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Sökning: WFRF:(Merilä J.)

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  • Verstraeten, A., et al. (författare)
  • Effects of tree pollen on throughfall element fluxes in European forests
  • 2023
  • Ingår i: Biogeochemistry. - Göteborg : Springer. - 0168-2563 .- 1573-515X. ; 165:3, s. 311-325
  • Tidskriftsartikel (refereegranskat)abstract
    • The effects of tree pollen on precipitation chemistry are not fully understood and this can lead to misinterpretations of element deposition in European forests. We investigated the relationship between forest throughfall (TF) element fluxes and the Seasonal Pollen Integral (SPIn) using linear mixed-effects modelling (LME). TF was measured in 1990-2018 during the main pollen season (MPS, arbitrary two months) in 61 managed, mostly pure, even-aged Fagus, Quercus, Pinus, and Picea stands which are part of the ICP Forests Level II network. The SPIn for the dominant tree genus was observed at 56 aerobiological monitoring stations in nearby cities. The net contribution of pollen was estimated as the TF flux in the MPS minus the fluxes in the preceding and succeeding months. In stands of Fagus and Picea, two genera that do not form large amounts of flowers every year, TF fluxes of potassium (K+), ammonium-nitrogen (NH4+-N), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) showed a positive relationship with SPIn. However- for Fagus- a negative relationship was found between TF nitrate-nitrogen (NO3--N) fluxes and SPIn. For Quercus and Pinus, two genera producing many flowers each year, SPIn displayed limited variability and no clear association with TF element fluxes. Overall, pollen contributed on average 4.1-10.6% of the annual TF fluxes of K+ > DOC > DON > NH4+--N with the highest contribution in Quercus > Fagus > Pinus > Picea stands. Tree pollen appears to affect TF inorganic nitrogen fluxes both qualitatively and quantitatively, acting as a source of NH4+--N and a sink of NO3--N. Pollen appears to play a more complex role in nutrient cycling than previously thought.
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  • Wennerström, Lovisa, et al. (författare)
  • Genetic biodiversity in the Baltic Sea: Species-specific patterns challenge management
  • 2013
  • Ingår i: Biodiversity and Conservation. - : Springer Science and Business Media LLC. - 0960-3115 .- 1572-9710. ; 22:13-14, s. 3045-3065
  • Tidskriftsartikel (refereegranskat)abstract
    • Information on spatial and temporal patterns of genetic diversity is a prerequisite to understanding the demography of populations, and is fundamental to successful management and conservation of species. In the sea, it has been observed that oceanographic and other physical forces can constitute barriers to gene flow that may result in similar population genetic structures in different species. Such similarities among species would greatly simplify management of genetic biodiversity. Here, we tested for shared genetic patterns in a complex marine area, the Baltic Sea. We assessed spatial patterns of intraspecific genetic diversity and differentiation in seven ecologically important species of the Baltic ecosystem-Atlantic herring (Clupea harengus), northern pike (Esox lucius), European whitefish (Coregonus lavaretus), three-spined stickleback (Gasterosteus aculeatus), nine-spined stickleback (Pungitius pungitius), blue mussel (Mytilus spp.), and bladderwrack (Fucus vesiculosus). We used nuclear genetic data of putatively neutral microsatellite and SNP loci from samples collected from seven regions throughout the Baltic Sea, and reference samples from North Atlantic areas. Overall, patterns of genetic diversity and differentiation among sampling regions were unique for each species, although all six species with Atlantic samples indicated strong resistence to Atlantic-Baltic gene-flow. Major genetic barriers were not shared among species within the Baltic Sea; most species show genetic heterogeneity, but significant isolation by distance was only detected in pike and whitefish. These species-specific patterns of genetic structure preclude generalizations and emphasize the need to undertake genetic surveys for species separately, and to design management plans taking into consideration the specific structures of each species. © 2013 The Author(s).
