Coral Reefs (2004) 23: 596–603 DOI 10.1007/s00338-004-0428-4

REPORT

Todd C. LaJeunesse Æ Daniel J. Thornhill Evelyn F. Cox Æ Frank G. Stanton Æ William K. Fitt Gregory W. Schmidt High diversity and host specificity observed among symbiotic dinoflagellates in reef coral communities from Hawaii

Received: 22 October 2003 / Accepted: 30 July 2004 / Published online: 11 September 2004 Ó Springer-Verlag 2004

Abstract The Hawaiian Islands represent one of the Introduction most geographically remote locations in the Indo- Pacific, and are a refuge for rare, endemic life. The Encircled by the waters of the North American diversity of symbiotic dinoflagellates (Symbiodinium sp.) Countercurrent, the Hawaiian archipelago is among inhabiting zooxanthellate corals and other symbiotic the most isolated subtropical regions in the Indo-Pa- cnidarians from the High Islands region was surveyed. cific (Simon 1987; Veron 1995). Due to its limited From the 18 host genera examined, there were 20 exchange with other central Pacific reef systems, Ha- genetically distinct symbiont types (17 in clade C, 1 in waii has the highest number of endemic corals in the clade A, 1 in clade B, and 1 in clade D) distinguished by Pacific (Hughes et al. 2002) and may potentially be a internal transcribed spacer region 2 sequences. Most place of unusual symbiont-host combinations. ‘‘types’’ were found to associate with a particular host Although, the Hawaiian High Islands experienced genus or species and nearly half of them have not been some coral bleaching in 1996, Hawaii’s high latitude identified in surveys of Western and Eastern Pacific and proximity to up-welled cold eastern Pacific waters hosts. A clear dominant generalist symbiont is lacking has mostly spared its corals from the severe bleaching among Hawaiian cnidarians. This is in marked contrast and mortality accompanying abnormally warm sea- with the symbiont community structures of the western surface temperatures associated with El Nino-Southern Pacific and Caribbean, which are dominated by a few ˜ Oscillations (Jokiel and Brown 2004). Such events prevalent generalist symbionts inhabiting numerous host have severely impacted shallow reef systems through- taxa. Geographic isolation, low host diversity, and a out the Indo-Pacific and Caribbean (Hoegh-Guldberg high proportion of coral species that directly transmit 1999) and have led, in some cases, to community their symbionts from generation to generation are shifts among coral taxa and their symbionts (Glynn implicated in the formation of a coral reef community et al. 2001; Loya et al. 2001). Collectively, these exhibiting high symbiont diversity and specificity. geographic, environmental, and biological attributes prompted our investigation of coral-algal symbioses in this region of the tropics. Communicated by H.R. Lasker We have learned much about the diversity, ecology, T. C. LaJeunesse (&) Æ D. J. Thornhill Æ G. W. Schmidt and evolution of Symbiodinium spp. and their host Department of Plant Biology, relations through the use of molecular genetic markers University of Georgia, GA 30602, USA (e.g. Rowan and Powers 1991; Rowan et al. 1997; E-mail: lajeunes@fiu.edu Baker and Rowan 1997; Coffroth et al. 2001; LaJeu- Tel.: +1-305-348 1317 Fax: +1-305-348 1986 nesse 2002; Baker 2003; LaJeunesse et al. 2003; Santos et al. 2004). Numerous biological, hydrogeological, T. C. LaJeunesse Æ D. J. Thornhill Æ W. K. Fitt Department of Ecology, University of Georgia, environmental, and historical factors determine the GA 30602, USA diversity of corals in a particular location (Veron 1995). For Symbiodinium spp., the taxonomic diversity E. F. Cox Department of Zoology, and relative abundance of host taxa (i.e. habitat Hawaii Institute of Marine Biology, USA diversity and availability from the symbiont point of view) seem to be an additional axis governing their F. G. Stanton Department of Biology, evolutionary diversification and ecological distribution Leeward Community College, Hawaii, USA (LaJeunesse 2002). Host communities are usually 597 dominated by few symbionts that occupy a broad LaJeunesse (2002). Products from these PCR reactions range of host taxa; however, host-specific, regionally were electrophoresed on denaturing gradient gels endemic, and/or ecologically rare lineages comprise the (45–80%) using a CBScientific system (Del Mar, CA). majority of symbiont diversity (>90%) (LaJeunesse As described in detail by LaJeunesse (2002) and 2002; LaJeunesse et al. 2003, 