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Pteridology |
Albrecht-von-Haller Institute of Plant Sciences, Georg-August Universty Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany
Received for publication August 9, 2005. Accepted for publication November 3, 2005.
ABSTRACT
The genus Platycerium is one of the few pantropical epiphytic fern genera with six species in Afro-Madagascar, 8–11 Australasian species, and a single species in tropical South America. Nucleotide sequences of four chloroplast DNA markers are employed to reconstruct the phylogeny of these ferns and to explore their historical biogeography. The data set was designed to resolve conflicting hypotheses on the relationships within the genus that were based on previous phylogenetic studies exploring morphological evidence. Our results suggest a basal split of Platycerium into two well-supported clades. One clade comprises species occurring in Africa, Madagascar, and South America, whereas the second clade contains exclusively Australasian species. The latter clade is further divided into a clade corresponding to P. bifurcatum and its putative segregates and a clade of seven species occurring from Indochina throughout the Malesian region to New Guinea and Australia. The Afro-Madagascan clade includes a clade of two species found in tropical Africa and a clade of four species that includes three species endemic to Madagascar. The single neotropical species of this genus, P. andinum, is nested within the Afro-Madagascan clade but is not closely related to any extant species.
Key Words: Africa • historical biogeography • Madagascar • Malesia • phylogeny • polygrammoid ferns • Polypodiaceae • South America
In several recent studies, the evolution of epiphytic ferns was explored with phylogenetic approaches using nucleotide sequence data (e.g., Schneider et al., 2002
, 2004a
, c; Haufler et al., 2003
; Janssen and Schneider, 2005
). This approach provided new insights in the relationships of these ferns, biogeography, and morphological evolution. In this context, a similar study on the staghorn fern genus, Platycerium Desv., is of particular interest because we may solve a longstanding controversy about the relationships within this genus and its biogeographic history (Hoshizaki, 1972
; Hennipman and Roos, 1982
: Hoshizaki and Price, 1990
; Hoshizaki and Moran, 2001
).
The staghorn fern genus, Platycerium Desv., stands out among ferns as one of the most commonly grown ornamental ferns (Hoshizaki and Moran, 2001
; Poremski and Biedinger, 2001
; Darnaedi and Praptosuwiryo, 2003
). Both the economic value and the accessibility of living plants is reflected in the frequent use of these ferns in studies on cytological, developmental, and physiological features of vascular plants (e.g., Camloh and Gogala, 1992
; Kwa et al., 1995
; Ong et al., 1995
; Brumme et al., 1998
; Camloh et al., 1999
; Holtum and Winter, 1999
; Abrozoic-Dolinsek et al., 2002
). These attractive plants are distinct from other ferns by the presence of stellate hairs (shared with Pyrrosia Mirbel) on the leaf lamina, the differentiation of the leaves into litter collectors—often called mantle leaves or base fronds—and dichotomously forked trophosporophylls with coenosoroid to acrosoroid patches of sporangia (Hoshizaki, 1970
, 1972
; Hennipman and Roos, 1982
; Lee, 1989
; Hoshizaki and Price, 1990
; Hoshizaki and Moran, 2001
). The genus consists of 15 to 18 species growing predominantly as epiphytes or sometimes on rocks in subtropical to tropical lowland forests. They are among the most frequent vascular plant epiphytes in those forests and predominantly grow in relatively open conditions (Boyer, 1964
; Hoshizaki, 1972
; Kornas, 1979
; Hennipman and Roos, 1982
; Benzing, 1990
; Gardette, 1996
; Leon and Young, 1996
; Hoshizaki and Moran, 2001
; Zotz and Hietz, 2001
). Occurrence of crassulacean-acid-metabolism (CAM) and formation of water-storage tissue are further conspicuous characters suggesting adaptation to open conditions in dry, semideciduous forests (e.g., Hennipman and Roos, 1982
; Benzing, 1990
; Burrows, 1990
; Ong et al., 1995
; Zotz and Hietz, 2001
).
Platycerium is one of the few genera of polygrammoid ferns with a pantropical distribution although only a single species, P. andinum Baker, is found in tropical South America (Hoshizaki, 1972
; Hennipman and Roos, 1982
: Hoshizaki and Price, 1990
; Hoshizaki and Moran, 2001
). Roughly one half (six species) of all species occurs in Africa and Madagascar, while 8–11 species are found in subtropical to tropical Asia, Malesia, and Australia. None of these species occurs in all three regions distinguished here, and the species diversity in the Afro-Madagascan region is notable because all other genera of polygrammoid ferns show a much lower rate of species diversity in Africa when compared to either the neotropics or the Australasian region.
