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  • 1.
    Andersson, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen. Stockholms universitet, Stockholm Resilience Centre.
    Bodin, Örjan
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen. Stockholms universitet, Stockholm Resilience Centre.
    Practical tool for landscape planning? An empirical investigation of network based models of habitat fragmentation.2009Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, nr 1, s. 123-132Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presents a graph-theoretical modelling approach using daily movements and habitat demands of different target bird species in an urban context to assess: 1) habitable land cover types, 2) threshold distances between patches of habitat, 3) the required minimum accessible habitat areas and 4) the effects of barriers and stepping stones. The modelling approach is tested using empirical data from field surveys in the urban area of Stockholm, Sweden.

    The results show that groups of small habitat patches can house the same species as larger contiguous patches as long as they are perceived as functionally connected by the inhabitant organisms. Furthermore, we found that binary habitat/non-habitat representations of the landscape could roughly explain the variation in species occurrence, as long as habitat was properly defined. However, the explanatory power of the landscape models increased when features of matrix heterogeneity such as stepping stones and barriers were accounted for.

    Synthesis and application: in a world where forest ecosystems are becoming increasingly fragmented there is an urgent need to find comprehensive and scientifically relevant methods for managing and planning ecosystems. This study shows that: 1) groups of well placed small habitat patches can, together, be sufficient to attract birds in intensively developed areas, 2) the presented modelling approach can help identify such groups of patches, 3) matrix heterogeneity should preferably be accounted for, and 4) proper assessments of habitable land cover types are important. Finally, we argue that the modelling approach applied here may substantially improve landscape management and planning at scales ranging from whole landscapes down to neighbourhoods.

  • 2.
    Angerbjörn, Anders
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Tannerfeldt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Lundberg, Håkan
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Geographical and temporal patterns of lemming population dynamics in Fennoscandia2001Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 24, nr 3, s. 298-308Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a long-lasting debate in ecology on cyclicity, synchrony and time lags of lemming population fluctuations. We have analysed 137 yr of previously published population data on the Norwegian lemming Lemmus lemmus in ten geographic regions of Fennoscandia. The dominating pattern was synchronous 4-yr cycles. There was no support for the hypothesis of a north-south gradient in cycle length. However. we found periods of prolonged interruptions in the cyclicity, which were more common in northern areas. Wa found a high degree of synchrony between regions. with only a weak relationship to distance, The observed pattern in lemming population dynamics was more consistent with effects from extrinsic factors, such as climate. than intrinsic factors. such as dispersal.

  • 3. Aston, Eoghan A.
    et al.
    Williams, Gareth J.
    Green, J. A. Mattias
    Davies, Andrew J.
    Wedding, Lisa M.
    Gove, Jamison M.
    Jouffray, Jean-Baptiste
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. Royal Swedish Academy of Sciences, Sweden.
    Jones, Timothy T.
    Clark, Jeanette
    Scale-dependent spatial patterns in benthic communities around a tropical island seascape2019Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 42, nr 3, s. 578-590Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding and predicting patterns of spatial organization across ecological communities is central to the field of landscape ecology, and a similar line of inquiry has begun to evolve sub-tidally among seascape ecologists. Much of our current understanding of the processes driving marine community patterns, particularly in the tropics, has come from small-scale, spatially-discrete data that are often not representative of the broader seascape. Here we expand the spatial extent of seascape ecology studies and combine spatially-expansive in situ digital imagery, oceanographic measurements, spatial statistics, and predictive modeling to test whether predictable patterns emerge between coral reef benthic competitors across scales in response to intra-island gradients in physical drivers. We do this around the entire circumference of a remote, uninhabited island in the central Pacific (Jarvis Island) that lacks the confounding effects of direct human impacts. We show, for the first time, that competing benthic groups demonstrate predictable scaling patterns of organization, with positive autocorrelation in the cover of each group at scales < similar to 1 km. Moreover, we show how gradients in subsurface temperature and surface wave power drive spatially-abrupt transition points in group dominance, explaining 48-84% of the overall variation in benthic cover around the island. Along the western coast, we documented ten times more sub-surface cooling-hours than any other part of the coastline, with events typically resulting in a drop of 1-4 degrees C over a period of < 5 h. These high frequency temperature fluctuations are indicative of upwelling induced by internal waves and here result in localized nitrogen enrichment (NO2 + NO3) that promotes hard coral dominance around 44% of the island's perimeter. Our findings show that, in the absence of confounding direct human impacts, the spatial organization of coral reef benthic competitors are predictable and somewhat bounded across the seascape by concurrent gradients in physical drivers.

  • 4.
    Auffret, Alistair G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Cousins, Sara A.O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Grassland connectivity by motor vehicles and grazing livestock2013Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, nr 10, s. 1150-1157Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In addition to habitat loss and fragmentation, agricultural change has led to a change in seed dispersal processes in therural landscape through a loss of structural and functional connectivity. Here, human-mediated dispersal vectors areprevalent, and we explored whether the loss of connectivity via free-ranging livestock could be mitigated by the increasein roads and motor vehicles. We found that structurally, 39% of all valuable semi-natural grassland habitats in southernSweden are adjacent to public road verges, which in the rural landscape are often considered to be suitable habitat forgrassland species. Additionally, by collecting mud attached to cars and farming machinery and manure from livestock(cattle, horse, sheep) grazing semi-natural grassland pasture, we found that motor vehicles are also capable seed dispers-ers. A similar number of species were dispersed by both vectors, although the composition of samples was quite different.Motor vehicles dispersed more grassland specialists than invasive species, although in much lower abundances than didgrazing livestock. Despite these differences, motor vehicles were found to be able to disperse species with the same kindsof dispersal traits as livestock. A high number of seeds, species and specialists in manure samples means that greater move-ment of livestock is desirable to increase functional grassland connectivity. However, effective management could improvethe suitability of roadsides as grassland corridors and increase the availability of seeds for long-distance human-mediateddispersal via cars and tractors. Our results suggest that in many rural landscapes, connectivity by road networks couldhelp mediate habitat loss and fragmentation of grasslands. However, such effects can be context dependent, and the con-nectivity provided by roads could have serious negative consequences in other regions.