2004). These observa- LaJeunesse et al. (2003), prominent bands characteristic tions suggest that niche partitioning through host of each unique fingerprint/profile were excised, ream- specialization and geographic isolation is important in plified, and sequenced. symbiont speciation (Futuyma and Moreno 1988). The redundancy PCR-DGGE and direct sequencing The evaluation of Symbiodinium spp. diversity in provides an important cross check of sequence identity Hawaii, as assessed by ribosomal internal transcribed with migration characteristics. PCR-DGGE also pro- spacer (ITS) DNA, was conducted under the same duces a fingerprint that shows dominant sequences methods and criteria as carried out on other reefs attributed to either intragenomic variation across (LaJeunesse 2002; LaJeunesse et al. 2003, 2004). The multiple ribosomal loci and/or the presence of multiple enumeration of the symbiont diversity and patterns of symbiont types (LaJeunesse 2002). A large proportion host association from this highly endemic, sub-prov- of ribosomal variants reported by investigators ince of the Pacific contributes to our understanding of sequencing ‘blindly’ appear to be artifacts, possibly Symbiodinium spp. biogeography, host specificity, and resulting from PCR and cloning errors (Speksnijder evolution. Moreover, the relatively low host diversity et al. 2001). Perhaps a greater source of variation is at this location allows a test of the hypothesis that from the sequencing of rare variants (occurring biological interactions influence the apparent inverse throughout the repeat region, but low in copy num- relation between host and symbiont diversity. ber) that are not indicative of a genome’s entire ribosomal array (Diekmann et al. 2003; LaJeunesse et al., unpublished). Materials and methods

Collections Phylogenetic analyses Host Cnidarians (multiple individuals from each tax- on) were collected using SCUBA or mask and snorkel Sequences were aligned manually using Sequence from Kaneohe Bay on the southeastern side of Oahu, Navigator version 1.0 software (ABI, Division of and from Haleiwa Trench, Wailua Bay on its north Perkin-Elmer, Foster City, CA). Sister lineages Fr1 shore. Coral fragments of 3–5 cm2 were stripped of (sensu Pochon et al. 2001) and type F1 in clade F tissue using an airbrush (Baker and Rowan 1997) and (Symbiodinium kawagutii (LaJeunesse 2001)) were used the resultant slurry of mucus, animal cell debris, and as outgroups (Genbank sequences AJ291520 and dinoflagellates was homogenized using a Tissue Tearor AF333515). ITS sequences among clade C types have a homogenizer (Biospec Ind.). After centrifugation at high proportion of invariant characters (only 17 800–1,000 g, the resulting algal pellets were transferred characters out of 308 are parsimony-informative). Base to a 1.5-ml microcentrifuge tube and preserved in 20% substitutions across the ITS rDNA in these Symbi- dimethylsulfoxide (DMSO), 0.25 M EDTA, sodium odinium spp. are far from approaching saturation. chloride-saturated water solution (Seutin et al. 1991). Therefore, maximum parsimony (under heuristic The symbionts from soft-bodied Actinarian, Zoanthi- search mode), which does not assume a particular dian, and Scyphozoan taxa were isolated as previously model of molecular evolution and allows for use of described (LaJeunesse 2002). Porites compressa and informative sequence gaps and insertions (considered a Montipora capitata (= verrucosa Maragos 1995), 5th character state), is thus a conservative method for displaying wide morphological variation under identi- phylogenetic inference of clade C. Maximum likeli- cal environmental conditions, were sampled extensively hood and neighbor-joining analyses (with gaps ex- to determine if any of these showed differences in their cluded) were also performed on the data using PAUP* symbiont affiliations. V. 4.0b10 software (Swofford 1999). A fourth method of phylogenetic inference using Baysian statistics was implemented using the software MrBayes version 3.0b4 DNA extractions, PCR-DGGE, and sequencing (Huelsenbeck and Ronquiest 2001). Under the HKY85 and general time reversible (GTR) models of sequence Nucleic acid extractions on 10 to 30 mg of dinoflagellate evolution, beginning with an unspecified tree topology, material were conducted using a modified Promega log probability of observing the data plateaued Wizard genomic DNA extraction protocol (LaJeunesse reaching stationarity early between 10,000 and 20,000 et al. 2003). The internal transcribed spacer region (ITS) generations. Both one-hundred thousand and one 2 was amplified from each extract using primers ‘‘ITS 2 million generations (with no discard, i.e. no burn-in, clamp’’ and ‘‘ITSintfor 2’’ (LaJeunesse and Trench hence probabilities are conservative estimates) under 2000) with the touch-down thermal cycle given in repeated trials produced near identical values. 598

