Phylogenetic relationships of Gomphillaceae and

Transcription

Phylogenetic relationships of Gomphillaceae and
Mycologia, 96(2), 2004, pp. 283–294.
q 2004 by The Mycological Society of America, Lawrence, KS 66044-8897
Phylogenetic relationships of Gomphillaceae and Asterothyriaceae: evidence
from a combined Bayesian analysis of nuclear and mitochondrial sequences
Robert Lücking1
INTRODUCTION
Department of Botany, Field Museum of Natural
History, 1400 S. Lake Shore Drive, Chicago,
Illinois 60605-2496
The ascomycete families Gomphillaceae and Asterothyriaceae form a medium-size group of mainly
tropical, crustose microlichens (Lücking 1999, Vezda
1979, Vezda and Poelt 1987). Numerous species grow
on leaves and form an important part of the tropical
diversity in the phyllosphere (Lücking 2001). The
Gomphillaceae morphologically are remarkable for
the presence of peculiarly shaped conidiomata that
are called hyphophores, while many Asterothyriaceae
are characterized by a unique thallus cortex (Henssen and Lücking 2002, Vezda 1979). Despite their importance for tropical lichen diversity and their morphological peculiarities, the phylogeny and taxonomy of Gomphillaceae and Asterothyriaceae largely
has been unsettled.
The Gomphillaceae consist of almost 300 species
currently classified into 14 genera (Lücking 1997,
Vezda and Poelt 1987). While most species grow on
living leaves, taxa occurring on bark of vascular
plants, over bryophytes, on soil and rock surfaces and
even lichenicolous species also are known in this
group (Lücking 1997, Lücking and Kalb 2002, Lücking and Sérusiaux 1998, Vezda and Poelt 1987).
Members of this family are characterized by apothecioid ascomata with hemiangiocarpous development,
a hamathecium consisting of thin, strongly gelatinized and richly branched and anastomosing paraphyses, and nonamyloid asci corresponding to the annelasceous type (Lücking 1997, Vezda and Poelt
1987). Apothecial morphology is variable, ranging
from sessile and biatorine (e.g., Gyalideopsis, Echinoplaca) to vertically elongate (Gomphillus) or immersed-erumpent and zeorine apothecia (Calenia,
Gyalectidium) (FIG. 1). The conidiomata, the socalled hyphophores, are usually stipitate and produce
conidia (‘‘diahyphae’’) at their tips, but many variations of this basic scheme occur and derived types
even resemble disk-shape diaspores or campylidioid
conidiomata (FIG. 2). Both apothecial morphology
and hyphophore type are employed for the delimitation of genera in the family.
Gomphillaceae originally was based on a single,
monospecific taxon, Gomphillus calycioides, an enigmatic lichen usually growing over bryophytes and
characterized by elongate apothecia with very long
asci and filiform ascospores (Nylander 1860, Hafell-
Bryan L. Stuart
Department of Zoology, Field Museum of Natural
History, 1400 S. Lake Shore Drive, Chicago,
Illinois 60605-2496
H. Thorsten Lumbsch
Department of Botany, Field Museum of Natural
History, 1400 S. Lake Shore Drive, Chicago,
Illinois 60605-2496
Abstract: The phylogeny and systematic position of
Gomphillaceae was reconstructed using a combined
Bayesian analysis of nuclear LSU rDNA and mitochondrial SSU rDNA sequences. Twenty-four partial
sequences of 12 taxa (11 Gomphillaceae and one Asterothyriaceae) plus two new sequences of Stictis radiata (Ostropales outgroup) were generated and
aligned with the corresponding sequences retrieved
from GenBank, resulting in an alignment of 82 taxa
that was analyzed using a Bayesian approach with
Markov chain Monte Carlo (B/MCMC) methods.
Our results confirm Gomphillaceae sensu Vezda and
Poelt plus Asterothyriaceae to be a monophyletic
group, with an unresolved relationship between the
two families. Placement of Gomphillaceae and Asterothyriaceae within Ostropales sensu Kauff and Lutzoni, as sister of Thelotremataceae, also is strongly
supported. Alternative hypotheses placing Gomphillaceae in Lecanorales (Cladoniaceae), Agyriales
(Baeomycetaceae) or within bitunicate Ascomycota
(Arthoniomycetes, Chaetothyriomycetes, Dothideomycetes) were rejected with our dataset. After recent
synonymization of Dimerella with Coenogonium (Ostropales: Coenogoniaceae), we propose the new combination Coenogonium pineti (one of our Ostropales
outgroup taxa in this analysis).
