| 1. |
- Carlson, Benny, et al.
(författare)
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Integration kräver flexibilitet
- 2014
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Ingår i: Skånska dagbladet. - 1103-9973.
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 2. |
- Gad, Helge, et al.
(författare)
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MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
- 2014
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 508:7495, s. 215-221
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Tidskriftsartikel (refereegranskat)abstract
- Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bindin the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.
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| 3. |
- Jeppsson, Tobias, et al.
(författare)
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Can Life History Predict the Effect of Demographic Stochasticity on Extinction Risk?
- 2012
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Ingår i: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 179, s. 706-720
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Tidskriftsartikel (refereegranskat)abstract
- Demographic stochasticity is important in determining extinction risks of small populations, but it is largely unknown how its effect depends on the life histories of species. We modeled effects of demographic stochasticity on extinction risk in a broad range of generalized life histories, using matrix models and branching processes. Extinction risks of life histories varied greatly in their sensitivity to demographic stochasticity. Comparing life histories, extinction risk generally increased with increasing fecundity and decreased with higher ages of maturation. Effects of adult survival depended on age of maturation. At lower ages of maturation, extinction risk peaked at intermediate levels of adult survival, but it increased along with adult survival at higher ages of maturation. These differences were largely explained by differences in sensitivities of population growth to perturbations of life history traits. Juvenile survival rate contributed most to total demographic variance in the majority of life histories. Our general results confirmed earlier findings, suggesting that empirical patterns can be explained by a relatively simple model. Thus, basic life history information can be used to assign life history-specific sensitivity to demographic stochasticity. This is of great value when assessing the vulnerability of small populations.
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| 4. |
- Jeppsson, Tobias
(författare)
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Empirical and theoretical studies of population trends and extinction risks
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Empirical and theoretical approaches are needed to solve the current problem of increased extinction risk for many species. Thus, this thesis focuses on: (1) ways to estimate population trends for a large number of species, and (2) a predictive framework for identifying vulnerable populations from species traits or life history traits to allow for more proactive conservation actions. I estimated long-term population trends and range-abundance dynamics of longhorn beetles using Natural History Collections. In general, negative population trends were not accompanied by declines in range, but range increased among species with increasing populations. The analysis also exemplified how the results can be used in the red listing process. Linking life history traits and two metrics of extinction risk (population trend and red list classification) in long horn beetles showed that generation time, overwintering stage, larval host plant specialisation, adult activity period and body size were related to extinction risk, often with interaction effects between predictor variables. Variability in population size is an important factor affecting population extinction risk. I modelled the effects of demographic and environmental stochasticity on extinction risk in small populations, for a large range of life history types. Extinction risk due to demographic stochasticity increased with increasing fecundity and decreasing age of maturation, whereas effects of adult survival interacted with maturation age. Including environmental stochasticity showed that the qualitative relationship between extinction risk and life history types changed, but also that combined effects of both stochasticities on extinction risk were most significant in short-lived life histories. The results suggest that data from Natural History Collections can be used to estimate long-term population trends, and that population declines may be underestimated if estimated from changes in range. My studies also suggest that life history traits and species traits can be used to predict population vulnerability to extinction and, hence, that certain groups of species are more vulnerable to extinction than others.
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| 5. |
- Jeppsson, Tobias
(författare)
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Longhorn beetles in Sweden – changes in distribution and abundance over the last two hundred years
- 2010
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Ingår i: Entomologisk tidskrift. - 0013-886X. ; 131, s. 241-512
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Tidskriftsartikel (refereegranskat)abstract
- The abandonment of traditional agricultural practices and the introduction of large-scale industrial forestry has transformed landscapes and changed the conditions for wood-living organisms. This study examines changes in distribution and abundance of the 118 species of longhorn beetles (Col. Cerambycidae) recorded from natural habitat in Sweden over the 19th and 20th centuries, based on extensive surveys of museums, private collections and information in the literature, all in all more than 57 000 specific records compiled by 1400 collectors. The primary results are presented as maps of species’ distributions (-1900; 1901-1950; 1951-1975, and 1976-2000), population size indices (PSI s) based on species frequencies in subsets of the total material obtained by comparable collection methods, and estimates of abundance compiled from a succession of insect faunas spanning two centuries. Changing practices and preferences of collectors are examined in order to interpret the maps and indices and separate real changes of distribution and/or abundance from artefacts due to sampling biases. Appendices include the phenology of individual species and sources of data in the literature. Distributions of most species have changed little during our period of study, and 45 of 103 species are still assigned to the same category of abundance today as in the faunas from the early 19th century. Similarly, tests and interpretations of the PSIs indicate that the abundances of 31 out of 76 analysed species have been quite stable since the 1950s. Other species seem to increase - 32 are considered more abundant today than in the early 19th century faunas, and 17 of the 76 analysed species appear to have become more common since the 1950s. However, there have also been substantial negative changes: 26 species are categorised as less abundant today than in the early 19th century, and 5-10 of these have probably gone extinct. Furthermore, tests and interpretations of the PSI s indicate that 16 of 76 analysed species have decreased in abundance over the last fifty years. Some of these are associated with burnt trees, a handful develop in large diameter sun-exposed dead oak wood, others utilise dead wood of lime, a couple live in open, grazed coniferous forests, two species mainly develop in old construction wood and one species is primarily found in old-growth spruce forests. Close to half of all Swedish species of longhorn beetles are red-listed. However, our analyses indicate that few red-listed species meet the IUCN thresholds for population decline, suggesting that the thresholds are set too high to detect declining longhorn beetles (and perhaps insects more generally), but also that some red-listed species seem to increase and should be removed from the list. Our results also indicate that red-listed species whose narrow distributions have been the same for a long time may be limited by other factors than substrate availability, and therefore be more resilient to habitat change than their red-list classification suggests. Conversely, species with recently contracting ranges of distribution may be even more at risk than their threat categories imply. A final section briefly discusses monitoring of future trends and gives some suggestions on how conservation measures may be designed to better meet regional conservation needs
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| 6. |
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| 7. |
- Jeppsson, Tobias, et al.