The occurrence of a particular symbiont in the ecosys- Results tem was therefore dependent on the presence of a par- ticular host taxon. Because a majority of host species A total of 20 distinctive symbiont types (17 clade C, 1 contained their own distinctive Symbiodinium type, the clade B, 1 clade A and 1 clade D), characterized by community composition for these reefs lacked a domi- PCR-DGGE fingerprinting and sequencing of the ITS 2 nant host generalist symbiont (Fig. 2). region (LaJeunesse 2001, 2002; LaJeunesse et al. 2003) The external physical environment was a factor in (Fig. 1), were identified from 23 host species represent- influencing certain partner combinations for several ing 18 genera (Table 1). As in other regions of the corals. In the host species, Montipora capitata Pacific, including the Pacific coast of Panama, southern (=verrucosa), M. flabellata ,andPorites compressa,a and central GBR, Okinawa, and Guam (Baker and change in the symbiont fingerprint was attributed to Rowan 1997; Loh et al. 1998; Pochon et al. 2001; depth of collection. Montipora capitata is morphologi- LaJeunesse et al. 2003, 2004), the community of sym- cally plastic and has two color morphs. The common biotic cnidarians maintained a disproportionate number ‘brown’ variety and all its morphological variants asso- of symbioses with clade C types, while symbioses ciated with C31 above 15 m, but hosted type C26a at involving members from clades A, B, and D were rare. greater depths. The less common and less palatable Identical fingerprint DGGE-PCR profiles were consis- shallow-dwelling ‘ruddy’ orange form of Montipora tently produced from replicate sampling of each host capitata associated with type D1a in clade D (Table 1). species surveyed (Table 1). Host-symbiont associations M. patula colonies above 10 m also hosted D1a (c.f. surveyed from each location on Oahu were the same. Rowan and Powers 1991). The symbiont described as Symbiodinium kawagutii from clade F (LaJeunesse 2001), originally cultured by R. Kinzie, and now main- Fig. 1 PCR-DGGE fingerprinting of the ITS 2 region character- tained in labs around the world, is most probably not izing the diversity of Symbiodinium spp. found among Hawaiian the ‘‘true’’ symbiont of M. capitata (= verrucosa) but corals. These analyses identified 17 different C-type signatures more likely an opportunistic contaminant from the ini- whose ribosomal gene arrays were either dominated by a single tial isolation process (c.f. Santos et al. 2001; LaJeunesse sequence or exhibited two or more co-dominant variants. Most types were found in a specific host genus (or a single species within 2002). that genus) whose identity is provided above. In fingerprints with Type C15, observed previously in Porites spp. from multiple bands, the relative band intensities in each pattern did not the west Pacific and western Indian Ocean (LaJeunesse change when observed in replicate host samples, indicating fixed et al. 2003; Baker and LaJeunesse, unpublished), was intragenomic variation. Mixed fingerprint profiles suggesting the presence of two or more different symbiont populations were never also identified in each of the five Porites spp. from detected within a host colony. An alphanumeric name for each Hawaii (Table 1). Morpho-types of Porites compressa, symbiont type is given above the corresponding fingerprint profile; sampled below 10 m contained C15b, a symbiont also uppercase letters indicate lineage (clade), numbers represent ITS found in the encrusting octocoral, Sarcothelia sp., living type, and lowercase letters denote a definitive rDNA co-dominant paralog, when one was clearly evident. Examples of heteroduplexes at similar depths. Interestingly, a purple-blue morph are indicated colony of P. compressa that was originally collected 599

