DNA Metabarcoding Reveals Cryptic Geographically-influenced Microbial Diversity After Anthropogenic Impact in Original Forest Soils on the Isolated Trindade Island, South Atlantic

Located 1,140 km from the South American coastline in the South Atlantic Ocean, and with an age of 4 million years, Trindade Island is the most recent volcanic component of Brazilian territory. Its vegetation was severely damaged by human influence in particular through the introduction of exotic grazing animals such as goats. However, since the complete eradication of goats and other feral animals in the late 1990s, the island’s vegetation has been recovering and even some endemic species that had been considered extinct have been rediscovered. In this study we set out to characterize the contemporary microbial diversity of Trindade Island forest soils using metabarcoding by High Throughput Sequencing (HTS). Sequences of representative of two domains (Bacteria and Archaea) and five kingdoms (Fungi, Metazoa, Protozoa, Chromista and Viridiplantae) were identified. Bacteria were represented by 20 phyla and 116 taxa, while and Archaea by only one taxon. Fungi were represented by seven phyla and 250 taxa, Viridiplantae by five phyla and six taxa, Protozoa by five phyla and six taxa, Metazoa by three phyla and four taxa and Chromista by two phyla and two taxa. Even after the considerable anthropogenic impacts and devastation of the island’s natural forest, our sequence data revealed the presence of a rich, diverse and complex diversity of microorganisms, invertebrates and plants.

Evolutionary Tracks of Chromosomal Diversification in Surgeonfishes (Acanthuridae: Acanthurus) Along the World’s Biogeographic Domains

Fishes of the genus Acanthurus (Acanthuridae) are strongly related to reef environments, in a broad biogeographic context worldwide. Although their biological aspects are well known, cytogenetic information related to this genus remains incipient. In this study, Acanthurus species from populations inhabiting coastal regions of the Southwest Atlantic (SWA), South Atlantic oceanic islands (Fernando de Noronha Archipelago and Trindade Island), Greater Caribbean (GC), and Indo-Pacific Ocean (the center of the origin of the group) were analyzed to investigate their evolutionary differentiation. For this purpose, we employed conventional cytogenetic procedures and fluorescence in situ hybridization of 18S rDNA, 5S rDNA, and H3 and H2B-H2A histone sequences. The Atlantic species (A. coeruleus, A. chirurgus, and A. bahianus) did not show variations among them, despite their vast continental and insular distribution. In contrast, A. coeruleus from SWA and GC diverged from each other in the number of 18S rDNA sites, a condition likely associated with the barrier created by the outflows of the Amazonas/Orinoco rivers. The geminate species A. tractus had a cytogenetic profile similar to that of A. bahianus. However, the chromosomal macrostructures and the distribution of rDNA and hisDNA sequences revealed moderate to higher rates of diversification when Acanthurus species from recently colonized areas (Atlantic Ocean) were compared to A. triostegus, a representative species from the Indian Ocean. Our cytogenetic data covered all Acanthurus species from the Western Atlantic, tracked phylogenetic diversification throughout the dispersive process of the genus, and highlighted the probable diversifying role of ocean barriers in this process.

The Unique Amphipoda and Tanaidacea (Crustacea: Peracarida) Associated With the Brown Algae Dictyota sp. From the Oceanic Trindade Island, Southwestern Atlantic, With Biogeographic and Phylogenetic Insights

Oceanic islands are known by their unique evolutionary histories and high endemicity caused by isolation. This is the first survey on the biodiversity of Peracarida from Trindade Island, a volcanic island located about 1,160 km off the Brazilian coast, with the first reports of Tanaidacea from the island and the description of Synapseudes isis sp. nov. and three new species of Amphipoda (Ampithoe thaixsp. nov., Elasmopus gabrielisp. nov., and Eusiroides lucaisp. nov.). The results of the phylogenetic analysis of Synapseudes based on morphological characters and its biogeography through the Bayesian Binary MCMC analysis (BBM) suggested an Indo-Pacific origin for the genus. Finally, the biodiversity of Trindade Island is compared to that of the Abrolhos Archipelago, the closest islands from the coast on the continental shelf, suggesting a high endemicity of Peracarida, corresponding to 44% of Amphipoda and 50% of Tanaidacea species in the island of Trindade.

Cyathea Sm. (Cyatheaceae) on Trindade Island (Brazil): An integrative approach

Trindade is a Brazilian oceanic island approximately 1,100 km from the American mainland. The Cyathea Sm. plants from Trindade were originally considered an endemic species, Cyathea copelandii Kuhn & Luerssen, but later included in Cyathea delgadii Sternb. Based on molecular data (trnL-trnF, trnG-trnR and rbcL-accD), morphometric analysis of leaf characters, scanning electron microscopy of indusia and spores, and habitat suitability modeling, the present study confirms the status of C. copelandii as a synonym of C. delgadii. Intraspecific molecular variation suggests phylogeographic structuring in C. delgadii and differentiation between the coastal Atlantic Forest domain and the Cerrado domain (savanna) in the interior of Brazil. The Trindade populations are more closely related to the Atlantic Forest populations, indicating a colonization of the island from the latter area.