Recent studies have provided evidence for pulses in the diversification of angiosperms, ferns, gymnosperms, and mosses as well as various groups of animals during the Cretaceous revolution of ...terrestrial ecosystems. However, evidence for such pulses has not been reported so far for liverworts. Here we provide new insight into liverwort evolution by integrating a comprehensive molecular dataset with a set of 20 fossil age constraints. We found evidence for a relative constant diversification rate of generalistic liverworts (Jungermanniales) since the Palaeozoic, whereas epiphytic liverworts (Porellales) show a sudden increase of lineage accumulation in the Cretaceous. This difference is likely caused by the pronounced response of Porellales to the ecological opportunities provided by humid, megathermal forests, which were increasingly available as a result of the rise of the angiosperms.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Some of the evolutionary history of land plants has been documented based on the fossil record and a few broad-scale phylogenetic analyses, especially focusing on angiosperms and ferns. Here, we ...reconstructed phylogenetic relationships among all 706 families of land plants using molecular data. We dated the phylogeny using multiple fossils and a molecular clock technique. Applying various tests of diversification that take into account topology, branch length, numbers of extant species as well as extinction, we evaluated diversification rates through time. We also compared these diversification profiles against the distribution of the climate modes of the Phanerozoic.
We found evidence for the radiations of ferns and mosses in the shadow of angiosperms coinciding with the rather warm Cretaceous global climate. In contrast, gymnosperms and liverworts show a signature of declining diversification rates during geological time periods of cool global climate.
This broad-scale phylogenetic analysis helps to reveal the successive waves of diversification that made up the diversity of land plants we see today. Both warm temperatures and wet climate may have been necessary for the rise of the diversity under a successive lineage replacement scenario.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The three bryophyte lineages have long-lived gametophytes that are either bisexual, producing both male- and female gametes, or sexually specialized and then producing only one type of gamete. ...Phylogenies suggest repeated evolutionary switches between these systems, implying that bryophyte sex chromosomes may have been gained and lost repeatedly. How this occurred is poorly understood, even though plant sex chromosomes were first discovered in liverworts. We explain how the sex chromosomes of haploid-dominant organisms are distinct from the better-studied X-Y and Z-W systems in the tree of life, summarise what is known about their distribution and genetic composition, and present new cytogenetic data for Frullania dilatata and Plagiochila asplenioides, the former with two U chromosomes and one V chromosome, the latter with one U chromosome and two V chromosomes; male and female C-values in F. dilatata are correspondingly asymmetric （the C-value of P. asplenioides is only known for female nuclei）. So far, there is a lack of high-throughput sequencing, quantification, and in situ study of the repetitive DNA, organellar DNA, and transposable elements, and it is therefore not known what causes the size difference of U and V chromosomes from the autosomes or each other. Heterochromatin was also first discovered in bryophytes, but its function in their sex regulation has not been addressed. Studies of bryophyte sex chromosomes with combined cytogenetic and genomic approaches are fundamental for a fuller understanding of sex chromosome evolution across the tree of life.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
•Cretaceous fossils of derived leptosporangiate ferns are exceedingly rare.•We show that diverse polypod ferns existed in mid-Cretaceous woodlands of Myanmar.•New fossil evidence is consistent with ...DNA based divergence time estimates.•Hypothesis of a Cretaceous diversification of polypods is confirmed.
