Morphological and Molecular Evolution Are Not Linked in Lamellodiscus (Plathyhelminthes, Monogenea)

Lamellodiscus Johnston & Tiegs 1922 (Monogenea, Diplectanidae) is a genus of common parasites on the gills of sparid fishes. Here we show that this genus is probably undergoing a fast molecular diversification, as reflected by the important genetic variability observed within three molecular markers (partial nuclear 18S rDNA, Internal Transcribed Spacer 1, and mitonchondrial Cytochrome Oxidase I). Using an updated phylogeny of this genus, we show that molecular and morphological evolution are weakly correlated, and that most of the morphologically defined taxonomical units are not consistent with the molecular data. We suggest that Lamellodiscus morphology is probably constrained by strong environmental (host-induced) pressure, and discuss why this result can apply to other taxa. Genetic variability within nuclear 18S and mitochondrial COI genes are compared for several monogenean genera, as this measure may reflect the level of diversification within a genus. Overall our results suggest that cryptic speciation events may occur within Lamellodiscus, and discuss the links between morphological and molecular evolution

Chronostratigraphy of the sedimentary core from Lake Acigol (Turkey) reveals a 2.4 Ma lacustrine record for western Asia with a high paleoclimatic archive potential.

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Phylogenetic analysis of Tomato mosaic virus from Hemerocallis sp. and Impatiens hawkeri Análise filogenética de Tomato mosaic virus isolado de Hemerocallis sp. e Impatiens hawkeri

The culture and commercialization of ornamental plants have considerably increased in the last years. To supply the commercial demand, several Hemerocallis and Impatiens varieties have been bred for appreciated qualities such as flowers with a diversity of shapes and colors. With the aim of characterizing the tobamovirus isolated from Hemerocallis sp. (tobamo-H) and Impatiens hawkeri (tobamo-I) from the USA and São Paulo, respectively, as well as to establish phylogenetic relationships between them and other Tobamovirus species, the viruses were submitted to RNA extraction, RT-PCR amplification, coat-protein gene sequencing and phylogenetic analyses. Comparison of tobamovirus homologous sequences yielded values superior to 98.5% of identity with Tomato mosaic virus (ToMV) isolates at the nucleotide level. In relation to tobamo-H, 100% of identity with ToMV from tomatoes from Australia and Peru was found. Based on maximum likelihood (ML) analysis it was suggested that tobamo-H and tobamo-I share a common ancestor with ToMV, Tobacco mosaic virus, Odontoglossum ringspot virus and Pepper mild mottle virus. The tree topology reconstructed under ML methodology shows a monophyletic group, supported by 100% of bootstrap, consisting of various ToMV isolates from different hosts, including some ornamentals, from different geographical locations. The results indicate that Hemerocallis sp. and I. hawkeri are infected by ToMV. This is the first report of the occurrence of this virus in ornamental species in Brazil.<br>O cultivo e comercialização de plantas ornamentais têm aumentado consideravelmente nos últimos anos. Para suprir a demanda comercial, diversas variedades de Hemerocallis sp. e Impatiens hawkeri têm sido desenvolvidas pelas qualidades apreciáveis como flores com diversidade de formas e cores. Com o objetivo de caracterizar o tobamovirus isolado de Hemerocallis sp. (tobamo-H) e Impatiens hawkeri (tobamo-I) provenientes dos EUA e São Paulo, respectivamente, assim como estabelecer relações filogenéticas entre os isolados e outras espécies de Tobamovirus, foram realizados extrações do RNA, RT-PCR, seqüenciamento do gene da capa protéica e análises filogenéticas. Quando foram comparadas seqüências homólogas de tobamovirus, valores superiores a 98,5% de identidade, ao nível de nucleotídeos, foram obtidos com isolados do Tomato mosaic virus (ToMV). Em relação ao tobamo-H, foi encontrado 100% de identidade com o ToMV isolado de tomateiro da Austrália e do Peru. Com base em análise de máxima verossimilhança (MV), sugere-se que o tobamo-H e tobamo-I compartilham um ancestral comum com ToMV, Tobacco mosaic virus, Odontoglossum ringspot virus e Pepper mild mottle virus. A topologia da árvore reconstruída a partir de MV mostra um grupo monofilético, sustentado por 100% de "bootstrap", formado por vários isolados de ToMV de diferentes hospedeiras, incluindo ornamentais, a partir de diferentes localizações geográficas. Os resultados indicam que Hemerocallis sp.e I. hawkeri estão infectados pelo ToMV, sendo esse o primeiro relato desse vírus em ornamentais, no Brasil

Topological Rearrangements and Local Search Method for Tandem Duplication Trees

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