| 1. |
- de Heij, Maaike E., et al.
(author)
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Experimental manipulation shows that the white wing patch in collared flycatchers is a male sexual ornament
- 2011
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In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 1:4
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Journal article (peer-reviewed)abstract
- Descriptive analysis suggests that a conspicuous white wing patch in dichromatic (black and white) pied and collared flycatchers is under sexual selection. Here, we use an experimental approach to test whether this trait is indeed the target of selection. We caught 100 collared flycatcher Ficedula albicollis males soon after their arrival on the breeding site. We reduced (blackened) part of the white wing patch in half of these males and recorded their mating success and within and extra-pair offspring production. Reduction of the size of the white wing patch lowered a male's probability to attract a secondary social female, but not a primary female. However, primary females paired to males with a reduced wing patch were smaller (in tarsus), suggesting that male choice of partner or female-female competition over mates occurs in this species. The probability of pairing with a primary female (but not other components of male reproductive success) declined with arrival time (proxied by the date of capture). Males with a reduced wing patch size tended to sire less extra-pair offspring, although this relationship was reversed in one of the three study plots, suggesting that mating dynamics are context dependent. While our findings show that wing patch size is the target of sexual selection, the pathways and the strength of selection on this ornament differed markedly from a previous descriptive study. Nonexperimental studies of sexual selection in the wild may overestimate its importance because male fitness and ornamentation both depend positively on environmental conditions.
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| 2. |
- Saether, Bernt-Erik, et al.
(author)
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Demographic routes to variability and regulation in bird populations
- 2016
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Journal article (peer-reviewed)abstract
- There is large interspecific variation in the magnitude of population fluctuations, even among closely related species. The factors generating this variation are not well understood, primarily because of the challenges of separating the relative impact of variation in population size from fluctuations in the environment. Here, we show using demographic data from 13 bird populations that magnitudes of fluctuations in population size are mainly driven by stochastic fluctuations in the environment. Regulation towards an equilibrium population size occurs through density-dependent mortality. At small population sizes, population dynamics are primarily driven by environment-driven variation in recruitment, whereas close to the carrying capacity K, variation in population growth is more strongly influenced by density-dependent mortality of both juveniles and adults. Our results provide evidence for the hypothesis proposed by Lack that population fluctuations in birds arise from temporal variation in the difference between density-independent recruitment and density-dependent mortality during the non-breeding season.
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| 3. |
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| 4. |
- Baltazar-Soares, Miguel, et al.
(author)
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Bringing to light nuclear-mitochondrial insertions in the genomes of nocturnal predatory birds
- 2023
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In: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 181
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Journal article (peer-reviewed)abstract
- Mito-nuclear insertions, or NUMTs, relate to genetic material of mitochondrial origin that have been transferred to the nuclear DNA molecule. The increasing amounts of genomic data currently being produced presents an opportunity to investigate this type of patterns in genome evolution of non-model organisms. Identifying NUMTs across a range of closely related taxa allows one to generalize patterns of insertion and maintenance in autosomes, which is ultimately relevant to the understanding of genome biology and evolution. Here we collected existing pairwise genome-mitogenome data of the order Strigiformes, a group that includes all the nocturnal bird predators. We identified NUMTs by applying percent similarity thresholds after blasting mitochondrial genomes against nuclear genome assemblies. We identified NUMTs in all genomes with numbers ranging from 4 in Bubo bubo to 24 in Ciccaba nigrolineata. Statistical analyses revealed NUMT size to negatively correlate with NUMT's sequence similarity to with original mtDNA region. Lastly, characterizing these nuclear insertions of mitochondrial origin in a comparative genomics framework produced variable phylogenetic patterns, suggesting in some cases that insertions might pre-date speciation events within Strigiformes.
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| 5. |
- Baltazar-Soares, Miguel, et al.