  • 5. Brehm, Gunnar
    et al.
    Zeuss, Dirk
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Colwell, Robert K.
    Moth body size increases with elevation along a complete tropical elevational gradient for two hyperdiverse clades2019Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 42, nr 4, s. 632-642Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The body size of an animal is probably its most important functional trait. For arthropods, environmental drivers of body size variation are still poorly documented and understood, especially in tropical regions. We use a unique dataset for two species-rich, phylogenetically independent moth taxa (Lepidoptera: Geometridae; Arctiinae), collected along an extensive tropical elevational gradient in Costa Rica, to investigate the correlates and possible causes of body-size variation. We studied 15 047 specimens (794 species) of Geometridae and 4167 specimens (308 species) of Arctiinae to test the following hypotheses: 1) body size increases with decreasing ambient temperature, as predicted by the temperature-size rule; 2) body size increases with increasing rainfall and primary productivity, as predicted from considerations of starvation resistance; and 3) body size scales allometrically with wing area, as elevation increases, such that wing loading (the ratio of body size to wing area) decreases with increasing elevation to compensate for lower air density. To test these hypotheses, we examined forewing length as a proxy for body size in relation to ambient temperature, rainfall, vegetation index and elevation as explanatory variables in linear and polynomial spatial regression models. We analysed our data separately for males and females using two principal approaches: mean forewing length of species at each site, and mean forewing length of complete local assemblages, weighted by abundance. Body size consistently increased with elevation in both taxa, both approaches, both sexes, and also within species. Temperature was the best predictor for this pattern (-0.98 < r < -0.74), whereas body size was uncorrelated or weakly correlated with rainfall and enhanced vegetation index. Wing loading increased with elevation. Our results support the temperature-size rule as an important mechanism for body size variation in arthropods along tropical elevational gradients, whereas starvation resistance and optimization of flight mechanics seem to be of minor importance.

  • 6. Bruun, Hans Henrik
    et al.
    Österdahl, Sofia
    Moen, Jon
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Distinct patterns in alpine vegetation around dens of the Arctic fox2005Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 28, nr 1, s. 81-87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The arctic fox Alopex lugopus excavates its dens in gravely ridges and hillocks, and creates a local environment quite distinct from the surrounding tundra or heath landscape. In northern Sweden, the vegetation of 18 dens of the arctic fox was investigated, as well as reference areas off the dens but in geologically and topographically similar locations. The species composition showed considerable differences between den and reference areas, with grasses and forbs occurring more abundantly on the dens, and evergreen dwarf-shrubs occurring more in reference areas. The effect of the foxes' activities is thought to be either through mechanical soil disturbance, or through nutrient enrichment via scats, urine, and carcasses. This was expected to result in differences in plant traits with key functional roles in resource acquisition and regeneration, when comparing dens with reference areas. We hypothesised that the community mean of specific leaf area (SLA) would differ if nutrient enrichment was the more important effect, and that seed weight, inversely proportional to seed number per ramet and hence dispersal ability, would differ if soil disturbance was the more important effect. Specific leaf area showed a significant difference, indicating nutrient enrichment to be the most important effect of the arctic fox on the vegetation on its dens. Arctic foxes act as ecosystems engineers on a small scale, maintaining niches for relatively short-lived nutrient demanding species on their dens in spite of the dominance of long-lived ericaceous dwarf-shrubs in the landscape matrix. Thus, foxes contribute to the maintenance of species richness on the landscape level.

  • 7.
    Cassel-Lundhagen, Anna
    et al.
    SLU, Uppsala.
    Tammaru, Toomas
    Tartu University, Estland.
    Windig, Jack J
    Wageningen University, Nederländerna.
    Ryrholm, Nils
    Högskolan i Gävle.
    Nylin, Sören
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Are peripheral populations special? Congruent patterns in two butterfly species2009Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, nr 4, s. 591-600Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Populations at range margins may be genetically different from more central ones for a number of mutually non-exclusive reasons. Specific selection pressures may operate in environments that are more marginal for the species. Genetic drift may also have a strong effect in these populations if they are small, isolated and/or have experienced significant bottlenecks during the colonisation phase. The question if peripheral populations are special, and if yes then how and why, is of obvious relevance for speciation theory, as well as for conservation biology. To evaluate the uniqueness of populations at range margins and the influence of gene flow and selection, we performed a morphometric study of two grassland butterfly species: Coenonympha arcania and C. hero (Lepidoptera: Nymphalidae). The samples were collected from Swedish populations that are peripheral and isolated from the main area of the species distributions and from populations in the Baltic states that are peripheral but connected to the main area of the species distributions. These samples were compared to those from central parts of the species distributions. The isolated populations in both species differed consistently from both peripheral and central populations in their wing size and shape. We interpret this as a result of selection caused by differences in population structure in these isolated locations, presumably favoring different dispersal propensity of these butterflies. Alternative explanations based on colonisation history, latitudinal effects, inbreeding or phenotypic plasticity appear less plausible. As a contrast, the much weaker and seemingly random among-region differences in wing patterns are more likely to be ascribed to weaker selection pressures allowing genetic drift to be influential. In conclusion, both morphological data and results from neutral genetic markers in earlier studies of the same system provide congruent evidence of both adaptation and genetic drift in the isolated Swedish populations of both species.

  • 8. De Frenne, Pieter
    et al.
    Graae, Bente J.
    Kolb, Annette
    Shevtsova, Anna
    Baeten, Lander
    Brunet, Jorg
    Chabrerie, Olivier
    Cousins, Sara A. O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Decocq, Guillaume
    Dhondt, Rob
    Diekmann, Martin
    Gruwez, Robert
    Heinken, Thilo
    Hermy, Martin
    Oster, Mathias
    Saguez, Robert
    Stanton, Sharon
    Tack, Wesley
    Vanhellemont, Margot
    Verheyen, Kris
    An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient2011Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, nr 1, s. 132-140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.

  • 9.
    Eggertsen, Linda
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Goodell, Whitney
    Cordeiro, César
    Cossa, Damboia
    Bouças, Marcos
    Berkström, Charlotte
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Franco, João
    Ferreira, Carlos Eduardo
    Bandeira, Salomão
    Gullström, Martin
    Where is the grass greenest? Influence of seascape structure and marine protected areas on fish distribution patterns in a seagrass-dominated landscapeInngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tropical seagrass beds are critical habitats for many resident- and nursery fish species. While numerous studies have explored factors that structure reef fish assemblages, few have investigated the relative influence of multiple factors at fine- and large spatial scales as well as MPAs on seagrass fish. To understand which are the most important factors structuring fish assemblages in tropical seagrass beds, and how this is related to life history of species, we investigated fish distribution patterns at 20 sites in 13 different seagrass beds across the Bazaruto Archipelago, Mozambique. Using boosted regression tree modelling, we assessed the influence of fine-scale variables (seagrass meadow characteristics) and seascape variables (distance to adjacent habitats) on abundance of four nursery taxa (Lutjanus fulviflamma, Lethrinus spp., Scarus ghobban and Gerres spp.) and two resident species (Pelates quadrilineatus and Leptoscarus vaigiensis). We found that seascape variables were generally more important than seagrass characteristics, and that the influence of different variables was highly taxon-specific. Fish distribution patterns in seagrass-dominated seascapes were related to life history traits of the species; nursery fish taxa were negatively correlated with distance to adult habitats, while resident species occurred in higher abundances far from reefs. Proximity to mangroves was important for taxa that utilised mangroves in addition to seagrass as nurseries. Most seascape variables influenced fish abundances on a large spatial scale (km). The influence of protected areas was taxon-specific, with stronger effects on resident species than on nursery species, with geographical placement shadowing potential effects of protection on fish abundance. Our results indicate that protection efforts in seagrass-dominated seascapes can have varying impacts on fish distribution, depending on the geographical location of the reserve. This highlights the importance of considering seascape arrangement and the ecology of targeted species for conservation and marine spatial planning in seagrass-dominated systems.

