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  • Arvanitis, Leena, et al. (författare)
  • Novel antagonistic interactions associated with plant polyploidization influence trait selection and habitat preference.
  • 2010
  • Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 13:3, s. 330-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Polyploidization is an important mechanism for sympatric speciation in plants. Still, we know little about whether plant polyploidization leads to insect host shifts, and if novel interactions influence habitat and trait selection in plants. We investigated herbivory by the flower bud gall-forming midge Dasineura cardaminis on tetraploids and octoploids of the herb Cardamine pratensis. Gall midges attacked only octoploid plant populations, and a transplantation experiment confirmed this preference. Attack rates were higher in populations that were shaded, highly connected or occurred along stream margins. Within populations, late-flowering individuals with many flowers were most attacked. Galling reduced seed production and significantly influenced phenotypic selection on flower number. Our results suggest that an increase in ploidy may lead to insect host shifts and that plant ploidy explains insect host use. In newly formed plant polyploids, novel interactions may alter habitat preferences and trait selection, and influence the further evolution of cytotypes.
  • Christiansen, Ditte M., 1990-, et al. (författare)
  • High-resolution data are necessary to understand the effects of climate on plant population dynamics of a forest herb
  • 2024
  • Ingår i: Ecology. - 0012-9658 .- 1939-9170. ; 105:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Climate is assumed to strongly influence species distribution and abundance. Although the performance of many organisms is influenced by the climate in their immediate proximity, the climate data used to model their distributions often have a coarse spatial resolution. This is problematic because the local climate experienced by individuals might deviate substantially from the regional average. This problem is likely to be particularly important for sessile organisms like plants and in environments where small-scale variation in climate is large. To quantify the effect of local temperature on vital rates and population growth rates, we used temperature values measured at the local scale (in situ logger measures) and integral projection models with demographic data from 37 populations of the forest herb Lathyrus vernus across a wide latitudinal gradient in Sweden. To assess how the spatial resolution of temperature data influences assessments of climate effects, we compared effects from models using local data with models using regionally aggregated temperature data at several spatial resolutions (≥1 km). Using local temperature data, we found that spring frost reduced the asymptotic population growth rate in the first of two annual transitions and influenced survival in both transitions. Only one of the four regional estimates showed a similar negative effect of spring frost on population growth rate. Our results for a perennial forest herb show that analyses using regionally aggregated data often fail to identify the effects of climate on population dynamics. This emphasizes the importance of using organism-relevant estimates of climate when examining effects on individual performance and population dynamics, as well as when modeling species distributions. For sessile organisms that experience the environment over small spatial scales, this will require climate data at high spatial resolutions. 
  • Dahlberg, C. Johan, et al. (författare)
  • Correlations between plant climate optima across different spatial scales
  • 2020
  • Ingår i: Environmental and Experimental Botany. - : Elsevier BV. - 0098-8472 .- 1873-7307. ; 170
  • Tidskriftsartikel (refereegranskat)abstract
    • Identifying the factors determining the abundance and distribution of species is a fundamental question in ecology. One key issue is how similar the factors determining species' distributions across spatial scales are (here we focus especially on spatial extents). If the factors are similar across extents, then the large scale distribution pattern of a species may provide information about its local habitat requirements, and vice versa. We assessed the relationships between landscape and national optima as well as landscape and continental optima for growing degree days, maximum temperature and minimum temperature for 96 bryophytes and 50 vascular plants. For this set of species, we derived landscape optima from abundance weighted temperature data using species inventories in central Sweden and a fine-grained temperature model (50 m), national optima from niche centroid modelling based on GBIF data from Sweden and the same fine-grained climate model, and continental optima using the same method as for the national optima but from GBIF data from Europe and Worldclim temperatures (c. 1000 m). The landscape optima of all species were positively correlated with national as well as continental optima for maximum temperature (r = 0.45 and 0.46, respectively), weakly so for growing degree days (r = 0.30 and r = 0.28), but sometimes absent for minimum temperature (r = 0.26 and r = 0.04). The regression slopes of national or continental optima on local optima did not differ between vascular plants and bryophytes for GDD and Tmax. However, the relationship between the optima of Tmin differed between groups, being positive in vascular plants but absent in bryophytes. Our results suggest that positive correlations between optima at different spatial scales are present for some climatic variables but not for others. Moreover, our results for vascular plants and bryophytes suggest that correlations might differ between organism groups and depend on the ecology of the focal organisms. This implies that it is not possible to routinely up- or downscale distribution patterns based on environmental correlations, since drivers of distribution patterns might differ across spatial extents.