Key words: foliicolous lichens, Lecanoromycetes,
mitochondrial small-subunit rDNA, nuclear large
subunit rDNA, systematics
Accepted for publication August 26, 3003.
1 Corresponding author. E-mail: [email protected]
283
284
MYCOLOGIA
FIG. 1. Morphological variation of apothecia in selected genera of Asterothyriaceae (A) and Gomphillaceae (B–H) A.
Asterothyrium longisporum (immersed-erumpent with recurved lobules). B. Gomphillus ophiosporus (vertically elongate). C.
Gyalideopsis vulgaris (sessile). D. Tricharia albostrigosa (sessile). E. Tricharia longispora (shortly stipitate). F. Echinoplaca
atrofusca (adnate and spot-like). G. Calenia aspidota (immersed-erumpent). H. Aulaxina submuralis (carbonized).
LÜCKING
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285
FIG. 2. Morphological variation of hyphophores in selected genera of Gomphillaceae. A. Calenia monospora (stipitate with
apical bunch of diahyphae visible). B. Tricharia cuneata (spatulate). C. Calenia aspidota (setiform). D. Tricharia dilatata
(hand-shaped). E. Echinoplaca gemmifera (resembling disk-shaped isidia). F. Gyalideopsis hyalina (resembling campylidia of
Pilocarpaceae). G. Gyalectidium filicinum (squamiform wirh horns). H. Hippocrepidea nigra (lunular).
286
MYCOLOGIA
TABLE I. Species and specimens of lichenized and nonlichenzied Ascomycota used in the current study. Taxa for which
sequences have been newly obtained are in boldface. F denotes voucher specimens deposited at the Field Museum of Natural
History
GenBank acc. no.
Species
Absconditella sphagnorum
Adelolecia pilati
Agonimia tristicula
Ainoa mooreana
Arthonia dispersa
Aspergillus flavus
Aspergillus nidulans
Asterothyrium longisporum
Aulaxina quadrangula
Baeomyces placophyllus
Beauveria bassiana
Berlesiella nigerrima
Bryophagus gloeocapsa
Cainia graminis
Calenia monospora
Calenia phyllogena
Calicium viride
Caloplaca flavorubescens
Capnodium citri
Capronia mansonii
Cephalotheca sulfurea
Ceramothyrium carniolicum
Cladonia rangiferina
Coenogonium pineti
Combea mollusca
Dendrographa minor
Diploschistes cinereocaesius
Diploschistes muscorum
Diploschistes rampoddensis
Diploschistes thunbergianus
Dothidea ribesia
Echinoplaca diffluens
Echinoplaca epiphylla
Echinoplaca leucotrichoides
Echinoplaca lucernifera
Eurotium rubrum
Glyphium elatum
Gomphillus ophiosporus
Gyalecta jenensis
Gyalectidium imperfectum
Specimen
nuLSU
mtSSU
—
—
—
—
—
—
—
Costa Rica (Cartago: Orosi), Lücking s.n. (F,
sample No. 4)
Costa Rica (Puntarenas: Las Cruces, Lücking
s.n. (F, sample No. 66)
—
—
—
—
—
Costa Rica (Cartago: Orosi), Lücking s.n. (F,
sample No. 1a)
Costa Rica (Heredia: La Selva), Lücking s.n.
(F, sample No. 32)
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Mexico (Veracruz: Lost Tuxtlas), Herrera et
al s.n. (F, sample No. M12)
Mexico (Veracruz: Lost Tuxtlas), Herrera et
al s.n. (F, sample No. M13)
Costa Rica (Heredia: La Selva), Lücking s.n.