  • 10. Emerson, Brent C.
    et al.
    Kolm, Niclas
    Uppsala universitet, Zooekologi.
    Response to comments on Species diversity can drive speciation2007Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 30, nr 3, s. 334-338Artikkel i tidsskrift (Fagfellevurdert)
  • 11.
    Eriksson, Ove
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Species pools in cultural landscapes - niche construction, ecological opportunity and niche shifts2013Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, nr 4, s. 403-413Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This paper discusses the ecology of species that were favoured by the development of the cultural landscape in central and NW Europe beginning in the Neolithic and the Bronze Age, with a focus on mechanisms behind species responses to this landscape transformation. A fraction of species may have maintained their realized niches from the pre- agricultural landscape and utilized similar niches created by the landscape transformation. However, I suggest that many species responded by altering their niche relationships, and a conceptual model is proposed for this response, based on niche construction, ecological opportunity and niche shifts. Human-mediated niche construction, associated with clearing of forests and creation of pastures and fields promoted niche shifts towards open habitats, and species exploited the ecological opportunity provided by these created environments. This process was initially purely ecological, i.e. the new habitats must have been included in the original fundamental niche of the species. Two other features of human-mediated niche construction, increased interconnectivity and increased spatial stability of open habitats, resulted in species accumulating in the habitats of the constructed landscape. As a consequence, selection processes were initiated favouring traits promoting fitness in the constructed landscape. This process implied a feed-back to niche shifts, but now also including evolutionary changes in fundamental niches. I briefly discuss whether this model can be applied also to present-day anthropogenic impact on landscapes. A general conclusion is that ecological and evolutionary changes in species niches should be more explicitly considered in modeling and predictions of species response to present-day landscape and land-use changes.

  • 12. Gibbs, Melanie
    et al.
    Wiklund, Christer
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Van Dyck, Hans
    Temperature, rainfall and butterfly morphology: does life history theory match the observed pattern?2011Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, nr 2, s. 336-344Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Butterfly distribution and abundance is known to be influenced by temperature and rainfall. What is not clear, however, is how life history and flight morphological traits are affected by changes in local weather conditions. During the period 1989-1999, we explored the effects of ambient temperature and rainfall during larval development on adult phenotypic traits (body mass, forewing loading, forewing surface area and forewing length) in a Swedish population of the speckled wood butterfly Pararge aegeria. As different seasonal cohorts correspond to different developmental pathways (larval hibernating, pupal hibernating and directly developing), we analysed these morphological time series relative to developmental pathway. Phenotypic variation in response to the temperature and rainfall levels experienced during larval development differed in both magnitude and direction depending on the developmental pathway, and hence seasonal cohort, examined (i.e. there was a pathway-specific response). We suggest that through its developmental flexibility P. aegeria may be able to adjust to variation in weather conditions over time. Other less flexible species, however, may not be so fortunately buffered. To truly estimate the impact of climate change on biodiversity more fine-scale, local studies are required that examine the mechanisms underlying the response of species to climate change.

  • 13.
    Hambäck, Peter
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Bergman, K-O
    Bommarco, R
    Krauss, J
    Kuussarri, M
    Pöyry, J
    Öckinger, E
    Allometric density responses in butterflies: The response to small and large patches by small and large species.2010Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, s. 1149-1156Artikkel i tidsskrift (Fagfellevurdert)
  • 14.
    Herfindal, Ivar
    et al.
    Norwegian University of Science and Technology.
    Linnell, John D. C.
    Norwegian Institute for Nature Research.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Andersen, Roy
    Norwegian Institute for Nature Research.
    Eide, Nina E
    Norwegian Institute for Nature Research.
    Frafjord, Karl
    Tromsö University.
    Henttonen, Heikki
    Metla - Finnish Forest Research Institute.
    Kaikusalo, Asko
    Metla - Finnish Forest Research Institute.
    Mela, Matti
    Metsähallitus - Finnish Park and Forestry Service.
    Tannerfeldt, Magnus
    Swedish Polar Research Secretariat.
    Dalén, Love
    Swedish Museum of Natural History.
    Strand, Olav
    Norwegian Institute for Nature Research.
    Landa, Arild
    Norwegian Institute for Nature Research.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Population persistence in a landscape context: the case of endangered arctic fox populations in Fennoscandia2010Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, nr 5, s. 932-941Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Anthropogenic fragmentation of habitat and populations is recognized as one of the most important factors influencing loss of biodiversity. Since it is difficult to quantify demographic parameters in small populations, we need alternative methods to elucidate important factors affecting the viability of local populations. The Fennoscandian arctic fox inhabits a naturally fragmented alpine tundra environment, but historic anthropogenic impacts have further fragmented its distribution. After almost 80 yr of protection, the population remains critically endangered. Both intrinsic factors (related to the isolation and size of sub-populations) and extrinsic factors (related to environmental conditions influencing patch quality and interspecific competition) have been proposed as explanations for the lack of population growth. To distinguish between these hypotheses, we conducted a spatially explicit analysis that compares areas where the species has persisted with areas where it has become locally extinct. We used characteristics of the fragments of alpine tundra habitat and individual arctic fox breeding dens (including both currently active dens and historically active dens) within the fragments to evaluate the importance of habitat characteristics and connectivity in explaining variation in persistence within a fragment. The number of reproductive events in a fragment was related to the size of the fragment, but not more than expected following a 1:1 relationship, suggesting little effect of fragment size on the relative number of reproductions. The likelihood of a den being used for breeding was positively associated with factors minimising interspecific competition as well as increasing within-fragment connectivity. These results support the idea that the failure of Fennoscandian arctic fox to recover is caused by demographic factors that can be related to fine-scale Allee or Allee-like effects, as well as environmental influences related to increased competition and exclusion by red foxes

  • 15. Jacobi, Martin Nilsson
    et al.
    Andre, Carl
    Döös, Kristofer
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Jonsson, Per R.
    Identification of subpopulations from connectivity matrices2012Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 35, nr 11, s. 1004-1016Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dispersal on the landscape/seascape scale may lead to complex spatial population structure with non-synchronous demography and genetic divergence. In this study we present a novel approach to identify subpopulations and dispersal barriers based on estimates of dispersal probabilities on the landscape scale. A theoretical framework is presented where the landscape connectivity matrix is analyzed for clusters as a signature of partially isolated subpopulations. Identification of subpopulations is formulated as a minimization problem with a tuneable penalty term that makes it possible to generate population subdivisions with varying degree of dispersal restrictions. We show that this approach produces superior results compared to alternative standard methods. We apply this theory to a dataset of modeled dispersal probabilities for a sessile marine invertebrate with free-swimming larvae in the Baltic Sea. For a range of critical connectivities we produce a hierarchical partitioning into subpopulations spanning dispersal probabilities that are typical for both genetic divergence and demographic independence. The mapping of subpopulations suggests that the Baltic Sea includes a fine-scale (100600 km) mosaic of invisible dispersal barriers. An analysis of the present network of marine protected areas reveal that protection is very unevenly distributed among the suggested subpopulations. Our approach can be used to assess the location and strength of dispersal barriers in the landscape, and identify conservation units when extensive genotyping is prohibitively costly to cover necessary spatial and temporal scales, e.g. in spatial management of marine populations.

