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  • 1. Angerbjörn, Anders
    et al.
    Tannerfeldt, Magnus
    Erlinge, Sam
    Predator-prey relationships: arctic foxes and lemmings1999In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 68, p. 34-49Article in journal (Refereed)
  • 2.
    Bunnefeld, Nils
    et al.
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Sci, SE-90183 Umea, Sweden..
    Boerger, Luca
    Univ Guelph, Dept Integrat Biol, Guelph, ON N1G 2W1, Canada..
    van Moorter, Bram
    Norwegian Univ Sci & Technol, Ctr Conservat Biol, Dept Biol, NO-7491 Trondheim, Norway..
    Rolandsen, Christer M.
    Norwegian Univ Sci & Technol, Ctr Conservat Biol, Dept Biol, NO-7491 Trondheim, Norway.;Norwegian Inst Nat Res, NO-7485 Trondheim, Norway..
    Dettki, Holger
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Sci, SE-90183 Umea, Sweden..
    Solberg, Erling Johan
    Norwegian Univ Sci & Technol, Ctr Conservat Biol, Dept Biol, NO-7491 Trondheim, Norway.;Norwegian Inst Nat Res, NO-7485 Trondheim, Norway..
    Ericsson, Göran
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Sci, SE-90183 Umea, Sweden..
    A model-driven approach to quantify migration patterns: individual, regional and yearly differences2011In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 80, no 2, p. 466-476Article in journal (Refereed)
    Abstract [en]

    P>1. Animal migration has long intrigued scientists and wildlife managers alike, yet migratory species face increasing challenges because of habitat fragmentation, climate change and over-exploitation. Central to the understanding migratory species is the objective discrimination between migratory and nonmigratory individuals in a given population, quantifying the timing, duration and distance of migration and the ability to predict migratory movements. 2. Here, we propose a uniform statistical framework to (i) separate migration from other movement behaviours, (ii) quantify migration parameters without the need for arbitrary cut-off criteria and (iii) test predictability across individuals, time and space. 3. We first validated our novel approach by simulating data based on established theoretical movement patterns. We then formulated the expected shapes of squared displacement patterns as nonlinear models for a suite of movement behaviours to test the ability of our method to distinguish between migratory movement and other movement types. 4. We then tested our approached empirically using 108 wild Global Positioning System (GPS)-collared moose Alces alces in Scandinavia as a study system because they exhibit a wide range of movement behaviours, including resident, migrating and dispersing individuals, within the same population. Applying our approach showed that 87% and 67% of our Swedish and Norwegian subpopulations, respectively, can be classified as migratory. 5. Using nonlinear mixed effects models for all migratory individuals we showed that the distance, timing and duration of migration differed between the sexes and between years, with additional individual differences accounting for a large part of the variation in the distance of migration but not in the timing or duration. Overall, the model explained most of the variation (92%) and also had high predictive power for the same individuals over time (69%) as well as between study populations (74%). 6. The high predictive ability of the approach suggests that it can help increase our understanding of the drivers of migration and could provide key quantitative information for understanding and managing a broad range of migratory species.

  • 3. Bystrom, P
    Recruitment pulses induce cannibalistic giants in Arctic char2006In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 75, no 2, p. 434-444Article in journal (Refereed)
    Abstract [en]

