SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Ehrlén Johan) srt2:(2015-2019);srt2:(2016)"

Sökning: WFRF:(Ehrlén Johan) > (2015-2019) > (2016)

  • Resultat 1-10 av 10
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Dahlberg, C. Johan, 1978- (författare)
  • The role of microclimate for the performance and distribution of forest plants
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt)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.
  •  
2.
  • Dahlgren, Johan P., et al. (författare)
  • The demography of climate-driven and density-regulated population dynamics in a perennial plant
  • 2016
  • Ingår i: Ecology. - 0012-9658 .- 1939-9170. ; 97:4, s. 899-907
  • Tidskriftsartikel (refereegranskat)abstract
    • Identifying the internal and external drivers of population dynamics is a key objective in ecology, currently accentuated by the need to forecast the effects of climate change on species distributions and abundances. The interplay between environmental and density effects is one particularly important aspect of such forecasts. We examined the simultaneous impact of climate and intraspecific density on vital rates of the dwarf shrub Fumana procumbens over 20 yr, using generalized additive mixed models. We then analyzed effects on population dynamics using integral projection models. The population projection models accurately captured observed fluctuations in population size. Our analyses suggested the population was intrinsically regulated but with annual fluctuations in response to variation in weather. Simulations showed that implicitly assuming variation in demographic rates to be driven solely by the environment can overestimate extinction risks if there is density dependence. We conclude that density regulation can dampen effects of climate change on Fumana population size, and discuss the need to quantify density dependence in predictions of population responses to environmental changes.
  •  
3.
  • Ehrlén, Johan, et al. (författare)
  • Advancing environmentally explicit structured population models of plants
  • 2016
  • Ingår i: Journal of Ecology. - 0022-0477 .- 1365-2745. ; 104:2, s. 292-305
  • Tidskriftsartikel (refereegranskat)abstract
    • The relationship between the performance of individuals and the surrounding environment is fundamental in ecology and evolutionary biology. Assessing how abiotic and biotic environmental factors influence demographic processes is necessary to understand and predict population dynamics, as well as species distributions and abundances. We searched the literature for studies that have linked abiotic and biotic environmental factors to vital rates and, using structured demographic models, population growth rates of plants. We found 136 studies that had examined the environmental drivers of plant demography. The number of studies has been increasing rapidly in recent years. Based on the reviewed studies, we identify and discuss several major gaps in our knowledge of environmentally driven demography of plants. We argue that some drivers may have been underexplored and that the full potential of spatially and temporally replicated studies may not have been realized. We also stress the need to employ relevant statistical methods and experiments to correctly identify drivers. Moreover, assessments of the relationship between drivers and vital rates need to consider interactive, nonlinear and indirect effects, as well as effects of intraspecific density dependence.Synthesis. Much progress has already been made by using structured population models to link the performance of individuals to the surrounding environment. However, by improving the design and analyses of future studies, we can substantially increase our ability to predict changes in plant population dynamics, abundances and distributions in response to changes in specific environmental drivers. Future environmentally explicit demographic models should also address how genetic changes prompted by selection imposed by environmental changes will alter population trajectories in the face of continued environmental change and investigate the reciprocal feedback between plants and their biotic drivers.
  •  
4.
  • Lehtilä, Kari, et al. (författare)
  • Forest succession and population viability of grassland plants : long repayment of extinction debt in Primula veris
  • 2016
  • Ingår i: Oecologia. - 0029-8549 .- 1432-1939. ; 181:1, s. 125-135
  • Tidskriftsartikel (refereegranskat)abstract
    • Time lags in responses of organisms to deteriorating environmental conditions delay population declines and extinctions. We examined how local processes at the population level contribute to extinction debt, and how cycles of habitat deterioration and recovery may delay extinction. We carried out a demographic analysis of the fate of the grassland perennial Primula veris after the cessation of grassland management, where we used either a unidirectional succession model for forest habitat or a rotation model with a period of forest growth followed by a clear-cut and a new successional cycle. The simulations indicated that P. veris populations may have an extinction time of decades to centuries after a detrimental management change. A survey of the current incidence and abundance of P. veris in sites with different histories of afforestation confirmed the simulation results of low extinction rates. P. veris had reduced incidence and abundance only at sites with at least 100 years of forest cover. Time to extinction in simulations was dependent on the duration of the periods with favourable and unfavourable conditions after management cessation, and the population sizes and growth rates in these periods. Our results thus suggest that the ability of a species to survive is a complex function of disturbance regimes, rates of successional change, and the demographic response to environmental changes. Detailed demographic studies over entire successional cycles are therefore essential to identify the environmental conditions that enable long-term persistence and to design management for species experiencing extinction debts.
  •  
5.