  • 16.
    Jonason, Dennis
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Ekroos, Johan
    Öckinger, Erik
    Helenius, Juha
    Kuussaari, Mikko
    Tiainen, Juha
    Smith, Henrik G.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Weak functional response to agricultural landscape homogenisation among plants, butterflies and birds2017Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 40, nr 10, s. 1221-1230Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Measures of functional diversity are expected to predict community responses to land use and environmental change because, in contrast to taxonomic diversity, it is based on species traits rather than their identity. Here, we investigated the impact of landscape homogenisation on plants, butterflies and birds in terms of the proportion of arable field cover in southern Finland at local (0.25 km2) and regional (> 10 000 km2) scales using four functional diversity indices: functional richness, functional evenness, functional divergence and functional dispersion. No uniform response in functional diversity across taxa or scales was found. However, in all cases where we found a relationship between increasing arable field cover and any index of functional diversity, this relationship was negative. Butterfly functional richness decreased with increasing arable field cover, as did butterfly and bird functional evenness. For butterfly functional evenness, this was only evident in the most homogeneous regions. Butterfly and bird functional dispersion decreased in homogeneous regions regardless of the proportion of arable field cover locally. No effect of landscape heterogeneity on plant functional diversity was found at any spatial scale, but plant species richness decreased locally with increasing arable field cover. Overall, species richness responded more consistently to landscape homogenisation than did the functional diversity indices, with both positive and negative effects across species groups. Functional diversity indices are in theory valuable instruments for assessing effects of land use scenarios on ecosystem functioning. However, the applicability of empirical data requires deeper understanding of which traits reliably capture species’ vulnerability to environmental factors and of the ecological interpretation of the functional diversity indices. Our study provides novel insights into how the functional diversity of communities changes in response to agriculturally derived landscape homogenisation; however, the low explanatory power of the functional diversity indices hampers the ability to reliably anticipate impacts on ecosystem functioning.

  • 17.
    Kolb, Gundula S.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Jerling, Lenn
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Essenberg, Carolina
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Palmborg, Cecilia
    Hambäck, Peter A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    The impact of nesting cormorants on plant and arthropod diversity2012Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 35, nr 8, s. 726-740Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seabirds can strongly affect several major factors correlated with species diversity by concentrating marine nutrients on their nesting islands and by physically disturbing island vegetation. In this study, we investigated the effects of nesting cormorants on the abundance, species richness, and composition of plants and arthropods (Coleoptera, Heteroptera, Araneae, and Chironomidae) on islands in Stockholm archipelago, Sweden. Nesting cormorants negatively affected plant species richness and vegetation cover and that changed plant species composition. The effect of nesting cormorants on island arthropods varied between feeding groups and sampling methods. Most orders did not change in abundance or species richness but some, such as coleopterans and spiders changed in species composition. Herbivorous coleopterans were generally negatively affected by cormorants whereas fungivorous species and scavengers were generally positively affected. In structural equation modeling we found that the effect of cormorants was sometimes direct, such as on scavengers, but many effects on island consumers were mediated by changes in vegetation caused by cormorant presence. Overall, arthropod communities were highly dissimilar between cormorant and reference islands, and we therefore conclude that nesting cormorants not only affect the diversity of their nesting islands but also of the archipelago as a whole. The total diversity in the archipelago may increase through regional increased habitat heterogeneity and by adding species which are favored by seabirds (e.g. scavenging and fungivorous coleopterans).

  • 18.
    Leimar, Olof
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för etologi.
    Norberg, Ulf
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för etologi.
    Wiklund, Christer
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Habitat preference and habitat exploration in two species of satyrine butterflies2003Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 26, s. 474-480Artikkel i tidsskrift (Fagfellevurdert)
  • 19.
    Lindborg, Regina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Cousins, Sara A. O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Eriksson, Ove
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Plant species response to land-use change - Campanula rotundifolia, Primula veris and Rhinanthus minor2005Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 28, nr 1, s. 29-36Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Land use change is a crucial driver behind species loss at the landscape scale. Hence, from a conservation perspective, species response to habitat degradation or improvement of habitat quality, is important to examine. By using indicator species it may be possible to monitor long-term survival of local populations associated with land use change. In this study we examined three potential indicator (response) species for species richness and composition in Scandinavian semi-natural grassland communities: Campanula rotundifolia, Primula veris and Rhinanthus minor. With field inventories and experiments we examined their response to present land use, habitat degradation and improvement of local habitat quality. At the time scale examined, C. rotundifolia was the only species responding to both habitat degradation and improvement of habitat quality. Neither R. minor nor P. veris responded positively to habitat improvements although both responded rapidly to direct negative changes in habitat quality. Even though C. rotundifolia responded quickly to habitat degradation, it did not disappear completely from the sites. Instead, the population structure changed in terms of decreased population size and flowering frequency. It also showed an ability to form remnant populations which may increase resilience of local habitats. Although P. veris and especially R. minor responded rapidly to negative environmental changes and may be useful as early indicators of land use change, it is desirable that indicators respond to both degradation and improvement of habitat quality. Thus, C. rotundifolia is a better response species for monitoring effects of land use change and conservation measures, provided that both local and regional population dynamics are monitored over a long time period.

  • 20.
    Lindborg, Regina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Helm, Aveliina
    Bommarco, Riccardo
    Heikkinen, Risto K.
    Kuehn, Ingolf
    Pykala, Juha
    Paertel, Meelis
    Effect of habitat area and isolation on plant trait distribution in European forests and grasslands2012Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 35, nr 4, s. 356-363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A number of studies show contrasting results in how plant species with specific life-history strategies respond to fragmentation, but a general analysis on whether traits affect plant species occurrences in relation to habitat area and isolation has not been performed. We used published data from forests and grasslands in north-central Europe to analyse if there are general patterns of sensitivity to isolation and dependency of area for species using three traits: life-span, clonality, and seed weight. We show that a larger share of all forest species was affected by habitat isolation and area as compared to grassland species. Persistence-related traits, life-span and clonality, were associated to habitat area and the dispersal and recruitment related trait, seed weight, to isolation in both forest and grassland patches. Occurrence of clonal plant species decreased with habitat area, opposite to non-clonal plant species, and long-lived plant species decreased with grassland area. The directions of these responses partly challenge some earlier views, suggesting that further decrease in habitat area will lead to a change in plant species community composition, towards relatively fewer clonal and long-lived plants with large seeds in small forest patches and fewer clonal plants with small seeds in small grassland patches. It is likely that this altered community has been reached in many fragmented European landscapes consisting of small and isolated natural and semi-natural patches, where many non-clonal and short-lived species have already disappeared. Our study based on a large-scale dataset reveals general and useful insights concerning area and isolation effects on plant species composition that can improve the outcome of conservation and restoration efforts of plant communities in rural landscapes.