Table 1 Host species, symbiont type and collection depth Host Depth (meters) Symbiont type (meters) of samples from Oahu (Genbank accession) Hawaii, north central Pacific. Numerals in parentheses next to Scleractinia host names indicate the number Acroporidae of colonies independently Montipora capitata 1.0–2.0 D1a sampled (orange color morph) (4) Montipora capitata (various colony 1.0–5.0 C31 (AY258496) morphologies) (14) Montipora capitata 20.0 C26/26a (AY239378/AY258501) (deep encrusting form) (2) Montipora flabellata 2.0 C32 (AY258498) Montipora flabellata 10.0–20.0 C32a Montipora patula (2) 3.0–15.0 D1a Montipora patula 20.0 C31 Pocilloporidae Pocillopora damicornis (dark morph) (4) 1.0–2.0 C1d (AY258488) Pocillopora meandrina (4) 2.0–20.0 C1c Pocillopora molokensis (5) 18.0–25.0 C34 (AY258499) Pocillopora eydouxi (2) 20.0 C1c Pocillopora ligulata 20.0 C1g (AY589730) Poritidae Porites compressa (various colony 1.0–4.0 C15 morphologies) (19) Porites compressa (3) 15.0–25.0 C15b (AY258491) Porites compressa (10-year transplant ) 1.0 (>10.0) C15b Porites evermanni (4) 5.0–20.0 C15 Porites lobata (5) 2.0–20.0 C15 Porites rus (3) 10.0–15.0 C15c (AY258492) Porites brighami (2) 20.0 C15 Siderastreidae Coscinaraea wellsi (1) 10.0–20.0 C1 Psammocora spp. (4) 2.0–5.0 C1f (AY258490) Fungiidae Fungia scutaria (5) 2.0–10.0 C1f Fungia scutaria (2) (acanthicauli) 3.0 C1f Cycloseris vaughani (1) 20.0 C1 Agariciidae Pavona varians (7) 2.0–20.0 C27 Pavona duerdeni (4) 10.0–25.0 C27 Leptoseris incrustans (2) 10.0–20.0 C1 Faviidae Leptastrea purpurea (6) 10.0–20.0 C1f Leptastrea bottae (3) 2.0 C1f Cyphastrea ocellina (3) 2.0 C1f Actiniaria Aiptasia pulchella (2) 1.0 B1 Boloceroides mcmurrichi 2.0 C3 Zoanthidea Palythoa sp. (2) 2.0–15.0 C1 Palythoa sp. 20.0 C3 Protopalythoa sp. (3) 1.0 C3m (AY258497) Zoanthus pacificus (3) 1.0 C29 (AY258494) Alcyonacea Sarcothelia ( edmondsoni ) sp. (2) 10.0–20.0 C15b Scyphozoa Cassiopeia sp. 3.0 A3 from a depth below 10 m off the Island of Hawaii and Neighbour-joining, Maximum Likelihood, and Bayesian transplanted to a shallow patch reef in Kaneohe Bay inference methods also yielded very similar trees. Be- (C. Hunter personal communication), possessed the cause gap data were not included, posterior probabilities ‘deep-water’ symbiont, C15b. That the symbiont popu- were not calculated for certain internal branch nodes lation in the transplanted P. compressa did not undergo (Fig. 3a). C3 is most basal among clade C sequences (c.f. a shift to C15 after 10 years raises fundamental ques- LaJeunesse 2002). Of potential ecological significance, tions regarding the flexibility of this symbiosis. host generalists in the west pacific and Caribbean, C1 Phylograms, derived by maximum parsimony, com- and C3, were found in host taxa uncommon or rare paring clade C ITS 2 sequences both rooted (Fig. 3a) around Oahu. The fingerprint of C1f, identified from and unrooted (Fig. 3b), have identical topologies. several Hawaiian coral taxa (Fig. 1), is not presently 600

tionary processes exhibited by these animal-algal endo- symbioses.

Diversity and community structure of Hawaii’s Symbiodinium spp.

The majority of zooxanthellae diversity surveyed in Hawaii and on other Pacific reefs (Baker and Rowan 1997; Pochon 2001; LaJeunesse et al. 2003, 2004), belongs to clade C. These Symbiodinium spp. appear to represent the most ecologically important group in the Indo-Pacific (Baker 2003). The community structures of Symbiodinium spp. characterized from Oahu’s host assemblage contrasts with Caribbean and western Pacific reefs where a greater percentage of host taxa share a common symbiont type (Fig. 2) (LaJeunesse 2002; LaJeunesse et al. 2003; LaJeunesse and Warner, unpublished). Absence of a dominant generalist combined with a high number of symbioses involving specialized symbionts, accounts for this proportionately high diversity relative to other reef systems around the world (Fig. 4). Two main factors probably contribute to high relative symbiont diversity among Hawaiian corals. Firstly, Hawaii has a high composition of host taxa in the genera Porites, Monti- pora , and Pocillopora, corals that directly transfer their symbionts to the next generation via vertical transmis- sion. Secondly, for coral communities displaying low species richness but high species evenness over evolu- tionary time scales, selection pressures may favor greater host-symbiont specialization in species that acquire their symbionts from environmental pools (Law 1985). Fig. 2 Symbiont diversity (separated by clade) and community In many symbiotic systems where host offspring ac- structure based on each symbiont’s prevalence among numbers of host genera for a Carrie Bow Cay, Belize Caribbean (LaJeunesse quire their symbionts directly from the parent (vertical and