| 1. |
- Englund, Göran, 1957-, et al.
(författare)
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Temperature dependence of the functional response
- 2011
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 14:9, s. 914-21
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Tidskriftsartikel (refereegranskat)abstract
- The Arrhenius equation has emerged as the favoured model for describing the temperature dependence of consumption in predator-prey models. To examine the relevance of this equation, we undertook a meta-analysis of published relationships between functional response parameters and temperature. We show that, when plotted in lin-log space, temperature dependence of both attack rate and maximal ingestion rate exhibits a hump-shaped relationship and not a linear one as predicted by the Arrhenius equation. The relationship remains significantly downward concave even when data from temperatures above the peak of the hump are discarded. Temperature dependence is stronger for attack rate than for maximal ingestion rate, but the thermal optima are not different. We conclude that the use of the Arrhenius equation to describe consumption in predator-prey models requires the assumption that temperatures above thermal optima are unimportant for population and community dynamics, an assumption that is untenable given the available data.
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| 2. |
- Finstad, Anders G., et al.
(författare)
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Migrate or stay : terrestrial primary productivity and climate drive anadromy in Arctic char
- 2012
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 18:8, s. 2487-2497
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Tidskriftsartikel (refereegranskat)abstract
- A shift in the magnitude and timing of animal migrations is one of the most documented ecological effects of climate change. Although migrations are largely driven by spatial variation in resource gradients, few studies connect expected changes in primary production with geographic patterns in migratory behavior. Here, we link lake primary production to the occurrence of sea migrations in the partially anadromous salmonid Arctic char (Salvelinus alpinus L.). We compiled presence/absence records of anadromous char populations spanning productivity and temperature gradients along the Norwegian coast. The probability of anadromy decreased with increasing migration distance, maximum slope of the migration route and lake productivity. There was a significant interaction between lake productivity and migration distance. The negative effect of longer migration distances was more severe in lakes with higher productivity, indicating reduced relative profitability of migration with increased feeding opportunities in freshwater. Lake productivity was mainly driven by terrestrial primary production in the catchment. We predicted future distributions of anadromous char given downscaled temperature and precipitation changes projected by two different emission scenarios and global climate models (GCMs). Projected increases in temperature and precipitation in 20712100 increased terrestrial primary production and, compared to the control scenario (19611990), decreased the range of anadromous populations. The prevalence of anadromy decreased by 53% in the HadAm3H GCM with the A2 emission scenario, 61% in HadAm3H with the B2 scenario and 22% in ECHAM4 with the B2 scenario. Cross-ecosystem studies (e.g., terrestrial to freshwater) are critical for understanding ecological impacts of climate change. In this case, climate-driven increases in terrestrial primary production are expected to increase primary production in lakes and ultimately reduce the prevalence of anadromy in Arctic char populations.
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| 3. |
- Hein, Catherine L, et al.
(författare)
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Dispersal through stream networks : modelling climate-driven range expansions of fishes
- 2011
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 17:4, s. 641-651
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Tidskriftsartikel (refereegranskat)abstract
- Aim To incorporate dispersal through stream networks into models predicting the future distribution of a native, freshwater fish given climate change scenarios. Location Sweden. Methods We used logistic regression to fit climate and habitat data to observed pike (Esox lucius Linnaeus) distributions in 13,476 lakes. We used GIS to map dispersal pathways through streams. Lakes either (1) contained pike or were downstream from pike lakes, (2) were upstream from pike lakes, but downstream from natural dispersal barriers, or (3) were isolated from streams or were upstream from natural dispersal barriers. We then used climate projections to model future distributions of pike and compared our results with and without including dispersal. Results Given climate and habitat, pike were predicted present in all of 99,249 Swedish lakes by 2100. After accounting for dispersal barriers, we only predicted pike presence in 31,538 lakes. Dispersal barriers most strongly limited pike invasion in mountainous regions, but low connectivity also characterized some relatively flat regions. Main conclusions The dendritic network structure of streams and interconnected lakes makes a two-dimensional representation of the landscape unsuitable for predicting range shifts of many freshwater organisms. If dispersal through stream networks is not accounted for, predictions of future fish distributions in a warmer climate might grossly overestimate range expansions of warm and cool-water fishes and underestimate range contractions of cold-water fishes. Dispersal through stream networks can be modelled in any region for which a digital elevation model and species occurrence data are available.
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| 4. |
- Hein, Catherine L., et al.
