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DNA barcoding can be useful for species identification and phylogenetic analysis, but its effectivity has not been verified in most neotropical cloud forest plants. We tested three plastid barcodes, rbcLa, matK , and trnH-psbA , in selected pteridophytes, a well-represented group in these forests, from a little-explored area in Oaxaca, Mexico, applying the CBOL criteria for barcoding. We used BLASTn, genetic distance, and monophyly tree-based analyses employing neighbor-joining (NJ), maximum likelihood (ML), and Bayesian inference methods. Universal primers for rbcLa and trnH-psbA were successfully amplified and bi-directionally sequenced, but matK could not be amplified for most species. rbcLa showed the highest species discrimination in BLASTn (66.67%). trnH-psbA exhibited higher significant interspecific divergence values than rbcL and rbcLa  +  trnH-psbA (two-sample sign test, P value < 2.2e−16). Using NJ and ML phylogenetic trees, monophyletic species were successfully resolved (100%), differing only in support values and displaying full agreement with the most recent fern classification. ML trees showed the highest mean support value (80.95%). trnH-psbA was the only barcode that could detect the Elaphoglossoideae subfamily. Species discrimination did not increase using rbcLa  +  trnH-psbA . rbcLa is useful for fern barcoding, trnH-psbA is most helpful for phylogenetic analyses, and matK may not work as a universal barcoding marker .

Some fern species are among the world’s worst weeds, but little is known about the establishment of alien ferns in relatively conserved ecosystems. Exotic species may outperform native ones during germination and facilitate invasion into new environments. Macrothelypteris torresiana is an Asian fern species that was introduced and spread throughout multiple areas of tropical America. We tested the hypothesis that germination of the exotic fern will be higher at high resource levels and will have wider ecological amplitude compared to native fern species in a cloud forest in central Mexico. Spore germination was evaluated through a gradient of water potential (0 to − 1.0 MPa), photon flux density (0 to 200 µmol m−2 s−1), and light quality (0 to 7.2 red:far-red ratio) in the laboratory, whereas plant relative frequency was determinate in the forest to describe the distribution of the ferns under the light environment. Comparing to three native ferns (sun-loving Hypolepis blepharochlaena and shade-loving Blechnum wardiae and Polystichum ordinatum), M. torresiana was more tolerant to water deficit, germinated better under low photon flux but responded similarly to light quality gradient, and occurred over a far wider range of field light conditions. Our results support the hypothesis that the germination requirements of the invasive fern species are less specific and thus facilitate the colonization of sites with diverse light conditions and water availability.

The phylogenetic position of Cheilanthes brandegeei, a fern endemic to the Baja California Peninsula of Mexico, was investigated using three plastid markers (atpA, rbcL, trnG-R) and comparative morphology. Here we present robust evidence for the recognition of C. brandegeei as a member of the bommeriids, the sister clade to all other cheilanthoid ferns, and evidence that it is sister to all Bommeria species within that clade. Because of its distinctive morphology within the bommeriid clade (pinnate leaf architecture, well-developed pseudoindusium, and narrow, concolorous red-brown rhizome scales), here we propose the new genus Baja to accommodate it. Our results place Baja brandegeei together with other taxa that have a distribution in the Baja California Peninsula and mainland Mexico, rather than with hypothesized congeners in South America and Africa. Morphological characters traditionally used to classify this species as a Cheilanthes (patterns of sporangial distribution, presence of a well-developed pseudoindusium, and fractiferous petioles) are extensively homoplasious across cheilanthoids. We identify three characters that unite the newly expanded bommeriid clade: leaf indument of acicular trichomes, reticulate-cristate perispore morphology, and lateral initiation of the gametophyte meristem.

