| 1. |
- Balint, Miklos, et al.
(författare)
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Environmental DNA time series in ecology
- 2018
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Ingår i: Trends in Ecology & Evolution. - London : Elsevier. - 0169-5347 .- 1872-8383. ; 33:12, s. 945-957
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Forskningsöversikt (refereegranskat)abstract
- Ecological communities change in time and space, but long-term dynamics at the century-to-millennia scale are poorly documented due to lack of relevant data sets. Nevertheless, understanding long-term dynamics is important for explaining present-day biodiversity patterns and placing conservation goals in a historical context. Here, we use recent examples and new perspectives to highlight how environmental DNA (eDNA) is starting to provide a powerful new source of temporal data for research questions that have so far been overlooked, by helping to resolve the ecological dynamics of populations, communities, and ecosystems over hundreds to thousands of years. We give examples of hypotheses that may be addressed by temporal eDNA biodiversity data, discuss possible research directions, and outline related challenges.
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| 2. |
- Bellard, Celine, et al.
(författare)
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Biotic and abiotic drivers of species loss rate in isolated lakes
- 2019
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Ingår i: Journal of Animal Ecology. - : WILEY. - 0021-8790 .- 1365-2656. ; 88:6, s. 881-891
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Tidskriftsartikel (refereegranskat)abstract
- Today, anthropogenic impacts are causing a serious crisis for global biodiversity, with rates of extinction increasing at an unprecedented rate. Extinctions typically occur after a certain delay, and understanding the mechanisms causing delays is a key challenge for both fundamental and applied perspectives. Here, we make use of natural experiments, the isolation of lakes by land uplift in Northern Scandinavia, to examine how yearly extinction rates are affected by time since isolation and a range of abiotic and biotic factors. In this aim, we adapted a model of delayed species loss within isolated communities to test the effects of time since isolation, area, pH, depth and the presence/absence of piscivores on extinction rates. As expected, we found that small and/or young lakes experience a higher annual rate of extinctions per species than larger and/or older ones. Compared to previous studies that were conducted for either young (few thousand years ago) or very old (>10,000 years ago) isolates, we demonstrated over a large and continuous temporal scales (50-5,000 years), similar relationship between extinction rates and age. We also show that extinction rates are modified by local environmental factors such as a strong negative effect of increasing pH. Our results urge for the need to consider the time since critical environmental changes occurred when studying extinction rates. In a wider perspective, our study demonstrates the need to consider extinction debts when modelling future effects of climate change, land-use changes or biological invasions on biodiversity.
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| 3. |
- Côté, Marianne, et al.
(författare)
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Towards modeling data-poor lakes at the regional scale using parameters from data-rich lakes and relationships to lake characteristics
- 2023
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Ingår i: Inland Waters. - : Taylor & Francis. - 2044-2041 .- 2044-205X. ; 13:3, s. 388-401
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Tidskriftsartikel (refereegranskat)abstract
- Lakes pivotal for recreation and economically relevant activities are often remote and not well studied, which hinders the application of predictive lake models for their management. Here, we provide an approach to simulate—by means of the process-oriented model MyLake—water temperature, ice cover duration, dissolved oxygen, and light attenuation in 198 data-poor lakes based on parameters obtained for a subgroup of 12 data-rich lakes and morphometric data. Specifically, the model is first calibrated using a genetic algorithm on well-studied lakes. Simple relationships between the fitted parameters and lake-catchment morphometric properties are then derived, and the results of simulations using fitted and derived parameters are compared. The loss in goodness-of-fit, expressed as root mean square error (RMSE) incurred by using estimated rather than calibrated parameters, is 0.17 °C for water temperature and 0.82 mg L−1 for dissolved oxygen. These general relationships are then used to provide the model parameters for 198 data-poor lakes distributed throughout Sweden and to model these lakes. Overall, this proof of concept allows simulating lakes selected based on their relevance for lake management rather than based on the availability of extensive field datasets.
