Systematic Botany (2011), 36(1): pp. 22–32 © Copyright 2011 by the American Society of Plant Taxonomists DOI 10.1600/036364411X553090 The Peat Moss Sphagnum cuspidatum in Australia: Microsatellites Provide a Global Perspective Eric F. Karlin , 1 , 5 Sandra B. Boles , 2 Rodney D. Seppelt , 3 Stefano Terracciano , 4 and A. Jonathan Shaw 2 1 School of Theoretical & Applied Science, Ramapo College, Mahwah, New Jersey 07340-1680, U. S. A. 2 Duke University, Department of Biology, Durham, North Carolina 27708, U. S. A. 3 Australian Antarctic Division, Channel Highway, Kingston 7050, Tasmania, Australia 4 Dipartimento di Biologia Strutturale e Funzionale, Universita’degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia — Edificio 7, 80126 Napoli, Italy 5 Author for correspondence ([email protected]) Communicating Editor: Fernando Zuloaga Abstract— The distribution of Sphagnum cuspidatum has been subject to controversy. Although historically reported from all continents except Antarctica recent authors consider S. cuspidatum to be endemic to Europe and eastern North America. Microsatellites from Australian plants morphologically identified as S. cuspidatum were compared to microsatellites of plants morphologically identified as S. cuspidatum col- lected from other regions. The species was found to occur in Australia as well as on every continent except Antarctica. The sample most closely related to the Australian plants was collected in the Philippines, and samples from Australia, the Philippines, Colombia, and Equatorial Guinea formed a subclade within S. cuspidatum . Microsatellites further show that S. cuspidatum is one of the parental species of the double allopolyploid S. falcatulum , a Holantarctic species which is reported from Tasmania, New Zealand, and Chile. Keywords— Allopolyploidy , Australasia , interploidal hybridization , phenotypic variation , phylogeography , Sphagnum falcatulum . Many closely related Sphagnum species are morphologi- Sphagnum falcatulum is a variable species having a pleth- cally similar and often difficult to distinguish from one ora of morphotypes ( Fife 1996 ; Karlin et al. 2009 ), with, as another. Systematic problems are compounded by the exten- noted above, some that are morphologically and ecologi- sive environmentally introduced morphological variation cally similar to S. cuspidatum ( Andrews 1949 ; Karlin et al. in some species. Thus, the determination of the geographic 2009 ; see Discussion). Unlike S. cuspidatum , which is reported distribution of Sphagnum species is often difficult to deter- to have haploid ( n = x ) gametophytes ( Fritsch 1991 ; Temsch mine when based solely upon morphology, particularly for et al. 1998 ; Szövényi et al. 2008 ), genetic analyses have shown species that are reported to be widespread. Sphagnum cuspi- S. falcatulum to be an allopolyploid (alloploid) complex of datum Ehrh. ex Hoffm. ( Sphagnum section Cuspidata ) is one plants having either allodiploid or allotriploid gametophytes such species. Plants morphologically similar to S. cuspida- ( Karlin et al. 2009 ). The allotriploid plants have a history of tum occur in many parts of the world and its distribution interploidal hybridization, with the allodiploid plants being has thus been the subject of controversy ( Table 1 ). Some con- one of the parent species ( Karlin et al. 2009 ). Both cytotypes sider S. cuspidatum to be a widespread species that is pres- appear to have parental species from two different sections: ent in both Northern and Southern hemispheres ( Warnstorf sections Subsecunda and Cuspidata ( Shaw and Goffinet 2000 ; 1911 ; Andrews 1919 , 1949 ; Eddy 1977 , 1985 , 1988 ; Crum 1984 , Karlin et al. 2009 ). Prior genetic study of S. falcatulum has 1994 ). Others, including the most current reports, conclude focused primarily on plants from South Island, New Zealand Delivered by Ingenta to IP: 192.168.39.211 on: Fri, 24 Sep 2021 11:45:24 Copyright (c) American Society for Plant Taxonomists. All rights reserved. that it is restricted to the northern hemisphere, occurring in ( Karlin et al. 2009 ), with genetic analyses having been reported Europe and eastern North America ( Andrus 1980 ; Daniels for just two Australian specimens of S. falcatulum , both from and Eddy 1985 ; McQueen and Andrus 2007 ; Anderson Tasmania ( Shaw and Goffinet 2000 ; Karlin et al. 2009 ). et al. 2009 ). Isozyme ( Hanssen et al. 2000 ) and microsatel- Twelve section Cuspidata specimens having a morphology lite ( Szövényi et al. 2008 ) studies detected little divergence closely matching that of S. cuspidatum were recently collected between European and eastern North American plants of from two coastal sites in Queensland, Australia. The two sites S. cuspidatum . A comparative study of the