(författare)
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Fish introductions reveal the temperature dependence of species interactions
- 2014
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 281:1775, s. 20132641-
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Tidskriftsartikel (refereegranskat)abstract
- A major area of current research is to understand how climate change will impact species interactions and ultimately biodiversity. A variety of environmental conditions are rapidly changing owing to climate warming, and these conditions often affect both the strength and outcome of species interactions. We used fish distributions and replicated fish introductions to investigate environmental conditions influencing the coexistence of two fishes in Swedish lakes: brown trout (Salmo trutta) and pike (Esox lucius). A logistic regression model of brown trout and pike coexistence showed that these species coexist in large lakes (more than 4.5 km(2)), but not in small, warm lakes (annual air temperature more than 0.9-1.5 degrees C). We then explored how climate change will alter coexistence by substituting climate scenarios for 2091-2100 into our model. The model predicts that brown trout will be extirpated from approximately half of the lakes where they presently coexist with pike and from nearly all 9100 lakes where pike are predicted to invade. Context dependency was critical for understanding pike-brown trout interactions, and, given the widespread occurrence of context-dependent species interactions, this aspect will probably be critical for accurately predicting climate impacts on biodiversity.
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| 5. |
- Hein, Catherine L., et al.
(författare)
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Future distribution of Arctic Char Salvelinus alpinus in Sweden under climate change : Effects of temperature, lake size and species interactions
- 2012
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Ingår i: Ambio. - : Springer Netherlands. - 0044-7447 .- 1654-7209. ; 41:3, s. 303-312
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Tidskriftsartikel (refereegranskat)abstract
- Novel communities will be formed as species with a variety of dispersal abilities and environmental tolerances respond individually to climate change. Thus, models projecting future species distributions must account for species interactions and differential dispersal abilities. We developed a species distribution model for Arctic char Salvelinus alpinus, a freshwater fish that is sensitive both to warm temperatures and to species interactions. A logistic regression model using lake area, mean annual air temperature (1961-1990), pike Esox lucius and brown trout Salmo trutta occurrence correctly classified 95 % of 467 Swedish lakes. We predicted that Arctic char will lose 73 % of its range in Sweden by 2100. Predicted extinctions could be attributed both to simulated temperature increases and to projected pike invasions. The Swedish mountains will continue to provide refugia for Arctic char in the future and should be the focus of conservation efforts for this highly valued fish.
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| 6. |
- Hollestelle, Antoinette, et al.
(författare)
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No clinical utility of KRAS variant rs61764370 for ovarian or breast cancer
- 2016
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Ingår i: Gynecologic Oncology. - : Elsevier BV. - 0090-8258 .- 1095-6859. ; 141:2, s. 386-401
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Tidskriftsartikel (refereegranskat)abstract
- Objective Clinical genetic testing is commercially available for rs61764370, an inherited variant residing in a KRAS 3′ UTR microRNA binding site, based on suggested associations with increased ovarian and breast cancer risk as well as with survival time. However, prior studies, emphasizing particular subgroups, were relatively small. Therefore, we comprehensively evaluated ovarian and breast cancer risks as well as clinical outcome associated with rs61764370. Methods Centralized genotyping and analysis were performed for 140,012 women enrolled in the Ovarian Cancer Association Consortium (15,357 ovarian cancer patients; 30,816 controls), the Breast Cancer Association Consortium (33,530 breast cancer patients; 37,640 controls), and the Consortium of Modifiers of BRCA1 and BRCA2 (14,765 BRCA1 and 7904 BRCA2 mutation carriers). Results We found no association with risk of ovarian cancer (OR = 0.99, 95% CI 0.94-1.04, p = 0.74) or breast cancer (OR = 0.98, 95% CI 0.94-1.01, p = 0.19) and results were consistent among mutation carriers (BRCA1, ovarian cancer HR = 1.09, 95% CI 0.97-1.23, p = 0.14, breast cancer HR = 1.04, 95% CI 0.97-1.12, p = 0.27; BRCA2, ovarian cancer HR = 0.89, 95% CI 0.71-1.13, p = 0.34, breast cancer HR = 1.06, 95% CI 0.94-1.19, p = 0.35). Null results were also obtained for associations with overall survival following ovarian cancer (HR = 0.94, 95% CI 0.83-1.07, p = 0.38), breast cancer (HR = 0.96, 95% CI 0.87-1.06, p = 0.38), and all other previously-reported associations. Conclusions rs61764370 is not associated with risk of ovarian or breast cancer nor with clinical outcome for patients with these cancers. Therefore, genotyping this variant has no clinical utility related to the prediction or management of these cancers.
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| 7. |
- Jane, Stephen F., et al.