(författare)
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Species' traits explain differences in Red list status and long-term population trends in longhorn beetles
- 2014
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Ingår i: Animal Conservation. - : Wiley. - 1367-9430 .- 1469-1795. ; 17, s. 332-341
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Tidskriftsartikel (refereegranskat)abstract
- Some species are more likely to go extinct than others and this is partially due to species' traits. Therefore, it is important to establish links between traits and extinction risks. Different aspects of a species' biology also relates to different sources of threat, such as fragmented populations or low population growth rate. In a comparative study of Swedish longhorn beetles (Coleoptera: Cerambycidae), we related species' traits to two aspects of extinction risk - population decline and small/fragmented populations - measured by long-term population trends and IUCN Red list classifications. Trait relationships were analysed with generalized linear models and multi-model inference. We found that extinction risk generally increased with longer generation times, corresponding to slower life histories. Adult activity period was also related to both metrics of extinction risk, but in different ways. We also found that extinction risk increased with larval host plant specialization, but only for Red list classification. Large body size was related to increased Red list classification in species overwintering as adults, and overwintering stage also structured the effects of several other traits. Our results show that both intrinsic demographic traits and ecological traits affect extinction risks, and also suggest that risks are shaped by multiple mechanisms. Therefore, researchers should carefully choose their metric of extinction risk for comparative studies, as the Red list classification may best capture current risk, whereas population trends can be used more proactively but may reflect historical relationships between traits and extinction risk.
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| 8. |
- Jeppsson, Tobias, et al.
(författare)
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The use of historical collections to estimate population trends: A case study using Swedish longhorn beetles (Coleoptera: Cerambycidae)
- 2010
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 143, s. 1940-1950
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Tidskriftsartikel (refereegranskat)abstract
- Long term data to estimate population trends among species are generally lacking. However, Natural History Collections (NHCs) can provide such information, but may suffer from biases due to varying sampling effort. To analyze population trends and range-abundance dynamics of Swedish longhorn beetles (Coleoptera: Cerambycidae), we used collections of 108 species stretching over 100 years. We controlled for varying sampling effort by using the total number of database records as a reference for non-red-listed species. Because the general frequency of red-listed species increased over time, a separate estimate of sampling effort was used for that group. We observed large interspecific variation in population changes, from declines of 60% to several hundred percent increases. Most species showed stable or increasing ranges, whereas few seemed to decline in range. Among increasing species, rare species seemed to expand their range more than common species did, but this pattern was not observed in declining species. Historically, rare species did not seem to be at larger risk of local extinction, and population declines were mostly due to lower population density and not loss of sub-populations. We also evaluated the species' declines under IUCN red-list criterion A, and four currently not red-listed species meet the suggested threshold for Near Threatened (NT). The results also suggested that species' declines may be overlooked if estimated only from changes in species range. (C) 2010 Elsevier Ltd. All rights reserved.
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| 9. |
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| 10. |
- Snäll, Tord, et al.
(författare)
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Evaluating temporal variation in Citizen Science Data against temporal variation in the environment
- 2014
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 37, s. 293-300
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Tidskriftsartikel (refereegranskat)abstract
- Citizen Science Data (CSD) is increasingly contributing to the assessment of biodiversity and ecosystems. However, there is a need to evaluate the usefulness of CSD for different purposes. Ideally, CSD from populations should be evaluated against independent population data collected using a proper sampling design, but such data are lacking for almost all species. We propose an approach for evaluating CSD against environmental data. First, an evaluation model is formulated based on knowledge of how environmental variables affect population dynamics. Second, the hypotheses of the evaluation model are tested statistically. Support for the evaluation model is interpreted as support for the CSD. We applied the approach to six longhorn beetle species using Swedish data from 1930-2000. The evaluation model assumed that early summer temperature affects larval development time. We found support for the evaluation model in two species, and some evidence in its favour in one species. This suggests that the CSD from these species reflect true inter-annual variation. We also found statistical evidence for population trends in three to four species. In two of these, the evaluation model was supported thus providing particular support for the trend estimates. Lack of support for the evaluation model may be due to biological inaccuracy, the general characteristics of CSD, or low resolution of the environmental evaluation data. We also discuss alternative environmental data for evaluating CSD.
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