  • Andersson, Petter, et al. (författare)
  • Plant patch structure influences plant fitness via antagonistic and mutualistic interactions but in different directions
  • 2016
  • Ingår i: Oecologia. - 0029-8549 .- 1432-1939. ; 180:4, s. 1175-1182
  • Tidskriftsartikel (refereegranskat)abstract
    • Plant patch structure and environmental context can influence the outcome of antagonistic and mutualistic plant-insect interactions, leading to spatially variable fitness effects for plants. We investigated the effects of herbivory and pollen limitation on plant reproductive performance in 28 patches of the self-compatible perennial herb Scrophularia nodosa and assessed how such effects varied with plant patch size, plant density and tree cover. Both antagonistic and mutualistic interactions had strong effects on plant reproductive performance. Leaf feeding from herbivores reduced both fruit production and seed germination, and leaf herbivory increased with plant patch size. Experimentally hand-pollinated flowers produced more seeds than open-pollinated flowers, and pollen limitation was more severe in patches with fewer plants. Our study on S. nodosa is one of few which documents that plant patch structure influences the outcome of both antagonistic and mutualistic plant-insect interactions. The results thus provide an example of how variation in plant patch structure and environmental factors can lead to spatially variable fitness effects from mutualistic and antagonistic interactions.
  •  
6.
  • Bolinder, Kristina, et al. (författare)
  • From near extinction to diversification by means of ashift in pollination mechanism in the gymnosperm relict Ephedra (Ephedraceae, Gnetales)
  • 2016
  • Ingår i: Botanical journal of the Linnean Society. - 0024-4074 .- 1095-8339. ; 180:4, s. 461-477
  • Tidskriftsartikel (refereegranskat)abstract
    • Pollination in gymnosperms is usually accomplished by means of wind, but some groups are insect-pollinated. We show that wind and insect pollination occur in the morphologically uniform genus Ephedra (Gnetales). Based on field experiments over several years, we demonstrate distinct differences between two Ephedra species that grow in sympatry in Greece in pollen dispersal and clump formation, insect visitations and embryo formation when insects are denied access to cones. Ephedra distachya, nested in the core clade of Ephedra, is anemophilous, which is probably the prevailing state in Ephedra. Ephedra foeminea, sister to the remaining species of the genus, is entomophilous and pollinated by a range of diurnal and nocturnal insects. The generalist entomophilous system of E.foeminea, with distinct but infrequent insect visitations, is in many respects similar to that reported for Gnetum and Welwitschia and appears ancestral in Gnetales. The Ephedra lineage is well documented already from the Early Cretaceous, but the diversity declined dramatically during the Late Cretaceous, possibly to near extinction around the Cretaceous-Palaeogene boundary. The clade imbalance between insect- and wind-pollinated lineages is larger than expected by chance and the shift in pollination mode may explain why Ephedra escaped extinction and began to diversify again.
  •  
7.
  • König, Malin A. E., et al. (författare)
  • Butterfly oviposition preference is not related to larval performance on a polyploid herb
  • 2016
  • Ingår i: Ecology and Evolution. - 2045-7758 .- 2045-7758. ; 6:9, s. 2781-2789
  • Tidskriftsartikel (refereegranskat)abstract
    • The preference-performance hypothesis predicts that female insects maximize their fitness by utilizing host plants which are associated with high larval performance. Still, studies with several insect species have failed to find a positive correlation between oviposition preference and larval performance. In the present study, we experimentally investigated the relationship between oviposition preferences and larval performance in the butterfly Anthocharis cardamines. Preferences were assessed using both cage experiments and field data on the proportion of host plant individuals utilized in natural populations. Larval performance was experimentally investigated using larvae descending from 419 oviposition events by 21 females on plants from 51 populations of two ploidy types of the perennial herb Cardamine pratensis. Neither ploidy type nor population identity influenced egg survival or larval development, but increased plant inflorescence size resulted in a larger final larval size. There was no correlation between female oviposition preference and egg survival or larval development under controlled conditions. Moreover, variation in larval performance among populations under controlled conditions was not correlated with the proportion of host plants utilized in the field. Lastly, first instar larvae added to plants rejected for oviposition by butterfly females during the preference experiment performed equally well as larvae growing on plants chosen for oviposition. The lack of a correlation between larval performance and oviposition preference for A. cardamines under both experimental and natural settings suggests that female host choice does not maximize the fitness of the individual offspring.
  •  
8.