(F, sample No. 18)
Costa Rica (Puntarenas: Monteverde), Lücking s.n. (F, sample No. 59a)
—
—
Costa Rica (Puntarenas: Las Alturas), WillWolf 10006a (F, sample No. 101)
—
Costa Rica (Cartago: Orosi) Lücking s.n. (F,
sample No. 2)
AY300824
AY300826
AY300828
AY212828
AY350578
AF109342
AF109337
AY341349
AY300872
AY300874
AY300876
AY212850
AY350570
AFU29214
V00653
AY341363
AY341350
AY341364
AF356658
AF280637
AY350579
AF465440
AF431949
AY341351
AY300878
AB027360
AY350571
AY300880
AF431952
AY341365
AY341352
AY341366
AF356670
AY300831
AY004337
AY004338
AF431950
AY004339
AY300832
AY300834
AY350580
AY350581
AY300835
AY300836
AF274094
AF274095
AY016360
AY341353
AY143402
AY143403
AF346421
AF346422
AF431953
AF346423
AY300881
AY300884
AY350572
AY350573
AY300885
AY300886
AF431954
AF431955
AY350574
AY341367
AY341354
AY341368
AY341355
AY341369
AY341356
AY341370
AY004346
AF346420
AY341357
AF346424
AF346425
AY341371
AF465450
AY341358
AF431956
AY341372
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ET AL:
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GOMPHILLACEAE
287
Continued
GenBank acc. no.
Species
Gyalideopsis sp. nov.
Lecania cyrtella
Lecanora intumescens
Lecidella meiococca
Lepraria usnica
Lobaria pulmonaria
Myriangium duriaei
Nephroma bellum
Neurospora crassa
Ochrolechia balcanica
Ochrolechia parella
Ochrolechia tartarea
Orceolina antarctica
Orceolina kerguelensis
Penicillium chrysogenum
Pertusaria albescens
Pertusaria corallina
Pertusaria scaberula
Pertusaria subventosa
Physcia aipolia
Placopsis bicolor
Placopsis gelida
Pyrrhospora quernea
Raciborskiomyces longisetosum
Ramonia sp.
Schismatomma pericleum
Scoliciosporum umbrinum
Speerschneidera euploca
Steinera glaucella
Stictis radiata
Stictis radiata
Stylodothis puccinioides
Thelotrema lepadinum
Thelotrema suecicum
Trapelia coarctata
Trapelia placodioides
Trapeliopsis flexuosa
Trapeliopsis granulosa
Tricharia longispora
Xanthoria parietina
Xylaria hypoxylon
Xylographa vitiligo
Specimen
nuLSU
mtSSU
Costa Rica (Puntarenas: Altamira), Nelsen
2066a (F, sample No. 103)
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Costa Rica (Cartago: Irazú), Will-Wolf s.n. (F,
sample No. 100)
—
—
—
—
—
—
—
Costa Rica (Heredia: La Selva), Lücking s.n.
(F, sample No. 37)
—
—
—
AY341359
AY341373
AY300840
AY300841
AY300842
AY300843
AF183934
AY016365
AY300844
M38154
AF329171
AF274097
AY300848
AF274115
AF274116
AF034857
AF329176
AY300850
AF274099
AY300854
AY300857
AY212834
AY212836
AY300858
AY016367
AY300871
AF279408
AY300861
AY300862
AY300863
AY300864
AY341361
AY300891
AY300892
AY300893
AY300894
AF069541
AY350575
AY300895
Z34001
AF329170
AF329173
AY300899
AY212852
AF381561
Z23072
AF329175
AY300901
AF431959
AY300905
AY143406
AY212857
AY212859
AY300908
AY350576
AY300921
AY350577
AY300911
AY300912
AY300913
AY300914
AY341362
AY004342
AY300866
AY300867
AF274117
AF274103
AF274118
AF274119
AY341360
AF346428
AY300916
AY300917
AY212874
AF431962
AY212875
AF381561
AY341374
AF356687
AF132333
AY212849
AY143408
AF431964
AY212878
ner 1984, Vezda 1979, Vezda and Poelt 1987). Because its apothecia superficially resemble podetia,
Gomphillus was placed close to genera such as Cladonia and Baeomyces (Räsänen 1943, Sato 1954), although Nylander (1860), Santesson (1952) and Jahns
(1970) had observed that the apothecia are vertically
elongate and what was erroneously interpreted as
‘‘stipe’’ represented a part of the hymenium.
Based on similarities in hamathecium structure
and ascus type, Vezda (1979) suggested that Gomphillus calycioides is related to four genera previously
included in Asterothyriaceae (Santesson 1952), viz.
Calenia, Gyalectidium, Echinoplaca and Tricharia.
This view was supported by the discovery of hyphophores in a second species of the genus, Gomphillus
americanus (Vezda and Poelt 1987). The genera pro-
288
MYCOLOGIA
ducing hyphophores and having a hamathecium
composed of anastomosing paraphyses subsequently
were transferred from Asterothyriaceae to the resurrected Gomphillaceae, while taxa lacking hyphophores and having unbranched paraphyses were retained in Asterothyriaceae s.str. (Eriksson and Hawksworth 1987, Vezda and Poelt 1987).