    Recent theoretical studies on the population dynamic consequences of cannibalism have focused on mechanisms behind the emergence of large cannibals (giants) in size-structured populations. Theoretically, giants emerge when a strong recruiting cohort imposes competition induced mortality on stunted adults, but also provides a profitable resource for a few adults that accelerate in growth and reach giant sizes. Here the effects of a recruitment pulse on the individual and population level in an allopatric Arctic char population have been studied over a 5-year period and these results were contrasted with theoretical model predictions for the conditions necessary for the emergence of cannibalistic giants. The recruitment pulse had negative effects on invertebrate resource abundance, and the decrease in body condition and increase in mortality of adult char suggested that strong intercohort competition took place. The frequency of cannibalism increased and a few char accelerated in growth and reached ‘giant’ sizes. The main discrepancy between model predictions and field data was the apparently small effect the recruited cohort had on resources and adult char performance during their first summer. Instead, the effects became pronounced when the cohort was 1 year old. This mismatch between model predictions and field observations was suggested to be due to the low per capita fecundity in char and the restricted nearshore habitat use in young-of-the-year (YOY) char. This study provides empirical evidence that the emergence of giants is associated with the breakthrough of a strong recruiting cohort and also suggests that the claimed stable char populations with large cannibals may instead be populations with dynamic size structure that results in intermittent breakthroughs of recruitment pulses, providing the conditions necessary for char to enter the cannibalistic niche. The data suggest that increased recruit survival through restricted habitat use may destabilize dynamics and cause the emergence of giants. However, they also suggest that this does not necessarily develop into populations with bi-modal size structure in populations with low per capita fecundity and size- and density-dependent habitat use of recruiting cohorts.

  • 4. Liess, Antonia
    et al.
    Guo, Junwen
    Lind, Martin I.
    Rowe, Owen
    Cool tadpoles from Arctic environments waste fewer nutrients – high gross growth efficiencies lead to low consumer-mediated nutrient recycling in the North2015In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 84, no 6, p. 1744-1756Article in journal (Refereed)
    Abstract [en]

    * Endothermic organisms can adapt to short growing seasons, low temperatures and nutrient limitation by developing high growth rates and high gross growth efficiencies (GGEs). Animals with high GGEs are better at assimilating limiting nutrients and thus should recycle (or lose) fewer nutrients. Longer guts in relation to body mass may facilitate higher GGE under resource limitation. * Within the context of ecological stoichiometry theory, this study combines ecology with evolution by relating latitudinal life-history adaptations in GGE, mediated by gut length, to its ecosystem consequences, such as consumer-mediated nutrient recycling. * In common garden experiments, we raised Rana temporaria tadpoles from two regions (Arctic/Boreal) under two temperature regimes (18/23 °C) crossed with two food quality treatments (high/low-nitrogen content). We measured tadpole GGEs, total nutrient loss (excretion + egestion) rates and gut length during ontogeny. * In order to maintain their elemental balance, tadpoles fed low-nitrogen (N) food had lower N excretion rates and higher total phosphorous (P) loss rates than tadpoles fed high-quality food. In accordance with expectations, Arctic tadpoles had higher GGEs and lower N loss rates than their low-latitude conspecifics, especially when fed low-N food, but only in ambient temperature treatments. Arctic tadpoles also had relatively longer guts than Boreal tadpoles during early development. * That temperature and food quality interacted with tadpole region of origin in affecting tadpole GGEs, nutrient loss rates and relative gut length, suggests evolved adaptation to temperature and resource differences. With future climate change, mean annual temperatures will increase. Additionally, species and genotypes will migrate north. This will change the functioning of Boreal and Arctic ecosystems by affecting consumer-mediated nutrient recycling and thus affect nutrient dynamics in general. Our study shows that evolved latitudinal adaption can change key ecosystem functions.

  • 5. Tenow, O.
    et al.
    Nilssen, A. C.
    Bylund, H.
    Hogstad, O.
    Waves and synchrony in Epirrita autumnata/Operophtera brumata outbreaks. I. Lagged synchrony: regionally, locally and among species2007In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 76, no 2, p. 258-268Article in journal (Refereed)
    Abstract [en]

