RESUMO
Changes in the sea level during the Holocene are regarded as one of the most prevalent drivers of the diversity and distribution of macroalgae in Brazil, influenced by the emergence of the Vitória-Trindade seamount chain (VTC). Gracilariopsis tenuifrons has a wide geographic distribution along the Brazilian coast, from Maranhão state (2°48'64.3" S) to Santa Catarina state (27.5°73'83" S). The knowledge of historical processes affecting diversity may allow the development of conservation strategies in environments against anthropogenic influence. Therefore, knowledge about phylogeography and populational genetic diversity in G. tenuifrons is necessary. Six populations were sampled along the northeastern tropical (Maranhão-MA, Rio Grande do Norte-RN, Alagoas-AL, and Bahia-BA States) and southeastern subtropical (São Paulo "Ubatuba"-SP1 and São Paulo "Itanhaém"-SP2 States) regions along the Brazilian coast. The genetic diversity and structure of G. tenuifrons were inferred using mitochondrial (COI-5P and cox2-3 concatenated) DNA markers. Gracilariopsis tenuifrons populations showed an evident separation between the northeast (from 2°48'64.3" S to 14°18'23" S; 17 haplotypes) and the southeast (from 23°50'14.9" S to 24°20'04.7" S; 10 haplotypes) regions by two mutational steps between them. The main biogeographical barrier to gene flow is located nearby the VTC. The southeast region (São Paulo State) is separated by two subphylogroups (SP1, three haplotypes and SP2, six haplotypes), and Santos Bay (estuary) has been considered a biogeographical barrier between them. The presence of genetic structure and putative barriers to gene flow are in concordance with previous studies reporting biogeographic breaks in the southwest Atlantic Ocean, including the genetic isolation between northeast and southeast regions for red and brown algae in the vicinity of the VTC.
Assuntos
Variação Genética , Rodófitas , Filogeografia , Brasil , Rodófitas/genética , Oceano Atlântico , Haplótipos , DNA Mitocondrial/genética , FilogeniaRESUMO
The Peyssonneliaceae represents the only family in the order Peyssonneliales, a clade of red encrusting algae distributed worldwide, including 136 species in eleven currently accepted genera. Delineation of genera in the Peyssonneliaceae has mostly been based on vegetative characteristics. Previous molecular phylogenies have shown that some traditionally circumscribed genera are not monophyletic and relationships among them are uncertain. We contribute to the knowledge of the evolutionary history of this clade, presenting a robust rbcL phylogeny that provides new insights on the origin and diversification of the Peyssonneliales. Based on a broad dataset and morphological analyses, we propose a revised taxonomic scheme for the Peyssonneliales resolved as monophyletic with well-supported main lineages. Our results show that Peyssonnelia is polyphyletic, and, therefore, we propose three new genera, Agissea, Olokunia, and Rhodowynnea to accommodate species currently assigned to Peyssonnelia, but distantly related to the clade with the type species of the genus. Additionally, barcoding techniques and analyzed criteria for specific delimitation supported the establishment of one new genus, Brasilophycus, and seven new species, from northeastern Brazil: Agissea amadoi, A. densissima, A. taberniforma, A. villatlantica, A. yemonjasagbae, Brasilophycus similis, and B. roseomarginatus. Our integrative taxonomic approach reveals underestimated diversity of Brazilian Peyssonneliales. Investment in broader sampling along the Brazilian coast and other tropical areas may reveal that its marine biodiversity can be expanded, enlightening our knowledge about this ecologically important group of red algae.