The systematic positions and the homogeneity of
the two families have been questioned by various authors. Hafellner (1984, 1988) interpreted the asci of
Gomphillus as being fissitunicate and separated the
genus into an independent order Gomphillales.
Based on the ascus type, he suggested a close relationship to bitunicate ascomycetes that currently are
placed in Arthoniomycetes, Dothideomycetes and
Chaetothyriomycetes (Eriksson 2001). As regards the
Asterothyriaceae, some genera were transferred from
that family to a separate family Solorinellaceae (Vezda and Poelt 1990), while Psorotheciopsis was included
in Megalosporaceae (Vezda 1973) and Asterothyrium
itself was suggested as belonging in Thelotremataceae (Aptroot in Aptroot et al 1994).
Anatomical, ontogenetic and phenotype-based
phylogenetic evidence, however, suggest that Gomphillaceae and Asterothyriaceae sensu Vezda and
Poelt (1987) are monophyletic and best placed in
Ostropales (Henssen and Lücking 2002, Lücking
1997, 1999). Recent molecular analyses indicate that
the circumscription of this order needs clarification.
In the most recent Outline of the Ascomycetes (Eriksson et al 2003), Gyalectales (including Gyalectaceae and Coenogoniaceae) and Ostropales (including Asterothyriaceae, Graphidaceae, Odontotremataceae, Phaneromycetaceae, Solorinellaceae, Stictidaceae and Thelotremataceae) are listed separately
and Gomphillaceae are included among ‘‘Ascomycota: Families of uncertain positions’’. However,
Kauff and Lutzoni (2002) showed that Gyalectales are
nested within and form part of Ostropales, which was
confirmed in a subsequent analysis by Lumbsch et al
(2004).
To clarify the uncertain phylogenetic relationships
of Gomphillaceae and to test the alternative relationships suggested by various authors, we gathered molecular data of representatives of this family and the
Asterothyriaceae. For this purpose, we targeted the
nuclear LSU (nuLSU) and the mitochondrial SSU
(mtSSU) region of the ribosomal DNA because combined analyses of these two genes have been used
successfully in previous approaches to the phylogeny
of Lecanoromycetes (Lumbsch and Schmitt 2002,
Lumbsch et al 2004). We chose a Bayesian approach
that allows efficient analysis of datasets while employing complex nucleotide substitution models in a
parametric statistical framework (Huelsenbeck et al
2001, Larget and Simon 1999). Bayesian phylogenetics also allows simultaneous estimation of uncertainty
in the phylogenetic topography, as well as hypothesis
testing of alternative topographies, because posterior
probabilities of alternative trees can be calculated
(Huelsenbeck et al 2000).
Our Ostropales outgroup taxa includes the widespread lichen Dimerella pineti (Coenogoniaceae). Because the genus Dimerella recently has been synonymized with Coenogonium, which was confirmed by a
molecular phylogenetic analysis (Kauff and Lutzoni
2002, Lücking and Kalb 2000), we propose the new
combination Coenogonium pineti in this paper.
MATERIALS AND METHODS
Taxon sampling.—Sequence data of the nuLSU rDNA and
mtSSU rDNA were collected from a total of 82 euascomycetes. Twenty-four new sequences were obtained from 12
species, as listed in TABLE I. Taxa were sampled to ensure
that representatives of the major clades within Lecanoromycetes and taxa of the major classes of euascomycetes were
included in the study.
Molecular methods.—Small samples prepared from freshly
collected and frozen herbarium specimens were deep frozen at 280 C for 30 min and ground with sterile plastic
pestles. Total genomic DNA was extracted using PureGene
Animal Tissue DNA Isolation Protocol (Gentra Systems
Inc.). Nuclear LSU rRNA was amplified by the polymerase
chain reaction (PCR; 95 C 3 min, then 35 cycles of 95 C 45
s, 54 C 45 s, 72 C 1 min) using the forward primers LIC15R,
LR0R, LIC24R (Miadlikowska et al 2002, Miadlikowska and
Lutzoni 2000, Rehner and Samuels 1994) or ALR1 (Döring
et al 2000), and the reverse primer LR3 (Vilgalys and Hester
1990). Mitochondrial SSU rRNA was amplified by PCR (95
C 3 min, 55 C 1 min, 72 C 1 min, then 35 cycles of 94 C 1
min, 55 C 1 min, 72 C 1 min) using the primers mrSSU1
(Zoller et al 1999) and MSU7 (Zhou and Stanosz 2001).