Warner, unpublished); b Heron Island, southern GBR transmission), genetic isolation and natural selection (LaJeunesse et al. 2003) and c Oahu, Hawaii. Hawaii lacks a clear promotes symbiont specialization (Douglas 1998; Loh host generalist that dominates the host community as found in et al. 2001). Most corals in the west Pacific broadcast other reef systems. Thus, Hawaii’s symbiont diversity is nearly equivalent to the southern GBR reef with only half the number of spawn (Richmond and Hunter 1990), producing off- genera and one-third the number of species surveyed. The number spring that must acquire symbionts from environmental of host genera surveyed from each region is given in the upper right sources (horizontal transmission). Porites and Monti- hand corner of each panel pora are common coral genera in the Indo-Pacific and are especially abundant in Hawaii, which mostly lacks known in western regions of the Pacific, and yet was the elsewhere abundant the Acropora spp. While species recently found in Psammocora spp. from the north- from these genera typically broadcast spawn, they all eastern Pacific (LaJeunesse et al. 2003, 2004; LaJeunesse release eggs containing vertically transmitted symbionts and Reyes-Bonilla, unpublished). Some of the new (Richmond and Hunter 1990). Depending on geographic symbiont fingerprints observed (Fig. 1) might be local- location, Pocillopora spp. brood and/or spawn. Both ized, or endemic, to this region of the Pacific. larvae and eggs, when released, possess symbionts ob- tained from their parents (Kinzie 1996). Together, these three ecologically dominant genera maintain specific Discussion associations with separate sub-cladal lineages within clade C Symbiodinium (Fig. 3). The number of specific Molecular-based surveys of Symbiodinium spp. diversity types from each of these sub-clades accounts for a large in various regions around the world, including Hawaii, proportion of the Symbiodinium spp. diversity found in reveal much about the genetic relatedness, host speci- Hawaii. ficity, and geographic distribution of these organisms. While direct symbiont transfer from generation to These phylogeographic data and ecological observations generation favors the evolution of specialist symbiont are essential in understanding the ecological and evolu- lines (Douglas 1998), high specificity and hence stability 601

Fig. 3 ITS 2 phylogenies inferred from maximum parsimony of are also observed in hosts that acquire symbionts from clade C Symbiodinium spp. identified from Hawaiian cnidarians. the environment (Wilkinson 2001). Adults and juveniles a Phylogeny rooted with the outgroup taxa Fr1 and Fr5 (S. kawagutii, in clade F type 1; in group Fr 5 sensu Pochon et al. of the mushroom coral Fungia scutaria, a broadcaster 2001) indicating that C3 is most basal among clade C sequences. with horizontal symbiont transmission, sampled from Values indicated for each internal branch node are bootstrap Kaneohe Bay and the North Shore possessed symbiont estimates (first number), bootstrap with resampling doubled to C1f regardless of depth. This symbiont when compared compensate for the high proportion of invariant characters against types C15, Cld, and C31, originating from P. (underlined), and Bayesian posterior probabilities (parentheses). Internal nodes that lack posterior probabilities are based on compressa, P. damicornis ,andM. capitata respectively, insertion/deletions, not assessed by Bayesian methods (b). Clade infects with greater success and achieves higher growth C taxa only (outgroup taxa omitted) were reanalyzed and rates in Fungia scutaria larvae (Weis et al. 2001; Rodri- presented as an unrooted polytomy. The topology is identical to guez-Lanetty et al. 2004). Most zoanthids surveyed from the boldfaced portion of the rooted phylogeny in panel ‘‘a.’’ A reanalysis of bootstrap support was conducted and the values the Pacific possess symbiont types not found in other shown are as described previously. Coral genera whose offspring hosts (LaJeunesse et al. 2003, 2004). This group, with acquire symbionts through vertical transmission, Porites, Monti- one known exception, consists primarily of broadcast pora, and Pocillopora, associate with Symbiodinium spp. that spawners that do not vertically transmit their symbionts form discrete sub-clades (shaded portions). Solid squares are symbiont taxa presently recorded only from Hawaii. Type C1d (Ryland 1997). Clearly, aspects other than mode of also occurs in P. damicornis from