  • Dahlberg, C. Johan, 1978-, et al. (författare)
  • Performance of Forest Bryophytes with Different Geographical Distributions Transplanted across a Topographically Heterogeneous Landscape
  • 2014
  • Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Most species distribution models assume a close link between climatic conditions and species distributions. Yet, we know little about the link between species’ geographical distributions and the sensitivity of performance to local environmental factors. We studied the performance of three bryophyte species transplanted at south- and north-facing slopes in a boreal forest landscape in Sweden. At the same sites, we measured both air and ground temperature. We hypothesized that the two southerly distributed species Eurhynchium angustirete and Herzogiella seligeri perform better on south-facing slopes and in warm conditions, and that the northerly distributed species Barbilophozia lycopodioides perform better on north-facing slopes and in relatively cool conditions. The northern, but not the two southern species, showed the predicted relationship with slope aspect. However, the performance of one of the two southern species was still enhanced by warm temperatures. An important reason for the inconsistent results can be that microclimatic gradients across landscapes are complex and influenced by many climate-forcing factors. Therefore, comparing only north- and south-facing slopes might not capture the complexity of microclimatic gradients. Population growth rates and potential distributions are the integrated results of all vital rates. Still, the study of selected vital rates constitutes an important first step to understand the relationship between population growth rates and geographical distributions and is essential to better predict how climate change influences species distributions.
  • Dahlberg, C. Johan, 1978-, et al. (författare)
  • Plant landscape climatic optima correlate with their continental range optima
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Aim Factors determining species’ distributions at smaller scales may inform us about larger scale distributions, and vice versa. We predicted that landscape and continental climatic optima for plants are positively correlated, and that species that have their optima outside a given focal landscape will cluster at the warmest or coldest landscape patches. Also, we predicted that the correlations of temperature optima are stronger for vascular plants than for bryophytes, since bryophytes may be regulated also by air moisture.LocationÅngermanland, Sweden (landscape scale); Europe (continental scale).MethodsWe derived landscape optima from fine-grained temperature models (50 m) and species inventories, and continental optima from MaxEnt niche modelling based on GBIF occurrences and Worldclim temperatures (c. 1000 m), for 96 bryophytes and 50 vascular plants. Optima were derived for growing degree days, and maximum and minimum temperature.ResultsThe landscape and continental optima of all species were positively correlated for growing degree days and maximum temperature (r = 0.19 and r = 0.44), but not for minimum temperature (r = -0.010). Species with their continental optima outside the focal landscape did not clearly cluster in the most extreme parts of the landscape. For vascular plants the correlation was positive for both growing degree days and maximum temperature (r = 0.50 and r = 0.64), but for bryophytes only for maximum temperature (r = 0.34).Main conclusionsThe optima correlations for maximum temperature and growing degree days indicate that we can infer large scale distribution patterns of plants from their local scale distributions, and suggest in which environments species occur if we only know their continental scale optima. The lack of clustering of southern and northern species limits the possibility for conservation actions targeting microrefugia. Lastly, the correlations indicate that the distributions of vascular plants were more influenced by temperature than bryophytes.
  • Dahlberg, C. Johan, 1978-, et al. (författare)
  • Population dynamics of moss transplants across microclimatic gradients
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • In order to determine the response of a species to climatic change it is important to study how climatic factors influence its vital rates and population growth rate across climatic gradients. We investigated how microclimate influence the population dynamics of transplants from northern and more southern populations of the forest bryophyte Hylocomiastrum umbratum. We predicted that its population growth rate is favored by moist microclimates with colder maximum temperatures, longer snow cover duration and less evaporation, and that annual shoots (segments) will be shorter under drier conditions. We also predicted that northern populations will have higher population growth rate and larger segments than southern populations when transplanted to the northern range. We placed transplants from three northern and three southern populations of H. umbratum at 30 forested sites in central Sweden differing in microclimate. We marked and followed the growth of individual shoots during two years, and calculated population growth rates and stable stage distributions of segment size classes using transition matrix models for northern and southern transplants, respectively, at each locality. Population growth rate was lower and shorter segments developed at sites with higher evaporation, corresponding to our hypothesis. There were no significant difference in population growth rate and stable stage segment length between southern and northern populations. Higher evaporation during the summer result in lower population growth rates of H. umbratum by affecting vital rates, in terms of less segment growth. Both climate change and forestry may alter evaporation conditions across the landscape and, thus, the future distribution of the species.
