Browsing by Author "Branco, Paulo"
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- Broad-scale sampling of primary freshwater fish populations reveals the role of intrinsic traits, inter-basin connectivity, drainage area and latitude on shaping contemporary patterns of genetic diversityPublication . Santos, Carla Sousa; Robalo, Joana Isabel; Pereira, Ana Martins; Branco, Paulo; Santos, José Maria; Ferreira, Maria Teresa; Sousa, Mónica; Doadrio, IgnacioBackground. Worldwide predictions suggest that up to 75% of the freshwater fish species occurring in rivers with reduced discharge could be extinct by 2070 due to the combined effect of climate change and water abstraction. The Mediterranean region is considered to be a hotspot of freshwater fish diversity but also one of the regions where the effects of climate change will be more severe. Iberian cyprinids are currently highly endangered, with over 68% of the species raising some level of conservation concern. Methods. During the FISHATLAS project, the Portuguese hydrographical network was extensively covered (all the 34 river basins and 47 sub-basins) in order to contribute with valuable data on the genetic diversity distribution patterns of native cyprinid species. A total of 188 populations belonging to 16 cyprinid species of Squalius, Luciobarbus, Achondrostoma, Iberochondrostoma, Anaecypris and Pseudochondrostoma were characterized, for a total of 3,678 cytochrome b gene sequences. Results. When the genetic diversity of these populations was mapped, it highlighted differences among populations from the same species and between species with identical distribution areas. Factors shaping the contemporary patterns of genetic diversity were explored and the results revealed the role of latitude, inter-basin connectivity, migratory behaviour, species maximum size, species range and other species intrinsic traits in determining the genetic diversity of sampled populations. Contrastingly, drainage area and hydrological regime (permanent vs. temporary) seem to have no significant effect on genetic diversity. Species intrinsic traits, maximum size attained, inter-basin connectivity and latitude explained over 30% of the haplotype diversity variance and, generally, the levels of diversity were significantly higher for smaller sized species, from connected and southerly river basins. Discussion. Targeting multiple co-distributed species of primary freshwater fish allowed us to assess the relative role of historical versus contemporary factors affecting genetic diversity. Since different patterns were detected for species with identical distribution areas we postulate that contemporary determinants of genetic diversity (species' intrinsic traits and landscape features) must have played a more significant role than historical factors. Implications for conservation in a context of climate change and highly disturbed habitats are detailed, namely the need to focus management and conservation actions on intraspecific genetic data and to frequently conduct combined genetic and demographic surveys.
- Mito-nuclear sequencing is paramount to correctly identify sympatric hybridizing fishesPublication . Santos, Carla Sousa; Pereira, Ana Martins; Branco, Paulo; Costa, Gonçalo J.; Santos, José M.; Ferreira, Maria Teresa; Lima, Cristina M.; Doadrio, Ignacio; Robalo, Joana IsabelBackground. Hybridization may drive speciation and erode species, especially when intrageneric sympatric species are involved. Five sympatric Luciobarbus species—Luciobarbus sclateri (Günther, 1868), Luciobarbus comizo (Steindachner, 1864), Luciobarbus microcephalus (Almaça, 1967), Luciobarbus guiraonis (Steindachner, 1866), and Luciobarbus steindachneri (Almaça, 1967)—are commonly identified in field surveys by diagnostic morphological characters. Assuming that i) in loco identification is subjective and observer-dependent, ii) there is previous evidence of interspecific hybridization, and iii) the technical reports usually do not include molecular analyses, our main goal was to assess the concordance between in loco species identification based on phenotypic characters with identifications based on morphometric indices, mtDNA only, and a combination of mito-nuclear markers. Materials and methods. Specimens of Luciobarbus from six Guadiana River sub-basins were collected and sequenced for the cytochrome b and beta-actin genes. For comparative purposes, samples of Luciobarbus from other 12 river basins were also used. Four levels of taxonomical identification were conducted based on: identification made in the field (in loco identification), cytb gene only, beta-actin gene only, and mito-nuclear combined genomes. Results. Results showed that interspecific hybridization seems to be high (around 41%) and likely favoured by non-random mating and the loss of fluvial connectivity. About 34% of the hybrids showed mito-nuclear discordance. Misidentifications were frequent when only phenotypic characters are considered, and the use of a single mitochondrial gene is not sufficient: the use of two mito-nuclear markers showed that around 82% of the in loco identifications based on the phenotype were not correct. Conclusion. Incorrect species assignment likely generated biased results in previous studies on the biology and ecology of Guadiana barbels and in the assignment of conservation status and, consequently, on the establishment of conservation management measures.