    1. In 1990-2003, during a complete 10-year outbreak cycle, the synchrony of the birch defoliating outbreaks of the geometrids Epirrita autumnata and Operophtera brumata was studied quantitatively in the northern part of the Fennoscandian mountain chain (the Scandes). Data were supplemented with similar data from 1964 to 1966 and historical information. A 30-year series of field data from one locality in southern Scandes made possible interregional comparisons. 2. In 1991, outbreaks started in north-eastern Fennoscandia and moved westward like a wave and reached the outer coast of north-western Norway in about 2000. This wave is a new observation. In the same years, a previously documented outbreak wave moved southward along the Scandes. 3. Outbreak periods have usually occurred around the middle of each decade. Seemingly unrelated population peaks at the decadal shift 2000 were reported from islands at the coast of north-western Norway. They are shown here to have been the final ripples of the east-west wave. 4. At some localities, O. brumata peaked 2 years after E. autumnata. A lag of 1 or 2 years also occurred at the locality in southern Scandes. This interspecific time lag is a new observation. In accordance with the north-south wave, a time-lag of 1-2 years occurred between the fluctuations of northern and southern E. autumnata and O. brumata populations. 5. The population peak of E. autumnata occurred 1 year earlier at one locality than at a nearby locality. This pattern and particular altitudinal shifts of the O. brumata population density at these localities repeated in two outbreak periods. This indicates that, for example, local climate may modify outbreak synchrony between nearby localities. 6. At the same localities, O. brumata peaked first at one altitude and 1 or 2 years later at another altitude. This vertical lag is a new observation. 7. E. autumnata shows fluctuation traits similar to some other cyclic animals, e.g. the larch budmoth in the European Alps, some European tetraonid birds and the Canadian snow-shoe hare. These similarities (and dissimilarities) in intra- and interspecific synchronies and causes of E. autumnata and O. brumata synchronies, regionally, locally and among the two species are discussed.

  • 6. Tenow, Olle
    et al.
    Nilssen, Arne C.
    Bylund, Helena
    Pettersson, Rickard
    Battisti, Andrea
    Bohn, Udo
    Caroulle, Fabien
    Ciornei, Constantin
    Csóka, György
    Delb, Horst
    De Prins, Willy
    Glavendekić, Milka
    Gninenko, Yuri I.
    Hrašovec, Boris
    Matošević, Dinka
    Meshkova, Valentyna
    Moraal, Leen
    Netoiu, Constantin
    Pajares, Juan
    Rubtsov, Vasily
    Tomescu, Romica
    Utkina, Irina
    Geometrid outbreak waves travel across Europe2013In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 82, no 1, p. 84-95Article in journal (Refereed)
    Abstract [en]

    * We show that the population ecology of the 9- to 10-year cyclic, broadleaf-defoliating winter moth (Operophtera brumata) and other early-season geometrids cannot be fully understood on a local scale unless population behaviour is known on a European scale. * Qualitative and quantitative data on O. brumata outbreaks were obtained from published sources and previously unpublished material provided by authors of this article. Data cover six decades from the 1950s to the first decade of twenty-first century and most European countries, giving new information fundamental for the understanding of the population ecology of O. brumata. * Analyses on epicentral, regional and continental scales show that in each decade, a wave of O. brumata outbreaks travelled across Europe. * On average, the waves moved unidirectionally ESE–WNW, that is, toward the Scandes and the Atlantic. When one wave reached the Atlantic coast after 9–10 years, the next one started in East Europe to travel the same c. 3000 km distance. * The average wave speed and wavelength was 330 km year−1 and 3135 km, respectively, the high speed being incongruous with sedentary geometrid populations. * A mapping of the wave of the 1990s revealed that this wave travelled in a straight E–W direction. It therefore passed the Scandes diagonally first in the north on its way westward. Within the frame of the Scandes, this caused the illusion that the wave moved N–S. In analogy, outbreaks described previously as moving S–N or occurring contemporaneously along the Scandes were probably the result of continental-scale waves meeting the Scandes obliquely from the south or in parallel. * In the steppe zone of eastern-most and south-east Europe, outbreaks of the winter moth did not participate in the waves. Here, broadleaved stands are small and widely separated. This makes the zone hostile to short-distance dispersal between O. brumata subpopulations and prevents synchronization within meta-populations. * We hypothesize that hostile boundary models, involving reciprocal host–herbivore–enemy reactions at the transition between the steppe and the broadleaved forest zones, offer the best explanation to the origin of outbreak waves. These results have theoretical and practical implications and indicate that multidisciplinary, continentally coordinated studies are essential for an understanding of the spatio-temporal behaviour of cyclic animal populations.

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