  • 21.
    Lönnell, Niklas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Jonsson, Bengt Gunnar
    Hylander, Kristoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Production of diaspores at the landscape level regulates local colonization: an experiment with a spore-dispersed moss2014Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 37, nr 6, s. 591-598Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Effective dispersal is crucial to species inhabiting transient substrates in order for them to be able to persist in a landscape. Bryophytes, pteridophytes, lichens and fungi all have wind-dispersed small diaspores and can be efficiently dispersed if their diaspores reach air masses above canopy height. However, empirical data on dispersal over landscape scales are scarce. We investigated how the colonization of an acrocarpous clay-inhabiting pioneer moss, Discelium nudum, varied between sites that differed in connectivity to potential dispersal sources at spatial scales from 1 to 20 km in a region in northern Sweden. We recorded the colonization on ˜25 introduced clay heaps at each of 14 experimental sites some months after the dispersal period. The colonization rate ranged from 0–82% and had a statistically significant relationship with a proxy for potential habitats (amount of clay-dominated soil) in a buffer of 20 km radius surrounding the experimental sites (and also weakly with the amount of substrate in a 10 km buffer). There were no significant relationships between colonization rate and connectivity at smaller scales (1 and 5 km). We made a rough estimate of the number of spores available for dispersal in a landscape, given the amount of clay-dominated soil, by recording the number of Discelium nudum colonies in two 25 × 25 km landscapes. The estimated available spore numbers in the different 20 km buffers were of the same order of magnitude as the deposition densities at the experimental sites calculated from the colonization rates. The results suggest that the spores of species with scattered occurrences and small diaspores (25 μm) in open landscapes can be deposited over extensive areas, at rates high enough to drive colonization patterns. This also implies that regional connectivity may be more important than local connectivity for these kinds of species.

  • 22.
    Meineri, Eric
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Hylander, Kristoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Fine-grain, large-domain climate models based on climate station and comprehensive topographic information improve microrefugia detection2017Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 40, nr 8, s. 1003-1013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Large-domain species distribution models (SDMs) fail to identify microrefugia, as they are based on climate estimates that are either too coarse or that ignore relevant topographic climate-forcing factors. Climate station data are considered inadequate to produce such estimates, a viewpoint we challenge here. Using climate stations and topographic data, we developed three sets of large-domain (450 000 km(2)), fine-grain (50m) temperature grids accounting for different levels of topographic complexity. Using these fine-grain grids and the Worldclim data, we fitted SDMs for 78 alpine species over Sweden, and assessed over-versus underestimations of local extinction and area of microrefugia by comparing modelled distributions at species' rear edges. Accounting for well-known topographic climate-forcing factors improved our ability to model fine-scale climate, despite using only climate station data. This approach captured the effect of cool air pooling, distance to sea, and relative humidity on local-scale temperature, but the effect of solar radiation could not be accurately accounted for. Predicted extinction rate decreased with increasing spatial resolution of the climate models and with increasing number of topographic climate-forcing factors accounted for. About half of the microrefugia detected in the most topographically complete models were not detected in the coarser SDMs and in the models calibrated from climate variables extracted from elevation only. Although major limitations remain, climate station data can potentially be used to produce fine-grain topoclimate grids, opening up the opportunity to model local-scale ecological processes over large domains. Accounting for the topographic complexity encountered within landscapes permits the detection of microrefugia that would otherwise remain undetected. Topographic heterogeneity is likely to have a massive impact on species persistence, and should be included in studies on the effects of climate change.

  • 23. Moreira, Xoaquín
    et al.
    Castagneyrol, Bastien
    Abdala-Roberts, Luis
    Berny-Mier y Teran, Jorge C.
    Timmermans, Bart G. H.
    Bruun, Hans Henrik
    Covelo, Felisa
    Glauser, Gaétan
    Rasmann, Sergio
    Tack, Ayco J. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Latitudinal variation in plant chemical defences drives latitudinal patterns of leaf herbivory2018Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 41, nr 7, s. 1124-1134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A long-standing paradigm in ecology holds that herbivore pressure and thus plant defences increase towards lower latitudes. However, recent work has challenged this prediction where studies have found no relationship or opposite trends where herbivory or plant defences increase at higher latitudes. Here we tested for latitudinal variation in herbivory, chemical defences (phenolic compounds), and nutritional traits (phosphorus and nitrogen) in leaves of a long-lived tree species, the English oak Quercus robur. We further investigated the underlying climatic and soil factors associated with such variation. Across 38 populations of Q. robur distributed along an 18 degrees latitudinal gradient, covering almost the entire latitudinal and climatic range of this species, we observed strong but divergent latitudinal gradients in leaf herbivory and leaf chemical defences and nutrients. As expected, there was a negative relationship between latitude and leaf herbivory where oak populations from lower latitudes exhibited higher levels of leaf herbivory. However, counter to predictions there was a positive relationship between leaf chemical defences and latitude where populations at higher latitudes were better defended. Similarly, leaf phosphorus and nitrogen increased with latitude. Path analysis indicated a significant (negative) effect of plant chemical defences (condensed tannins) on leaf herbivory, suggesting that the latitudinal gradient in leaf herbivory was driven by an inverse gradient in defensive investment. Leaf nutrients had no independent influence on herbivory. Further, we found significant indirect effects of precipitation and soil porosity on leaf herbivory, which were mediated by plant chemical defences. These findings suggest that abiotic factors shape latitudinal variation in plant defences and that these defences in turn underlie latitudinal variation in leaf herbivory. Overall, this study contributes to a better understanding of latitudinal variation in plant-herbivore interactions by determining the identity and modus operandi of abiotic factors concurrently shaping plant defences and herbivory.

  • 24. Ockinger, Erik
    et al.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). Stockholms universitet, Stockholm Resilience Centre.
    Sjödin, N. Erik
    Bommarco, Riccardo
    Landscape matrix modifies richness of plants and insects in grassland fragments2012Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 35, nr 3, s. 259-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is an increasing awareness that not only area and isolation, but also the characteristics of the landscape surrounding habitat patches influence population persistence and species diversity in fragmented landscapes. In this study, we examine the effects of grassland fragmentation and land use in the landscape matrix (on a 2 km scale) on species richness of plants, butterflies, bees and hoverflies. These organisms were studied in replicated remnant patches of different sizes and isolation, embedded in landscapes dominated either by forest, arable land or a mix of these. We found positive effects of patch area on species richness of the three insect taxa, but not of plants. Isolation had a negative effect only on hoverflies. Matrix type had contrasting effects on the studied taxa. Species richness of plants and butterflies was lowest in patches in landscapes dominated by arable land and highest in forest-dominated landscapes. For hoverflies, the negative effect of small patch area was strongest in forest-dominated landscapes, and there was a similar non-significant trend for bees. Our study shows the importance of considering matrix characteristics when studying responses to habitat fragmentation. Differences in matrix response among organism groups probably impinge on differing mechanisms. A forest matrix is likely to provide additional resources for butterflies but either constitute a barrier to dispersal or deprive resources as compared to an arable matrix for hoverflies. Enhanced plant diversity in grassland patches embedded in forested landscapes can be explained by habitat generalists more easily invading these patches, or by an unpaid extinction debt in these landscapes.

