| 1. |
- Catry, Paulo, et al.
(författare)
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Provenance does matter : links between winter trophic segregation and the migratory origins of European robins
- 2016
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 182:4, s. 985-994
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Tidskriftsartikel (refereegranskat)abstract
- Amongst migratory species, it is common to find individuals from different populations or geographical origins sharing staging or wintering areas. Given their differing life histories, ecological theory would predict that the different groups of individuals should exhibit some level of niche segregation. This has rarely been investigated because of the difficulty in assigning migrating individuals to breeding areas. Here, we start by documenting a broad geographical gradient of hydrogen isotopes (δ2H) in robin Erithacus rubecula feathers across Europe. We then use δ2H, as well as wing-tip shape, as surrogates for broad migratory origin of birds wintering in Iberia, to investigate the ecological segregation of populations. Wintering robins of different sexes, ages and body sizes are known to segregate between habitats in Iberia. This has been attributed to the despotic exclusion of inferior competitors from the best patches by dominant individuals. We find no segregation between habitats in relation to δ2H in feathers, or to wing-tip shape, which suggests that no major asymmetries in competitive ability exist between migrant robins of different origins. Trophic level (inferred from nitrogen isotopes in blood) correlated both with δ2H in feathers and with wing-tip shape, showing that individuals from different geographic origins display a degree of ecological segregation in shared winter quarters. Isotopic mixing models indicate that wintering birds originating from more northerly populations consume more invertebrates. Our multi-scale study suggests that trophic-niche segregation may result from specializations (arising in the population-specific breeding areas) that are transported by the migrants into the shared wintering grounds.
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| 2. |
- Gordinho, Luís, et al.
(författare)
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Asymmetric song recognition between recently diverged subspecies of reed bunting
- 2016
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 27:5, s. 1413-1423
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Tidskriftsartikel (refereegranskat)abstract
- Acoustic divergence among populations may result in assortative mating, behavioral isolation, and speciation. In birds, the recogni- tion of suitable mates depends to a large extent on learning, generally resulting in a tendency to discriminate against nonlocal stimuli. However, there may be geographical variation in the discrimination against nonlocal stimuli, and this may allow inferring the mechanisms behind the evolution of vocal recognition. We tested territorial males of 3 west European subspecies of reed bunting (Emberiza schoeniclus schoeniclus, Emberiza schoeniclus lusitanica, and Emberiza schoeniclus witherbyi) using song playback to determine the level of song discrimination. We found that witherbyi and, to some extent lusitanica, males largely ignored schoeniclus songs. However, witherbyi reacted less strongly to the songs of lusitanica than lusitanica did to songs of witherbyi. In contrast, schoenic- lus males did not discriminate the songs of the different subspecies, reacting strongly to all. Differential territorial defense behavior suggest that intruding males with different songs do not represent the same competitive threat, and provide evidence of premating reproductive isolation among these recently evolved subspecies. The high discrimination exhibited by witherbyi and lusitanica seems associated with the high level of local adaptation. Overall, the pattern of premating reproductive isolation appears to agree more with the ecological than with the neutral genetic divergences between subspecies, suggesting that there is an ongoing process of ecological speciation in this study system.
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| 3. |
- Gordinho, Luís de Oliveira, et al.
(författare)
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Song divergence between subspecies of reed bunting is more pronounced in singing styles under sexual selection
- 2015
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Ingår i: Animal Behaviour. - : Elsevier BV. - 1095-8282 .- 0003-3472. ; 107, s. 221-231
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Tidskriftsartikel (refereegranskat)abstract
- Song divergence between populations of a species can lead to reproductive isolation and speciation. However, birds may have different singing styles used in distinct social contexts, and songs of each style may change at different rates over time and space. Here, we tested whether song divergence between subspecies of reed bunting, Emberiza schoeniclus, differs with singing style, by comparing song traits of its three singing styles among three subspecies breeding in northern and western Europe. We show that the two singing styles under sexual selection (dawn and fast songs, related to obtaining extrapair and social mates, respectively) diverged significantly more than the slow songs (used as an all-clear signal to nest- attending social females). Multiple song traits differed significantly between the subspecies in all singing styles, with E. s. lusitanica generally being intermediate between E. s. schoeniclus and E. s. witherbyi, and the pattern of song complexity opposing the expected latitudinal gradient (of increasing complexity with increasing latitude). Cluster analyses of populations indicate that sexually selected singing styles are better for discriminating subspecies, describing a scenario of a major split in song features between the migratory, northern E. s. schoeniclus and the two resident, southern subspecies, rather than a clinal variation. The greater song divergence in fast and dawn singing styles suggests that sexual selection may be playing an important role in the incipient speciation of reed buntings.