(author)
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Genomic basis of melanin-associated phenotypes suggests colour-specific environmental adaptations in tawny owls
- 2024
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In: Molecular Ecology. - : WILEY. - 0962-1083 .- 1365-294X.
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Journal article (peer-reviewed)abstract
- Feathers comprise a series of evolutionary innovations but also harbour colour, a key biological trait known to co-vary with life history or complex traits. Those relationships are particularly true in melanin-based pigmentation species due to known pleiotropic effects of the melanocortin pathway - originating from melanin-associated phenotypes. Here, we explore the molecular basis of melanin colouration and expected co-variation at the molecular level in the melanin-based, colour polymorphic system of the tawny owl (Strix aluco). An extensive body of literature has revealed that grey and brown tawny owl colour morphs differ in a series of life history and behavioural traits. Thus, it is plausible to expect co-variation also at molecular level between colour morphs. To investigate this possibility, we assembled the first draft genome of the species against which we mapped ddRADseq reads from 220 grey and 150 brown morphs - representing 10 years of pedigree data from a population in Southern Finland - and explored genome-wide associations with colour phenotype. Our results revealed putative molecular signatures of cold adaptation strongly associated with the grey phenotype, namely, a non-synonymous substitution in MCHR1, plus 2 substitutions in non-coding regions of FTCD and FAM135A whose genotype combinations obtained a predictive power of up to 100% (predicting grey colour). These suggest a molecular basis of cold environment adaptations predicted to be grey-morph specific. Our results potentially reveal part of the molecular machinery of melanin-associated phenotypes and provide novel insights towards understanding the functional genomics of colour polymorphism in melanin-based pigmented species.
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| 6. |
- Bradter, Ute, et al.
(author)
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Decomposing the spatial and temporal effects of climate on bird populations in northern European mountains
- 2022
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In: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 28:21, s. 6209-6227
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Journal article (peer-reviewed)abstract
- The relationships between species abundance or occurrence versus spatial variation in climate are commonly used in species distribution models to forecast future distributions. Under “space-for-time substitution”, the effects of climate variation on species are assumed to be equivalent in both space and time. Two unresolved issues of space-for-time substitution are the time period for species' responses and also the relative contributions of rapid- versus slow reactions in shaping spatial and temporal responses to climate change. To test the assumption of equivalence, we used a new approach of climate decomposition to separate variation in temperature and precipitation in Fennoscandia into spatial, temporal, and spatiotemporal components over a 23-year period (1996–2018). We compiled information on land cover, topography, and six components of climate for 1756 fixed route surveys, and we modeled annual counts of 39 bird species breeding in the mountains of Fennoscandia. Local abundance of breeding birds was associated with the spatial components of climate as expected, but the temporal and spatiotemporal climatic variation from the current and previous breeding seasons were also important. The directions of the effects of the three climate components differed within and among species, suggesting that species can respond both rapidly and slowly to climate variation and that the responses represent different ecological processes. Thus, the assumption of equivalent species' response to spatial and temporal variation in climate was seldom met in our study system. Consequently, for the majority of our species, space-for-time substitution may only be applicable once the slow species' responses to a changing climate have occurred, whereas forecasts for the near future need to accommodate the temporal components of climate variation. However, appropriate forecast horizons for space-for-time substitution are rarely considered and may be difficult to reliably identify. Accurately predicting change is challenging because multiple ecological processes affect species distributions at different temporal scales.
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| 7. |
- Brommer, Jon E., et al.