  • 25. Ranc, Nathan
    et al.
    Santini, Luca
    Rondinini, Carlo
    Boitani, Luigi
    Poitevin, Françoise
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Maiorano, Luigi
    Performance tradeoffs in target-group bias correction for species distribution models2017Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 40, nr 9, s. 1076-1087Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Species distribution models (SDMs) are often calibrated using presence-only datasets plagued with environmental sampling bias, which leads to a decrease of model accuracy. In order to compensate for this bias, it has been suggested that background data (or pseudoabsences) should represent the area that has been sampled. However, spatially-explicit knowledge of sampling effort is rarely available. In multi-species studies, sampling effort has been inferred following the target-group (TG) approach, where aggregated occurrence of TG species informs the selection of background data. However, little is known about the species-specific response to this type of bias correction. The present study aims at evaluating the impacts of sampling bias and bias correction on SDM performance. To this end, we designed a realistic system of sampling bias and virtual species based on 92 terrestrial mammal species occurring in the Mediterranean basin. We manipulated presence and background data selection to calibrate four SDM types. Unbiased (unbiased presence data) and biased (biased presence data) SDMs were calibrated using randomly distributed background data. We used real and TG-estimated sampling efforts in background selection to correct for sampling bias in presence data. Overall, environmental sampling bias had a deleterious effect on SDM performance. In addition, bias correction improved model accuracy, and especially when based on spatially-explicit knowledge of sampling effort. However, our results highlight important species-specific variations in susceptibility to sampling bias, which were largely explained by range size: widely-distributed species were most vulnerable to sampling bias and bias correction was even detrimental for narrow-ranging species. Furthermore, spatial discrepancies in SDM predictions suggest that bias correction effectively replaces an underestimation bias with an overestimation bias, particularly in areas of low sampling intensity. Thus, our results call for a better estimation of sampling effort in multispecies system, and cautions the uninformed and automatic application of TG bias correction.

  • 26. Reinecke, J.
    et al.
    Wulf, M.
    Baeten, L.
    Brunet, J.
    Decocq, G.
    De Frenne, G.
    Diekmann, M.
    Graae, B. J.
    Heinken, T.
    Hermy, M.
    Jamoneau, A.
    Lenoir, J.
    Plue, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Orczewska, A.
    Van Calster, H.
    Verheyen, K.
    Naaf, T.
    Acido- and neutrophilic temperate forest plants display distinct shifts in ecological pH niche across north-western Europe2016Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 39, nr 12, s. 1164-1175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ecological niches of organisms vary across geographical space, but niche shift patterns between regions and the underlying mechanisms remain largely unexplored. We studied shifts in the pH niche of 42 temperate forest plant species across a latitudinal gradient from northern France to boreo-nemoral Sweden. We asked 1) whether species restrict their niches with increasing latitude as they reach their northern range margin (environmental constraints); 2) whether species expand their niches with increasing latitude as regional plant species richness decreases (competitive release); and 3) whether species shift their niche position toward more acidic sites with increasing latitude as the relative proportion of acidic soils increases (local adaptation). Based on 1458 vegetation plots and corresponding soil pH values, we modelled species response curves using Huisman-Olff-Fresco models. Four niche measures (width, position, left and right border) were compared among regions by randomization tests. We found that with increasing latitude, neutrophilic species tended to retreat from acidic sites, indicating that these species retreat to more favorable sites when approaching their range margin. Alternatively, these species might benefit from enhanced nitrogen deposition on formerly nutrient-poor, acidic sites in southern regions or lag behind in post-glacial recolonization of potential habitats in northern regions. Most acidophilic species extended their niche toward more base-rich sites with increasing latitude, indicating competitive release from neutrophilic species. Alternatively, acidophilic species might benefit from optimal climatic conditions in the north where some have their core distribution area. Shifts in the niche position suggested that local adaptation is of minor importance. We conclude that shifts in the pH niche of temperate forest plants are the rule, but the directions of the niche shifts and possible explanations vary. Our study demonstrates that differentiating between acidophilic and neutrophilic species is crucial to identify general patterns and underlying mechanisms.

  • 27. Rohner, Patrick T.
    et al.
    Pitnick, Scott
    Blanckenhorn, Wolf U.
    Snook, Rhonda R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Bächli, Gerhard
    Lüpold, Stefan
    Interrelations of global macroecological patterns in wing and thorax size, sexual size dimorphism, and range size of the Drosophilidae2018Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 41, nr 10, s. 1707-1717Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Support for macroecological rules in insects is mixed, with potential confounding interrelations between patterns rarely studied. We here investigate global patterns in body and wing size, sexual size dimorphism and range size in common fruit flies (Diptera: Drosophilidae) and explore potential interrelations and the predictive power of Allen's, Bergmann's, Rensch's and Rapoport's rules. We found that thorax length (r2 = 0.05) and wing size (r2 = 0.09) increased with latitude, supporting Bergmann's rule. Contrary to patterns often found in endothermic vertebrates, relative wing size increased towards the poles (r2 = 0.12), a pattern against Allen's rule, which we attribute to selection for increased flight capacity in the cold. Sexual size dimorphism decreased with size, evincing Rensch's rule across the family (r2 = 0.14). Yet, this pattern was largely driven by the virilis–repleta radiation. Finally, range size did not correlate with latitude, although a positive relationship was present in a subset of the species investigated, providing no convincing evidence for Rapoport's rule. We further found little support for confounding interrelations between body size, wing loading and range size in this taxon. Nevertheless, we demonstrate that studying several traits simultaneously at minimum permits better interpretation in case of multiple, potentially conflicting trends or hypotheses concerning the macroecology of insects.

  • 28.
    Sandman, Antonia Nyström
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Wikström, Sofi A. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Blomqvist, Mats
    Kautsky, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Isaeus, Martin
    Scale-dependent influence of environmental variables on species distribution: a case study on five coastal benthic species in the Baltic Sea2013Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, nr 3, s. 354-363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Statistical modelling can be used to relate biological survey data to environmental factors, thereby providing a basis for predictive mapping of species or communities. Although environmental variables vary and influence biota at different scales, models are often fitted without discussion of how scale dependency influences the results. In this study, we analysed the relative importance of environmental factors for the distribution of aquatic species as a function of extent, using data on the cover of five common benthic species (four macrophytes and one animal), from 1731 sites along the Swedish Baltic Sea coast. We modelled the cover and distribution of the five species in relation to salinity, depth, slope, wave exposure and substrate in scale steps from 25 to 1500 km, and analysed the relative contribution of the environmental variables to each species model. The average total deviance explained by the models was generally quite high, and decreased with increasing scale for all macrophyte species, while it increased for the animal, the Baltic Sea blue mussel Mytilus edulis. The relative contribution of different environmental variables changed with scale, and responses also differed between species. The average contribution of salinity increased for all species when moving from local to Baltic Sea scale, and for the Baltic Sea blue mussel it was the single most important factor at the Baltic Sea scale. The average contribution of depth decreased with increasing scale for all species. However, regardless of scale, depth was the most important environmental factor to explain the distribution of all but one of the investigated macrophyte species. This shows that fine scale predictor variables can be of major importance also for species distribution models covering large areas.