  • Stålhandske, Sandra, 1986-, et al. (författare)
  • Phenological matching rather than genetic variation in host preference underlies geographical variation in host plants used by the orange tip butterflies
  • 2016
  • Ingår i: Biological Journal of the Linnean Society. - 0024-4066 .- 1095-8312. ; 119:4, s. 1060-1067
  • Tidskriftsartikel (refereegranskat)abstract
    • An insect species that shows variation in host species association across its geographical range may do so either because of local adaptation in host plant preference of the insect, or through environmentally or genetically induced differences in the plants, causing variation in host plant suitability between regions. Here we experimentally investigate host plant preference of Anthocharis cardamines (orange tip butterfly) of two populations from UK and two from Sweden. Previous reports indicate that A. cardamines larvae are found on different host plant species in different regions of the United Kingdom, and some variation has been reported in Sweden. Host plant choice trials showed that females prefer to oviposit on plants in an earlier phenological stage, as well as on larger plants. When controlling for plant phenological stage and size, the host species had no statistically significant effect on the choice of the females. Moreover, there were no differences in host plant species preference among the four butterfly populations. Based on our experiment, the oviposition choice by A. cardamines mainly depends on the phenological stage and the size of the host plant. This finding supports the idea that the geographical patterns of host-plant association of A. cardamines in the UK and Sweden are consequences of the phenology and availability of local hosts, rather than regional genetic differences in host species preference of the butterfly.
  •  
9.
  • Toftegaard, Tenna, 1982- (författare)
  • Temperature and the synchrony of plant-insect interactions
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Increasing temperatures resulting from climate change have within recent years been shown to advance phenological events in a large number of species worldwide. Species can differ in their response to increasing temperatures, and understanding the mechanisms that determine the response is therefore of great importance in order to understand and predict how a warming climate can influence both individual species, but also their interactions with each other and the environment. Understanding the mechanisms behind responses to increasing temperatures are however largely unexplored.The selected study system consisting of host plant species of the Brassicaceae family and their herbivore Anthocharis cardamines, is assumed to be especially vulnerable to climatic variations. Through the use of this study system, the aim of this thesis is to study differences in the effect of temperature on development to start of flowering within host plant species from different latitudinal regions (study I), and among host plant species (study II). We also investigate whether different developmental phases leading up to flowering differ in sensitivity to temperature (study II), and if small-scale climatic variation in spring temperature influence flowering phenology and interactions with A. cardamines (study III). Finally, we investigate if differences in the timing of A. cardamines relative to its host plants influence host species use and the selection of host individuals differing in phenology within populations (study IV).Our results showed that thermal reaction norms differ among regions along a latitudinal gradient, with the host plant species showing a mixture of co-, counter- and mixed gradient patterns (study I). We also showed that observed differences in the host plant species order of flowering among regions and years might be caused by both differences in the distribution of warm days during development and differences in the sensitivity to temperature in different phases of development (study II). In addition, we showed that small-scale variations in temperature led to variation in flowering phenology among and within populations of C. pratensis, impacting the interactions with the butterfly herbivore A. cardamines. Another result was that the less the mean plant development stage of a given plant species in the field deviated from the stage preferred by the butterfly for oviposition, the more used was the species as a host by the butterfly (study IV). Finally, we showed that the later seasonal appearance of the butterflies relative to their host plants, the higher butterfly preference for host plant individuals with a later phenology, corresponding to a preference for host plants in earlier development stages (study IV).For our study system, this thesis suggest that climate change will lead to changes in the interactions between host plants and herbivore, but that differences in phenology among host plants combined with changes in host species use of the herbivore might buffer the herbivore against negative effects of climate change. Our work highlights the need to understand the mechanisms behind differences in the responses of developmental rates to temperature between interacting species, as well as the need to account for differences in temperature response for interacting organisms from different latitudinal origins and during different developmental phases in order to understand and predict the consequences of climate change. 
  •  
10.
  • Toftegaard, Tenna, et al. (författare)
  • Variation in plant thermal reaction norms along a latitudinal gradient - more than adaptation to season length
  • 2016
  • Ingår i: Oikos. - 0030-1299 .- 1600-0706. ; 125:5, s. 622-628
  • Tidskriftsartikel (refereegranskat)abstract
    • Little is known about the extent to which observed phenological responses to changes in climate are the result of phenotypic plasticity or genetic changes. We also know little about how plasticity, in terms of thermal reaction norms, vary spatially. We investigated if the thermal reaction norms for flower development of five crucifer species (Brassicaceae) differed among three regions along a south-north latitudinal gradient in replicated experiments. The mean response (elevation) of thermal reaction norms of flowering differed among regions in all study species, while sensitivity of flower development to temperature (slope) differed in only one of the species. Differences in mean responses corresponded to cogradient patterns in some species, but countergradient patterns in other. This suggests that differences among regions were not solely the result of adaptation to differences in the length of the growing season, but that other factors, such as herbivory, play an important role. Differences in development rate within species were mainly explained by variation in early phases of bud formation in some species but by variation in later phases of bud formation in other species. The differences in latitudinal patterns of thermal reaction norms among species observed in this study are important, both to identify agents of selection and to predict short- and long-term responses to a warming climate.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 10

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy