No abstract

The Araucaria Forests in southern Brazil are part of the Atlantic Rainforest, a key hotspot for global biodiversity. This habitat has experienced extensive losses of vegetation cover due to commercial logging and the intense use of wood resources for construction and furniture manufacturing. The absence of precise taxonomic tools for identifying Araucaria Forest tree species motivated us to test the ability of DNA barcoding to distinguish species exploited for wood resources and its suitability for use as an alternative testing technique for the inspection of illegal timber shipments. We tested three cpDNA regions (matK, trnH-psbA, and rbcL) and nrITS according to criteria determined by The Consortium for the Barcode of Life (CBOL). The efficiency of each marker and selected marker combinations were evaluated for 30 commercially valuable woody species in multiple populations, with a special focus on Lauraceae species. Inter- and intraspecific distances, species discrimination rates, and ability to recover species-specific clusters were evaluated. Among the regions and different combinations, ITS was the most efficient for identifying species based on the ‘best close match’ test; similarly, the trnH-psbA + ITS combination also demonstrated satisfactory results. When combining trnH-psbA + ITS, Maximum Likelihood analysis demonstrated a more resolved topology for internal branches, with 91% of species-specific clusters. DNA barcoding was found to be a practical and rapid method for identifying major threatened woody angiosperms from Araucaria Forests such as Lauraceae species, presenting a high confidence for recognizing members of Ocotea. These molecular tools can assist in screening those botanical families that are most targeted by the timber industry in southern Brazil and detecting certain species protected by Brazilian legislation and could be a useful tool for monitoring wood exploitation.

The reproductive biology of the endemic Cattleya elongata and the endemic and critically endangered Cattleya tenuis (Orchidaceae) was studied in areas of 'campo rupestre' and 'caatinga' vegetation, respectively, in the Chapada Diamantina, north-eastern Brazil. Floral visitors and their behavior were recorded, and experimental pollinations were carried out to determine the breeding systems of these species. The species have similar flower morphology, flower in synchrony and both are pollinated by queens of Bombus ( Fervidobombus ) brevivillus (Apidae, Bombina). Flowers of both species do not present nectar despite the presence of a nectary-like cuniculus. Cattleya tenuis presented low natural fruit set (10%), while C. elongata presented a higher fruit set (25%). Both species are selfcompatible, and only C. tenuis presented inbreeding depression, expressed as reduced seed viability in self-pollinations compared with cross-pollinations. The species have a parapatric distribution and differences in their habitats probably act as the principal barriers to the formation of natural hybrids.

Pantropical Bulbophyllum, with ∼2,200 species, is one of the largest genera in Orchidaceae. Although phylogenetics and taxonomy of the ∼60 American species in the genus are generally well understood, some species complexes need more study to clearly delimit their component species and provide information about their evolutionary history. Previous research has suggested that the plastid genome includes phylogenetic markers capable of providing resolution at low taxonomic levels, and thus it could be an effective tool if these divergent regions can be identified. In this study, we sequenced the complete plastid genome of eight Bulbophyllum species, representing five of six Neotropical taxonomic sections. All plastomes conserve the typical quadripartite structure, and, although the general structure of plastid genomes is conserved, differences in ndh-gene composition and total length were detected. Total length was determined by contraction and expansion of the small single-copy region, a result of an independent loss of the seven ndh genes. Selection analyses indicated that protein-coding genes were generally well conserved, but in four genes, we identified 95 putative sites under positive selection. Furthermore, a total of 54 polymorphic simple sequence repeats were identified, for which we developed amplification primers. In addition, we propose 10 regions with potential to improve phylogenetic analyses of Neotropical Bulbophyllum species.

No abstract

Bulbophyllum sect. Didactyle e B.sect. Xiphizusa são grupos monofiléticos irmãos, inseridos no clado neotropical do gênero. As espécies ocorrem como epífitas ou rupícolas em áreas montanhosas com predomínio dos campos rupestres. O objetivo foi descrever comparativamente a anatomia dos órgãos vegetativos de 13 espécies dessas seções. O trabalho evidencia pela primeira vez a secreção lipofílica dos tricomas na folha jovem; caracteres xeromorfos uniformes entre as duas seções, como a cutícula espessa, presença de idioblastos, parênquima aquífero e fibras junto aos feixes vasculares; a ausência de cristais prismáticos na raiz e bulbo nas espécies de B.sect. Didactyle e a ausência de idioblastos com espessamento espiralados na raiz, espessamento na parede epidérmica do pseudobulbo e predomínio de mesofilo heterogêneo nas folhas das espécies de B. sect. Xiphizusa podem ser considerados estados de caractere sinapomórficos para as seções mostrando a importância da anatomia em estudos sistemáticos.

This study reports complete plastome sequences for six species of Neotropical Cranichideae and focuses on identification of the most variable regions (hotspots) in this group of orchids. These structure of these six plastomes is relatively conserved, exhibiting lengths ranging between 142,599 to 154,562 bp with 36.7% GC on average and exhibiting typical quadripartite arrangement (LSC, SSC and two IRs). Variation detected in the LSC/IR and SSC/IR junctions is explained by the loss of ndhF and ycf1 length variation. For the two genera of epiphytic clade in Spiranthinae, almost whole sets of the ndh-gene family were missing. Eight mutation hotspots were identified based on nucleotide diversity, sequence variability and parsimony-informative sites. Three of them (rps16-trnQ, trnT-trnL, rpl32-trnL) seem to be universal hotspots in the family, and the other five (trnG-trnR, trnR-atpA, trnP-psaJ, rpl32-infA, and rps15-ycf1) are described for the first time as orchid molecular hotspots. These regions have much more variation than all those used previously in phylogenetics of the group and offer useful plastid markers for phylogenetic, barcoding and population genetic studies. The use of whole plastomes or exclusive no-gap matrices also positioned with high support the holomycotrophic Rhizanthella among Orchidoideae plastomes in model-based analyses, showing the utility of plastomes for phylogenetic placement of this unusual genus.

The colonization of the epiphytic niche of Neotropical forest canopies played an important role in orchid's extraordinary diversification, with rare reversions to the terrestrial habit. To understand the evolutionary context of those reversals, we investigated the diversification of Galeandra, a Neotropical orchid genus which includes epiphytic and terrestrial species. We hypothesized that reversion to the terrestrial habit accompanied the expansion of savannas. To test this hypothesis we generated a comprehensive time-calibrated phylogeny and employed comparative methods. We found that Galeandra originated towards the end of the Miocene in Amazonia. The terrestrial clade originated synchronously with the rise of dry vegetation biomes in the last 5 million years, suggesting that aridification dramatically impacted plant diversification and habits in the Neotropics. Shifts in habit impacted floral spur lengths and geographic range size, but not climatic niche. The longer spurs and narrower ranges characterize epiphytic species, which probably adapted to specialized long-tongued Euglossini bee pollinators inhabiting forested habits. The terrestrial species present variable floral spurs and wider distribution ranges, with evidence of self-pollination, suggesting the loss of specialized pollination system and concomitant range expansion. Our study highlights how climate change impacted habit evolution and associated traits such as mutualistic interactions with pollinators.