genetics of plants are at the northern limit of the reported distribution for S. fal- morphologically identified as S. cuspidatum on a global basis catulum ( Seppelt 2006 ). Six specimens were collected by H. B. has not been undertaken. Hines from one site on North Stradbroke Island. The plants Warnstorf (1911) reported S. cuspidatum for Australia and were growing in small isolated clumps in a heath/sedge wet- New Zealand. He also reported 13 other section Cuspidata land at the southern end of Brown Lake (27.4947° S, 153.4322° species as endemic to one or both of these two countries. He E; :55 m above sea level). Plants in the six collections from further considered S. falcatulum Besch. (section Cuspidata ) as this site closely matched the description of S. cuspidatum endemic to Patagonia. Noting that S . falcatulum was “slightly, subsp. cuspidatum given by Eddy (1977 , 1988 ). Six other speci- perhaps questionably, distinct” from S. cuspidatum, Andrews mens were collected by R. D. Patterson from a second loca- (1949) concluded that S. falcatulum likely co-occurred in tion some 121 km north of Brown Lake at Marcus Beach in Patagonia and in Australasia. He further concluded that S. fal- Noosa National Park (26.4500° S, 153.0833° E, 30 m above sea catulum was probably the only section Cuspidata species pres- level). The plants grew in partial shade under Melaleuca quin- ent in Australasia ( Andrews 1949 ). Subsequent researchers quenervia (Cav.) S. F. Blake open forest in a shallow swale on accepted Andrews’ conclusions ( Sainsbury 1955 ; Beever et al. a Quaternary coastal sand dune system. This was a season- 1992 ; Scott and Stone 1976 ; Catcheside 1980 ; Fife 1996 ; Seppelt ally moist habitat and the morphology of the plants collected 2006 ) and the Holantarctic S. falcatulum is currently the only there reflected their occurrence in a nonaquatic environ- section Cuspidata species reported for Australasia ( Fife 1996 ; ment. They were smaller and more compact than the Brown Seppelt 2006 ). Lake plants ( Fig. 1a, b ), closely matching the description for 22 2011] KARLIN ET AL.: SPHAGNUM CUSPIDATUM IN AUSTRALIA 23 Table 1. Reported distribution of Sphagnum cuspidatum . “E”: limited within North America to eastern North America. Source Europe North America Southeast Asia Northeast Asia Australasia South America Africa Warnstorf ( 1911 ) + + - + + - - Andrews ( 1919 , 1949 ) + E - + - + - Eddy ( 1977 , 1985 , 1988 ) + + + + - ? + Andrus ( 1980 ) + E - - - - - Crum ( 1984 , 1994 ) + + + + - + - Daniels and Eddy ( 1985 ) + E - + - - - McQueen and Andrus ( 2007 ) + E - - - - - Anderson et al. ( 2009 ) + E - - - - - This study + E + + + + + S. cuspidatum subsp. subrecurvum (Warnst.) A. Eddy ( Eddy sion at 60°C for 30 min. Amplification products were diluted in sterile 1977 , 1988 ). These twelve specimens were either S. cuspida- water, and 1.2 µl of the dilution was mixed with GS500 size standard and Hi-Di™ Formamide (Applied Biosystems, Foster City, California) for elec- tum (which is not currently reported for Australasia) or mor- trophoresis on an ABI 3730 sequencer. Size determinations and genotype phological variants of S. falcatulum . Genetic analysis was thus assignments were made using GeneMarker 1.75 software (Softgenetics, required to identify these plants, and here we refer to them as State College, Pennsylvania). Australian “ S. cuspidatum.” Ploidy Determination— Ploidy in all samples was inferred from mic- The objective of this study was to use microsatellites to rosatellite markers ( Karlin et al. 2009 ; Ricca et al. 2008 ). Plants with one allele at all, or all but one marker, were interpreted as being gametophyti- study the genetic relationship of Australian “ S. cuspidatum ” cally haploid. Plants having two alleles at most markers were interpreted to S. falcatulum and to plants morphologically identified as as being gametophytically diploid. S. cuspidatum from other regions. Statistical Analyses— Microsatellite repeat numbers were not calcu- lated, as it was clear from sequencing selected fragments that some of the allelic variation could be attributed to indels in flanking regions rather Materials and Methods than to variation in repeat number alone (data not shown). To compare microsatellite variation between the allodiploid S. falcatulum and S. cus- At the two Australian sites, collections were made across the extent of pidatum and S. recurvum (which both have haploid gametophytes), the occurrence of S. cuspidatum , with a minimum of one m between collection alleles for the latter two species were scored as being homozygous at all points. In addition to the twelve specimens of Australian “ S. cuspidatum,” loci, with the exception of specimens which had one heterozygous locus 39 herbarium