Adding 5 mL of purified, 10 mg/mL bovine serum albumin
(BSA, New England BioLabs Inc.) to 25 mL total PCR reactions greatly improved amplification success. PCR products were electrophoresed in a 1% low-melt agarose TALE
gel stained with ethidium bromide and visualized under ultraviolet light. The bands containing DNA were excised and
agarose was digested from bands using GELase (Epicentre
Technologies). PCR products were sequenced with the amplifying primers in both directions by direct double-strand
cycle sequencing using Big Dye version 1 chemistry (Perkin
Elmer). Cycle sequencing products were precipitated with
ethanol and 3 M sodium acetate and sequenced with a
Prism 3100 Genetic Analyzer (ABI). Sequences were edited
with Sequencher version 4.1 (Genecodes). About 300 bp of
the 59 part of the nuLSU could be generated for representatives of Gomphillaceae and Asterothyriaceae. This limitation probably was due to a splicosomal intron specific to
these two families, starting at about position 350 of the 59
part of the nuLSU, and this phenomenon is currently under further investigation by us.
LÜCKING
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PHYLOGENY
TABLE II. Probabilities of five phylogenetic null hypotheses being correct. Each test is based on a B/MCMC tree
sample of 1000 trees. Probabilities significant at ,0.1% are
denoted‘‘***’’
Null hypothesis
Gomphillaceae
Gomphillaceae
Gomphillaceae
Gomphillaceae
Gomphillaceae
placed
placed
placed
placed
placed
in
in
in
in
in
Arthoniomycetes
Chaetothyriomycetes
Dothideomycetes
Agyriales
Lecanorales
Probability
0.00***
0.00***
0.00***
0.00***
0.00***
Sequence alignments.—The mtSSU dataset contains sequence portions that are highly variable. Because standard
multiple alignment programs, such as Clustal (Thompson
et al 1994), become less reliable when sequences are highly
divergent, we instead have used an alignment procedure
employing a linear Hidden Markov Model (HMM) for the
alignment, as implemented in the software SAM (Hughey
and Krogh 1996; http://www.cse.ucsc.edu/research/
compbio/sam.html). Sequences of 82 species (TABLE II)
were aligned separately for the two genes. Regions that
could not be aligned with statistical confidence were excluded from the phylogenetic analysis.
Phylogenetic analysis.—The alignment was analyzed using
the programs PAUP* 4.0b10 (Swofford 2003) and MrBayes
3.0 (Huelsenbeck and Ronquist 2001). The polarity of characters was assessed selecting four representatives of Dothideomycetes as outgroup because this group repeatedly was
found as basal within inoperculate euascomycetes in recent
phylogenetic estimates of euascomycetes (e.g., Liu et al
1999, Lumbsch et al 2002). The data were analyzed using
a Bayesian approach (Huelsenbeck et al 2000, Larget and
Simon 1999). Posterior probabilities were approximated by
sampling trees using a Markov chain Monte Carlo (MCMC)
method. The posterior probabilities of each branch were
calculated by counting the frequency of trees that were visited during the course of MCMC analysis.
The program MrBayes was used to sample trees. The
analysis was performed assuming the general time-reversible model (Rodriguez et al 1990), including estimation of
invariant sites and assuming a discrete gamma distribution
with six rate categories (GTR1I1G) for the single-gene and
the combined analyses. The nucleotide substitution model
was selected with a likelihood ratio test (Huelsenbeck and
Crandall 1997) with the program Modeltest (Posada and
Crandall 1998). No molecular clock was assumed. Initial
runs were conducted, starting with random, NJ or ME trees
to check the number of simultaneous MCMC chains necessary to avoid being trapped on local optima. For this, the
separate initial analyses were run with 200 000 generations
with an increasing number of chains (starting with four).
When the separate analyses converged at a similar likelihood value, it was assumed that the number of chains was
sufficient. This was the case with eight chains. To allow an
additional range of security, we have chosen to run the analyses employing 12 simultaneous chains that started with a
random tree. The analyses started with a random tree and
OF
GOMPHILLACEAE
289
was run with 2 000 000 generations. Eleven of these chains
were heated. During its search in the universe of trees, a
cold chain might become stuck in isolated peaks. To circumvent this, heated chains that can jump to other areas
in the universe of trees run simultaneously. These heated
chains act as scouts to enable the cold chain to escape local
optima. Every 100th tree sampled was saved into a file.