the eastern Pacific (open symbiont transmission are important in the evolution of square), but is possibly absent from the western Pacific specific host-symbiont associations. The host cell envi- (LaJeunesse et al. 2003, 2004). Remaining branch termini ronment, modified by the external physical environment, without symbols are known from hosts in the western Pacific must promote niche diversification among symbiont (LaJeunesse et al. 2003, 2004). Intra-genomic variants (in parentheses), not used to distinguish a different symbiont, were taxa (Futuyma and Moreno 1988; LaJeunesse 2002). included to show their phylogenetic positions relative to sister Ecological and evolutionary trade-offs exist between sequences from the same genome. Neighbour-joining, Maximum symbionts associating with numerous host taxa versus Likelihood, and Baysian based analyses (insertions/deletion data those specializing with a narrow host range (Futuyma removed) yielded near identical trees and Moreno 1988). Selection pressures supporting the maintenance of a generalist or the evolution of special- 602

found in hosts from the GBR and Okinawa indicates that the Central Pacific province contains many types not found in the west Pacific (Fig. 3) (LaJeunesse et al. 2003, 2004). Surveys of coral reefs nearest to Hawaii and throughout the rest of the central Pacific will be necessary to determine if any of these ‘new’ types are endemic to Hawaii. The geographic distribution of different symbiont types are potentially useful for investigating genetic connectivity between coral reef systems, even over limited spatial scales such as the Caribbean (Santos et al. 2004). Genetically similar symbionts from each of the pocilloporid, montiporid and poritid sub-clades illustrated in Fig. 3 are also present in regions from the West Pacific. While some share exact identity with those from Hawaii, many others have slight sequence differences that distinguish them regionally. For example, type C1c has an extensive geographic distri- bution and is found in Pocillopora spp. from the GBR Fig. 4 Symbiont diversity versus host diversity for various Pacific and Okinawa (LaJeunesse et al. 2003, unpublished), and Caribbean reefs. For each location, the number of Symbiodi- nium ITS types were divided by the number of host genera and in Pavona spp. from the eastern Pacific (Iglesias- surveyed. This standardized value was then graphed against total Prieto et al. 2004). This is in contrast to the distribu- host generic diversity. Hawaii (1) possesses the lowest host tion of a closely-related type, C1d, that occurs in diversity, yet exhibits proportionately high symbiont diversity. P. damicornis from Hawaii and the eastern Pacific but, The host assemblages surveyed at Feather (10) and Rib reefs (9) (Central GBR, LaJeunesse et al. 2004) contain a low number of appears not to be present in the western Pacific symbionts in proportion to their host diversity (>50 genera). (LaJeunesse et al. 2003, 2004). Types C1 g and C34, Caribbean reefs near Lee Stocking, Bahamas (2) (LaJeunesse, known only from Hawaiian pocilloporids, may have unpublished) and Carrie Bow Cay, Belize (3) (LaJeunesse and more restricted geographic distributions and are Warner, unpublished) also exhibit a relatively high Symbiodinium spp. diversity. Reef communities from Key Largo Florida, USA possibly endemic (Fig. 3). (4), and Curac¸ao Island (inshore Central GBR) (6), which are Many coral-algal symbioses, even those with flexible exposed to more variable and/or stressful environments, have low partnerships, remain stable over wide geographic dis- host and symbiont diversities. Other symbiont-to-host valuations tances as long as the external environment remains are recorded for Zamami Island, Okinawa, Japan (7) (LaJeunesse similar (LaJeunesse and Trench 2000; Coffroth et al. et al. 2004), Heron Island, Australia (southern GBR) (8) (LaJeunesse et al. 2003), and Puerto Morelos, Mexico (5) 2001; Loh et al. 2001; LaJeunesse 2002). Entire sym- (LaJeunesse 2002). Open circles around numerals indicate Carib- biont communities appear to be maintained over geo- bean reefs, while solid squares indicate Pacific reefs graphic ranges even as great as that encompassed by the barrier reef along the western Caribbean (LaJeu- ists may shift depending on host taxa abundances nesse et al., unpublished). While the high islands of (habitat availability) and diversity (habitat heterogene- Hawaii, Kauai, and Maui, among others, were not ity) (Law 1985). The