Ferns have been considered ecological indicators of soil nutrient composition and can be adapted to limestone (calcicole), volcanic substrates (calcifuge), or both (generalists). However, how many species exhibit substrate preferences and how these substrates affect their leaf nutrient composition remains unclear. We studied the occurrence of fern species across 37 sites in Veracruz and Puebla, Mexico, identifying their possible soil preferences (limestone vs volcanic), and performing an elemental analysis (C, N, P, K, Na, Ca, Mg, S, Fe, Al, and Mn) of leaf tissues and underlying substrates. We found 13 species confined to limestone, five to volcanic substrates, and one generalist species on both substrates. Limestone substrates had higher Ca but lower Fe, Mn, and P concentrations than igneous substrates, and calcicole ferns had higher Ca, Mg, and N concentrations than calcifuge ferns, each independent from elevation. A further ordination based on nutrient composition split calcicole ferns into two groups. Group I had lower nutrient concentrations except for higher Al, Fe, and Mn concentrations, and group II showed the opposite nutrient pattern. Additionally, group I consisted of species growing mainly at higher elevations than group II. The soil generalist had higher Ca and Al concentrations on limestone than on volcanic substrates. Fern species differed considerably in nutrient composition even within calcicole and calcifuge groups and most leaf nutrients decreased with elevation. Calcium concentrations, however, were consistently higher in calcicole than in calcifuge ferns regardless of elevation and may serve as a nutrient indicator for limestone specialists.

We studied the ability of Argyrochosma formosa growing in an arsenic heavily contaminated site to accumulate this metalloid; morphological characteristics and translocation of arsenic were evaluated in the organs. Population census of wild specimens of A. formosa was done, and 14 samples of ferns and rhizosphere soil were collected randomly. We recorded morphological characteristics with scanning electronic microscopy (SEM); concentrations of As in organs of fern plants (root, rhizome, and fronds) were evaluated with inductively coupled plasma-optic emission spectrometry (ICP-OES). Two hundred ninety-four individuals at different stages of development were identified, indicating the establishment of fern on the site. Morphological characteristics of A. formosa in fern plant organs did not show structural effects, compared with herbarium plants. Arsenic distribution in fern plant tissues was 192.2–763.6 mg/kg, 188–1017 mg/kg, and 113–2008 mg/kg, in roots, rhizomes, and fronds, respectively. The calculated bioaccumulation factor in fronds ranged from 2 to 7 and the translocation factor from 0.6 to 2.1. Our data suggest that A. formosa is an arsenic-tolerant species and propose it for phytoremediation on contaminated sites with As concentrations similar to that of the studied location. Further studies should be performed to evaluate the mechanisms of accumulation of As in plant tissues.

Questions: How do species richness and composition of fern assemblages change with elevation and, within elevational belts, in differently impacted forest habitats? Is there a relationship between fern assemblages and microclimate, both along gradients of elevation and disturbance? Which species are most sensitive to habitat disturbance and microclimatic changes? Location: From sea level close to the Gulf of Mexico 81 km away in a direct line on the eastern slopes of the Cofre de Perote at 3500 m, central Veracruz, Mexico. Methods: We studied the richness and composition of fern assemblages in 120 study plots at eight elevations from 20–3500 m in three forest types: natural forest (NF), disturbed forest (DF) subjected to timber extraction and grazing, and secondary forest (SF) regrown after total clearance 15–20 yr ago. In addition, we measured microclimatic conditions in the three forest types at five elevations over a year. Results: Fern richness peaked in humid montane forests at mid-elevations and was low in the drier habitats at the ends of the gradient. Humid montane forests were most sensitive to disturbance, showing increases in mean annual temperatures by about 1 °C and reduction in relative air humidity by about 20% in DF and SF compared to NF. This was together with a reduction in fern species richness of 5–60% and marked changes in species composition. In contrast, drought-deciduous forests at low elevations and coniferous forests at high elevations already had low humidity and high light intensity in NF and were less affected by human impact: their microclimatic conditions and fern assemblages did not change markedly in DF and SF. Conclusions: The conservation of much of the humidity-dependent biota (ferns and presumably also groups such as bryophytes and amphibians) in humid montane forests depends on the protection of natural fragments without human disturbance. In contrast, the naturally open forests at the ends of the gradient can be subjected to some exploitation while conserving much of their fern flora as long as a general forest structure is maintained.