We plotted the log-likelihood scores of sample points
against generation time using Microsoft Excel and determined that stationarity was achieved when the log-likelihood values of the sample points reached a stable equilibrium value (Huelsenbeck and Ronquist 2001). The initial
2000 trees that showed a linear increase in likelihood values
were discarded as burn-in before stationarity was reached.
Using PAUP*, majority-rule consensus trees were calculated
from 18 000 trees sampled after reaching likelihood convergence to calculate the posterior probabilities of the tree
nodes. Unlike nonparametric bootstrap values (Felsenstein
1985), these are estimated probabilities of the clades under
the assumed model (Rannala and Yang 1996) and hence
posterior probabilities equal to and above 95% are considered significant supports. Phylogenetic trees were drawn using TreeView (Page 1996).
We used a Bayesian approach to examine the heterogeneity in phylogenetic signal between the two data partitions
(Buckley et al 2002). For the two genes and the concatenated analyses, the set of topologies reaching 0.95 posterior
probability was estimated. The combined analysis topology
then was compared for conflict with the 0.95 posterior intervals of the single gene analyses. If no conflict was evident,
it was assumed that the two datasets were congruent and
could be combined. If conflict was evident, the two datasets
were interpreted as incongruent and thus the concatenated
analysis might be potentially misleading (Bull et al 1993).
Five hypothesized phylogenetic relationships of Gomphillaceae expressed in recent publications were tested as
null hypotheses using a MCMC tree sampling procedure as
described above. For hypothesis testing, a run as described
above was performed with the same settings as in the estimation of the phylogeny. One thousand trees at the equilibrium state per null hypothesis were used from this analysis. The probability of the null hypothesis being correct is
calculated by counting the presence of this topology in the
MCMC sample (Lewis 2001, Lumbsch et al 2004). The frequency of trees in the MCMC sample agreeing with the null
hypothesis was calculated using the filter command in
PAUP* with constraints used to describe the null hypothesis. The constraints were constructed so that only the single
node of interest was resolved.
To examine the possibility that the inferred phylogenetic
relationships were due to long-branch attraction (Felsenstein 1978), we employed a x2-test for deviant nucleotide
composition using TREE-PUZZLE (Strimmer and von Haeseler 1996) and a relative-rate test using RRTREE (Robinson-Rechavi and Huchon 2000).
RESULTS
We generated a total of 12 new mitochondrial SSU
rDNA and 12 new nuclear LSU rDNA sequences for
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MYCOLOGIA
this study (TABLE I). The sequences were aligned
with 70 mtSSU and 70 nuLSU rDNA sequences obtained from Genbank (TABLE I) to produce a matrix
of 270 unambiguously aligned nucleotide position
characters in the nu LSU and 766 in the mt SSU
dataset. One hundred thirty-three characters in the
nu LSU and 656 in the mt SSU dataset were variable.
The Bayesian approach for testing datasets for incongruence indicated that the topology of the majorityrule consensus tree from the combined analysis lies
within the 0.95 posterior intervals for the two separate datasets (data not shown). This is consistent with
the hypothesis that the two partitions have evolved
along the same underlying topology and hence a
combined analysis was performed. The combined
alignment is available in TreeBASE (http://
herbaria.harvard.edu/treebase/).
The likelihood parameters in the sample of the
combined analysis (values of the separate analyses
not shown) had these average values (6 one standard
deviation): base frequenices p(A) 5 0.298 (60.008),
p(C) 5 0.172 (60.005), p(G) 5 0.244 (60.006),
p(T) 5 0.286 (60.008), rate matrix r(AC) 5 1.130
(60.104), r(AG) 5 2.866 (60.219), r(AT) 5 2.283
(60.201), r(CG) 5 1.057 (60.103), r(CT) 5 4.774
(60.389), r(GT) 5 1.0 (60.0), gamma shape parameter alpha 5 0.532 (60.032), and the proportion of
invariable site p(invar) 5 0.246 (60.092).
In the majority-rule consensus tree of 18 000 sampled trees (FIG. 3), the currently accepted classes,
such as Lecanoromycetes or Sordariomycetes (Eriksson et al 2003), are monophyletic with strong support
(posterior probability [pp] 1.0 for all classes). Chaetothyriomycetes and Eurotiomycetes appear as a sister group of Lecanoromycetes, but this relationship
lacks support. The Lecanoromycetes includes two
major clades, one comprising Ostropales sensu lato
and the other Lecanorales, Pertusariales and Agyriales. The latter group, however, again lacks support.