(author)
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Body size and immune defense of nestling blue tits (Cyanistes Caeruleus) in response to manipulation of ectoparasites and food supply
- 2011
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In: The AUK. - : Oxford University Press (OUP). - 0004-8038 .- 1938-4254. ; 128:3, s. 556-563
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Journal article (peer-reviewed)abstract
- A developing organism faces a dilemma: whether to allocate available resources to building its body structures (growth) or to the development of its immune system. The outcome of this tradeoff is likely to be modified by parasites. We manipulated the abundance of ectoparasitic Hen Fleas (Ceratophyllus gallinae) on nestling Blue Tits (Cyanistes caeruleus) by microwaving nests and subsequently adding 200 Hen Fleas (15 infested nests) or not (16 reduced-infestation nests). In addition, we manipulated the host nestlings' food resources by supplementary feeding 10-15% of daily energy needs to half the nestlings in a nest during the key developmental period (days 2-12). Feather growth (tail and wing length) and hematocrit were reduced by the presence of Hen Fleas, indicating negative effects on nestling development. In comparison to the control nestlings, food-supplemented nestlings aged 16 days were larger (tarsus, residual body mass), but only in reduced-infestation nests (interaction between both treatments). Body size of fed male offspring increased in relation to that of females, but only in the absence of ectoparasites. We hypothesized that supplemented resources are allocated to immune defense when ectoparasites are present, but humoral immune function (total immunoglobulin concentration) and cell-mediated immune defense (phytohemagglutinin response) were not affected by either treatment. Either the nestlings allocated additional resources away from growth (into an unknown developmental component) when parasites were abundant, or the ectoparasites preferentially fed on supplementary-fed host nestlings and thereby equalized the development of soma and immune defense of nestlings despite provision of additional resources.
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| 8. |
- Brommer, Jon E., et al.
(author)
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Passerine Extrapair Mating Dynamics : A Bayesian Modeling Approach Comparing Four Species
- 2010
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In: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 176:2, s. 178-187
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Journal article (peer-reviewed)abstract
- In many socially monogamous animals, females engage in extrapair copulation (EPC), causing some broods to contain both within-pair and extrapair young (EPY). The proportion of all young that are EPY varies across populations and species. Because an EPC that does not result in EPY leaves no forensic trace, this variation in the proportion of EPY reflects both variation in the tendency to engage in EPC and variation in the extrapair fertilization (EPF) process across populations and species. We analyzed data on the distribution of EPY in broods of four passerines (blue tit, great tit, collared flycatcher, and pied flycatcher), with 18,564 genotyped nestlings from 2,346 broods in two to nine populations per species. Our Bayesian modeling approach estimated the underlying probability function of EPC (assumed to be a Poisson function) and conditional binomial EPF probability. We used an information theoretical approach to show that the expected distribution of EPC per female varies across populations but that EPF probabilities vary on the above-species level (tits vs. flycatchers). Hence, for these four passerines, our model suggests that the probability of an EPC mainly is determined by ecological (population-specific) conditions, whereas EPF probabilities reflect processes that are fixed above the species level.
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| 9. |
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| 10. |
- Brommer, Jon E., et al.
(author)
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The intersexual genetic correlation for lifetime fitness in the wild and its implications for sexual selection
- 2007
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 2:8, s. e744-
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Journal article (peer-reviewed)abstract
- Background The genetic benefits of mate choice are limited by the degree to which male and female fitness are genetically correlated. If the intersexual correlation for fitness is small or negative, choosing a highly fit mate does not necessarily result in high fitness offspring. Methodology/Principal Finding Using an animal-model approach on data from a pedigreed population of over 7,000 collared flycatchers (Ficedula albicollis), we estimate the intersexual genetic correlation in Lifetime Reproductive Success (LRS) in a natural population to be negative in sign (−0.85±0.6). Simulations show this estimate to be robust in sign to the effects of extra-pair parentage. The genetic benefits in this population are further limited by a low level of genetic variation for fitness in males. Conclusions/Significance The potential for indirect sexual selection is nullified by sexual antagonistic fitness effects in this natural population. Our findings and the scarce evidence from other studies suggest that the intersexual genetic correlation for lifetime fitness may be very low in nature. We argue that this form of conflict can, in general, both constrain and maintain sexual selection, depending on the sex-specific additive genetic variances in lifetime fitness.
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