High Islands began their emergence surveyed in this study, they probably have similar during the Miocene-Pliocene transition (Clague and symbioses as observed on Oahu. These islands have Dalrymple 1987), as coral reef communities from older similar coral communities and probably constitute a islands experienced major turnover (Jokiel 1987; Kay connected system (Veron 1995; Jokiel 1987). Host- and Paulumbi 1987). Since then, isolation, low coloni- symbiont combinations described on the north shore zation rates, and periodic extinctions have suppressed and southeast side of Oahu were identical, and the host diversity in this remote region, a situation that may P. compressa transplant from the Island of Hawaii promote symbiont specialization for even those corals possessed the same symbiont type as P. compressa that acquire symbionts from environmental pools at the from similar depths on Oahu. These data suggest that beginning of each generation. the symbioses characterized on Oahu also are present nearby islands. Biogeography Acknowledgments The authors thank the participants in the Hawaii Institute of Marine Biology’s ‘‘Molecular biology of corals’’, Edwin Various Symbiodinium spp, like their coral hosts, show W. Pauley summer program of 2002. CBS Scientific generously differences in geographic distribution (LaJeunesse loaned their DGGE electrophoresis system for this course. Cynthia 2002; LaJeunesse et al. 2004). Some are distributed L. Hunter for helpful discussions and field assistance. T.C.L thanks over great distances, even to different oceans, while Michael P. Lesser and Jo-Ann Leong for facilitating his course participation and stay on Coconut Island. This work was sup- many are regionally localized and possibly endemic. A ported by the Edwin W. Pauley foundation, National Science comparison of symbionts from Hawaii with those Foundation grant OCE- 0137007 to WK Fitt and GW Schmidt, a 603 grant from the Smithsonian Center for Caribbean Research, and a LaJeunesse TC, Trench RK (2000) The biogeography of two spe- NSF graduate research fellowship to D. J. Thornhill. cies of Symbiodinium (Freudenthal) inhabiting the intertidal anemone, Anthopleura elegantissima (Brandt). Biol Bull 199:126–134 LaJeunesse TC, Loh WKW, van Woesik R, Hoegh-Guldberg O, References Schmidt GW, Fitt WK (2003) Low symbiont diversity in southern Great Barrier Reef corals relative to those of the Baker AC (2001) Corals bleach to survive change. Nature 411:765– Caribbean. Limnol Oceanogr 48:2046–2054 766 LaJeunesse TC, Bhagooli R, Hidaka M, Done T, deVantier L, Baker AC (2003) Flexibility and specificity in coral-algal symbiosis: Schmidt GW, Fitt WK, Hoegh-Guldberg (2004) Closely-related diversity, ecology and biogeography of Symbiodinium. Ann Symbiodinium spp. differ in relative dominance within coral reef Rev Ecol Evol Syst 34:661–689 host communities across environmental, latitudinal, and Baker AC, Rowan R (1997) Diversity of symbiotic dinoflagellates biogeographic gradients. Mar Ecol Prog Ser (zooxanthellae) in scleractinian corals of the Caribbean and Law R (1985) Evolution in a mutualistic environment. In: Boucher eastern Pacific. Proc 8th Int Coral Reef Symp 2:1301–1306 DH (ed) The biology of mutualism: ecology and evolution. Buddemeier RW, Fautin DG (1993) Coral bleaching as an adaptive Oxford University Press, New York, pp 145–170 mechanism. BioScience 43:320–326 Loh WK, Loi T, Carter D, Hoegh-Guldberg O (2001) Genetic Clague DA, Dalrymple GB (1987) In: Volcanism in Hawaii. variability of the symbiotic dinoflagellates from the wide Decker RW, Wright TL, Stauffer PH (eds) US Govt Printing ranging coral species Seriatopora hystrix and Acropora longi- Office pp 5–54 cyathus in the Indo-West Pacific. MEPS 222:97–107 Coffroth MA, Santos SR, Goulet TL (2001) Early ontogenic Loya Y, Sakai K, Yamazato K, Nakano Y, Sambali H, Van expression of specificity in a cnidarian-algal symbiosis. Mar Woesik R (2001) Coral bleaching: the winners and the losers. Ecol Prog Ser 222:85–96 Ecol Lett 4:122–131 Diekmann OE, Olsen JL, Stam WT, Bak RPM (2003) Genetic Maragos JE (1995) Revised checklist of extant shallow-water coral variation within Symbiodinium clade B from the coral genus species from Hawaii (Cnidaria: Anthozoa: Scleractinia). Bishop Madracis in the Caribbean (Netherlands Antilles) Coral Reefs Museum Occ Papers 42:54–55 22:29–33 Pochon X, Pawlowski J, Zaninetti L, Rowan R (2001) High genetic Douglas AE (1998) Host benefit and the evolution of specialization diversity