Two studies explored the relationships among the species of Platycerium using morphological evidence and a cladistic approach to analyze these data (Hoshizaki, 1972
; Hennipman and Roos, 1982
), but both analyses generated strongly divergent hypotheses. They disagree in the proposed relationships of several species, although their data sets are based on more or less the same morphological characters. They differ mainly in the homology assessment of some characters and by differently weighing the information of other characters (Hennipman and Roos, 1982
; Hoshizaki and Price, 1990
). In contrast to Hennipman and Roos (1982)
, the phylogenetic hypothesis of Hoshizaki (Hoshizaki, 1972
; Hoshizaki and Price, 1990
) suggested a strong correlation between clade differentiation and geographical distribution. The Afro-Madagascan species together with the neotropical taxa form one clade, whereas the Australasian species form its sister clade. This second clade was divided into two putative natural groups in which one corresponds to the P. bifurcatum (Cav.) C. Chr. complex consisting of either a single species with four varieties or of four morphological quite similar species with partly overlapping distributions (Hoshizaki, 1972
; Hennipman and Roos, 1982
; Bostock and Spokes, 1998
; Hoshizaki and Moran, 2001
). The phylogenetic hypothesis of Hoshizaki (1972)
suggests an early split of Platycerium into an African clade and an Asiatic clade, whereas Hennipman and Roos (1982)
hypothesize a more complex pattern created by repeated long-distance dispersal and/or extinction events. So far, the phylogeny of staghorn ferns has not been explored using DNA sequence data, which may provide new evidence in the ongoing controversy.
The introduction of phylogenetic studies based on cpDNA sequence data has strongly improved our understanding of the evolution of polygrammoid ferns (Schneider et al., 2002
, 2004a
, c; Ranker et al., 2004
). These studies have confirmed some of the proposed relationships but challenged other generally accepted or controversial hypotheses of natural relationships. Whereas most of these studies focused on global relationships, some data sets were designed to explore the relationships in particular lineages/genera of polygrammoid ferns, such as the grammitid fern Adenophorus (Ranker et al., 2003
), the ant-fern Lecanopteris (Haufler et al., 2003
), the non-natural genus Polypodium and its relatives (Haufler and Ranker, 1995
; Haufler et al., 2000
; Schneider et al., in press), and the drynarioid ferns (Janssen and Schneider, 2005
). The study on drynarioids is of particular interest for the study of Platycerium because both lineages were studied with a cladistic approach using morphological evidence and share the occurrence of a single, well-studied sister lineage. The cpDNA data supported most of the relationships suggested by morphological evidence (Roos, 1985
), improved our understanding of their evolution based on the clearly defined sister clade, and increased information about the phylogenetic distance among species (Janssen and Schneider, 2005
; H. Schneider and T, Janssen, in preparation). The sister lineage of Platycerium, the genus Pyrrosia, was studied in a comprehensive monographic study using morphological evidence (Hovenkamp, 1986
). The relationships of both genera were assumed based on the shared character of stellate hairs on the lamina, which was subsequently supported in global phylogenetic studies of polygrammoids (Schneider et al., 2002
, 2004c).
In this study, we explore the phylogeny of Platycerium using sequences of four cpDNA regions for all currently accepted species. Using this evidence, we want to infer the hypotheses of Hoshizaki (1972)
and Hennipman and Roos (1982)
as well as reconstruct the biogeographic history of this fern lineage. It has been proposed that the neotropical species P. andinum is closely related to the Madagascan P. quadridichotomum (Bonap.) Tardieu (Hoshizaki, 1972
; Hennipman and Roos, 1982
; Hoshizaki and Price, 1990
; Moran and Smith, 2001
), and this putative species pair was included in a list of possible vicariance events between South America and Africa (Moran and Smith, 2001
). However, neither the fossil record (van Uffelen, 1991
; Collinson, 2001
) nor divergence time estimates (Schneider et al., 2004b
) support an origin of these ferns before the breakup of Gondwana, which is required in the vicariance hypothesis. In general, historical biogeography of these ferns may provide unique insights into the evolution of epiphytic vegetation in extant subtropical and tropical forests.
