phylogeny reconstructions based on molecular methods it is also possible to use recent taxa Contents in studies on evolutionary trends in habitat preferences. Only few examples are known from the marine realm. Introduction ................................................................................... 199 For instance, Lindner et al. (2008) found that recent sty- Material and methods .................................................................. 201 lasterid corals (Hydrozoa: Stylasteridae), the second Study area ............................................................................... 201 largest group of hard corals, evolved mainly in the deep Data sampling ....................................................................... 201 Phylogeny reconstruction ................................................... 202 sea, and invaded shallow waters from there. Evolution of onshore-offshore and bathymetric Studies of onshore-offshore distribution patterns distribution ranges ............................................................... 204 of recent coral reef species usually concern shallow, Species co-occurrences: cluster analyses of tropical shelf seas, with various examples known abundance and incidence data ......................................... 204 from the Great Barrier Reef (Done, 1982; Williams, Ordination of species co-occurrences ............................. 204 Results ............................................................................................. 205 1982; Dinesen, 1983; Williams and Hatcher, 1983; Onshore-offshore distributions ......................................... 205 Russ, 1984; Wilkinson and Trott, 1985; Preston and Evolutionary trends in cross-shelf distributions .......... 205 Doherty, 1990, 1994; DeVantier et al., 2006) and the Downloaded from Brill.com10/04/2021 01:37:58PM via free access 200 Hoeksema – Evolution of cross-shelf mushroom coral distributions Spermonde Archipelago in southwest Sulawesi (Moll, come available, which enabled an evolutionary study 1983; de Beer, 1990; Hoeksema, 1990, 2012; Verheij of their life history traits (Gittenberger et al., 2011) and and Prud’homme van Reine, 1993; Troelstra et al., their associated fauna (Hoeksema et al., 2012). In ad- 1996; de Voogd et al., 1999, 2006; Renema et al., 2001; dition, field data on the cross-shelf bathymetric distri- Cleary et al., 2005; Becking et al., 2006; Cleary and bution patterns of 34 mushroom coral species were de Voogd, 2007; Hoeksema and Crowther, 2011). To obtained on the Spermonde shelf (Hoeksema, 2012). study the evolutionary history of cross-shelf distribu- Use of their phylogenetic relations may help to clarify tion patterns, it would be ideal to use a phylogenetic the evolution of their habitat preferences along envi- ecological model in which detailed information on ronmental gradients, like depth (reflected in reef zona- onshore-offshore distributions can be combined with tion) and increasing distance from the mainland in a a phylogeny reconstruction of a monophyletic species direction from onshore to offshore. group abundantly represented in various shelf habitats. Mushroom corals are suitable for such studies be- A recent molecular phylogenetic study of 50 mush- cause most species have an adult free-living (antho- room coral species (Scleractinia: Fungiidae) has be- cyathus) phase in their life history (Wells, 1966; o 119 5‘ 10‘ 15‘ 20‘ 25‘ 30‘ 4A 5o 2A N 4B 3A 1A 2B 5‘ 3B 3C 1B m Tello 2C 1C 1D 100 2D MAKASSAR STRAIT 1D Makassar 10‘ Jene Berang Zone 4Zone3 Zone2 Zone 1 5 km Fig. 1. The locations of 52 transects around coral reefs in four zones on the central section of the Spermonde Shelf where mushroom coral abundances were measured. The names of the reefs are listed in Table 1. After Hoeksema (2012). 0 10 20 Depth (m) 30 40 oshore oshore onshore 50 60 Zone 4 Zone 3 oshore Zone 2 Zone 1 40 30 20 10 0 Distance oshore (km) Fig. 2. Schematic cross-section of the central Spermonde Shelf (approximately W-E) from the Makassar Strait to the mainland. After Hoeksema (2012). Downloaded from Brill.com10/04/2021 01:37:58PM via free access Contributions to Zoology, 81 (4) – 2012 201 Hoeksema, 1989), which enables them to inhabit vari- itats could indeed have been representative for the ear- ous kinds of substrata, including sandy reef bases liest mushroom corals. (Goreau and Yonge, 1968; Fisk, 1983; Chadwick, 1988; Hoeksema 1988, 2012; Chadwick-Furman and Loya, 1992). Initially, mushroom corals are attached to a Material and methods hard substratum, but individuals of free-living species eventually detach themselves (Yamashiro and Yamaz- Study area ato, 1987a, b, 1996; Hoeksema, 1989; Hoeksema and Yee min, 2011). About 20% of all mushroom coral spe- Mushroom coral distribution patterns were studied on cies remain attached after settlement on a solid sub- the central part of the Spermonde Shelf, off southwest strate. They belong to the genera Cantharellus (n=3), Sulawesi in the southern Makassar Strait, which bears Cyclo seris (n=3), Lithophyllon (n=2), and Podabacia a large group of cay-crowned reefs and shoals known (n=4) (see Hoeksema, 1989, 1993a, 2009; Benzoni et as the Spermonde Archipelago (Fig. 1). The reefs are al., 2012). arranged in parallel rows in N-S direction, in between Mushroom corals usually occur in mixed multi- the coastline of SW Sulawesi and the outer barrier species assemblages (Pichon, 1974; Claereboudt, 1988; reef, which is situated about 40 km from the mainland Hoeksema and Moka, 1989; Hoeksema 1991b, 2012; in the study area (Hoeksema, 1990, 2012). The shelf Latypov, 2007; Elahi, 2008; Hoeksema and Koh, 2009; can be divided into four zones from the coastline to the Hoeksema and Matthews, 2011). High concentrations westward shelf edge (Figs 1-2). Zone 1 is 5 km wide of mushroom corals can be the result of either sexual where the sea floor reaches a maximum depth of 20 m. or asexual reproduction (Nishihira and Poung-In, Zone 2 ranges 5-12.5 km away from the coastline, 1989; Yamashiro et al., 1989; Krupp et al., 1992; Kra- where the depth of the sea floor varies approximately marsky-Winter and Loya, 1996; Littler et al., 1997; between 20 and 30 m. Zone 3 is