Browsing by Author "Valente, Alexandre"
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- First record of Philometra ovata (Nematoda) infection in Gobio lozanoi in PortugalPublication . Saraiva, A.; Hermida, M.; Costa, M. J.; Maia, Carla; Reis, A. R.; Cruz, C.; Valente, AlexandreGobio lozanoi, from the River Febros northern Portugal, contained female Philometra ovata in the body cavity causing abdominal swelling. A mild chronic inflammation and some tissue necrosis were observed in infected fish. Significant correlations were found between occurrence of infection and host length, and gonado-somatic index; and between intensity of infection and condition factor.
- Identification of ESUs in the critically endangered portuguese minnow Chondrostoma lusitanicum Collares-Pereira 1980, based on a phylogeographical analysisPublication . Robalo, Joana Isabel; Doadrio, Ignacio; Valente, Alexandre; Almada, Vítor CarvalhoIn this paper, we analysed the phylogeography of the Critically Endangered fish Chondrostoma lusitanicum (Cyprinidae) endemic to Portugal. A fragment of the mitochondrial cyt b gene and one from the nuclear beta-actin gene were sequenced. The results support recognition of 3 ESU’s distributed as follows: 1) Sado River, 2) the Tagus River basin and 3 independent nearby coastal rivers (collectively named ‘‘West’’) and 3) Lagoa de Albufeira, a small coastal lagoon between Tagus and Sado basins.
- Insights on speciation patterns in the genus Iberochondrostoma (Cyprinidae): Evidence from mitochondrial and nuclear dataPublication . Robalo, Joana Isabel; Doadrio, Ignacio; Valente, Alexandre; Almada, Vítor CarvalhoIn this paper, the patterns of cladogenesis in the cyprinid fish genus Iberochondrostoma were analysed using a mitochondrial (cytochrome b) and a nuclear (beta-actin) gene fragment. The two genes yielded discordant results. While the cytochrome b gene yielded a fully dichotomous tree, where all species of the genus are monophyletic, the much slower beta-actin gene yielded star-like relationships. However, when information from both genes was considered together, the data suggested the persistence of a very large central unit from which at least two peripheral clades arose at different times. This pattern which is akin to peripatric speciation was shown to be compatible with the paleogeographical information available. It is suggested that combining the techniques of phylogeny and phylogeography and the use of multiple markers varying in their rate of evolution may enrich our understanding of speciation and evolution of clades beyond species level.
- Mitochondrial DNA fails to reveal genetic structure in sea-lampreys along european shoresPublication . Almada, Vítor Carvalho; Pereira, Ana Martins; Robalo, Joana Isabel; Fonseca, João Paulo; Levy, André; Maia, Carla; Valente, AlexandreInexistente
- Phylogeographical analysis reveals multiple conservation units in brook lampreys Lampetra planeri of portuguese streamsPublication . Pereira, Ana Martins; Robalo, Joana Isabel; Freyhof, J.; Maia, Carla; Fonseca, João Paulo; Valente, Alexandre; Almada, Vítor CarvalhoThe populations of brook lamprey Lampetra planeri of Portuguese Rivers were analysed phylogeographically using a fragment of 644 bp of the mitochondrial control region of 158 individuals from six populations. Samples representing L. planeri and migratory lampreys Lampetra fluviatilis of rivers draining to the North Sea and the Baltic Sea were also included to assess the relationships of Portuguese samples. The data support a clear differentiation of all the populations studied. Several populations, which are isolated among themselves and also from the migratory lampreys, proved to be entirely composed of private haplotypes, a finding that supports some time of independent evolutionary history for these populations. This, combined with the geographic confinement to small water bodies, justifies the recognition of at least four conservation units in the Portuguese rivers Sado, São Pedro, Nabão and Inha.