MATERIALS AND METHODS
Samples of leaf material were collected of all currently accepted species of Platycerium from the Old Botanical Garden of the University of Göttingen and from the garden of Charles Alford (Florida). At least a single representative was collected of each species including representatives of all four putative segregates of the P. bifurcatum complex, both variations of P. stemaria (Beauv.) Desv., and three collections of P. alcicorne Desv. Sequences of other polygrammoid ferns were predominantly used in previous studies (Schneider et al., 2002
, 2004a
, c; Janssen and Schneider 2005
; Schneider et al., in press), but some additional sequences, especially for Pyrrosia, were added in this study. Voucher specimens were deposited at the herbarium of the University Göttingen (GOET), whereas all new sequence data were submitted to GenBank (see Appendix for voucher information and GenBank accession numbers).
|
; Schneider et al., 2004a
, c; Janssen and Schneider, 2005
). PCR products were prepared for sequencing with a BigDye Terminator Cylce Sequencing kit, version 3.1 (ABI Prism, Applied Biosystems, Foster Coty, California, USA) and sequenced using an ABI capillary sequencer 3100 (Applied Biosystems). All sequences were assembled and manually aligned using BioEdit (http://www.mbio.ncsu.edu/BioEdit/bioedit.html, and the final alignment was adjusted manually in MacClade 4.0 (Maddison and Maddison, 2000
). Ambiguously aligned regions were excluded from all analyses. Taxonomically informative indels were identified visually.
Maximum parsimony (MP) and maximum likelihood (ML) analyses were performed with PAUP* version 4.0b10 (Swofford, 2000
). Model and parameters were selected using the hierarchical likelihood ratio test and the Akaike information criterion as implemented in Modeltest (Posada and Crandall, 1998
). MP and ML analyses were calculated using the heuristic mode with 1000 respectively 100 random-addition-sequence replicates, tree-bisection-reconnection (TBR) branch swapping to completion, and MULPARS on. Bootstrap support values were estimated by calculating 100 or 1000 respectively 100 bootstrap replicates, each with 10 random-addition-sequence replicates, TBR branch swapping, and MULPARS on. NeighborNet (Bryant and Moultan, 2004
) and split decomposition analyses (Huson, 1998
), based on a distance matrix calculated using the general-time-reversible (GTR) model, were applied to estimate alternative relationships within Platycerium, indicated by subset of characters.
The distribution ranges of ancestral nodes were inferred using the software DIVA (Ronquist, 1997
), which allows us to estimate ancestral distributions by taking dispersal and vicariance events into account. In addition, a maximum parsimony approach was applied to reconstruct ancestral distributions with both ACCTRAN and DELTRAN optimization of character state changes as implemented in MacClade 4.0. Likelihood estimates of ancestral area estimates were calculated using the one-parameter Markov K-state model (Lewis, 2001
) as implemented in the ancestral state reconstruction packages for Mesquite 9.0 (Maddison and Maddison, 2003; website, http://mesquiteproject.org). This approach maximizes the probability of arriving at the distribution of terminal taxa, given a stochastic model of evolution (Schluter et al., 1997
; Pagel, 1999). Information about species distributions was obtained from herbarium specimens and literature (Hennipman and Roos, 1982
; Johns, 1991
; Bostock, 1998
; Roux, 2001
; Fernandez, 2003
). The influence of the hypothetical basal lineage of African Pyrrosia, as suggested in a phylogenetic analysis of this genus (Hovenkamp, 1986
), was inferred by generating a hypothetical phylogeny in which such a lineage is placed as the sister to all other lineages within Pyrrosia. Patterns of character evolution were reconstructed using MacClade 4.0 by plotting the character matrices of previous studies (Hoshizaki, 1972
; Hennipman and Roos, 1982
) onto the phylogeny recovered using the combined cpDNA data set.
RESULTS
Phylogeny of Platycerium
Maximum parsimony and maximum likelihood analyses of the combined data sets found the same general topology (Figs. 1, 2). The maximum parsimony analyses resulted in 36 most parsimonious trees of a length 3729 steps (consistency index [CI] = 04.421, homoplasy index [HI] = 0.579, retention index [RI] = 0.727, rescaled consistency index [RC) = 0.364), whereas the maximum likelihood found a single tree with a –ln = 24 041.06 using the GTR model with the parameters based on a base-pair distribution of A = 0.3035, C = 0.1863, G = 0.2087, T = 0.3017, rate of invariable sites I = 0.3067, and a gamma distribution of 
= 1.200. Pyrrosia was found to be sister to a monophyletic genus Platycerium, which consists of three lineages with 100% bootstrap support in maximum parsimony and maximum likelihood analyses. These clades correspond to the Afro-American group, Javan-Australian group, and Malayan-Asian group proposed by Hoshizaki (1972)
. All analyses recovered with considerable support the Afro-Madagascan-neotropical clade as sister to the other two clades. Analyses of the single-gene data sets did not give any evidence for conflicting information among the four cpDNA data sets.
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The Javan-Australian clade is synonymous to the P. bifurcatum complex, which occurs throughout the Sunda Islands and eastern Australia. The four cpDNA markers were more or less identical in the four samples that correspond to one representative of each putative species [P. bifurcatum (Cav.) C. Chr., P. hillii T. Moore, P. veitchii (Underw.) C. Chr., P. willinckii T. Moore].