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| 4. |
- Englund, Göran, 1957-
(författare)
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Competition in caddis larvae
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with behavioural strategies used by caddis larvae in pairwise contests and when selecting microhabitats. Effects of caddis larvae on survival and habitat selection of other insect taxa have also been studied.The behaviours used by Arctopsyche ladogensis larvae fighting for nets, and Agrypnia pagetana larvae fighting for cases, agreed well with predictions from the sequential assessment game, which is an ESS model of animal fighting behaviour.Establishment by net-spinning Hydropsyche siltalai larvae on artificial substrates was highest at intermediate densities of residents. Emigration/mortality was density independent, and it was higher at a poor site (low food availability) than at a rich site. Establishment was unaffected by site quality. Growth was density dependent because larvae in upstream positions reduced both current velocity and concentration of food particles for larvae in downstream positions.A field experiment involved manipulations of the density of H. siltalai larvae and their nets in a lake outlet stream. H. siltalai larvae affected all abundant taxa, but the mechanism involved varied between taxa. Rhyacophila nubila (Trichoptera) and chironomid larvae benefited from the presence of H. siltalai nets. Negative effects on nymphs of the mayfly Ephemerella ignita were due to predation by H. siltalai larvae, while a combination of predation and increased emigration in response to nets depressed densities of Simulium truncatum blackfly larvae.
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| 5. |
- Englund, Göran, 1957-, et al.
(författare)
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Holocene extinctions of a top predator : effects of time, habitat area and habitat subdivision
- 2020
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656. ; 89:5, s. 1202-1215
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Tidskriftsartikel (refereegranskat)abstract
- Loss of habitat and changes in the spatial configuration of habitats are major drivers of species extinctions, but the responses to these drivers differ between organisms. To advance theory on how extinction risk from different types of habitat alteration relates to species-specific traits, there is a need for studies of the long-term extinction dynamic of individual species. The goal of this study was to quantify how habitat area and the spatial configuration of habitats affect extinction rate of an aquatic top predator, the northern pike Esox lucius L. We recorded the presence/absence of northern pike in 398 isolated habitat fragments, each one consisting of a number of interconnected lakes. Time since isolation of the habitat fragments, caused by cut-off from the main dispersal source in the Baltic Sea, varied between 0 and 10,000 years. Using survival regression, we analysed how pike population survival was affected by time since isolation, habitat size and habitat subdivision. The approach builds on the assumptions that pike colonized all fragments before isolation and that current absences result from extinctions. We verified these assumptions by testing (a) if pike was present in the region throughout the entire time period when the lakes formed and (b) if pike typically colonize lakes that are formed today. We also addressed the likelihood that unrecorded anthropogenic introductions could bias our estimates of extinction rate. Our results supported the interpretation that current patterns of presence/absence in our study system are shaped by extinctions. Further, we found that time since isolation and fragment area had strong effects on pike population survival. In contrast, spatial habitat subdivision (i.e. if a fragment contained few large lakes or many small lakes) and other environmental covariates describing climate and productivity were unrelated to pike survival. Over all, extinction rate was high in young fragments and decreased sharply with increasing fragment age. Our study demonstrates how the link between extinction rate and habitat size and spatial structure can be quantified. More similar studies may help us find generalizations that can guide management of habitat size and connectivity.
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| 6. |
- 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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| 7. |
- Englund, Undis, 1957-, et al.
(författare)
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Active commuting reduces the risk of wrist fractures in middle-aged women : the UFO study
- 2013
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Ingår i: Osteoporosis International. - : Springer. - 0937-941X .- 1433-2965. ; 24:2, s. 533-540
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Tidskriftsartikel (refereegranskat)abstract
- Middle-aged women with active commuting had significantly lower risk for wrist fracture than women commuting by car/bus.INTRODUCTION: Our purpose was to investigate whether a physically active lifestyle in middle-aged women was associated with a reduced risk of later sustaining a low-trauma wrist fracture.METHODS: The Umeå Fracture and Osteoporosis (UFO) study is a population-based nested case-control study investigating associations between lifestyle and fragility fractures. From a cohort of ~35,000 subjects, we identified 376 female wrist fracture cases who had reported data regarding their commuting habits, occupational, and leisure physical activity, before they sustained their fracture. Each fracture case was compared with at least one control drawn from the same cohort and matched for age and week of reporting data, yielding a total of 778 subjects. Mean age at baseline was 54.3 ± 5.8 years, and mean age at fracture was 60.3 ± 5.8 years.RESULTS: Conditional logistic regression analysis with adjustments for height, body mass index, smoking, and menopausal status showed that subjects with active commuting (especially walking) were at significantly lower risk of sustaining a wrist fracture (OR 0.48; 95 % CI 0.27-0.88) compared with those who commuted by car or bus. Leisure time activities such as dancing and snow shoveling were also associated with a lower fracture risk, whereas occupational activity, training, and leisure walking or cycling were unrelated to fracture risk.CONCLUSION: This study suggests that active commuting is associated with a lower wrist fracture risk, in middle-aged women.