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  • Eriksson, Britas Klemens, et al. (författare)
  • Habitat segregation of plate phenotypes in a rapidly expanding population of three-spined stickleback
  • 2021
  • Ingår i: Ecosphere. - : Wiley. - 2150-8925 .- 2150-8925. ; 12:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Declines of large predatory fish due to overexploitation are restructuring food webs across the globe. It is now becoming evident that restoring these altered food webs requires addressing not only ecological processes, but evolutionary ones as well, because human-induced rapid evolution may in turn affect ecological dynamics. We studied the potential for niche differentiation between different plate armor phenotypes in a rapidly expanding population of a small prey fish, the three-spined stickleback (Gasterosteus aculeatus). In the central Baltic Sea, three-spined stickleback abundance has increased dramatically during the past decades. The increase in this typical mesopredator has restructured near-shore food webs, increased filamentous algal blooms, and threatens coastal biodiversity. Time-series data covering 22 years show that the increase coincides with a decline in the number of juvenile perch (Perca fluviatilis), the most abundant predator of stickleback along the coast. We investigated the distribution of different stickleback plate armor phenotypes depending on latitude, environmental conditions, predator and prey abundances, nutrients, and benthic production; and described the stomach content of the stickleback phenotypes using metabarcoding. We found two distinct lateral armor plate phenotypes of stickleback, incompletely and completely plated. The proportion of incompletely plated individuals increased with increasing benthic production and decreasing abundances of adult perch. Metabarcoding showed that the stomach content of the completely plated individuals more often contained invertebrate herbivores (amphipods) than the incompletely plated ones. Since armor plates are defense structures favored by natural selection in the presence of fish predators, the phenotype distribution suggests that a novel low-predation regime favors stickleback with less armor. Our results suggest that morphological differentiation of the three-spined stickleback has the potential to affect food web dynamics and influence the persistence and resilience of the stickleback take-over in the Baltic Sea.
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  • Etzold, Sophia, et al. (författare)
  • Nitrogen deposition is the most important environmental driver of growth of pure, even-aged and managed European forests
  • 2020
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 458
  • Tidskriftsartikel (refereegranskat)abstract
    • Changing environmental conditions may substantially interact with site quality and forest stand characteristics, and impact forest growth and carbon sequestration. Understanding the impact of the various drivers of forest growth is therefore critical to predict how forest ecosystems can respond to climate change. We conducted a continental-scale analysis of recent (1995–2010) forest volume increment data (ΔVol, m3 ha−1 yr−1), obtained from ca. 100,000 coniferous and broadleaved trees in 442 even-aged, single-species stands across 23 European countries. We used multivariate statistical approaches, such as mixed effects models and structural equation modelling to investigate how European forest growth respond to changes in 11 predictors, including stand characteristics, climate conditions, air and site quality, as well as their interactions. We found that, despite the large environmental gradients encompassed by the forests examined, stand density and age were key drivers of forest growth. We further detected a positive, in some cases non-linear effect of N deposition, most pronounced for beech forests, with a tipping point at ca. 30 kg N ha−1 yr−1. With the exception of a consistent temperature signal on Norway spruce, climate-related predictors and ground-level ozone showed much less generalized relationships with ΔVol. Our results show that, together with the driving forces exerted by stand density and age, N deposition is at least as important as climate to modulate forest growth at continental scale in Europe, with a potential negative effect at sites with high N deposition.
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  • Gonda, A., et al. (författare)
  • Predation- and competition-mediated brain plasticity in Rana temporaria tadpoles
  • 2010
  • Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 23:11, s. 2300-2308
  • Tidskriftsartikel (refereegranskat)abstract
    • An increasing number of studies have demonstrated phenotypic plasticity in brain size and architecture in response to environmental variation. However, our knowledge on how brain architecture is affected by commonplace ecological interactions is rudimentary. For example, while intraspecific competition and risk of predation are known to induce adaptive plastic modifications in morphology and behaviour in a wide variety of organisms, their effects on brain development have not been studied. We studied experimentally the influence of density and predation risk on brain development in common frog (Rana temporaria) tadpoles. Tadpoles grown at low density and under predation risk developed smaller brains than tadpoles at the other treatment combinations. Further, at high densities, tadpoles developed larger optic tecta and smaller medulla oblongata than those grown at low densities. These results demonstrate that ecological interactions - like intraspecific competition and predation risk - can have strong effects on brain development in lower vertebrates.