Among the seven species of the Malayan-Asian clade, P. coronarium (J. König ex O.F. Müll.) Desv. and P. ridleyi forms a strongly supported subclade. These two species occur more or less sympatric in western Malesia (Malay Peninsula, Sumatra, Java, Borneo), the Philippines, and the southern part of Indochina (only P. coronarium). The remaining five species are also grouped in a strongly supported clade, but their internal relationships were poorly resolved. Two species pairs were found without bootstrap support, P. grande (Fée) Kunze + P. holttumii de Jonch. & Hennipman, P. superbum de Jonch. & Hennipman + P. wandae Racib., leaving P. wallichii Hook. as an isolated taxon.
The neighborNet and split-decomposition analyses found no alternatives to the strongly supported clades but indicate that the current data set is insufficient to distinguish between alternative relationships among the P. wallichii group and the clade comprising three species endemic to Madagascar.
Several clades of Platycerium possess clade-specific deletion or insertion with a length of more than two base pairs in the two studied chloroplast spacer regions. None of the clades showed more than one indel. These signatures allow us to recognize the major phylogenetic groups using these two IGS regions.
Phylogenetic biogeography of Platycerium
The phylogeny suggests an early split into an Afro-Madagascan lineage and an Australasian lineage (Fig. 3). The first one splits into a tropical African lineage with two species and an East African-Madagascan lineage with four species of which three are endemic to Madagascar. Platycerium alcicorne is sister to an exclusively Madagascan clade and its occurrence in both East Africa and Madagascar may indicate a dispersal from East Africa to Madagascar. However, likelihood reconstruction allows us to suggest an origin of this species in Madagascar with a subsequent expansion of its distribution to East Africa, the Comoros, and Mascarenes. The ancestor of the neotropical P. andinum likely occurred in the Afro-Madagascan region, but the exact pattern is ambiguous. The Australasian sister lineage of the Afro-Madagascan clade may have originated either in Australia or SE Asia as indicated by likelihood and maximum parsimony reconstructions of ancestral distributions. The Javan-Australian lineage may have originated in Australia and expanded its distribution towards Java. The alternative concept of an origin in Java and migration to Australia cannot be excluded based on current data. Its sister lineage, the Australasian clade, may have its ancestral distribution either in Australia or Indochina + western Malesia, but likelihood estimates gave slightly higher probabilities for the second hypothesis. The ancestors of the clade containing P. suberbum and P. wandae were growing in central or western Malesia, whereas the alternative hypothesis of origin in eastern Malesia to Australia is less likely, according to the phylogenetic reconstructions. The clade comprising P. coronarium and P. ridleyi is more or less restricted to western Malesia + Philippines. Likewise, P. wallichii occurs in Thailand, Burma, and northern India. The other two putative species pairs may be the result of disruptions of their ancestral distribution. Platycerium grande from the Philippines is sister to P. holttumii occurring in Indochina, whereas P. superbum from eastern Australia is sister to P. wandae occurring in New Guinea. In general, the ancestral distributions for many basal nodes are poorly resolved.
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Hypotheses for Platycerium phylogeny
The Malayan-Asian clade of Platycerium is easily recognized by the soral patches, of which there are only one or two per frond. In the sister species P. coronarium and P. ridleyi, these patches are localized at specialized lobes of the lamina, whereas in the other five species of this lineage these patches are on conspicuously broadened sinuses (Hoshizaki, 1972
; Hoshizaki and Price, 1990
). Hennipman and Roos (1982)
did not accept the homology of the soral patches and found those taxa nested in different clades. Their cpDNA data support the homology assessment of Hoshizaki (1972)
by providing evidence for a putative transformation of the sorus location at broadened sinuses to specialized lobes of the lamina. The two species with the specialized lobes, P. coronarium and P. ridleyi, were found to be sister species, and their position as sister to the other species with soral patches leaves it unclear if this condition evolved from those patches as found in the P. wallichii clade. The sister pair P. coronarium and P. ridleyi share several unique morphological characters, such as reduced sporangia containing only eight spores instead of sixty-four, the shape of the paraphyses, and the ornamentation of the spores (Hoshizaki, 1972
; Hennipman and Roos, 1982
). The relationships among the remaining taxa of the Malyan-Asian clade are still not fully discovered. Platycerium wallichii is isolated morphologically by several autapomorphic character states such as the lack of marginal scale indument. Reduction of one main branch in the foliage frond, horizontally exposed soral patches, and the long paraphyses rays have been interpreted as character states that suggest relationships to the African P. elephantotis. These homology assessments were criticized because the character states are too variable in this fern genus (Hoshizaki and Price, 1990
). The structure of the stipe cortex and the soral patches indicates the alternative relationships with members of the Malayan-Asian clade that are strongly supported by cpDNA evidence. In contrast to conflicting hypotheses concerning P. wallichii, close relationships among the remaining four species of this lineage were undisputed, based on the presence of more or less sinuate base frond margin with a conspicuous fringe and the very dense set of hairs on the rhizome scales (Hoshizaki, 1972
; Hennipman and Roos, 1982
; Hoshizaki and Price, 1990
).