  • Dahlberg, C. Johan, 1978- (författare)
  • The role of microclimate for the performance and distribution of forest plants
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Microclimatic gradients may have large influence on individual vital rates and population growth rates of species, and limit their distributions. Therefore, I focused on the influence of microclimate on individual performance and distribution of species. Further, I examined differences in how microclimate affect species with contrasting distributions or different ecophysiological traits, and populations within species. More specifically, I investigated the performance of northern and southern distributed forest bryophytes that were transplanted across microclimatic gradients, and the timing of vegetative and reproductive development among northern, marginal and more southern populations of a forest herb in a common garden. Also, I compared the landscape and continental distributions across forest bryophytes and vascular plants and, thus, their distribution limiting factors at different spatial scales. Lastly, I examined the population dynamics across microclimatic gradients of transplants from northern and southern populations of a forest moss. The effects of microclimatic conditions on performance differed among bryophytes with contrasting distributions. There were no clear differences between northern and southern populations in the timing of development of a forest herb or in the population dynamics of a moss. However, within each region there was a differentiation of the forest herb populations, related to variation in local climatic conditions and in the south also to proportion of deciduous trees. The continental distributions of species were reflected in their landscape distributions and vice versa, in terms of their occurrence optima for climatic variables. The variation in landscape climatic optima was, however, larger than predicted, which limit the precision for predictions of microrefugia. Probably, the distributions of vascular plants were more affected by temperature than the distributions of bryophytes. Bryophytes are sensitive to moisture conditions, which was demonstrated by a correlation between evaporation and the population growth rate of a forest moss. We might be able to predict species’ landscape scale distributions by linking microclimatic conditions to their population growth rates, via their vital rates, and infer larger scale distribution patterns.
  • Dahlgren, Johan, et al. (författare)
  • Incorporating environmental change over succession in an integral projection model of population dynamics of a forest herb
  • 2011
  • Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 120:8, s. 1183-1190
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite seemingly obvious effects of environmental drivers, mechanisms behind long-term changes in plant population sizes over time are often poorly known. We investigated how soil potassium concentration and seed predation are likely to change over time as a result of succession from deciduous forest to spruce forest, and how this affects population trajectories of Actaea spicata. Observations and addition experiments showed that high soil potassium concentration increased individual growth rates. Among-site comparisons showed that soil potassium concentration was lower where proportion spruce was higher. Incorporation of a gradual increase in spruce over time in an integral projection model where individual growth depended on potassium suggested a net decrease in A. spicata population sizes over forest succession. This result suggests that small changes in factors with small effects on individual performance can influence patterns of species occupancy along successional gradients. We incorporated also density independent and density dependent effects of pre-dispersal seed predation over succession into the same model. Seed predation influenced the tree composition at which A. spicata population growth was positive. However, significant effects of A. spicata population size on seed predation intensity did not translate into important feedback effects on population growth trajectories over succession. Our results illustrate how demographic models can be used to gain understanding of the mechanisms behind effects of environmental change on species abundances and distributions by the simultaneous inclusion of changing abiotic and biotic factors.
  • Dahlgren, Johan, et al. (författare)
  • Linking environmental variation to population dynamics of a forest herb
  • 2009
  • Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 97:4, s. 666-674
  • Tidskriftsartikel (refereegranskat)abstract
    • . Although necessary for understanding and predicting population dynamics, abiotic and biotic interactions have only rarely been coupled to demography and population dynamics. 2. We estimated effects of 11 environmental factors on survival, growth and fertility of the perennial herb Actaea spicata and incorporated significant factors into integral projection models to assess their effect on population dynamics. 3. Statistical models suggested that high soil potassium concentration increased individual growth and that seed predation and, to a lesser extent, canopy cover reduced seed production. 4. Demographic models showed that both soil potassium concentration and pre-dispersal seed predation could reverse population growth from positive to negative. The observed range of soil potassium concentration corresponded to growth rates (lambda) between 0.96 and 1.07, at mean observed seed predation intensity. At observed mean potassium concentration, growth rate ranged from 0.99 to 1.02 over observed seed predation intensities. 5. Sensitivity of population growth rate to different vital rates strongly influenced the relative effects of the two factors. Elasticity analysis suggested that proportional changes in soil potassium concentration result in seven times larger effects on population growth rate than changes in seed predation. 6. Synthesis. We conclude that relatively weak associations between environmental factors and vital rates can have substantial long-term effects on population growth. Approaches based on detailed demographic models, that simultaneously assess abiotic and biotic effects on population growth rate, constitute important tools for establishing the links between the environment and dynamics of populations and communities.
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