(författare)
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Widespread deoxygenation of temperate lakes
- 2021
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 594:7861, s. 66-70
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Tidskriftsartikel (refereegranskat)abstract
- The concentration of dissolved oxygen in aquatic systems helps to regulate biodiversity(1,2), nutrient biogeochemistry(3), greenhouse gas emissions(4), and the quality of drinking water(5). The long-term declines in dissolved oxygen concentrations in coastal and ocean waters have been linked to climate warming and human activity(6,7), but little is known about the changes in dissolved oxygen concentrations in lakes. Although the solubility of dissolved oxygen decreases with increasing water temperatures, long-term lake trajectories are difficult to predict. Oxygen losses in warming lakes may be amplified by enhanced decomposition and stronger thermal stratification(8,9) or oxygen may increase as a result of enhanced primary production(10). Here we analyse a combined total of 45,148 dissolved oxygen and temperature profiles and calculate trends for 393 temperate lakes that span 1941 to 2017. We find that a decline in dissolved oxygen is widespread in surface and deep-water habitats. The decline in surface waters is primarily associated with reduced solubility under warmer water temperatures, although dissolved oxygen in surface waters increased in a subset of highly productive warming lakes, probably owing to increasing production of phytoplankton. By contrast, the decline in deep waters is associated with stronger thermal stratification and loss of water clarity, but not with changes in gas solubility. Our results suggest that climate change and declining water clarity have altered the physical and chemical environment of lakes. Declines in dissolved oxygen in freshwater are 2.75 to 9.3 times greater than observed in the world's oceans(6,7) and could threaten essential lake ecosystem services(2,3,5,11).
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| 8. |
- Karlsson, Jan, et al.
(författare)
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Terrestrial organic matter input suppresses biomass production in lake ecosystems
- 2015
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Ingår i: Ecology. - : Ecological Society of America. - 0012-9658 .- 1939-9170. ; 96:11, s. 2870-2876
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Tidskriftsartikel (refereegranskat)abstract
- Terrestrial ecosystems export large amounts of organic carbon (t-OC) but the net effect of this OC on the productivity of recipient aquatic ecosystems is largely unknown. In this study of boreal lakes, we show that the relative contribution of t-OC to individual top consumer (fish) biomass production, and to most of their potential prey organisms, increased with the concentration of dissolved organic carbon (DOC; dominated by t-OC sources) in water. However, the biomass and production of top consumers decreased with increasing concentration of DOC, despite their substantial use (up to 60%) of t-OC. Thus, the results suggest that although t-OC supports individual consumer growth in lakes to a large extent, t-OC input suppresses rather than subsidizes population biomass production.
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| 9. |
- Rodriguez, Patricia, et al.
(författare)
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Benthic organic carbon release stimulates bacterioplankton production in a clear-water subarctic lake
- 2013
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Ingår i: Freshwater Science. - : Society for Freshwater Science. - 2161-9565 .- 2161-9549. ; 32:1, s. 176-182
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Tidskriftsartikel (refereegranskat)abstract
- We carried out a set of experiments in a small clear-water lake in northern Sweden during summer 2010 to assess the effect of organic C (OC) released from epipelic algae on pelagic bacterial production (BP). The release rate of OC (dissolved and particulate) from epipelic algae was similar to 45.4 ng C m(-2) h(-1) Bacterioplankton uptake of dissolved OC was P-limited, and pelagic primary production (PP) was colimited by N and P. Pelagic BP (3.2 +/- 6 mu g C L-1 h(-1)) exceeded pelagic PP (0.012 +/- 0.008 mu g C L-1 h(-1)). Pelagic BP was higher in lake water in contact with sediments and the epipelic algae growing on their surface than in water separated from the sediments. Epipelic algae release OC to lake water and potentially stimulate pelagic BP. However, exploitation of benthic OC probably is suboptimal because of nutrient limitation (primarily by inorganic P) of BP.
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| 10. |
- Wang, Anqi, et al.
(författare)
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Characterizing prostate cancer risk through multi-ancestry genome-wide discovery of 187 novel risk variants
- 2023
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Ingår i: Nature Genetics. - : Springer Nature. - 1061-4036 .- 1546-1718. ; 55:12, s. 2065-2074
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Tidskriftsartikel (refereegranskat)abstract
- The transferability and clinical value of genetic risk scores (GRSs) across populations remain limited due to an imbalance in genetic studies across ancestrally diverse populations. Here we conducted a multi-ancestry genome-wide association study of 156,319 prostate cancer cases and 788,443 controls of European, African, Asian and Hispanic men, reflecting a 57% increase in the number of non-European cases over previous prostate cancer genome-wide association studies. We identified 187 novel risk variants for prostate cancer, increasing the total number of risk variants to 451. An externally replicated multi-ancestry GRS was associated with risk that ranged from 1.8 (per standard deviation) in African ancestry men to 2.2 in European ancestry men. The GRS was associated with a greater risk of aggressive versus non-aggressive disease in men of African ancestry (P = 0.03). Our study presents novel prostate cancer susceptibility loci and a GRS with effective risk stratification across ancestry groups.
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