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  • Kaar, P, et al. (författare)
  • Sexual conflict and remarriage in preindustrial human populations: Causes and fitness consequences
  • 1998
  • Ingår i: Evolution and human behavior. - 1090-5138 .- 1879-0607. ; 19:3, s. 139-151
  • Tidskriftsartikel (refereegranskat)abstract
    • Sexual conflict is said to occur when one mating partner has an opportunity to increase its fitness at the cost of the other. We analyzed the effect of remarriage on lifetime reproductive success (LRS) in three preindustrial (1700–1900) socially monogamous Sami populations. In all populations, ever-married women’s age-specific mortality rates exceeded those of ever-married men during reproductive years. After the death of a spouse, men had a higher probability of remarriage than did women of the same age. Remarried men had a higher LRS than men who married only once, but this was not true for women. The higher LRS of the twice-married men was probably due to their longer (+5 years; p < .05) reproductive lifespan (RLS) as compared to once-married men. There was no difference in the RLS of women who married once or twice. These results suggest the sexual conflict in these populations was won by men because women paid a higher cost from reproduction (i.e., reduced survival), and men were able to remarry more often than women, thereby realizing more of their higher reproductive potential. Consequently, serial monogamy seem to have been an important male reproductive strategy in these historical populations.
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  • Knopp, T., et al. (författare)
  • Contrasting levels of variation in neutral and quantitative genetic loci on island populations of moor frogs (Rana arvalis)
  • 2007
  • Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 8:1, s. 45-56
  • Tidskriftsartikel (refereegranskat)abstract
    • Reduced levels of genetic variability and a prominent differentiation in both neutral marker genes and phenotypic traits are typical for many island populations as compared to their mainland conspecifics. However, whether genetic diversity in neutral marker genes reflects genetic variability in quantitative traits, and thus, their evolutionary potential, remains typically unclear. Moreover, the phenotypic differentiation on islands could be attributable to phenotypic plasticity, selection or drift; something which seldom has been tested. Using eight polymorphic microsatellite loci and quantitative genetic breeding experiments we conducted a detailed comparison on genetic variability and differentiation between Nordic islands (viz. Gotland, Öland and Læsø) and neighbouring mainland populations of moor frogs (Rana arvalis). As expected, the neutral variation was generally lower in island than in mainland populations. But as opposed to this, higher levels of additive genetic variation (V A) in body size and tibia length were found on the island of Gotland as compared to the mainland population. When comparing the differentiation seen in neutral marker genes (F ST) with the differentiation in genes coding quantitative traits (Q ST) two different evolutionary scenarios were found: while selection might explain a smaller size of moor frogs on Gotland, the differentiation seen in tibia length could be explained by genetic drift. These results highlight the limited utility of microsatellite loci alone in inferring the causes behind an observed phenotypic differentiation, or in predicting the amount of genetic variation in ecologically important quantitative traits.
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  • Merilä J, Sheldon BC (författare)
  • Avian quantitative genetics
  • 2001
  • Ingår i: Current Ornithology. ; 16, s. 179-255
  • Tidskriftsartikel (refereegranskat)
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  • Merilä, J, et al. (författare)
  • Temporal stability and microgeographic homogeneity of heritability estimates in a natural bird population
  • 1996
  • Ingår i: Journal of Heredity. - 0022-1503 .- 1465-7333. ; 87:3, s. 199-204
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Temporal and spatial variation in heritability estimates and additive genetic covariances of seven morphological traits were studied over a 9-year period in a natural population of the collared flycatcher, Ficedula albicollis. In spite of significant differences in trait means among young born in different years, we found no evidence for between-years variation in heritability estimates in any of the traits. Likewise, the elements of genetic covariance matrices were significantly correlated among the different study years, and the null hypothesis of no similarity was rejected. Furthermore, despite significant differences in mean tarsus length of birds born in different nestbox areas (habitats), we found no evidence for differences in heritability of tarsus length in different habitats. Our results indicate that the assumption on the constancy of quantitative genetic parameters over time and environments in evolutionary models may hold at least over short temporal or spatial distances.