and relative specificity among Symbiodinium -like in symbiosis. Heredity 81:599–603 endosymbiotic dinoflagellates in soritid foraminiferans. Mar Futuyma DJ, Moreno G (1988) The evolution of ecological spe- Biol 139:1069–1078 cialization. Ann Rev Ecol Syst 19:207–233 Richmond RH, Hunter CL (1990) Reproduction and recruitment Glynn PW, Mat JL, Baker AC, Calderon MO (2001) Coral of corals: comparisons among the Caribbean, the tropical bleaching and mortality in Panama and Ecuador during the Pacific and the Red Sea. MEPS 60:185–203 1997–1998 El Nino-southern oscillation event: spatial/temporal Rodriguez-Lanetty M, Krupp D, Weis VM. (2004) Distinct ITS patterns and comparisons with the 1982–1983 event. Bull Mar types of Symbiodinium in clade C correlate to cnidarian/dino- Sci 69:79–109 flagellate specificity during symbiosis onset. Mar Ecol Prog Ser Hoegh-Guldberg O (1999) Climate change, coral bleaching and the 275:97-102 future of the world’s coral reefs. Mar Freshwater Res 50:839–866 Rowan R, Powers DA (1991) A molecular genetic classification of Huelsenbeck JP, Ronquist F (2001) MrBays: Bayesian inference of zooxanthellae and the evolution of animal-algal symbiosis. phylogenetic trees. Bioinformatics 17:754–755 Science 251:1348–1351 Hughes TP, Bellwood DR, Connolly SR (2002) Biodiversity hot- Rowan R, Knowlton N, Baker A, Jara J (1997) Landscape ecology spots, centers of endemicity, and the conservation of coral reefs. of algal symbionts creates variation in episodes of coral Ecol Lett 5:775–784 bleaching. Nature 388:265–269 Hunter CL (1988) Genotypic diversity and population structure of Ryland JS (1997) Reproduction in zoanthidea (Anthozoa: Hexa- the Hawaiian reef coral Porites compressa. Dissertation. Uni- corallia) Invert. Reprod Dev. 31:177–188 versity of Hawaii, 136 pp Santos SR, Taylor DJ, Coffroth MA (2001) Genetic comparisons Iglesias-Prieto R, Trench RK (1997) Photoadaptation, photoacc- of freshly isolated vs. cultured symbiotic dinoflagellates: impli- limation and niche diversification in invertebrate-dinoflagellate cations for extrapolating to the intact symbiosis. J Phycol symbioses. Proc 8th Int Coral Reef Symp 2:1319–1324 37:900–912 Iglesias-Prieto R, Beltra´n VH, LaJeunesse TC, Reyes-Bonilla H, Santos SR, Shearer TL, Hannes AR, Coffroth, MA (2004) Fine- Thome´PE (2004) Different algal symbionts explain the vertical scale diversity and specificity in the most prevalent lineage of distribution of dominant reef corals in the eastern Pacific. Proc symbiotic dinoflagellates (Symbiodinium, Dinophyceae) of the R Soc Lond 271: 1757-1763 Caribbean. Molec Ecol 13:459–469 Jokiel PL (1987) Ecology, biogeography and evolution of corals in Seutin G, White BN, Boag PT (1991) Preservation of avian blood Hawaii. TREE 2:179–182 and tissue samples for DNA analyses. Can J Zool 69:82–92 Jokiel PL, Brown EK (2004) Global warming, regional trends and Simon C (1987) Hawaiian evolutionary biology: an introduction. inshore environmental conditions influence coral bleaching in TREE 2:175–178 Hawaii. Global Change Biol Speksnijder AGCL, Kowalchuk GA, De Jong S, Kline E, Stephan Jokiel PL, Coles SL (1990) Response of Hawaiian and other Indo- JR, Laanbroek HJ (2001) Microvariation artifacts introduced Pacific reef corals to elevated temperature. Coral Reefs 8:155– by PCR and cloning of closely related 16S rRNA gene 162 sequences. Appl Environ Microbiol 67:469–472 Kay AE, Paulumbi SR (1987) Endemism and evolution in Swofford DL (1999) PAUP*, Phylogenetic Analysis Using Parsi- Hawaiian marine invertebrates. TREE 2:183–186 mony (*and other methods), Version 4.0b10, Sinauer, Sunder- Kinzie RA (1996) Modes of speciation and reproduction in land, Mass. archaeocoeniid corals. Galaxea 13:47–64 Veron JEN (1995) Corals in space and time. UNSW Press, Sydney, LaJeunesse TC (2001) Investigating the biodiversity, ecology, and pp 321 phylogeny of endosymbiotic dinoflagellates in the genus Weis VM, Reynolds WS, deBoer MD, Krupp DA (2001) Host- Symbiodinium using the internal transcribed spacer region: in symbiont specificity during onset of symbiosis between the di- search of a ‘‘species’’ level marker. J Phycol 37:866–880 noflagellates Symbiodinium spp. and planula larvae of the LaJeunesse TC (2002) Diversity and community structure of sym- scleractinian coral Fungia scutaria. Coral Reefs 20:301–308 biotic dinoflagellates from Caribbean coral reefs. Mar Biol Wilkinson DM (2001) Horizontally acquired mutualisms, an 141:387–400 unsolved problem in ecology? Oikos 92:377–384