The Javan-Australian clade is easily recognized by the occurrence of subpeltate to peltate rhizome scales. The presented data does not provide further insights into the differentiation of this clade because sampling is insufficient (only four specimens), and the markers are not variable enough to resolve the internal phylogeny of this clade.
The Afro-American clade is characterized by the presence of well-developed central meristeles in the stipes and by the ability to proliferate through root buds, although root buds are also found in P. bifurcatum s.s. Hoshizaki (1972)
regards P. andinum as a lineage apart within the Afro-American clade sharing only plesiomorphic traits with the others, especially P. quadridichotomum. Our results strongly support the lack of any morphological synapomorphic character state distinguishing P. andinum and P. quadridichotomum. Characters such as brown, mature base fronds and the position of the fertile fronds and soral patches are either homoplastic or plesiomorphic. The two tropical African species, P. elephantotis and P. stemaria, are characterized by the occurrence of mixed sporangia (intermingling of sporangia of different maturity in the same sporangia patch) and distantly inserted receptacles (0.6–0.9 mm apart), but these features occur also in some Asiatic taxa (Hoshisaki, 1972).
Inference of Platycerium phylogeny using morphological characters is difficult because of the variability of some features and the absence of many critical characters in the sister clade Pyrrosia (Hovenkamp, 1986
). Denser sampling is not likely to smooth out this gap because none of the extant species of Pyrrosia resembles closely the morphology of Platycerium. Hovenkamp (1986)
stressed out the occurrence of asymmetric leaves in Pyrrosia africana (Kunze) F. Ballard as a single character suggesting close relationships between this species and the Platycerium lineage, but we did not have access to DNA from this species. Some putatively interesting traits, such as the evolution of CAM, are impossible to investigate based on the paucity of observations (Ong et al., 1995
; Holtum and Winter, 1999
; Zotz and Hietz, 2001
).
A further issue is the limitation of available DNA sequence data to the chloroplast genome, which is likely inherited maternally in these ferns (Vogel et al., 1998
). These data make it impossible to detect misleading information that is caused by introgression and/or hybrid speciation (Linder and Rieseberg, 2004
). However, the few hybrids reported for these ferns are only known to arise only in cultivation (Hoshizaki, 1975
; Hoshizaki and Price, 1990
; Hoshizaki and Moran, 2001
), and no hybrids were ever reported to occur in the wild. This is similar to other groups of polygrammoid ferns in which nearly all known natural hybrids are members of the temperate Polypodium s.s. lineage. Based on a study of the epiphytic polygrammoid fern genus Pleopeltis in Mexico, Haufler et al. (2000)
suggested different speciation mechanisms in Pleopeltis vs. temperate Polypodium. Similar results were found for the epiphytic asplenioid fern, Asplenium nidus, in Australasia (Yatabe et al., 2001
). This hypothesis implies that hybridization and introgression are rare or at least less common in tropical epiphytic ferns.
