Rosemary Wilson

Testing Hypotheses on Species Delimitations and Disjunctions in the Liverwort Bryopteris (Jungermanniopsida: Lejeuneaceae)

Nucleotide sequence variation in the ITS1‐5.8S‐ITS2 region of nuclear ribosomal DNA and in the trnL‐trnF region of chloroplast DNA from 49 specimens of Bryopteris (Lejeuneaceae) and three outgroup species was analyzed using maximum parsimony and maximum likelihood. The nrITS region exhibits high levels of nucleotide variation, whereas the trnL‐trnF region is fairly similar among samples of the same species. Three major clades were found corresponding to the Neotropical species Bryopteris diffusa and Bryopteris filicina, as well as Bryopteris gaudichaudii from the Malagasy region. Morphological characters utilized in earlier studies to distinguish five microspecies within B. filicina are diffusely distributed in the molecular topologies and do not trace monophyletic lineages. The nrITS signal suggests a separation into two biogeographically defined B. filicina clades—one mainly Andean clade and one mainly northern Neotropical clade—but these clades lack statistical support. The two clades can possibly be explained by the hypothesis that the nrITS signal reflects a former disjunct range of B. filicina with a few subsequent dispersal events. Bryopteris gaudichaudii is resolved as sister of B. filicina; these species are in turn sister to B. diffusa. Clocklike evolution of nrITS1 and 2 and nrITS sequence divergence estimates from the literature allow for a rough estimation of the divergence time of Bryopteris, indicating a separation of B. gaudichaudii from B. filicina in the Miocene, separation of B. diffusa in the Early Tertiary, and an emergence of Bryopteris in the Cretaceous. The African‐American range of Bryopteris is not the result of vicariance but of dispersal.

Cryptic speciation in Herbertus (Herbertaceae, Jungermanniopsida): Range and morphology of Herbertus sendtneri inferred from nrITS sequences

Abstract.Maximum likelihood and parsimony analyses of nrITS1-5.8S-ITS2 sequences place Austrian Herbertus sendtneri in a well bootstrap supported clade with Herbertus azoricus and Neotropical accessions which were alternatively assigned to Herbertus subdentatus or Herbertus dicranus. Asian and African Herbertus dicranus form a separate lineage which is placed sister to several European Herbertus taxa. Herbertus borealis from the British Isles is placed sister to H. stramineus in a robust sister relationship, indicating that the species does not belong in the synonymy of H. dicranus. As a result of the molecular investigation, the range of Herbertus sendtneri is extended to the Neotropics and H. azoricus is placed into the synonymy of H. sendtneri. Without much doubt, Herbertusdicranus does not occur in tropical America. Morphologically, H. sendtneri and H. dicranus can at most be separated by weak tendencies. Herbertus sendtneri is characterized by the frequent occurrence of coarse appendages at the leaf margins and often completely papillose leaves. H. dicranus often has small appendages and a nearly smooth basal leaf half. Herbertus borealis, which is nonmonophyletic with H. dicranus in the molecular trees, cannot be separated morphologically from forms of H. dicranus with small appendages. Herbertus subdentatus is not identical with H. sendtneri. Morphological homoplasy and cryptic speciation are obviously common in Herbertus.

Reinstatement of Lophocoleaceae (Jungermanniopsida) based on chloroplast gene rbcL data: exploring the importance of female involucres for the systematics of Jungermanniales

Maximum likelihood analysis of 113 rbcL sequences leads to a well resolved phylogeny of Jungermanniales. All species with perigynia or marsupia are found in one clade, whereas species with coelocaules are placed in several lineages. The broadly circumscribed Geocalycaceae (including Lophocoleaceae) of most recent authors are resolved as polyphyletic. Geocalycaceae genera which develop female involucres without involvement of stem tissue (Chiloscyphus, Heteroscyphus, Leptoscyphus, Physotheca) form a robust clade which is placed sister to Plagiochilaceae whereas the genera with involucres originating at least partly from stem tissue (Geocalycaceae s.str., Geocalyx, Harpanthus, Saccogyna) are nested within the paraphyletic Jungermanniaceae. This topology leads to the exclusion of the strictly perianth-bearing species from Geocalycaceae and the reinstatement of Lophocoleaceae. Campanocolea is nested within Chiloscyphus. Physotheca and Chiloscyphus breutelii are placed within an unsupported clade with several accessions of Leptoscyphus. Heteroscyphus forms a paraphyletic grade at the base of Chiloscyphus.

Steady diversification of derived liverworts under Tertiary climatic fluctuations.

Tropical forests contain the majority of extant plant diversity and their role as a cradle and/or museum of biodiversity is an important issue in our attempts to assess the long-term consequences of global climate change for terrestrial biomes. Highly diverse groups of liverworts are an often ignored but extremely common element in rainforests, and thus their evolution may shed light on the ecological robustness of rainforest biomes to climate fluctuations. We record a remarkable constant accumulation of diversity through time for the most species-rich family of liverworts, Lejeuneaceae, inferred by divergence time estimates. The observed pattern supports the recently developed concept of a dual role of the tropics as both a museum and a cradle of biodiversity.

The Synammia Enigma: Evidence for a Temperate Lineage of Polygrammoid Ferns (Polypodiaceae, Polypodiidae) in Southern South America

Abstract Evidence for a southern South American lineage of polygrammoid ferns was inferred from analyses using four cpDNA markers. The lineage corresponds to the genus Synammia, which has usually been treated as a synonym of the polyphyletic genus Polypodium. Seven specimens of two of the three recognized species were sampled to infer the phylogenetic relationships of this lineage to other polygrammoid ferns and the diversity within this lineage. All approaches found Synammia clearly separated from other polygrammoid ferns, but the exact relationships are still unclear. Model-based methods recovered Synammia as sister to a mainly Neotropical clade of polygrammoid ferns, but support for this hypothesis was provided only by Bayesian inference of phylogeny. The deletion of nearly the whole rps4-trnS IGS is a synapomorphy of Synammia. The lineage is separated from other extant polygrammoid ferns, but very low to zero sequence diversity was found among the seven samples of Synammia. The results strongly support an independent lineage of polygrammoid ferns in southern South America.

Different Fates of Two Mitochondrial Gene Spacers in Early Land Plant Evolution

Plant mitochondrial DNA is generally characterized by slow sequence drift but frequent genomic recombination. Accordingly, gene sequences in plant mitochondria are informative for old cladogenic events, whereas intergenic regions have so far not been considered for phylogenetic reconstruction because high recombinational activity rearranges mitochondrial gene orders too frequently. Here we report that an ancient gene continuity, the nad5‐nad4‐nad2 gene arrangement, is conserved among the bryophyte lineages: mosses, liverworts, and hornworts. The nad4‐nad2 spacer is surprisingly conserved at a size of only 26 bp in all three bryophyte lineages. In striking contrast, the small ancestral nad5‐nad4 spacer, of only 57 bp in the alga Chara, is significantly increased in size, to about 600 bp in mosses and 1000–1300 bp in liverworts, and even exceeds 3000 bp in hornworts. A large group II intron fragment and a nad6 pseudogene sequence, respectively, contribute to the expanded spacer sizes in liverworts and in hornworts. The small nad4‐nad2 intergenic region is retained in the lycophyte Isoetes lacustris, whereas no linkage between nad5 and nad4 could be detected in this quillwort. Given its size and sequence variability, the intergenic region between nad5 and nad4 holds promise as a locus for phylogenetic analyses within the bryophyte lineages.