Cretaceous fossils of derived leptosporangiate ferns (Polypodiales) are exceedingly rare yet they are needed to confirm the hypothesis of a Cretaceous diversification of polypod ferns as predicted by DNA-based divergence time estimates. Here we show that diverse polypod ferns existed in the mid-Cretaceous woodlands of Myanmar. We describe isolated sporangia with a vertical, broken annulus ring containing a differentiated stomium as well as distinguished pinnae fragments. Krameropteris resinatus gen. et sp. nov. is described based on a pinnae-fragment with free branched veins, exindusiate sori and polypod sporangia with trilete spores, and assigned to the early diverging polypod fern lineage Dennstaedtiaceae. Integration of the new fossil evidence in a phylogenetic framework provides support to the hypothesis of a Cretaceous diversification of polypod ferns.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Understanding the biogeographical and diversification processes explaining current diversity patterns of subcosmopolitan-distributed groups is challenging. We aimed at disentangling the historical ...biogeography of the subcosmopolitan liverwort genus Lejeunea with estimation of ancestral areas of origin and testing if sexual system and palaeotemperature variations can be factors of diversification. We assembled a dense taxon sampling for 120 species sampled throughout the geographical distribution of the genus. Lejeunea diverged from its sister group after the Paleocene-Eocene boundary (52.2 Ma, 95% credibility intervals 50.1-54.2 Ma), and the initial diversification of the crown group occurred in the early to middle Eocene (44.5 Ma, 95% credibility intervals 38.5-50.8 Ma). The DEC model indicated that (1) Lejeunea likely originated in an area composed of the Neotropics and the Nearctic, (2) dispersals through terrestrial land bridges in the late Oligocene and Miocene allowed Lejeunea to colonize the Old World, (3) the Boreotropical forest covering the northern regions until the late Eocene did not facilitate Lejeunea dispersals, and (4) a single long-distance dispersal event was inferred between the Neotropics and Africa. Biogeographical and diversification analyses show the Miocene was an important period when Lejeunea diversified globally. We found slight support for higher diversification rates of species with both male and female reproductive organs on the same individual (monoicy), and a moderate positive influence of palaeotemperatures on diversification. Our study shows that an ancient origin associated with a dispersal history facilitated by terrestrial land bridges and not long-distance dispersals are likely to explain the subcosmopolitan distribution of Lejeunea. By enhancing the diversification rates, monoicy likely favoured the colonisations of new areas, especially in the Miocene that was a key epoch shaping the worldwide distribution.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Aim: How disjunct distributions arise and why organisms differ in diversification patterns remain some of the most compelling fundamental questions in biogeography. We carry out phylogeographical ...analyses of the pantropical liverwort genus Ceratolejeunea to identify its geographical origin and the dispersal routes by which it gained its Neotropical-African disjunction. Furthermore, we investigate whether there is geographical structure in Ceratolejeunea on islands and whether island diversity is a result of radiations or recurrent migration. Location: America, Africa and Australasia. Methods: Sequences of two chloroplast regions (trnL-F, rbcL) and the nuclear ribosomal ITS region were obtained for 55 accessions of 20 species to explore the phylogeny, divergence times and ancestral areas of Ceratolejeunea. The phylogeny was reconstructed using maximum likelihood and Bayesian inference approaches, and divergence times were estimated with a Bayesian relaxed clock method and fossil and secondary calibrations. Ancestral areas were estimated using BioGeoBEARS. Results: Ceratolejeunea likely originated in the Neotropics during the Palaeogene (42.2 Ma, 95% HPD: 22.2-64.8) and the initial diversification of its crown group took place between the Eocene and Miocene (25.5 Ma, 95% HPD: 16.6-35.8). Although boreotropical migration and subsequent extinction in northern regions cannot be rejected, the observed disjunctions are best explained by four transoceanic dispersal events from the Neotropics to Africa during the late Oligocene to Pleistocene. Geographical structure is prevalent on islands, particularly in the C. cornuta complex. Three species and the subgenus Ceratolejeunea are recovered as paraphyletic. Main conclusions: Widespread paraphyly and sister group relationships between disjunct taxa indicate an important role of cryptic speciation and transoceanic dispersal with subsequent genetic differentiation in the evolution of Ceratolejeunea. On islands, recurrent migration, rather than radiation, has shaped bryophyte diversity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
One of the most important issues in molecular dating studies concerns the incorporation of reliable fossil taxa into the phylogenies reconstructed from DNA sequence variation in extant taxa. Lichens ...are symbiotic associations between fungi and algae and/or cyanobacteria. Several lichen fossils have been used as minimum age constraints in recent studies concerning the diversification of the Ascomycota. Recent evolutionary studies of Lecanoromycetes, an almost exclusively lichen-forming class in the Ascomycota, have utilized the Eocene amber inclusion Alectoria succinic as a minimum age constraint. However, a re-investigation of the type material revealed that this inclusion in fact represents poorly preserved plant remains, most probably of a root. Consequently, this fossil cannot be used as evidence of the presence of the genus Alectoria (Parmeliaceae, Lecanorales) or any other lichens in the Paleogene. However, newly discovered inclusions from Paleogene Baltic and Bitterfeld amber verify that alectorioid morphologies in lichens were in existence by the Paleogene. The new fossils represent either a lineage within the alectorioid group or belong to the genus Oropogon.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The monospecific fern genus Cystodium (Cystodiaceae; Polypodiales) occurs exclusively in the tropical forests of the Malay Archipelago, the Admiralty Islands, the Louisiade Archipelago, and the ...Solomon Islands. Divergence time estimates suggest that the genus originated in the Mesozoic; however, fossil evidence to validate this suggestion has been lacking. Amber from Myanmar (Burmese amber) is an important source of new information on the diversity of vascular cryptogams in the Cretaceous. This paper describes the fossil taxon Cystodium sorbifolioides nov. sp. based on a fragment of a fertile leaf preserved in Burmese amber that represents the first fossil evidence of the family Cystodiaceae. Cystodium sorbifolioides is used to obtain a minimum age estimate for the Cystodiaceae and the closely related, monogeneric Lonchitidaceae and Lindsaeaceae. The fossil strengthens the hypothesis that the forest ecosystems of Malesia and Melanesia represent refugia for many tropical plant lineages that originated in the Cretaceous.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Lejeunea is a largely epiphytic, subcosmopolitan liverwort genus with a complex taxonomic history. Species circumscriptions and their relationships are subject to controversy; biogeographic history ...and diversification through time are largely unknown.