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| 8. |
- Englund, Undis, 1957-, et al.
(författare)
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Physical activity in middle-aged women and hip fracture risk : the UFO study
- 2011
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 22:2, s. 499-505
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Tidskriftsartikel (refereegranskat)abstract
- Summary: In a population-based case-control study, we demonstrate that middle-aged women who were active with walking or in different physical spare time activities were at lower risk of later sustaining a hip fracture compared to more sedentary women.Introduction: In middle-aged women participating in the Umeå Fracture and Osteoporosis (UFO) study, we investigated whether physical activity is associated with a subsequent decreased risk of sustaining a hip fracture.Methods: The UFO study is a nested case-control study investigating associations between bone markers, lifestyle, and osteoporotic fractures. We identified 81 female hip fracture cases that had reported lifestyle data before they sustained their fracture. Each case was compared with two female controls who were identified from the same cohort and matched for age and week of reporting data, yielding a total cohort of 237 subjects. Mean age at baseline was 57.2 ± 5.0 years, and mean age at fracture was 65.4 ± 6.4 years.Results: Conditional logistic regression analysis with adjustments for height, weight, smoking, and menopausal status showed that subjects who were regularly active with walking or had a moderate or high frequency of physical spare time activities (i.e. berry/mushroom picking and snow shovelling) were at reduced risk of sustaining a hip fracture (OR 0.14; 95% CI; 0.05–0.53 for walking and OR 0.19; 95% CI; 0.08–0.46, OR 0.17, 95% CI; 0.05–0.64 for moderate and high frequency of spare time activities, respectively) compared to more sedentary women.Conclusion: An active lifestyle in middle age seems to reduce the risk of future hip fracture. Possible mechanisms may include improved muscle strength, coordination, and balance resulting in a decreased risk of falling and perhaps also direct skeletal benefits.
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| 9. |
- Fall, Johanna, et al.
(författare)
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Predator–prey overlap in three dimensions : cod benefit from capelin coming near the seafloor
- 2021
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Ingår i: Ecography. - : John Wiley & Sons. - 0906-7590 .- 1600-0587. ; 44:5, s. 802-815
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Tidskriftsartikel (refereegranskat)abstract
- Spatial overlap between predator and prey is a prerequisite for predation, but the degree of overlap is not necessarily proportional to prey consumption. This is because many of the behavioural processes that precede ingestion are non-linear and depend on local prey densities. In aquatic environments, predators and prey distribute not only across a surface, but also vertically in the water column, adding another dimension to the interaction. Integrating and simplifying behavioural processes across space and time can lead to systematic biases in our inference about interaction strength. To recognise situations when this may occur, we must first understand processes underlying variation in prey consumption by individuals. Here we analysed the diet of a major predator in the Barents Sea, the Atlantic cod Gadus morhua, aiming to understand drivers of variation in cod's feeding on its main prey capelin Mallotus villosus. Cod and capelin only partly share habitats, as cod mainly reside near the seafloor and capelin inhabit the free water masses. We used data on stomach contents from ~2000 cod individuals and their surrounding environment collected over 12 years, testing hypotheses on biological and physical drivers of variation in cod's consumption of capelin, using generalized additive models. Specifically, effects of capelin abundance, capelin depth distribution, bottom depth and cod abundance on capelin consumption were evaluated at a resolution scale of 2 km. We found no indication of food competition as cod abundance had no effect on capelin consumption. Capelin abundance had small effects on consumption, while capelin depth distribution was important. Cod fed more intensively on capelin when capelin came close to the seafloor, especially at shallow banks and bank edges. Spatial overlap as an indicator for interaction strength needs to be evaluated in three dimensions instead of the conventional two when species are partly separated in the water column.
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| 10. |
- 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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