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Michael Wink - One of the best experts on this subject based on the ideXlab platform.
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genetic admixture despite ecological segregation in a north african sparrow hybrid zone aves Passeriformes Passer domesticus Passer hispaniolensis
Ecology and Evolution, 2019Co-Authors: Martin Packert, Abdelkrim Ait Belkacem, Hannes Wolfgramm, Oliver Gast, David Canal, Gabriele Giacalone, Mario Lo Valvo, Melita Vamberger, Michael WinkAbstract:Under different environmental conditions, hybridization between the same species might result in different patterns of genetic admixture. Particularly, species pairs with large distribution ranges and long evolutionary history may have experienced several independent hybridization events over time in different zones of overlap. In birds, the diverse hybrid populations of the house sparrow (Passer domesticus) and the Spanish sparrow (Passer hispaniolensis) provide a striking example. Throughout their range of sympatry, these two species do not regularly interbreed; however, a stabilized hybrid form (Passer italiae) exists on the Italian Peninsula and on several Mediterranean islands. The spatial distribution pattern on the Eurasian continent strongly contrasts the situation in North Africa, where house sparrows and Spanish sparrows occur in close vicinity of phenotypically intermediate populations across a broad mosaic hybrid zone. In this study, we investigate patterns of divergence and admixture among the two parental species, stabilized and nonstabilized hybrid populations in Italy and Algeria based on a mitochondrial marker, a sex chromosomal marker, and 12 microsatellite loci. In Algeria, despite strong spatial and temporal separation of urban early-breeding house sparrows and hybrids and rural late-breeding Spanish sparrows, we found strong genetic admixture of mitochondrial and nuclear markers across all study populations and phenotypes. That pattern of admixture in the North African hybrid zone is strikingly different from i) the Iberian area of sympatry where we observed only weak asymmetrical introgression of Spanish sparrow nuclear alleles into local house sparrow populations and ii) the very homogenous Italian sparrow population where the mitogenome of one parent (P. domesticus) and the Z-chromosomal marker of the other parent (P. hispaniolensis) are fixed. The North African sparrow hybrids provide a further example of enhanced hybridization along with recent urbanization and anthropogenic land-use changes in a mosaic landscape.
David Canal - One of the best experts on this subject based on the ideXlab platform.
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genetic admixture despite ecological segregation in a north african sparrow hybrid zone aves Passeriformes Passer domesticus Passer hispaniolensis
Ecology and Evolution, 2019Co-Authors: Martin Packert, Abdelkrim Ait Belkacem, Hannes Wolfgramm, Oliver Gast, David Canal, Gabriele Giacalone, Mario Lo Valvo, Melita Vamberger, Michael WinkAbstract:Under different environmental conditions, hybridization between the same species might result in different patterns of genetic admixture. Particularly, species pairs with large distribution ranges and long evolutionary history may have experienced several independent hybridization events over time in different zones of overlap. In birds, the diverse hybrid populations of the house sparrow (Passer domesticus) and the Spanish sparrow (Passer hispaniolensis) provide a striking example. Throughout their range of sympatry, these two species do not regularly interbreed; however, a stabilized hybrid form (Passer italiae) exists on the Italian Peninsula and on several Mediterranean islands. The spatial distribution pattern on the Eurasian continent strongly contrasts the situation in North Africa, where house sparrows and Spanish sparrows occur in close vicinity of phenotypically intermediate populations across a broad mosaic hybrid zone. In this study, we investigate patterns of divergence and admixture among the two parental species, stabilized and nonstabilized hybrid populations in Italy and Algeria based on a mitochondrial marker, a sex chromosomal marker, and 12 microsatellite loci. In Algeria, despite strong spatial and temporal separation of urban early-breeding house sparrows and hybrids and rural late-breeding Spanish sparrows, we found strong genetic admixture of mitochondrial and nuclear markers across all study populations and phenotypes. That pattern of admixture in the North African hybrid zone is strikingly different from i) the Iberian area of sympatry where we observed only weak asymmetrical introgression of Spanish sparrow nuclear alleles into local house sparrow populations and ii) the very homogenous Italian sparrow population where the mitogenome of one parent (P. domesticus) and the Z-chromosomal marker of the other parent (P. hispaniolensis) are fixed. The North African sparrow hybrids provide a further example of enhanced hybridization along with recent urbanization and anthropogenic land-use changes in a mosaic landscape.
Martin Packert - One of the best experts on this subject based on the ideXlab platform.
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genetic admixture despite ecological segregation in a north african sparrow hybrid zone aves Passeriformes Passer domesticus Passer hispaniolensis
Ecology and Evolution, 2019Co-Authors: Martin Packert, Abdelkrim Ait Belkacem, Hannes Wolfgramm, Oliver Gast, David Canal, Gabriele Giacalone, Mario Lo Valvo, Melita Vamberger, Michael WinkAbstract:Under different environmental conditions, hybridization between the same species might result in different patterns of genetic admixture. Particularly, species pairs with large distribution ranges and long evolutionary history may have experienced several independent hybridization events over time in different zones of overlap. In birds, the diverse hybrid populations of the house sparrow (Passer domesticus) and the Spanish sparrow (Passer hispaniolensis) provide a striking example. Throughout their range of sympatry, these two species do not regularly interbreed; however, a stabilized hybrid form (Passer italiae) exists on the Italian Peninsula and on several Mediterranean islands. The spatial distribution pattern on the Eurasian continent strongly contrasts the situation in North Africa, where house sparrows and Spanish sparrows occur in close vicinity of phenotypically intermediate populations across a broad mosaic hybrid zone. In this study, we investigate patterns of divergence and admixture among the two parental species, stabilized and nonstabilized hybrid populations in Italy and Algeria based on a mitochondrial marker, a sex chromosomal marker, and 12 microsatellite loci. In Algeria, despite strong spatial and temporal separation of urban early-breeding house sparrows and hybrids and rural late-breeding Spanish sparrows, we found strong genetic admixture of mitochondrial and nuclear markers across all study populations and phenotypes. That pattern of admixture in the North African hybrid zone is strikingly different from i) the Iberian area of sympatry where we observed only weak asymmetrical introgression of Spanish sparrow nuclear alleles into local house sparrow populations and ii) the very homogenous Italian sparrow population where the mitogenome of one parent (P. domesticus) and the Z-chromosomal marker of the other parent (P. hispaniolensis) are fixed. The North African sparrow hybrids provide a further example of enhanced hybridization along with recent urbanization and anthropogenic land-use changes in a mosaic landscape.