We employed sequences of two chloroplast regions (trnL-trnF, rbcL) and the nuclear ribosomal ITS region of 332 accessions to explore the phylogeny of the Harpalejeunea-Lejeunea-Microlejeunea complex. Lejeunea forms a well-supported clade that splits into two main lineages corresponding to L. subg. Lejeunea and L. subg. Crossotolejeunea. Neotropical accessions dominate early diverging lineages of both main clades of Lejeunea. This pattern suggests an origin in the Neotropics followed by several colonizations from the Neotropics into the Paleotropics and vice versa. Most Afro-Madagascan clades are related to Asian clades. Several temperate Lejeunea radiations were detected. Eighty two of the 91 investigated Lejeunea species could be identified to species level. Of these 82 species, 54 were represented by multiple accessions (25 para- or polyphyletic, 29 monophyletic). Twenty nine of the 36 investigated species of L. subg. Lejeunea were monoicous and 7 dioicous. Within L. subg. Crossotolejeunea, 15 of the 46 investigated species were monoicous and 31 dioicous. Some dioicous as well as some monoicous species have disjunct ranges.
We present the first global phylogeny of Lejeunea and the first example of a Neotropical origin of a Pantropical liverwort genus. Furthermore, we provide evidence for the Neotropics as a cradle of Lejeunea lineages and detect post-colonization radiations in Asia, Australasia, Afro-Madagascar and Europe. Dioicy/monoicy shifts are likely non-randomly distributed. The presented phylogeny points to the need of integrative taxonomical studies to clarify many Lejeunea binomials. Most importantly, it provides a framework for future studies on the diversification of this lineage in space and time, especially in the context of sexual systems in Lejeuneaceae.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Qinghai-Tibetan Plateau (QTP) and its southern and southeastern mountain ranges, Himalaya-Hengduan Mountains (HHM), are one of the most extensive habitats for alpine plants in the world. How ...ferns occurring in QTP and HHM changed their distribution ranges in response to Quaternary climatic oscillations remains almost unknown.
We employed sequences of two chloroplast DNA regions, rps4-trnS and trnL-trnF, to reconstruct phylogeography of the Sino-Himalayan fern Lepisorus clathratus, occurring mainly in the QTP and HHM. Individuals of this species have either dehiscent or indehiscent sporangia with the latter evolved from the plesiomorphic dehiscent forms. Based on a range-wide sampling, we detected 27 cpDNA haplotypes that were divided into five groups by network analyses. Populations in the Hengduan Mountains possess the highest genetic diversity, while a single haplogroup is detected across the north-central region. A distinct phylogeographical subdivision was detected between the Hengduan Mountains and north-central region by AMOVA analysis. The haplogroup distribution pattern, coalescence and AMOVA analysis suggest that a long term survival area (refugia) of the species was located in the Hengduan Mountains during glaciations, with probable range expansions into north-central regions during interglacial periods. Populations with indehiscent sporangium can carry private haplotypes and are inclined to maintain genetic homogeneity. One group with indehiscent sporangia most likely survived in situ on the QTP during glaciations.
This study for the first time sheds light on the response of alpine ferns in the QTP and HHM to the Quaternary climatic oscillations.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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