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| 4. |
- Hamed, Tareq Abu, et al.
(författare)
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Multiscale in modelling and validation for solar photovoltaics
- 2018
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Ingår i: EPJ Photovoltaics. - : EDP Sciences. - 2105-0716. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Photovoltaics is amongst the most important technologies for renewable energy sources, and plays a key role in the development of a society with a smaller environmental footprint. Key parameters for solar cells are their energy conversion efficiency, their operating lifetime, and the cost of the energy obtained from a photovoltaic system compared to other sources. The optimization of these aspects involves the exploitation of new materials and development of novel solar cell concepts and designs. Both theoretical modeling and characterization of such devices require a comprehensive view including all scales from the atomic to the macroscopic and industrial scale. The different length scales of the electronic and optical degrees of freedoms specifically lead to an intrinsic need for multiscale simulation, which is accentuated in many advanced photovoltaics concepts including nanostructured regions. Therefore, multiscale modeling has found particular interest in the photovoltaics community, as a tool to advance the field beyond its current limits. In this article, we review the field of multiscale techniques applied to photovoltaics, and we discuss opportunities and remaining challenges.
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| 5. |
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| 6. |
- Neto, Júlio Manuel, et al.
(författare)
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Stable isotopes reveal differences in diet among reed bunting subspecies that vary in bill size
- 2017
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 48:2, s. 284-294
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Tidskriftsartikel (refereegranskat)abstract
- Reed bunting Emberiza schoeniclus subspecies vary considerably in bill size and shape and seem to be at an early stage of speciation, in which bill might be indirectly causing reproductive isolation. Hence, we evaluated whether bill size, as well as age and sex, are associated with foraging niche in three west European subspecies of reed bunting: the thin-billed schoeniclus, the intermediate-billed lusitanica and the thick-billed witherbyi. Blood sampling was undertaken at three sites in southwest Europe during the winter (when these subspecies co-occur), and stable isotope analyses (carbon and nitrogen) were performed to assess their foraging niches. Stable isotope analyses of potential food items confirmed uniform baseline isotopic composition among sites. schoeniclus showed a significantly broader isotopic niche than lusitanica and witherbyi, which seemed otherwise similar despite the fact that witherbyi is more divergent in bill traits. Stable isotope ratios were consistent with the latter two subspecies feeding on C3-plant-feeding insects, whereas schoeniclus diet also included C4 plant material. Despite its lower sexual dimorphism, sex and age differences were found only in schoeniclus, but these differences vary between locations in a complex manner. Our results suggest that bill size and shape differentiated between northern, migratory and southern, resident subspecies as a consequence of natural selection through competition during the winter, which is now reflected in isotopic niche divergence between subspecies. The potential roles of sexual selection, reed thickness and summer temperature on the difference in bill size (and greater sexual dimorphism) between lusitanica and witherbyi are discussed.
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| 7. |
- Neto, Julio, et al.
(författare)
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Prevalence and diversity of Plasmodium and Haemoproteus parasites in the globally-threatened Aquatic Warbler Acrocephalus paludicola.
- 2015
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Ingår i: Parasitology. - 1469-8161. ; 142:9, s. 1183-1189
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Tidskriftsartikel (refereegranskat)abstract
- The diversity and prevalence of malaria parasites of the genera Plasmodium and Haemoproteus were determined in the globally-threatened Aquatic Warbler Acrocephalus paludicola. Birds were sampled during migration in Portugal and at the wintering quarters in Senegal and parasites were detected using molecular methods. Only three generalist parasite lineages (Plasmodium) were found. There were no significant differences in the prevalence of parasites between sexes in Europe, but adults had higher prevalence than first-year birds, and birds in Europe had higher prevalence than those captured in Africa. When comparing with other Acrocephalus species and taking sample size into account, Aquatic Warblers had the lowest prevalence and, together with another threatened species, the Seychelles Warbler Acrocephalus sechellensis, the lowest diversity of malaria parasites. We hypothesize that the low diversity of parasites and absence of specialist lineages of Aquatic Warblers are caused by its small population size and fragmented distribution. Furthermore, Aquatic Warblers' extreme habitat specialization may decrease their exposure to malaria parasites, but other explanations such as high mortality (which would constraint the sampling of infected birds) or, in contrast, very efficient immunological system in clearing the infections cannot be ruled out. This study contributes to explain variation in prevalence and diversity of malaria parasites among hosts.