Ostropales sensu lato is strongly supported (pp
1.0). Within this order, Stictidaceae (Stictis, Absconditella) appear basal, while monophyletic Thelotremataceae (Diploschistes, Thelotrema) are strongly supported (pp 1.0). Gyalectaceae (Bryophagus, Xerothrema, Gyalecta) appear paraphyletic when including
Bryophagus, whereas Coenogoniaceae is represented
by a single species only (Coenogonium pineti [Schrad.
ex Ach.] Lücking & Lumbsch comb. nov.; Lecidea pineti Schrad. ex Ach., Lich. Univ.: 195. 1810; Acharius,
Syn. Lich.: 41. 1814; Dimerella pineti [Schrad. ex
Ach.] Vezda, Lich. Sel. Exs. (Pruhonice) 52, No.
1279. 1975).
Gomphillaceae plus Asterothyriaceae form a
monophyletic lineage within Ostropales sensu lato
(pp 1.0), and this lineage is sister of Thelotremata-
ceae, supported by pp of 0.99. The only representative of Asterothyriaceae, Asterothyrium longisporum, is
nested within Gomphillaceae. The chiefly nonlichenized Stictidaceae show a sister-group relationship with
other taxa of Ostropales sensu lato.
To evaluate the potential presence of long-branch
attraction, we performed a x2-test and a relative-rate
test. All sequences included in the study passed the
x2-test (P 5 0.19–0.94 for Asterothyriaceae/Gomphillaceae, P 5 0.12–0.99 for other euascomycetes),
indicating that none of the sequences had a significantly deviating nucleotide composition. The results
of the relative-rate tests showed that the Asterothyriaceae/Gomphillaceae and Thelotremataceae clades
do not differ significantly in their substitution rate
from other Lecanoromycetes. The results were not
significant in all three cases examined (P 5 0.296 for
Asterothyriaceae/Gomphillaceae versus Thelotremataceae, P 5 0.892 for Thelotremataceae versus other
Lecanoromycetes excluding Asterothyriaceae/Gomphillaceae, P 5 0.229 for Asterothyriaceae/Gomphillaceae versus other Lecanoromycetes excluding Thelotremataceae).
DISCUSSION
Our analysis confirms that Gomphillaceae and Asterothyriaceae (here represented by the single species
Asterothyrium longisporum) are closely related and
form a monophyletic lineage that is part of the Ostropalean clade in Lecanoromycetes. These results
correspond well to previous studies on the anatomy
and ontogeny of Gomphillaceae and Asterothyriaceae, including phenotype-based phylogenetic approaches (Aptroot and Lücking 2003, Dennetière
and Péroni 1998, Henssen and Lücking 2002, Lücking 1997, 1999, Vezda 1979, Vezda and Poelt 1987).
They also support the utility of phenotype-based analyses for hypothesis-building, even in lichen-forming
fungi that are notorious for their variable and often
homoplasious morphological characters. It also is
clear from the analysis that Gomphillus is related
closely to other members of Gomphillaceae sensu
Vezda and Poelt (1987) and does not form an isolated member of this family, although its very elongate
asci and ascospores are different from the clavate to
ovoid asci and ellipsoid to cylindrical ascospores
found in all other genera.
We were unable to confirm a sister group relationship between the Asterothyriaceae and Gomphillaceae, as assumed in previous contributions (Henssen
and Lücking 2002, Lücking 1997, 1999). However,
because only one representative of the first family
could be included in this analysis, this might be an
artifact of insufficient taxon sampling. Generic delim-
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ET AL:
PHYLOGENY
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GOMPHILLACEAE
291
FIG. 3. Majority-rule consensus tree based on 18 000 trees from a B/MCMC tree sampling procedure. Posterior probabilities equal or above 0.95 indicated at branches. Ordinal and/or class placement of taxa indicated at margin.
292
MYCOLOGIA
itation within Gomphillaceae is also in flux (Lücking
1997) and is being studied by us using a larger set of
mtSSU and nuLSU data. Taxa included here that are
currently assigned to the genera Calenia and Echinoplaca accordingly do not form monophyletic groups
in our analysis. However, our data suggest that taxa
with sessile or adnate, biatorine apothecia (Gyalideopsis, Gomphillus, Tricharia, Echinoplaca) are derived
from those with immersed-erumpent, zeorine or carbonized apothecia (Calenia, Gyalectidium, Aulaxina).