Scenarios of historical biogeography
The reconstruction of the history of Platycerium is hindered by the absence of fossils allowing us to estimate the distribution of this genus in space and time. Inference of divergence times is problematic for the whole lineage of polygrammoid ferns due to their poor fossil record and equivocal assignment of these few fossils to extant lineages (van Uffelen, 1991
; Collinson, 2001
; Kvacek et al., 2004
). However, the current fossil record of derived ferns and existing divergence time estimates indicate that this genus did not originate before the Eocene (Schneider et al., 2004b
). The observed split into an Afro-American and Australasian lineage is unlikely to be the result of the breakup of Gondwana. Similar, the proposed vicariance between P. andinum and other members of the Afro-American clade does not fit in with the time of the Gondwana break-up. Long-distance dispersal with subsequent speciation events is therefore the preferred explanation for the observed origin of the Southern American species from Afro-Madagascan ancestors. A similar problem arises with the separation of the Afro-Madagascan and Australasian clades of Platycerium. The sister clade, Pyrrosia, also occurs in both regions but has a considerably higher species diversity in Australasia than in the Afro-Madagascan region. Unfortunately, current sampling of Pyrrosia is insufficient to test the hypothesis of an African clade as sister to the remaining clades of Pyrrosia, as suggested by Hovenkamp (1986)
. To test the putative influence of this putative sister clade to the remaining species of Pyrossia missing in this study, we reconstructed ancestral areas using DIVA, MP, and ML analyses with and without inclusion of this putative clade. However, both analyses failed to provide unambiguous support for either an Afro-Madagascan or Australasian origin. The pattern recovered within the Afro-Madagascan clade fits best with the hypothesis of a colonization of Madagascar by species occurring in Africa followed by a subsequent speciation event(s). The three species endemic to Madagascar occur mainly in the northern habitats that may have evolved since the Eocene/Oigocene (Wells, 2003
). The diversification of these ferns in the Australasian region is mysterious, but a few conclusions seem to be possible. This region evolved as a result of the collision between Southeast Asia and the Australian croton in the Miocene (Hall, 2002
). In a recent study on drynarioid ferns, evidence was found for a correlation of the distribution pattern and species diversity of these ferns with the formation of the Malesian region in the Miocene (H. Schneider and T. Janssen, unpublished manuscript). Whereas drynarioid ferns often grow in wet rainforests dominating the core of Malesia, Platycerium occurs predominantly in seasonally dry forests found in Indochina, the Sunda Islands, and eastern Australia (Hoshizaki, 1972
; Hennipman and Roos, 1982
). The phylogenetic patterns may, therefore, reflect the unfolding of these habitats since the drift of Australia from the southern Pacific towards SE Asia. Long distance dispersal events may have been an important factor, but we also need to consider the transformation of the vegetation in Malesia during and after the Pleistocene glaciations. Currently available information is insufficient to fully explore these hypotheses.
In summary, the current distribution of Platycerium appears to be created by the combination of long-distance dispersals and subsequent speciation(s) in Madagascar and Australasia.
FOOTNOTES
We thank C. Alford who kindly shared several less frequently grown species and the curator/gardeners of the Old Botanical Garden Göttingen for their continuing efforts to grow these ferns. The project was supported financially by a German Science Foundation grant to H.S. (SCHN 785/2-1) under the Schwerpunkt Programm SPP 1127 "Radiations—Origin of Biological Diversity." 
2 Author for correspondence (e-mail: hschnei3{at}gwdg.de
)
LITERATURE CITED
Abrozoic-Dolinsek J Camloh H Bohanec B Zel J 2002 Apospory in leaf culture of staghorn fern (Platycerium bifurcatum). Plant Cell Reports 20: 791-796[CrossRef][Web of Science]
Benzing D. H 1990 Vascular epiphytes: general biology and related biota Cambridge University Press Cambridge, UK
Bostock P. D Spoles T. M 1998 Polypodiaceae. Flora of Australia 48: 468-495
Boyer Y 1964 Contribution á l'étude de l'écophyosiologe de deix fougères épiphytes: Platycerium stemaria (Beauv.) Desv. et P. angolense Welw. Annales des Sciences Naturelles: Botanique 12: 87-228
