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  • 1
    Electronic Resource
    Electronic Resource
    The genetics of maintenance of an all-male lineage in the Squalius albuvnoides complex (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 60 (2002), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Squalius alburnoides is a complex of minnows common to the Iberian Peninsula, consisting of two distinct forms. The most common form is comprised of diploid and polyploid asexual hybrids heterozygous for several diagnostic allozyme loci contributed by Squalius pyrenaicus or Squalius carolitertii and a missing ancestor. The other form is diploid and homozygous for the allele contributed by the missing ancestor at these same loci. Present results from analyses of sex ratio and cytochrome b sequences are not consistent with the evolutionary distinctiveness of this non-hybrid form and suggest that it represents an all-male lineage imbedded within an almost all-female complex. This all-male lineage allowed preservation of the ancestral paternal nuclear genome after the paternal ancestor became extinct in all or most drainages, withimportant evolutionary implications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2002.tb01691.x
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  • 2
    Electronic Resource
    Electronic Resource
    Genetic variation and divergence of Leuciscus pyrenaicus and L. carolitertii (Pisces, Cyprinidae) (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 47 (1995), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The taxonomy of the genus Leuciscus in the Iberian Peninsula has been presented on the basis of morphological analysis. Two species are believed to occur in Portuguese inland waters, L. carolitertii, the northern basins chub, and L. pyrenaicus, which was described for the Tejo and southern basins. Since only slight differences in the meristic and morphometric characters are observed, the distinction between the two species has been made previously mainly on the basis of osteology. In order to investigate the patterns of genetic differentiation between these species, 24 sites were sampled for both species, and examined electrophoretically for the study of variation at 27 presumptive loci. The results pointed to different levels of population differentiation among drainages and support the recognition of the species level for L. pyrenaicus and L. carolitertii. Our results also suggested that the distribution area of L. pyrenaicus is probably restricted to Tejo and to the small drainages near Tejo, while L. carolitertii seems to have a widespread distribution area, including Lima, Douro, Vouga, Mondego, Guadina and Sado drainages. Moreover, concerning the southern populations, Mira and Arade, the surprisingly high level of differentiation observed at several loci, supports the existence of a further species occurring in these small drainages. The evolutionary aspects related to that differentiation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1995.tb06059.x
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  • 3
    Electronic Resource
    Electronic Resource
    Phylogenetic relationships of Eurasian and American cyprinids using cytochrome b sequences (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 61 (2002), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Neighbour-joining and parsimony analyses identified five lineages of cyprinids: (1) European leuciscins (including Notemigonus)+North American phoxinins (including Phoxinus phoxinus); (2) European gobionins+Pseudorasbora; (3) primarily Asian groups [cultrins+acheilognathins+ gobionins (excluding Abbotina)+xenocyprinins]; (4) Abbottina+Sinocyclocheilus+Acrossocheilus; (5) cyprinins [excluding Sinocyclocheilus and Acrossocheilus]+barbins+labeonins. Relationships among these lineages and the enigmatic taxa Rhodeus were not well-resolved. Tests of monophyly of subfamilies and previously proposed relationships were examined by constraining cytochrome b sequences data to fit previous hypotheses. The analysis of constrained trees indicated that sequence data were not consistent with most previously proposed relationships. Inconsistency was largely attributable to Asian taxa, such as Xenocypris and Xenocyprioides. Improved understanding of historical and taxonomic relationships in Cyprinidae will require further morphological and molecular studies on Asian cyprinids and taxa representative of the diversity found in Africa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2002.tb01853.x
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  • 4
    Electronic Resource
    Electronic Resource
    Seasonal changes in fish community structure of intermittent streams in the middle reaches of the Guadiana basin, Portugal (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 54 (1999), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Seven sites on three tributaries with intermittent flow regimes in the middle reaches of the Guadiana, i.e. Xévora, Caia and Degebe, were sampled approximately every 3 months from April 1995 to April 1997. The density and biomass of fish were greater in downstream rivers and sites. Along the Xévora River, a series of point abundance samples showed evidence of fish zonation along the river. Canonical correspondence analysis (CCA) suggested a simple relationship between the different species and their preferred habitat. The small-sized Rutilus alburnoides and Leuciscus pyrenaicus used most or all of the habitats with some cover and flowing water. Greater concentrations of larger fish were found in downstream reaches which generally had greater depths as stream width increased: large Barbus microcephalus, B. steindachneri and B. comiza preferred such sites on the Degebe River. Droughts in seasonal Mediterranean streams such as the Guadiana River are a predictable natural disturbance. In the summer, flow ceases and some stretches of river consist of isolated pools. This results in intense aggregations of fish and possible competition for food and/or space. Although some species are well adapted to natural droughts, habitat degradation and possibly the introduction of exotic species contribute to marked variability in species composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1999.tb00827.x
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  • 5
    Electronic Resource
    Electronic Resource
    Reassessment of the generic position of the Iberian cyprinid alburnoides complex: its return to the genus Leuciscus (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 54 (1999), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The generic position of the Iberian unisexual fish complex alburnoides is reassessed based on genetic evidence of a hybrid ancestry and of a monophyletic relationship with endemic Leuciscus taxa. There is a continuous movement of genes between the different forms of the complex and the main mode of reproduction is by meiotic hybridogenesis. Thus its return to the original generic position Leuciscus is recommended. © 1999 The Fisheries Society of the British Isles
