Abstract The chloroplast psbB-psbT-psbN-psbH gene cluster was sequenced in 123 individuals from 12 populations of Cenostigma macrophyllum and C. tocantinum, revealing only four haplotypes. Low diversity indices were due to the small number of unique haplotypes and their restricted sharing among nearby sites. Phylogenetic and haplotype network analyses confirmed clear genetic differentiation between the two species. Within C. macrophyllum, genetic differences were observed between northern and southern populations in Piauí and Maranhão, likely representing intraspecific variation in a morphologically variable species rather than formal taxonomic subdivision. Populations from Teresina and nearby areas are best interpreted as regionally structured groups, possibly shaped by restricted seed-mediated gene flow. Analysis of molecular variance further supported population structuring, while Bayesian clustering identified three main haplogroups across both species. These results also provide a basis for future taxonomic studies and highlight the importance of integrating nuclear markers to better resolve evolutionary processes. Additionally, we uncovered the potential of the psbB-psbT-psbN-psbH gene cluster as an informative standard for the identification of tree species, notwithstanding the limitations of single-locus plastid data.
Abstract Nicotiana alata (hawkmoth-pollinated) and N. forgetiana (hummingbird-pollinated) are two closely related species that were considered reproductively isolated due to their divergent pollination systems. However, the discovery of a natural hybrid zone challenges this view. Floral volatile profiles of these species and their natural hybrids were characterized to identify possible mechanisms and consequences of unexpected gene flow. Organ-specific (corolla, pollen) and diel (day, night) volatile emissions were analyzed using HS-SPME-GC-MS. Corolla scents were dominated by oxygenated monoterpenoids, while pollen blends were rich in microbial-associated compounds, such as acetoin. Hybrid scent profiles more closely match their floral phenotype than their genomic ancestry, with intermediate hybrids emitting blends distinct from those of both parental species. The discovery of a natural hybrid zone, combined with phenotype-specific scent emissions, challenges the view of strict pollinator isolation. Floral scent presents a complex, modular trait that may facilitate hybridization in this system.
Abstract Seed bank (SB) formation in temporary ponds is key to the local resilience of macrophyte species after drought disturbance. Studying seed germinability and its response to temperature is crucial to understanding regeneration strategies in wetlands, where seed banks play a central role. The objective of this work was to evaluate, through two experiments, the effect of storage period and temperature on the germination of the macrophyte seed bank from a temporary pond in the Brazilian semiarid region. In the first experiment, germinability was compared between fresh samples and samples stored in a cold chamber. In the second experiment, the effect of temperature on germination was evaluated using stored sediment. The fresh SB showed higher richness and lower seedling density than the stored sample. The higher temperature treatment (37 °C) led to higher richness and seedling density. Lemna sp. and Heteranthera limosa were the only species that germinated and emerged from the SB under all tested temperature conditions. The study concluded that cold storage can aid the conservation of temporary pond seed banks and that, within the temperature range, seed bank germinability was maintained under elevated temperatures representative of projected climate scenarios.
Abstract Biodiversity loss exacerbated by climate change compromises habitat conservation and restoration strategies. Analyzing the functional traits of secondary xylem is a valuable tool for understanding how species respond to environmental conditions. This study aimed to characterize the anatomical structures of the secondary xylem in Miconia prasina (Sw.) DC. (Melastomataceae) and Nectandra membranacea (Sw.) Griseb. (Lauraceae) and investigate how wood anatomical variations contribute to understanding intraspecific variation in these species across the ombrophilous forest and restinga areas. To achieve this, we collected branches from five individuals of each species in both study areas, totaling 20 samples. The secondary xylem samples were subjected to plant anatomy techniques, including transverse, tangential, radial sectioning, staining, and microscopic analysis. We observed low intraspecific variability in the anatomical traits of the secondary xylem of M. prasina and N. membranacea across different phytophysiognomies. In M. prasina, the tangential vessel diameter, wall thickness, and vessel element length were greater in the ombrophilous forest than in the restinga. In contrast, N. membranacea exhibited functional stability, with conservative traits such as sparse axial parenchyma in both phytophysiognomies, reflecting a strategy focused on safety and water storage. Understanding these variations is essential for predicting species acclimation in heterogeneous environments and contributing to conservation strategies in the face of anthropogenic impacts and extreme climatic events.
Abstract Tucumã is a palm of notable economic and cultural relevance in the Amazon region. Although its nomenclatural status is formally settled under the International Code of Nomenclature for algae, fungi, and plants, its scientific name in the literature remains characterized by persistent misapplication. The name Astrocaryum aculeatum has been applied to this species for several decades, replacing A. tucuma, the previously accepted name. However, nearly twenty years ago, it was demonstrated that the type specimen of A. aculeatum corresponds to a distinct palm, A. gynacanthum. Considering this misapplied name, a proposal to conserve A. aculeatum with a conserved type for the tucumã was submitted in 2008, but subsequently not recommended by the Nomenclature Committee for Vascular Plants in 2011. In the same report, this Committee suggested the reestablishment of A. tucuma as the correct name and the submission of a new proposal to deal with the names A. aculeatum and A. gynacanthum. These decisions were later evaluated and ratified by the General Committee in 2011. Despite these committees evaluations, a review of the literature from 2011 to 2025 indicates that the scientific community did not adopt the change suggested. The name A. aculeatum remains dominant for the tucumã palm, appearing 60 times more frequently than A. tucuma, which was identified in only 1.6% of the eligible records. This study elucidates the intricate nomenclatural history of the species and underscores the necessity of reaffirming A. tucuma as the correct name. The continued application of A. aculeatum to the tucumã palm, after the exhaustion of all procedures established by the Code, represents a persistent ambiguity that must be resolved to ensure nomenclatural stability and accuracy within the genus.
