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  • 1
    Electronic Resource
    Electronic Resource
    The role of life history in the relationship between population dynamics and environmental variability in two Mediterranean stream fishes (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of fish biology 63 (2003), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chub Squalius torgalensis and nase Chondrostoma lusitanicum, in a Mediterranean stream, showed important differences in life-history traits and population dynamics. Both species reached mean maturity at age 2 years. Chub lived up to age 5 years, spawned in March to June, grew at a maximum rate of 0·59 mm mm−1 year−1 and showed a low reproductive allocation, with fecundity and egg size increasing with body size. Nase lived up to age 4 years, spawned in January to April, grew at a maximum rate of 0·46 mm mm−1 year−1 and showed a high reproductive allocation, with egg size independent of body size. Both chub and nase showed moderate fluctuations in population size during 1991–1998, but differed in factors driving density at age. Density of age 1 year juvenile chub decreased following severe summer droughts and proportionate survival prevailed thereafter. Density of age 2 year adult nase decreased following severe spring floods, but neither environmental nor parental stock effects were detected for juveniles and older fishes. The results illustrated the interplay between life history and environmental variability in driving fish population dynamics, with impacts of both summer droughts and spring floods being contingent on species-specific patterns of spawning and reproductive investment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1095-8649.2003.00148.x
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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Variability in diet and foraging behaviour between sexes and ploidy forms of the hybridogenetic Squalius alburnoides complex (Cyprinidae) in the Guadiana River basin, Portugal (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 66 (2005), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Samples of the Squalius alburnoides complex, a hybridogenetic Iberian minnow composed of diploid, triploid and, less commonly, tetraploid forms, were collected from a tributary of the Ardila River (Guadiana River basin) between February 1999 and January 2001. Seasonal variation in diet was evident, and was probably linked to prey availability. Distinct foraging behaviours between ploidy forms were found towards several prey items, suggesting that diploid adult males fed mostly near the surface, whereas diploid adult females tended to feed near the bottom and submerged vegetation. Triploid females exhibited an intermediate foraging behaviour, although there was greater affinity towards diploid male feeding behaviour. Diploid males which, in contrast to diploid and triploid females, have non-hybrid genomes in the Guadiana drainage, exhibited a higher specialization for food. Despite considerable dietary overlap, there appeared to be spatial segregation of feeding niches between the three forms, especially during dry periods when prey availability was lower, which may be a strategy for diminishing competition for food. Therefore, considering asexual generalist and specialist hypotheses, it appears that the different ploidy levels are generalist, opportunistic feeders that partition the resources when limited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2005.00611.x
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  • 4
    Electronic Resource
    Electronic Resource
    Observations on the ecology of a landlocked population of allis shad in Aguieira Reservoir, Portugal (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 55 (1999), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A landlocked population of the anadromous clupeid Alosa alosa from Aguieira Reservoir in Portugal is described. The individuals are fast-growing, mature in their third year of life, live for 5+ years, and consequently spawn more than once.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1999.tb00706.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
    Anaecypris hispanica (Steindachner), a cyprinid fish in danger of extinction (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 37 (1990), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1990.tb05047.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
    Analysis of Leptospira isolates from mainland Portugal and the Azores islands (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 185 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: From 228 recent Leptospira isolates from mainland Portugal and Azorean wild mammals, 149 were characterized at the serovar level by monoclonal antibodies (MAbs), a quick serological method in epidemiological studies. In order to compare this antigenic information with that from new genetic techniques, a sample of isolates was analyzed through pulsed-field agarose gel electrophoresis (PFGE) (n=71), mapped restriction site polymorphisms (MRSPs) in PCR-amplified rRNA genes (n=45, including 13 saprophytes) and arbitrarily primed polymerase chain reaction (AP-PCR) fingerprinting (n=32). MRSP and AP-PCR lead to species identification of the studied 32 pathogenic isolates: Leptospira interrogans (n=3), Leptospira kirschneri (n=8) and Leptospira borgpetersenii (n=21). MAbs and PFGE characterized pathogenic isolates at the serovar level and resulted mainly in agreement (64%) although many discrepancies (35%) were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09059.x
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