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1999.tb00845.x
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  • 6
    Electronic Resource
    Electronic Resource
    Diploids v . triploids of Rutilus alburnoides: spatial segregation and morphological differences (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 52 (1998), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Rutilus alburnoides complex is a common and widely distributed Iberian cyprinid, whose natural populations include mainly diploid and triploid forms. The Guadiana populations of R. alburnoides were studied to determine whether habitat segregation and morphological differences exist between these forms. The ploidy level of each specimen was determined by measuring erythrocyte DNA content using flow cytometry. Evidence of spatial segregation between diploid males and the two female forms was found. Diploid males were best represented in the River Degebe, which was shallow, with higher temperatures (especially during the spring and summer), and silt and sandy substrate. Diploid females were found in deeper water, on steeper gradients and coarse substrata, while triploid females preferred higher current velocity and a high proportion of instream cover, especially during the spring. The ecological differences may reduce competitive interactions, and should promote a stable coexistence of the different forms. Morphological distinction between fish of different ploidy levels was not established, but differences were found between the males and females. Discriminant analysis allowed, with a 10% error, the separation of both sexes through six morphological characteristics that could be recorded in the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1998.tb00822.x
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  • 7
    Electronic Resource
    Electronic Resource
    Genetic variation and population subdivision of the endangered Iberian cyprinid Chondrostoma lusitanicum (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 44 (1994), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Products of 24 presumptive enzyme loci were used to analyse the consequences on genetic structure and variation of the Chondrostoma lusitanicum population decline within the Tejo basin. This rare cyprinid is endemic to the Iberian Peninsula and has a very restricted distribution. Five samples from the Tejo catchment were compared with a sample from a small basin, the Samarra, that has not suffered obvious anthropogenic pressures and where the fish is still abundant. Heterozygosity and polymorphism were higher overall in the Samarra. Several lines of evidence indicate a high degree of population subdivision within the Tejo basin. In fact, about half of the total gene diversity detected in the Tejo population was due to differences among samples. This differentiation appeared to be caused by genetic drift and possibly differential local selection, coupled with reduced gene flow among localities. The accelerated process of habitat degradation occurring in the lowland streams of the Tejo basin will lead to the inevitable reduction of intraspecies genetic diversity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1994.tb01239.x
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  • 8
    Electronic Resource
    Electronic Resource
    Biometrical analysis of Chondrostoma polylepis × Rutilus arcasi natural hybrids (Osteichthyes—Cypriniformes—Cyprinidae) (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 23 (1983), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The biometrical analysis of 95 natural hybrids of Chondrostoma polylepis and Rutilus arcasi is presented and discussed. The authors confirmed their existence in the Douro basin and, based on these data, they try to explain their non-accidental character. The possibility of introgression, and other aspects of hybridization are analysed in an attempt to explain the variability observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1983.tb02930.x
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  • 9
    Electronic Resource
    Electronic Resource
    Leuciscus torgalensis, and L. aradensis, two new cyprinids for Portuguese fresh waters (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 52 (1998), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The description of two new Portuguese freshwater fish species is presented. Leuciscus torgalensis occurs in the Mira basin and Leuciscus aradensis in the Arade basin and in two other small southern basins. The type material is deposited in the collections of the Museu Bocage, Lisbon (MB). The general external similarity between L. torgalensis and L. aradensis and two further species, L. carolitertii and L. pyrenaicus is high. The main external diagnostic character for both new taxa is the lower number of scales of the lateral line, despite the slight differences between them. Head form is a distinctive character between the two new species; such that head width is greater in L. aradensis. Distinct osteological characters between both L. torgalensis and L. aradensis and the other Iberian Leuciscus species are: the supraorbital canal and the modal vertebral formula that are shorter and lower in the new species, respectively. The preopercular–mandibular canal communication exists in L. aradensis, but not in L. torgalensis. Allozyme and mitochondrial DNA data also supported a monophyletic clade of Mira and Arade and the distinction of the two new species. The differentiation of the new species occurred either by an early isolation of the Mira and the Arade basins or by ecological conditions after the disjunction of all basins in Portugal, during the early Quaternary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1998.tb00594.x
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  • 10
    Electronic Resource
    Electronic Resource
    Riparian ecotones and spatial variation of fish assemblages in Portuguese lowland streams (1995)
    Springer
    Hydrobiologia 303 (1995), S. 93-101 
    Details
    ISSN: 1573-5117
    Keywords: riparian ecotones ; fish assemblages ; spatial variation ; Iberian streams
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The first results of a long-term study on the role of riparian ecotones on the population and community dynamics of Iberian stream fish are presented and discussed. Riparian and macrophyte cover, bank slope and depth were among the most important variables affecting fish distribution. In general small fish favoured shallow areas with high macrophyte cover, whereas large fish dominated in deep areas with a high riparian cover. Slight spatial changes in terrestrial prey use were found suggesting a minor role for this resource during autumn. Finally, no significant spatial differences were found for linear growth, although some differences were obtained for the condition factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034047
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