Bernterik Saether - One of the best experts on this subject based on the ideXlab platform.
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dispersal of introduced house sparrows Passer domesticus an experiment
Proceedings of The Royal Society B: Biological Sciences, 2007Co-Authors: Sigrun Skjelseth, Thor Harald Ringsby, Jarle Tufto, Henrik Jeldtoft Jensen, Bernterik SaetherAbstract:An important issue concerning the introduction of non-indigenous organisms into local populations is the potential of the introduced individuals to spread and interfere both demographically and genetically with the local population. Accordingly, the potential of spatial dispersal among introduced individuals compared with local individuals is a key parameter to understand the spatial and temporal dynamics of populations after an introduction event. In addition, if the variance in dispersal rate and distance is linked to individual characteristics, this may further affect the population dynamics. We conducted a large-scale experiment where we introduced 123 house sparrows from a distant population into 18 local populations without changing population density or sex ratio. Introduced individuals dispersed more frequently and over longer distances than residents. Furthermore, females had higher probability of dispersal than males. In females, there was also a positive relationship between the wing length and the probability of dispersal and dispersal distance. These results suggest that the distribution and frequency of introduced individuals may be predicted by their sex ratio as well as their phenotypic characteristics.
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fertile house ssparrow x tree sparrow Passer domesticus xPasser montanus hybrids
Journal of Ornithology, 2000Co-Authors: Erling Johan Solberg, Thor Harald Ringsby, Andreas Altwegg, Bernterik SaetherAbstract:Viability and a seemingly successful breeding of a F1 House Sparrow x Tree Sparrow hybrid are reported from islands off the coast of northern Norway. From two consecutive clutches of House Sparrow x Tree Sparrow hybrids recorded in 1995, only one of 7 chicks survived the first year. The surviving individual was later, in 1997, found attending the nest with a female House Sparrow and feeding the young in two consecutive clutches. Neither of the F2 hybrids were observed after fledging. Despite the fact that House Sparrows indulge in frequent extra pair copulation, we find it unlikely that both clutches fed by the male hybrid could have been fathered by a House Sparrow male and therefore conclude that the F1 male hybrid was fertile. The hybridisation may have been facilitated by the fragmented structure and small size (from 5 to 100 individuals) of the sub-populations found in our study area.
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factors affecting juvenile survival in house sparrow Passer domesticus
Journal of Avian Biology, 1998Co-Authors: Thor Harald Ringsby, Bernterik Saether, Erling Johan SolbergAbstract:We studied how variation in different reproductive traits (hatching date, clutch number and clutch size) in addition to mass, size and condition of the fledgling influenced its probability of survival until recruitment in a House Sparrow population living on islands off the coast of northern Norway in 1993 and 1994. Twenty-three and 21% of the fledglings were recorded alive in the population the year after hatching, respectively. Most mortality occurred just after fledging. In both years larger-sized fledglings survived better than smaller ones. Juvenile survival was independent of clutch size. Multiple logistic regression analyses showed that in both years juvenile survival increased with body size (expressed as tarsus length). In addition, in 1993 fledglings in high body condition survived better, whereas in 1994 hatching day explained a significant proportion of the variation in juvenile survival. However, this last year both body condition and size increased significantly with hatching date, suggesting that juvenile survival rate may have been dependent on body condition also in this year. These results demonstrate that losses of juveniles during the non-breeding season are strongly influenced by factors during the breeding season that affect the size and condition of the fledglings.
J M Cabrera - One of the best experts on this subject based on the ideXlab platform.
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analysis of microstructure and strengthening in cumg alloys deformed by equal channel angular pressing
Journal of Alloys and Compounds, 2015Co-Authors: Pablo Rodriguezcalvillo, N Ferrer, J M CabreraAbstract:Abstract The microstructural and strengthening behavior of two CuMg alloys, with 0.2 and 0.5 m.-% of Mg, were analyzed after severe plastic deformation by Equal Channel Angular Pressing (ECAP). Both alloys were passed through a 90° inner angle ECAP die at room temperature up to 16 passes following route Bc. The EBSD analysis of the deformed microstructure revealed a significant grain refinement after the 2nd pass. Average grain sizes as fine as 0.31 and 0.24 μm for the CuMg0.2 and CuMg0.5, respectively, were obtained after 16 passes. The tensile strength of the ECAPed samples of the present CuMg alloys did not reach a saturation level, attaining 570 and 750 MPa after 16 passes for the CuMg0.2 and CuMg0.5, respectively. The dependence of the yield stress on deformation (i.e. number of ECAP passes) and Mg content was evaluated in terms of the Hall–Petch effect (influence of grain size), dislocation density (through the subgrain hardening effect) and solid solution strengthening. Results indicated that the stronger effect comes from the subgrain microstructure rather than from High Angle Grain Boundaries (HAGB). A minor effect of the chemical composition was also noticed.