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  • Söderman, Fredrik, 1968- (författare)
  • Comparative Population Ecology in Moor Frogs with Particular Reference to Acidity
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis is an attempt to describe how different environmental factors influence life history traits in different populations, sexes and developmental stages in the moor frog, Rana arvalis. The studied populations are located along 1100 km latitudinal gradient, with pH varying between 4.0 and 8.5. I have used data from both natural populations and common garden experiments. Reproducing moor frogs were larger and older at high latitudes, indicating a selective advantage of large size at high latitudes and/or earlier reproduction at low latitudes. When controlling for age I found that frogs were older and smaller at low pH, which may be a result of a reduced growth rate due to acid stress. The both sexes respond differently to different environments, with the lowest sexual dimorphism in body size found in the acid environments. This is possibly caused by a trade-off between growth and reproduction. Being large is considered to be advantageous, in females due to increased fecundity, and in males due to higher ability to compete for mates, while the cost of high growth is a reduced possibility to survive until the next mating season. Moor frog embryos originating from an acid population survived better under acid stress than embryos from a neutral population. Using quantitative genetic techniques I found strong maternal effects and small additive genetic variation for the traits in acid and non acid populations. The variation in acid stress tolerance owed largely to non-genetic effects. Females from acid localities lay larger eggs, which probably improves the performance of tadpoles under acid conditions. The trade-off between egg size and fecundity was stronger in acid populations indicating that females in acid populations reduced fecundity to increase offspring size. Finally, frogs from acidified environments were more asymmetric in skeletal traits further indicating the developmental stress created by acidification.
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  • Teacher, A. G., et al. (författare)
  • Oceanographic connectivity and environmental correlates of genetic structuring in Atlantic herring in the Baltic Sea
  • 2013
  • Ingår i: Evolutionary Applications. - : Wiley. - 1752-4571. ; 6:3, s. 549-567
  • Tidskriftsartikel (refereegranskat)abstract
    • Marine fish often show little genetic structuring in neutral marker genes, and Atlantic herring (Clupea harengus) in the Baltic Sea are no exception; historically, very low levels of population differentiation (FST ≈ 0.002) have been found, despite a high degree of interpopulation environmental heterogeneity in salinity and temperature. Recent exome sequencing and SNP studies have however shown that many loci are under selection in this system. Here, we combined population genetic analyses of a large number of transcriptome-derived microsatellite markers with oceanographic modelling to investigate genetic differentiation and connectivity in Atlantic herring at a relatively fine scale within the Baltic Sea. We found evidence for weak but robust and significant genetic structuring (FST = 0.008) explainable by oceanographic connectivity. Genetic differentiation was also associated with site differences in temperature and salinity, with the result driven by the locus Her14 which appears to be under directional selection (FST = 0.08). The results show that Baltic herring are genetically structured within the Baltic Sea, and highlight the role of oceanography and environmental factors in explaining this structuring. The results also have implications for the management of herring fisheries, the most economically important fishery in the Baltic Sea, suggesting that the current fisheries management units may be in need of revision. © 2013 The Authors. Published by Blackwell Publishing Ltd.
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  • Trokovic, N., et al. (författare)
  • Brain plasticity over the metamorphic boundary : carry-over effect of larval environment on froglet brain development
  • 2011
  • Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 24:6, s. 1380-1385
  • Tidskriftsartikel (refereegranskat)abstract
    • Brain development shows high plasticity in response to environmental heterogeneity. However, it is unknown how environmental variation during development may affect brain architecture across life history switch points in species with complex life cycles. Previously, we showed that predation and competition affect brain development in common frog (Rana temporaria) tadpoles. Here, we studied whether larval environment had carry-over effects in brains of metamorphs. Tadpoles grown at high density had large optic tecta at metamorphosis, whereas tadpoles grown under predation risk had small diencephala. We found that larval density had a carry-over effect on froglet optic tectum size, whereas the effect of larval predation risk had vanished by metamorphosis. We discuss the possibility that the observed changes may be adaptive, reflecting the needs of an organism in given environmental and developmental contexts.
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