Assuntos
Rodófitas , Biodiversidade , Evolução Biológica , Brasil , Filogenia , Rodófitas/genéticaRESUMO
The classification of Cystoclonium obtusangulum has been questioned since the species was first described by Hooker and Harvey as Gracilaria? obtusangula. The objective of this study was to provide the first comprehensive taxonomic analysis of Cystoclonium obtusangulum, based on DNA sequences coupled with morphological observations made on syntype specimens and new collections. Sequence divergences of rbcL, UPA, and COI-5P, and maximum-likelihood phylogenies for rbcL and 18S demonstrated that specimens identified as Cystoclonium obtusangulum represent a clade of two distinct species that are distantly related to the generitype Cystoclonium purpureum. A new genus, Meridionella gen. nov., is proposed for this clade. The two species placed in this new genus were morphologically indistinguishable cryptic species, but have disjunct distributions, with Meridionella obtusangula comb. nov. found from temperate to cold coasts of South America and the Falkland Islands and Meridionella antarctica sp. nov., occurring in Antarctic waters. Vegetative and reproductive characters of Meridionella gen. nov. are described, and implications of our results for the biogeography of the family Cystocloniaceae are discussed.
Assuntos
Rodófitas , Regiões Antárticas , Filogenia , RNA Ribossômico 16S , Rodófitas/genética , Análise de Sequência de DNA , América do SulRESUMO
Populations of the marine benthic red macroalgae Hypnea musciformis and Hypnea pseudomusciformis along the Atlantic and Pacific Oceans were tested for phylogeographic structure using the DNA barcode COI-5P combined with rbcL for the construction of the phylogenetic tree. Strong patterns of genetic structure were detected across 210 COI-5P DNA sequences, and 37 COI-5P haplotypes were found, using multiple statistical approaches. Hypnea musciformis was found in the Northeast and Northwest Atlantic, the Mediterrean Sea, Namibia, and along the Pacific coast of Mexico. Two new putative species were detected, Hypnea sp. 1 in the Caribbean Sea and Hypnea sp. 2 in the Dominican Republic. Three distinct marine phylogeographic provinces were recognized in the Southern Hemisphere for H. pseudomusciformis: Uruguay, South-Southeast Brazil, and Northeast Brazil. The degree of genetic isolation and distinctness among these provinces varied considerably. The Uruguay province was the most genetically distinct, as characterized by four unique haplotypes not shared with any of the Brazilian populations. Statistically significant results support both, isolation by distance and isolation by environment hypotheses, explaining the formation and mantainance of phylogeographic structuring along the Uruguay-Brazil coast. Geographic, taxonomic and molecular marker concordances were found between our H. pseudomusciformis results and published studies. Furthermore, our data indicate that the Hawaiian introduced populations of H. musciformis contain Hypnea sp. 1 haplotypes, the current known distribution of which is restricted to the Caribbean.
Assuntos
Rodófitas , Oceano Atlântico , Brasil , Região do Caribe , DNA Mitocondrial , Variação Genética , Haplótipos , Havaí , México , Oceano Pacífico , Filogenia , Filogeografia , Análise de Sequência de DNARESUMO
The genus Ectocarpus (Ectocarpales, Phaeophyceae) contains filamentous algae widely distributed in marine and estuarine habitats of temperate regions in both hemispheres. While E. siliculosus has become a model organism for genomics and genetics of the brown macroalgae, accurate species delineation, distribution patterns and diversity for the genus Ectocarpus remain problematic. In this study, we used three independent species delimitation approaches to generate a robust species hypothesis for 729 Ectocarpus specimens collected mainly along the European and Chilean coasts. These approaches comprised phylogenetic reconstructions and two bioinformatics tools developed to objectively define species boundaries (General Mixed Yule Coalescence Method and Automatic Barcode Gap Discovery). Our analyses were based on DNA sequences of two loci: the mitochondrial cytochrome oxidase subunit 1 and the nuclear internal transcribed spacer 1 of the ribosomal DNA. Our analyses showed the presence of at least 15 cryptic species and suggest the existence of incomplete lineage sorting or introgression between five of them. These results suggested the possible existence of different levels of reproductive barriers within this species complex. We also detected differences among species in their phylogeographic patterns, range and depth distributions, which may suggest different biogeographic histories (e.g., endemic species or recent introductions).