This contradicts previous hypotheses about the evolution of the group (Lücking 1997) but is in accordance with our present results that Gomphillaceae
plus Asterothyriaceae are sister of Thelotremataceae
(here represented by Thelotrema and Diploschistes),
which are characterized by immersed-erumpent, zeorine apothecia.
Indeed, the sister-group relationship of Asterothyriaceae plus Gomphillaceae with Thelotremataceae is
supported significantly. However, the branch leading
to the Gomphillaceae is unusually long, suggesting
that this relationship might be due to long-branch
attraction (Felsenstein 1978). If two unrelated lineages have had an accelerated substitution rate compared to other included groups in a study, they will
have accumulated characters that will distance them
from other taxa in an analysis, resulting in a false
clustering based on convergences (Swofford et al
1996). However, the results of the x2-test and the relative-rate tests reject such an assumption. The Asterothyriaceae/Gomphillaceae clade and the Thelotremataceae do not differ significantly in their nucleotide composition and substitution rate from the other
Lecanoromycetes.
Our studies thus confirm placement of Gomphillaceae/Asterothyriaceae as a further clade within Ostropales sensu lato (Kauff and Lutzoni 2002), as previously suggested by Lücking (1997) and Henssen
and Lücking (2002). This order originally was restricted to the chiefly nonlichenized Stictidaceae and
allies, while lichenized Thelotremataceae and Graphidaceae were kept in a separate order Graphidales
(Sherwood 1977). Recent molecular studies have not
demonstrated only that Graphidales but also Gyalectales, with the two families Gyalectaceae and Coenogoniaceae, form part of Ostropales (Kalb et al pers
comm 2003, Kauff and Lutzoni 2002, Lumbsch et al
2004, Winka et al 1998). Thus, Ostropales, in its present circumscription, consists of four lineages: (i)
Stictidaceae and allies (Ostropales s.str.), (ii) Gyalectaceae/Coenogoniaceae (former Gyalectales), (iii)
Thelotremataceae/Graphidaceae (former Graphidales), and (iv) Gomphillaceae/Asterothyriaceae (former Gomphillales).
In all available analyses, Stictidaceae and allies,
which include a few lichenized forms (Absconditella,
Conotrema) but are otherwise nonlichenized, appear
to be basal within the order and either monophyletic
(Lumbsch et al 2004) or paraphyletic. Gyalectaceae/
Coenogoniaceae are related most closely to Thelotremataceae/Gomphillaceae and appear either paraphyletic (Lumbsch et al 2004) or monophyletic
(Kauff and Lutzoni 2002), depending on whether
Bryophagus is included here or in the Stictidaceae
lineage. The Thelotremataceae/Graphidaceae clade
always appears monophyletic in different studies
(Kalb et al pers comm 2003, Kauff and Lutzoni 2002,
Lumbsch et al 2004) and so does the previously unexplored Gomphillaceae/Asterothyriaceae clade in
our study.
Experience with Lecanoromycetes has shown that
initially paraphyletic lineages eventually turn out to
be monophyletic in more detailed studies with higher
taxa and character resolution (Lumbsch et al 2004),
and this cannot be excluded for Ostropales sensu
lato, in which case the previously distinguished orders Gyalectales, Graphidales and Gomphillales
could be reinstated or more appropriately be used at
the subordinal level. This would correspond to the
situation in Lecanorales sensu lato, where Peltigerineae and Teloschistineae currently are listed as suborders (Eriksson et al 2003) but could also be treated
as orders parallel to Lecanorales sensu stricto.
ACKNOWLEDGMENTS
We wish to thank Jutta Buschbom (Chicago) for advice with
sequencing of lichens. The sampling of specimens from
which new sequences were generated was supported by the
National Science Foundation (Grant DEB 0206125 to Robert Lücking), the Mexican CONACYT (Grant 35008-V to
Marı́a Herrera-Campos and Robert Lücking) and the Deutsche Forschungsgemeinschaft (grants LU 597/1-1-LU 597/
4-1 to Robert Lücking). DNA extraction and sequencing at
the Field Museum’s Pritzker Laboratory for Molecular Systematics and Evolution were supported by start-up funds of
the Field Museum to Robert Lücking.
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