Brumme S Kruft V Schmitz U. K Braun H. P 1998 New insights into the co-evolution of cytochrome c reductase and the mitochondrial processing peptidase. Journal of Biological Chemistry 273: 13143-13149
Bryant D Moulton V 2004 Neighbor-Net: an agglomerative method for the construction of phylogenetic networks. Molecular Biology and Evolution 21: 255-265
Burrows J. E 1990 Southern African ferns and fern allies Frandsen Sandton, South Africa
Camloh M Gogala N 1992 In vitro culture of Platycerium bifurcatum gametophytes. Scientia Horticulturae (Amsterdam) 51: 343-346[CrossRef]
Camloh M Vilhar B Zel J Ravnikar M 1999 Jasmonic acid stimulates development of rhizoids and shoots in fern leaf culture. Journal of Plant Physiology 155: 798-801[Web of Science]
Collinson M 2001 Cainozoic ferns and their distribution. Brittonia 53: 173-235[Web of Science]
Darnaedi D Praptosuwiryo T. N 2003 Platycerium bifurcatum. In W. P. de Winter, and V. B. Amoroso [eds.] Plant resources of South-East Asia, vol. 15(2), Cryptogams: ferns and fern allies 157-159 Backhuys Publishers, Leiden, Netherlands
Fernandez B 2003 New records for Platycerium andinum Baker in Peru. American Fern Journal 93: 160-163[CrossRef][Web of Science]
Gardette E 1996 Microhabitats of epiphytic fern communities in large lowland rain forest plots in Sumatra. In J. M. Camus, M. Gibby, and R. J. Johns [eds.] Pteridology in perspective 655-658 Royal Botanic Gardens, Kew, UK
Hall R 2002 Cenozoic geological and plant tectonic evolution of SE Asia and the SW Pacific: computer-based reconstructions, models and animations. Journal of Asian Earth Science 20: 353-431[CrossRef]
Haufler C. H Grammer W. A Hennipman E Ranker T. A Smith A. R Schneider H 2003 Systematics of the ant-fern genus Lecanopteris: testing phylogenetic hypotheses with DNA sequences. Systematic Botany 28: 217-227[Web of Science]
Haufler C. H Hooper E. A Therrien J. P 2000 Modes and mechanisms of speciation in pteridophytes: implications of contrasting patterns in ferns representing temperate and tropical habitats. Plant Species Biology 15: 223-236[CrossRef]
Haufler C. H Ranker T. A 1995 rbcL sequences provide phylogenetic insights among sister species of the fern genus Polypodium. American Fern Journal 85: 361-374[CrossRef][Web of Science]
Hennipman E Roos M. C 1982 A monograph of the fern genus Platycerium (Polypodiaceae). Verhandelingen der Koninklijke Nederlands Akademie van Wetenschappen, Afdeeling Natuurkunde, Tweede Reeks 80: 1-126
Holtum J. A. M Winter K 1999 Degrees of crassulacean acid metabolism in tropical epiphytic and lithophytic ferns. Australian Journal of Plant Physiology 26: 749-757[Web of Science]
Hoshizaki B. J 1970 Rhizome scales of Platycerium. American Fern Journal 60: 144-160[CrossRef]
Hoshizaki B. J 1972 Morphology phylogeny of Platycerium species. Biotropica 4: 93-117[CrossRef]
Hoshizaki B. J 1975 A staghorn fern (Platycerium) hybrid. American Fern Journal 65: 99-101[CrossRef]
Hoshizaki B. J Moran R 2001 Fern grower's manual, 2nd ed Timber Press Portland, Oregon, USA
Hoshizaki B. J Price M. C 1990 Platycerium update. American Fern Journal 80: 53-69[CrossRef][Web of Science]
Hovenkamp P. H 1986 A monograph of the fern genus Pyrrosia. Leiden Botanical Series 9: 1-310
Huson D 1998 SplitsTree: a program for analyzing and visualizing evolutionary data. Bioinformatics 14: 68-73
Janssen T Schneider H 2005 Exploring the evolution of humus collecting leaves in drynarioid ferns (Polypodiaceae, Polypodiidae) based on phylogenetic evidence. Plant Systematics and Evolution 252: 175-197[CrossRef][Web of Science]
Johns R. J 1991 Pteridophytes of tropical east Africa, a preliminary check-list of the species Royal Botanical Gardens Kew, UK
Kornas J 1979 Distribution and ecology of the pteridophytes in Zambia Polska Akademia Nauk Wydzial II Nauk Biologiczynch Krakow, Poland
Kwacek Y Daskowam J Zetter R 2004 A re-examination of Cenozoic Polypodium in North America. Review of Palaeobotany and Palynology 128: 219-227[CrossRef][Web of Science]
Kwa S. H Wee Y. C Kumar P. P 1995 Role of ethylene in the production of sporophytes from Platycerium coronarium (Koenig) Desv. Frond and rhizome pieces cultured in vitro. Journal of Plant Growth Regulation 14: 183-139[CrossRef][Web of Science]
Lee Y. H 1989 Development of mantle leaves in Platycerium bifurcatum (Polypodiaceae). Plant Systematics and Evolution 165: 199-209[CrossRef][Web of Science]
Leon B Young K. R 1996 Distribution of pteridophyte diversity and endemism in Peru. In J. M. Camus, M. Gibby, and R. J. Johns [eds.] Pteridology in perspective 77-91 Royal Botanic Gardens, Kew, UK
Lewis P. O 2001 A likelihood approach to estimating phylogeny from discrete morphological character data. Systematic Biology 50: 913-925
