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Background and Aims: Endoreduplication, the duplication of the nuclear genome without mitosis, is a common process in plants, especially in angiosperms and mosses. Accumulating evidence supports the relationship between endoreduplication and plastic responses to stress factors. Here, we investigated the level of endoreduplication in Ceratodon (Bryophyta), which includes the model organism Ceratodon purpureus., Methods: We used flow cytometry to estimate the DNA content of 294 samples from 67 localities and found three well-defined cytotypes, two haploids and one diploid, the haploids corresponding to C. purpureus and Ceratodon amazonum, and the diploid to Ceratodon conicus, recombination occurring between the former two., Key Results: The endoreduplication index (EI) was significantly different for each cytotype, being higher in the two haploids. In addition, the EI of the haploids was higher during the hot and dry periods typical of the Mediterranean summer than during spring, whereas the EI of the diploid cytotype did not differ between seasons., Conclusions: Endopolyploidy may be essential in haploid mosses to buffer periods of drought and to respond rapidly to desiccation events. Our results also suggest that the EI is closely related to the basic ploidy level, but less so to the nuclear DNA content as previously suggested., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Annals of Botany Company.)

The common cord moss Funaria hygrometrica has a worldwide distribution and thrives in a wide variety of environments. Here, we studied the genetic diversity in F. hygrometrica along an abiotic gradient in the Mediterranean high mountain of Sierra Nevada (Spain) using a genome scan method. Eighty-four samples from 17 locations from 24 to 2700 m were fingerprinted based on their amplified fragment length polymorphism (AFLP) banding pattern. Using PCA and Bayesian inference we found that the genetic diversity was structured in three or four clusters, respectively. Using a genome scan method we identified 13 outlier loci, which showed a signature of positive selection. Partial Mantel tests were performed between the Euclidean distance matrices of geographic and climatic variables, versus the pair-wise genetic distance of the AFLP dataset and AFLP-positive outliers dataset. AFLP-positive outlier data were significantly correlated with the gradient of the climatic variables, suggesting adaptive variation among populations of F. hygrometrica along the Sierra Nevada Mountains. We highlight the additional analyses necessary to identify the nature of these loci, and their biological role in the adaptation process., (© 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Premise of the Study: The Baas Becking tenet posits that 'everything is everywhere, but the environment selects' to explain cosmopolitan distributions in highly vagile taxa. Bryophyte species show wider distributions than vascular plants and include examples of truly cosmopolitan ranges, which have been interpreted as a result of high dispersal capacities and ecological plasticity. In the current study, we documented patterns of genetic structure and diversity in the cosmopolitan moss Bryum argenteum along an elevational gradient to determine if genetic diversity and structure is homogenized by intense migrations in the lack of ecological differentiation. •, Methods: 60 specimens were collected in the Sierra Nevada Mountains (Spain) between 100 and 2870 m and sequenced for ITS and rps4. Comparative analyses, genetic diversity estimators, and Mantel's tests were employed to determine the relationship between genetic variation, elevation, and geographic distance and to look for signs of demographic shifts. •, Key Results: Genetic diversity peaked above 1900 m and no signs of demographic shifts were detected at any elevation. There was a strong phylogenetic component in elevational variation. Genetic variation was significantly correlated with elevation, but not with geographic distance. •, Conclusions: The results point to the long-term persistence of Bryum argenteum in a range that was glaciated during the Late Pleistocene. Evidence for an environmentally driven pattern of genetic differentiation suggests adaptive divergence. This supports the Baas Becking tenet and indicates that ecological specialization might play a key role in explaining patterns of genetic structure in cosmopolitan mosses.

Bryophyte floras typically exhibit extremely low levels of endemism. The interpretation, that this might reflect taxonomic shortcomings, is tested here for the Macaronesian flora, using the moss species complex of Rhynchostegium riparioides as a model. The deep polyphyly of R. riparioides across its distribution range reveals active differentiation that better corresponds to geographic than morphological differences. Morphometric analyses are, in fact, blurred by a size gradient that accounts for 80% of the variation observed among gametophytic traits. The lack of endemic diversification observed in R. riparioides in Macaronesia weakens the idea that the low rates of endemism observed in the Macaronesian bryophyte flora might solely be explained by taxonomic shortcomings. To the reverse, the striking polyphyly of North American and European lineages of R. riparioides suggests that the similarity between the floras of these continents has been over-emphasized. Discriminant analyses point to the existence of morphological discontinuities among the lineages resolved by the molecular phylogeny. The global rate of error associated to species identification based on morphology (0.23) indicates, however, that intergradation of shape and size characters among species in the group challenges their identification., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background and Aims: The recent assembly of the complete sequence of the plastid genome of the model taxon Physcomitrella patens (Funariaceae, Bryophyta) revealed that a 71-kb fragment, encompassing much of the large single copy region, is inverted. This inversion of 57% of the genome is the largest rearrangement detected in the plastid genomes of plants to date. Although initially considered diagnostic of Physcomitrella patens, the inversion was recently shown to characterize the plastid genome of two species from related genera within Funariaceae, but was lacking in another member of Funariidae. The phylogenetic significance of the inversion has remained ambiguous., Methods: Exemplars of all families included in Funariidae were surveyed. DNA sequences spanning the inversion break ends were amplified, using primers that anneal to genes on either side of the putative end points of the inversion. Primer combinations were designed to yield a product for either the inverted or the non-inverted architecture., Key Results: The survey reveals that exemplars of eight genera of Funariaceae, the sole species of Disceliaceae and three generic representatives of Encalyptales all share the 71-kb inversion in the large single copy of the plastid genome. By contrast, the plastid genome of Gigaspermaceae (Funariales) is characterized by a gene order congruent with that described for other mosses, liverworts and hornworts, and hence it does not possess this inversion., Conclusions: The phylogenetic distribution of the inversion in the gene order supports a hypothesis only weakly supported by inferences from sequence data whereby Funariales are paraphyletic, with Funariaceae and Disceliaceae sharing a common ancestor with Encalyptales, and Gigaspermaceae sister to this combined clade. To reflect these relationships, Gigaspermaceae are excluded from Funariales and accommodated in their own order, Gigaspermales order nov., within Funariideae.