This study compiles and updates the checklist of ferns and lycophytes from the Sierra Madre Occidental (SMOc). For this, we revised information on these taxa from regional floristic studies, databases, and herbaria. Our updated list includes 312 species, of which 276 are ferns and 36 are lycophytes integrated into 27 families and 75 genera. The richest families are Pteridaceae (118), Polypodiaceae (31), Selaginellaceae (30), Aspleniaceae (25), and Dryopteridaceae (25). The three most diverse genera were Selaginella (30), Asplenium (25), and Myriopteris (22). The species-rich Mexican states that include the SMOc are Durango (166 species), Chihuahua (149), and Jalisco (146). As in other tropical mountains, species richness in the SMOc is concentrated at the elevation interval of 1500 to 2000 m (236 species). The mid-mountain vegetation forests (Quercus and Pinus-Quercus forests) harbor the most pteridoflora richness (52% of the species). Four species of ferns are listed as threatened in the Mexican Official Norm NOM-059-SEMARNAT-2010, 17 species are listed in the IUCN, and only one tree ferns are in CITES. The SMOc has a Nearctic affinity, and its fern and lycophyte diversity are lower than in other Mexican Transition Zone mountain chains, such as the Sierra Madre del Sur, the Trans-Mexican Volcanic Belt, and the Sierra Madre Oriental. Notwithstanding, its biological composition is unique and distinctive. The species number reported in the SMOc represents 31% of the pteridoflora diversity recorded in Mexico.

•The project focusses on the use of pollen in geolocation for trade compliance, criminal investigation and counter-terrorism endeavors.•Geolocation based on pollen is possible because each plant has a pollen grain that is specific to it, and each pollen grain has a unique morphology.•The problem is to generate prints from a region of interest to compare to pollen found on a suspect or items if these regions are no longer accessible.•This manuscript describes an innovative approach to use historical museum collections to gather intelligence data from sensitive locations.•It is a timely paper to showcase the significance of Museum collections in the context of homeland security. The use of pollen as a forensic tool for geolocation is a well-established practice worldwide in cases ranging from the provenance of drugs and other illicit materials to tracking the travel of individuals in criminal investigations. Here we propose a novel approach to generation of pollen databases that uses pollen vacuumed from mammal pelts collected historically from international areas that are now deemed too high risk to visit. We present the results of a study we conducted using mammal pelts collected from Mexico. This new investigative technique is important because, although it would seem that the ubiquitous and geo-specific nature of pollen would make pollen analysis among the most promising forensic tools for law enforcement and intelligence agencies, it is not the case. The process is notoriously slow because pollen identification is a tedious task requiring trained specialists (palynologists) who are few in number worldwide, and the reference materials necessary for geolocation usually are rare or absent, especially from regions of the world that are no longer safe to visit because of war or threat of terrorism. Current forensic palynological work is carried out by a few highly trained palynologists who require accurate databases of pollen distribution, especially from sensitive areas, to do their jobs accurately and efficiently. Our project shows the suitability of using the untapped museum pelt resources to support homeland security programs. This first palynological study using museum pelts yielded 133 different pollen and spore types, including 8 moss or fern families, 12 gymnosperm genera and 112 angiosperm species. We show that the palynological print from each region is statistically different with some important clustering, demonstrating the potential to use this technique for geolocation.

From the saprotrophs that decay plant material to the pathogens and mutualists that shape plant demography at local and regional scales, fungi are major drivers of tropical forest dynamics. Although endophytic fungi are abundant and diverse in many biomes, they reach their greatest diversity in tropical forests, where they can influence plant physiology, performance and survival. The number of quantitative studies regarding endophytes has increased dramatically in the past two decades, but general rules have not yet emerged regarding the biogeography, host affiliations, local or regional distributions, or phylogenetic diversity of endophytes in most tropical settings. Here, endophytic fungal communities associated with 18 species of eupolypod fern were compared among forest reserves in Panama, Costa Rica and Mexico. Molecular sequence data for >2000 isolates were used to determine the relationships of host taxonomy, forest (site), and environmental dissimilarity to endophyte community composition. Communities in related ferns differed significantly among forests, reflecting the interplay of geographic distance and environmental dissimilarity. Although the same phyla and classes of fungi were prevalent at each site, they differed in relative abundance. All sites were dominated by the same order (Xylariales), but sites differed in the phylogenetic clustering vs. evenness of their endophyte communities. By addressing the relationship of endophyte communities to host taxonomy, geographic distance and environmental factors, this study complements previous work on angiosperms and contributes to a growing perspective on the factors shaping communities of ecologically important fungi in tropical forests.