Linder C. R Rieseberg L. H 2004 Reconstructing patterns of reticulate evolution in plants. American Journal of Botany 91: 1700-1708
Maddison D. R Maddison W. P 2000 MacClade 4.05 Sinauer Sunderland, Massachusetts, USA
Moran R Smith A. R 2001 Phytogeographic relationships between neotropical and Africa-Madagascan pteridophytes. Brittonia 53: 304-351[Web of Science]
Ong B. L Ng S. L Wee Y. C 1995 Photosynthesis in Platycerium coronacrium (Koenig ex Mueller) Desv. Photosynthetica 31: 59-69[Web of Science]
Pagel Y. H 1989 The maximum likelihood approach to reconstructing ancestral character states of discrete characters on phylogenies. Systematic Biology 48: 612-622[CrossRef]
Poremski S Biedinger N 2001 Epiphytic ferns for sale: influence of commercial plant collection on the frequency of Platycerium stemaria (Polypodiaceae) in coconut plantations on the southeastern Ivory Coast. Plant Biology (Stuttgart) 3: 72-76[CrossRef]
Posada D Crandall K. A 1998 Modeltest: testing the model of DNA substitution. Bioinformatics 14: 817-818
Ranker T. A Geiger J. M. O Kennedy S. C Smith A. R Haufler C. H Parris B. S 2003 Molecular phylogenetics and evolution of the endemic Hawaiian genus Adenophorus (Grammitidaceae). Molecular Phylogenetics and Evolution 26: 337-347[CrossRef][Web of Science][Medline]
Ranker T. A Smith A. R Parris B. S Geiger J. M. O Haufler C. H Straub S. C. K Schneider H 2004 Phylogeny and evolution of grammitid ferns (Grammitidaceae): a case of rampant morphological homoplasy. Taxon 53: 415-428[CrossRef][Web of Science]
Ronquist F 1997 Dispersal-vicariance analysis: a new approach to the quantification of historical biogeography. Systematic Biology 46: 195-203
Roos M. C 1985 Phylogenetic systematics of the Dynarioideae (Polypodiaceae). Verhandelingen der Koninklijke Nederlands Akademie van Wetenschappen, Afdeling Natuurkunde, Tweede Reeks 85: 1-138
Roux J. P 2001 Conspectus of southern African pteridophyta. Southern African Botanical Diversity Network Report 13: 1-223
Schneider H Janssen T Hovenkamp P Smith A. R Cranfill R Haufler C. H Ranker T. A 2004a Phylogenetic relationships of the enigmatic Malesian fern Thylacopteris (Polypodiaceae, Polypodiidae). International Journal of Plant Sciences 165: 1077-1087[CrossRef][Web of Science]
Schneider H Kreier H.-P Wilson R Smith A. R In press The Synammia enigma: evidence for a temperate lineage of polygrammoid ferns (Polypodiaceae, Polypodiidae) in southern South America. Systematic Botany
Schneider H Schuettpelz E Pryer K. M Cranfill R Magallón S Lupia R 2004b Ferns diversified in the shadow of angiosperms. Nature 428: 553-557[CrossRef][Medline]
Schneider H Smith A. R Cranfill R Haufler C. H Ranker T. A Hildebrand T 2002 Gymnogrammitis dareiformis is a polygrammoid fern (Polypodiaceae)—resolving an apparent conflict between morphological and molecular data. Plant Systematics and Evolution 234: 121-136[CrossRef][Web of Science]
Schneider H Smith A. R Cranfill R Hildebrand T. J Haufler C. H Ranker T. A 2004c Unravelling the phylogeny of polygrammoid ferns (Polypodiaceae and Grammitidaceae): exploring aspects of the diversification of epiphytic plants. Molecular Phylogenetics and Evolution 31: 1041-1063[CrossRef][Web of Science][Medline]
Schluter D Price T Mooers A. O Ludwig D 1997 Likelihood of ancestor states in adaptive radiations. Evolution 51: 1699-1711[CrossRef][Web of Science]
Swofford D. L 2000 PAUP*: phylogenetic analysis using parsimony (*and other methods), version 4 Sinauer Sunderland, Massachusetts, USA
Van Uffelen G 1991 Fossil Polypodiaceae and their spores. Blumea 36: 253-272[Web of Science]
Vogel J. C Russell S. J Rumsey F. J Barrett J. A Gibby M 1998 Evidence for maternal transmission of chloroplast DNA in the genus Asplenium (Aspleniaceae, Pteridophyta). Botanica Acta 111: 247-249[Web of Science]
Wells N. A 2003 Some hypotheses on the Mesozoic and Cenozoic paleoenvironmental history of Madagascar. In S. Goodman, and J. P. Renstead [eds.] Natural history of Madagascar 16-34 University of Chicago Press, Chicago, Illinois, USA
Yatabe Y Masuyama S Darnaedi D Murakami N 2001 Molecular systematics of the Asplenium nidus complex from Mt. Halimum National Park, Indonesia: evidence for reproductive isolation among three sympatric rbcL sequence types. American Journal of Botany 88: 1517-1522
Zotz G Hietz P 2001 The physiological ecology of vascular epiphytes: current knowledge, open questions. Journal of Experimental Botany 52: 2967-2978
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95% in ML bootstrap analyses. Sketches of fertile leaves illustrate the typical position of the coenosori (gray areas) in the major lineages of Platycerium. The sketches are based on Hoshizaki (1972)