  • 29.
    Schmalholz, Martin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Hylander, Kristoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Microtopography creates small-scale refugia for boreal bryophytes during clear-cut loggingInngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The biotic response of ecological systems to disturbances has traditionally been explained by attributes of the disturbance event itself, such as its intensity, the distribution of traits within a community related to resistance (e.g., physiological, morphological or life-history) or their interaction. Another less investigated mechanism explaining variation in response to disturbance is microtopographic heterogeneity, which might modify survival rates unevenly. We tested the hypothesis that forest floor microtopography creates small-scale refugia for bryophytes following conventional clear-cut logging by comparing a) survival of transplanted bryophytes and b) compositional changes of forest floor bryophytes among three different positions: on the northern side of boulders and stumps and on unsheltered forest floor. The investigation was carried out as a before-and-after study in 12 Swedish boreal forests (eight stands subjected to clear-cutting and four reference stands). Significantly more bryophyte transplants survived where they were shelter by boulders and stumps (30 % and 29 % respectively) compared to on level forest floor (10 %) and and less compositional changes occurred in sheltered microtopographic positions compared to on level forest floor. Shelter from boulders and stumps increased survival from both microclimatic stress and mechanical disturbance but not from burying by logging residues. Our findings provide evidence that microtopography can modify initial responses to disturbances by creating small-scale refugia. Further studies are needed to determine whether this phenomenon is commonly occurring among other organisms and in other ecosystems and to what extent scattered in-situ survivors can increase the recovery rate following disturbances.

  • 30.
    Schmalholz, Martin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Hylander, Kristoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Microtopography creates small-scale refugia for boreal forest floor bryophytes during clear-cut logging2011Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, nr 4, s. 637-648Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The biotic response of ecological systems to disturbances has traditionally been explained by attributes of the disturbance event itself, such as its intensity, the distribution of traits within a community related to resistance (e. g. physiological, morphological or life-history) or their interaction. Another less investigated mechanism explaining variation in response to disturbance is microtopographic heterogeneity, which might modify survival rates unevenly. We tested the hypothesis that forest floor microtopography creates small-scale refugia for bryophytes following conventional clear-cut logging by comparing a) survival of transplanted bryophytes and b) compositional changes of forest floor bryophytes among three different positions: on the northern side of boulders and stumps and on unsheltered forest floor. The investigation was carried out as a before-and-after study in 12 Swedish boreal forests (eight stands subjected to clear-cutting and four reference stands). Significantly more bryophyte transplants survived where they were sheltered by boulders and stumps (30 and 29% respectively) compared to on level forest floor (10%) and less compositional changes occurred in sheltered microtopographic positions than on level forest floor. Shelter from boulders and stumps increased survival from both microclimatic stress and mechanical disturbance but not from burial by logging residues. Our findings provide evidence that microtopography can modify initial responses to disturbances by creating small-scale refugia. Further studies are needed to determine whether this phenomenon is commonly occurring among other organisms and in other ecosystems and to what extent scattered in-situ survivors can increase the recovery rate following disturbances.

  • 31.
    Staveley, Thomas A. B.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Perry, Diana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Gullström, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Seascape structure and complexity influence temperate seagrass fish assemblage composition2017Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 40, nr 8, s. 936-946Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding how spatial patterning relates to ecological processes is fundamental to define important species-environment associations at broader scales. Analyses targeting habitat structure (i.e. composition and configuration) in terrestrial landscapes are increasing, but similar studies in marine landscapes are still relatively uncommon. In this study, we explored how seascape structure and complexity (determined from significant spatial pattern metrics) influenced summer and autumn fish assemblage composition in 30 seagrass (Zostera marina) meadows along the west coast of Sweden. Species density was not influenced by seascape structure in any season. In contrast, the majority of significant fish assemblage variables were influenced by seascape structure during the summer (i.e. abundance and proportion of juveniles, abundance of Labridae and abundance of occasional shallow-water visitors) whilst fewer in the autumn (i.e. abundance of occasional shallow-water visitors and Synganthidae). For instance, less complex seascapes were more suitable for juvenile assemblages in summer, as these seascapes exhibit larger patch sizes of appropriate habitat (e.g. Z. marina) and less edge boundaries providing refuges from predators and food resources. Abundances of migrating fish, such as the sea trout Salmo trutta, also responded positively to a less complex seascape in the summer though perhaps ecological processes, such as prey availability, were additional contributing factors driving this relationship. High complexity seascapes only had a positive influence on the abundance of taxa using multiple habitats (Labridae during the summer). Our study shows that fish assemblages in temperate marine environments are significantly linked to spatial habitat patterning and seascape complexity. This offers valuable insights into species-habitat-seascape linkages, information important for coastal conservation and marine spatial planning.

  • 32.
    Stoessel, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Vinka, Mikael
    Hellström, Peter
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The fluctuating world of a tundra predator guild: bottom‐up constraints overrule top‐down species interactions in winter2019Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 42, nr 3, s. 488-499Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Global warming is predicted to change ecosystem functioning and structure in Arctic ecosystems by strengthening top‐down species interactions, i.e. predation pressure on small herbivores and interference between predators. Yet, previous research is biased towards the summer season. Due to greater abiotic constraints, Arctic ecosystem characteristics might be more pronounced in winter. Here we test the hypothesis that top‐down species interactions prevail over bottom‐up effects in Scandinavian mountain tundra (Northern Sweden) where effects of climate warming have been observed and top‐down interactions are expected to strengthen. But we test this ‘a priori’ hypothesis in winter and throughout the 3–4 yr rodent cycle, which imposes additional pulsed resource constraints. We used snowtracking data recorded in 12 winters (2004–2015) to analyse the spatial patterns of a tundra predator guild (arctic fox Vulpes lagopus, red fox Vulpes vulpes, wolverine Gulo gulo) and small prey (ptarmigan, Lagopus spp). The a priori top‐down hypothesis was then tested through structural equation modelling, for each phase of the rodent cycle. There was weak support for this hypothesis, with top‐down effects only discerned on arctic fox (weakly, by wolverine) and ptarmigan (by arctic fox) at intermediate and high rodent availability respectively. Overall, bottom‐up constraints appeared more influential on the winter community structure. Cold specialist predators (arctic fox and wolverine) showed variable landscape associations, while the boreal predator (red fox) appeared strongly dependent on productive habitats and ptarmigan abundance. Thus, we suggest that the unpredictability of food resources determines the winter ecology of the cold specialist predators, while the boreal predator relies on resource‐rich habitats. The constraints imposed by winters and temporary resource lows should therefore counteract productivity‐driven ecosystem change and have a stabilising effect on community structure. Hence, the interplay between summer and winter conditions should determine the rate of Arctic ecosystem change in the context of global warming.