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| 8. |
- Nus, Tim Van, et al.
(författare)
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Urban Roost of Wintering Barn Swallows Hirundo rustica in Aveiro, Portugal
- 2017
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Ingår i: Ardea. - : Netherlands Ornithologists' Union. - 0373-2266. ; 105:1, s. 73-78
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Tidskriftsartikel (refereegranskat)abstract
- We describe the finding of an urban roost of wintering Barn Swallows Hirundo rustica in Aveiro, Portugal, which remained stable with c.150 individuals from at least early December to mid-January 2015/16. The stability in numbers and the occurrence of freshly-shed primary feathers below the roost strongly indicate that these were indeed wintering birds that completed their annual moult and suffered a relatively low mortality during this period. The number of roosting Barn Swallows steeply declined in late January, coinciding with the appearance of singing males in the area and the arrival of numerous migrants from Africa to Portugal. The site characteristics and roosting behaviour are described, and the potential advantages of urban roosting discussed. Although this particular winter was unusually mild, observations indicate that this roost may have been present in previous years, and others may occur elsewhere in the Iberian Peninsula.
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| 9. |
- Raković, Marko, et al.
(författare)
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Geographic patterns of mtDNA and Z-linked sequence variation in the Common Chiffchaff and the ‘chiffchaff complex’
- 2019
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- The Common Chiffchaff Phylloscopus collybita is an abundant, polytypic Palearctic bird. Validity of some of its subspecies is controversial and birds from some parts of the species range remain unclassified taxonomically. The relationships among populations from different geographic areas have not been sufficiently explored with molecular data. In this study we analyzed the relationships among the four species in the ‘chiffchaff complex’ (Common Chiffchaff, Iberian Chiffchaff P. ibericus, Canary Islands Chiffchaff P. canariensis and Mountain Chiffchaff P. sindianus), and the patterns of intraspecific geographic variation in the mtDNA ND2 gene and intron 9 of the Z-linked aconitase gene (ACO1I9) across the Common Chiffchaff range, including a recently discovered population breeding on Mt. Hermon (Anti-Lebanon mountains). Our data supported the monophyly of the chiffchaff complex and its current systematics at the species level. Within the Common Chiffchaff, the Siberian race P. c. tristis was the most differentiated subspecies and may represent a separate or incipient species. Other Common Chiffchaff subspecies also were differentiated in their mtDNA, however, lineages of neighboring subspecies formed wide zones of introgression. The Mt. Hermon population was of mixed genetic origin but contained some birds with novel unique lineage that could not be assigned to known subspecies. All Common Chiffchaff lineages diverged at the end of the Ionian stage of Pleistocene. Lineage sorting of ACO1I9 alleles was not as complete as that of mtDNA. Chiffchaff species were mostly distinct at ACO1I9, except the Common and Canary Islands Chiffchaffs that shared multiple alleles. An AMOVA identified geographic structure in Common Chiffchaff ACO1I9 variation that was broadly consistent with that of mtDNA ND2 gene. The genetic and other data suggest the chiffchaff complex to be a group of evolutionarily young taxa that represent a paradigm of ‘species evolution in action’ from intergrading subspecies through to apparently complete biological speciation.
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| 10. |
- Wojczulanis-Jakubas, Katarzyna, et al.
(författare)
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Differential timing and latitudinal variation in sex ratio of Aquatic Warblers during the autumn migration
- 2017
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Ingår i: Die Naturwissenschaften. - : Springer Science and Business Media LLC. - 1432-1904. ; 104:11-12, s. 101-101
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Tidskriftsartikel (refereegranskat)abstract
- Differential migration has been extensively reported in spring, but less so in autumn, particularly in relation to sex in monomorphic bird species. Here, we analysed the autumn passage of a monomorphic, globally threatened passerine, the Aquatic Warbler Acrocephalus paludicola throughout Western Europe, with regard to age and sex. We showed that, overall, adults migrated earlier than first-year birds, and males migrated earlier than females during the autumn migration. This may be caused by an overall social dominance of adults over immatures, and differentiated migration strategy of males and females. In addition, we found male-skewed sex proportions, with a tendency to an equalised ratio in more southern stopover sites. This may indicate a male bias in the global population or different migration strategies of the sexes. Differential migration may cause the age and sex classes to be exposed differently to various threats affecting demographic structure of the species.
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