RESUMO
Ants in the genera Anochetus and Odontomachus belong to one of the largest clades in the subfamily Ponerinae, and are one of four lineages of ants possessing spring-loaded "trap-jaws." Here we present results from the first global species-level molecular phylogenetic analysis of these trap-jaw ants, reconstructed from one mitochondrial, one ribosomal RNA, and three nuclear protein-coding genes. Bayesian and likelihood analyses strongly support reciprocal monophyly for the genera Anochetus and Odontomachus. Additionally, we found strong support for seven trap-jaw ant clades (four in Anochetus and three in Odontomachus) mostly concordant with geographic distribution. Ambiguity remains concerning the closest living non-trap-jaw ant relative of the Anochetus+Odontomachus clade, but Bayes factor hypothesis testing strongly suggests that trap-jaw ants evolved from a short mandible ancestor. Ponerine trap-jaw ants originated in the early Eocene (52.5Mya) in either South America or Southeast Asia, where they have radiated rapidly in the last 30million years, and subsequently dispersed multiple times to Africa and Australia. These results will guide future taxonomic work on the group and act as a phylogenetic framework to study the macroevolution of extreme ant mouthpart specialization.
Assuntos
Formigas/classificação , África , Animais , Formigas/genética , Sudeste Asiático , Austrália , Teorema de Bayes , Citocromos b/classificação , Citocromos b/genética , Citocromos b/metabolismo , Variação Genética , Filogenia , Filogeografia , RNA Ribossômico 28S/classificação , RNA Ribossômico 28S/genética , RNA Ribossômico 28S/metabolismo , América do SulRESUMO
Traditionally, species identification in nudibranch gastropods relies heavily on body color pattern. The Felimida clenchi species complex, a group of brightly colored Atlantic and Mediterranean species in the family Chromodorididae, has a history of exceptional controversy and discussion among taxonomists. The most widely accepted hypothesis is that the complex includes four species (Felimida clenchi, F. neona, F. binza and F. britoi), each with a characteristic body color pattern. In this study, we investigated the taxonomic value of coloration in the Felimida clenchi complex, using molecular phylogenetics, species-delimitation analyses (ABGD, GMYC, PTP), haplotype-network methods, and the anatomy of the reproductive system. None of our analyses recovered the traditional separation into four species. Our results indicated the existence of three species, a result inconsistent with previous taxonomic hypotheses. We distinguished an undescribed species of Felimida and redefined the concepts of F. clenchi and F. binza, both highly polychromatic species. For the first time, molecular data support the existence of extreme color polymorphism in chromatic nudibranch species, with direct implications for the taxonomy of the group and its diversity. The polychromatism observed in the F. clenchi complex apparently correlates with the regional occurrence of similar color patterns in congeneric species, suggesting different mimicry circles. This may represent a parallel in the marine environment to the mechanisms that play a major role in the diversification of color in terrestrial and fresh-water chromatic groups, such as heliconian butterflies.
Assuntos
Gastrópodes/classificação , África , Animais , Brasil , Região do Caribe , Citocromos c/classificação , Citocromos c/genética , Citocromos c/metabolismo , DNA/química , DNA/isolamento & purificação , DNA/metabolismo , Bases de Dados Genéticas , Haplótipos , Histonas/classificação , Histonas/genética , Histonas/metabolismo , Filogenia , Filogeografia , Pigmentação , RNA Ribossômico 16S/classificação , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , RNA Ribossômico 28S/classificação , RNA Ribossômico 28S/genética , RNA Ribossômico 28S/metabolismo , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
Splitting and apparent splicing of ribosomal RNA, both previously unknown in vertebrates, were found in rodents of the genus Ctenomys. Instead of being formed by a single molecule of 4.4 kb, 28S rRNA is split in two molecules of 2.6 and 1.8 kb. A hidden break, mapping within a 106 bp 'intron' located in the D6 divergent region, is expressed in mature ribosomes of liver, lung, heart and spleen, as well as in primary fibroblast cultures. Testis-specific processing eliminates the intron and concomitantly the break site, producing non-split 28S rRNA molecules exclusively in this organ. The intron is flanked by two 9 bp direct repeats, revealing the acquisition by insertion of a novel rRNA processing strategy in the evolution of higher organisms.