  • 33.
    Tannerfeldt, Magnus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Life history strategies in a fluctuating environment: establishment and reproductive success in the arctic fox1996Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 19, nr 3, s. 209-220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Natal dispersal, territoriality and reproductive success can have a major impact on the range, genetics and risk of extinction of a population. The proportions of animals that disperse have often been investigated, but not their fate. We have studied the lifetime reproductive success of arctic foxes that successfully emigrated, travelled and settled. Of these, some settled in the vicinity of their natal site as residents and some immigrated from other ai eas, i.e. short- and long-range dispersers respectively. We round no seu bias in migration patterns. In presaturation years, more immigrants residents settled. Immigrant females had higher reproductive success than resident females. There was strong support for the ultimate hypothesis of Competition For Resources (CFR), but not for tile hypotheses of Competition For Mates (CFM), Resident Fitness (RFH) and Inbreeding Avoidance (IA). Our data on arctic foxes could not be fully explained by and of four proximate hypotheses. We suggest that the reason is that dispersal and establishment should be considered as state dependent life history characteristics of individuals rather than population averages.

  • 34.
    Tannerfeldt, Magnus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Arvidson, Bengt
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The Effect of Summer Feeding on Juvenile Arctic Fox Survival - a Field Experiment1994Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 17, nr 1, s. 88-96Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The arctic fox Alopex lagopus L. population in Sweden is small and its numbers fluctuate widely with food availability, i.e. rodent populations. This fluctuation is mediated through differences in recruitment rates between years. The recruitment can be divided into three phases: number of litters born, number of cubs per litter and cub survival rates. The number of litters and their sizes have been shown to depend on food availability during winter and spring. To examine cub survival during the summer and how it relates to food availability, we conducted a feeding experiment in northern Sweden during 1990, a year of low rodent density, involving six occupied arctic fox dens. Feeding at dens lowered cub mortality rates. However, condition and growth rates of juveniles were not influenced by supplementary feeding at dens, nor were they related to the probability of survival for an individual. Thus arctic foxes seem to minimize risks rather than maximize growth. The juvenile mortality from weaning and over the next 6 wk was 21%, mostly due to starvation. Only 8.2% survived from weaning to the first breeding season. Of the one-year-old foxes, 50% survived their second year. Supplementary feeding of juveniles had no effect on the final survival rates over these two years. However, the immediate, positive effect on cub survival could be used in a long-term, extensive management programme if combined with winter feeding.

  • 35. Valdes, Alicia
    et al.
    Garcia, Daniel
    Garcia, Maria B.
    Ehrlén, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Contrasting effects of different landscape characteristics on population growth of a perennial forest herb2014Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 37, nr 3, s. 230-240Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Anthropogenic changes in landscape structure, such as habitat loss, habitat subdivision and edge increase, can strongly affect the performance of plants, leading to population declines and extinctions. Many studies to date have focused on single characteristics of landscape structure or single life-cycle phases, but they poorly discern the different pathways through which landscape change influences plant population dynamics via different vital rates. In this study, we evaluated the effect of two structural characteristics (habitat quantity and edge length) on vital rates and population growth rates of a perennial forest plant (Primula vulgaris) in a historically managed landscape. Areas with higher amounts of forest habitat had higher population growth rates due to higher recruitment, survival and growth of seedlings, while increased forest edge length was positively associated with population growth rates primarily due to a higher survival of reproductive individuals. Effects were stronger during the first of the two transition intervals studied. The results demonstrate that changes in different landscape structural characteristics may result in opposing effects acting via different vital rates, and highlight the need for integrative analyses to evaluate the effects of rapid landscape transformation on the current and long term plant population dynamics.

  • 36. Villellas, Jesus
    et al.
    Ehrlén, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Olesen, Jens M.
    Braza, Rita
    Garcia, Maria B.
    Plant performance in central and northern peripheral populations of the widespread Plantago coronopus2013Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, nr 2, s. 136-145Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Peripheral populations have long been predicted to show lower vital rates, higher demographic fluctuations, and lower densities than central populations. However, recent research has questioned the existence of clear patterns across species' ranges. To test these hypotheses, we monitored five central and six northern peripheral populations of the widespread herb Plantago coronopus along the European Atlantic coast during 5 yr. We estimated population density, and calculated mean values and temporal variability of four vital rates (survival, individual growth, fecundity and recruitment) in hundreds of plants in permanent plots. Central populations showed higher fecundity, whereas peripheral populations had higher recruitment per reproductive plant, indicating a higher overall reproductive success in the periphery. Central populations showed a marginally significant tendency for higher growth, and there were no differences between range positions in survival. Fecundity and growth were affected by intraspecific competition, and recruitment was affected by precipitation, highlighting the importance of local environmental conditions for population performance. Central and peripheral populations showed no significant differences in temporal variability of vital rates. Finally, density was significantly higher in peripheral than in central populations, in discrepancy with the abundant-centre model. Density was correlated to seedling recruitment, which would counterbalance in peripheral populations the lower fecundity and the tendency for lower growth of established plants. Such compensations among vital rates might be particularly common in widespread plants, and advise against simplistic assumptions of population performance across ranges. The whole species' life cycle should be considered, since different arrangements of vital rates are expected to maximize fitness in local environments. Our results show also the importance of discerning between geographical periphery and ecological marginality. In a context of climate-induced range shifts, these considerations are crucial for the reliability of niche-models and the management of plant peripheral populations.

  • 37. Voda, Raluca
    et al.
    Dapporto, Leonardo
    Dinca, Vlad
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Universitat Pompeu Fabra, Spain; University of Guelph, Canada.
    Vila, Roger
    Cryptic matters: overlooked species generate most butterfly beta-diversity2015Inngår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 38, nr 4, s. 405-409Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The cryptic fraction of biodiversity is composed of morphologically similar species that are or have been overlooked by scientists. Although current research is increasingly documenting new cases, cryptic species are frequently ignored in large-scale studies and monitoring programs, either because they have not yet been discovered, or because of the practical difficulties involved in differentiating them. However, it is unknown if this could represent a bias extending beyond the number of missed species. By analyzing the butterfly fauna of the west Mediterranean (335 species), we defined cryptic species based on the current consensus of the scientific community, compared their properties to other congeneric species and investigated the consequences of their inclusion/exclusion in beta-diversity analyses. We show that, as defined, the cryptic fraction of butterfly diversity represents about 25% of the west Mediterranean fauna and is overwhelmingly composed by groups of species that are not sympatric. Our results show that co-occurrence among cryptic species is significantly lower than among congeneric non-cryptic species. Accordingly, albeit the frequency of cryptic species is homogenously distributed over the study area, their distribution pattern accounts for most beta-diversity turnover over sea (from 50 to 100%). Beta-diversity turnover, a direct measure of the frequency of species replacement from site to site, is recognized as a fundamental parameter in ecology and is widely used to detect biogeographic patterns. These findings represent a change of paradigm in showing that cryptic diversity comprises original qualitative aspects in addition to merely quantitative ones. This highlights the importance of differentiating cryptic species for various research fields and opens the door to the study of further potential particularities of cryptic diversity.

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