| 1. |
- Ehrlén, Johan, et al.
(författare)
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Flowering schedule in a perennial plant; life-history trade-offs, seed predation, and total offspring fitness
- 2015
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 96:8, s. 2280-2288
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Tidskriftsartikel (refereegranskat)abstract
- Optimal timing of reproduction within a season may be influenced by several abiotic and biotic factors. These factors sometimes affect different components of fitness, making assessments of net selection difficult. We used estimates of offspring fitness to examine how pre-dispersal seed predation influences selection on flowering schedule in an herb with a bimodal flowering pattern, Actaea spicata. Within individuals, seeds from flowers on early terminal inflorescences had a higher germination rate and produced larger seedlings than seeds from flowers on late basal inflorescences. Reproductive value, estimated using demographic integral projection models and accounting for size-dependent differences in future performance, was two times higher for intact seeds from early flowers than for seeds from late flowers. Fruits from late flowers were, however, much more likely to escape seed predation than fruits from early flowers. Reproductive values of early and late flowers balanced at a predation intensity of 63%. Across 15 natural populations, the strength of selection for allocation to late flowers was positively correlated with mean seed predation intensity. Our results suggest that the optimal shape of the flowering schedule, in terms of the allocation between early and late flowers, is determined by the trade-off between offspring number and quality, and that variation in antagonistic interactions among populations influences the balancing of this trade-off. At the same time they illustrate that phenotypic selection analyses that fail to account for differences in offspring fitness might be misleading.
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| 2. |
- Bisang, Irene, et al.
(författare)
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No evidence of sexual niche partitioning in a dioecious moss with raresexual reproduction
- 2015
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290.
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims. Roughly half of the species of bryophytes have separate sexes (dioecious) and half are hermaphroditic (monoecious). This variation has major consequences for the ecology and evolution of the different species. In some sexually reproducing dioecious bryophytes, sex ratio has been shown to vary with environmental conditions. This study focuses on the dioecious wetland moss Drepanocladus trifarius, which rarely produces sexual branches or sporophytes and lacks apparent secondary sex characteristics, and examines whether genetic sexes exhibit different habitat preferences, i.e. whether sexual niche partitioning occurs.Methods. A total of 277 shoots of D. trifarius were randomly sampled at 214 locations and 12 environmental factors were quantified at each site. Sex was assigned to the individual shoots collected in the natural environments, regardless of their reproductive status, using a specifically designed molecular marker associated with female sex.Key Results. Male and female shoots did not differ in shoot biomass, the sexes were randomly distributed with respect to each other, and environmental conditions at male and female sampling locations did not differ. Collectively, this demonstrates a lack of sexual niche segregation. Adult genetic sex ratio was female-biased, with 28 females for every male individual.Conclusions. The results show that although the sexes of D. trifarius did not differ with regard to annual growth, spatial distribution or habitat requirements, the genetic sex ratio as nevertheless significantly female-biased. This supports the notion that factors other than sex-related differences in reproductive costs and sexual dimorphism can also drive the evolution of biased sex ratios in plants
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| 3. |
- Ehrlén, Johan
(författare)
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Selection on flowering time in a life-cycle context
- 2015
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 124:1, s. 92-101
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Tidskriftsartikel (refereegranskat)abstract
- The main way in which plants can exert control over their local environment is by the timing of different events within their life cycles. Regarding timing of flowering as an integrated part of both the annual cycle and of the whole life cycle, rather than as an isolated event, has important implications for how we assess selection on timing of reproduction and interpret existing phenological patterns in perennial plants. I argue that: 1) we have little unequivocal evidence of pollinator-mediated selection on flowering time, but perhaps more evidence of antagonist-mediated selection; 2) much of selection on flowering time might occur before flowers have developed and after reproduction; 3) vital rates of non-flowering individuals can influence the strength and direction of selection on flowering time, and 4) differences in the direction of selection on flowering date between years might well correspond to consistent selection on the mechanisms determining flowering time. Overall, a life cycle perspective on timing of flowering is likely to facilitate the identification of selective agents and the understanding of the complex mechanisms underlying spatial and temporal variation in selection as well as to enable more accurate predictions of responses to environmental change.
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| 4. |
- Elmhagen, Bodil, et al.
(författare)
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Interacting effects of change in climate, human population, land use, and water use on biodiversity and ecosystem services
- 2015
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Ingår i: Ecology and Society. - 1708-3087. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Human population growth and resource use, mediated by changes in climate, land use, and water use, increasingly impact biodiversity and ecosystem services provision. However, impacts of these drivers on biodiversity and ecosystem services are rarely analyzed simultaneously and remain largely unknown. An emerging question is how science can improve the understanding of change in biodiversity and ecosystem service delivery and of potential feedback mechanisms of adaptive governance. We analyzed past and future change in drivers in south-central Sweden. We used the analysis to identify main research challenges and outline important research tasks. Since the 19th century, our study area has experienced substantial and interlinked changes; a 1.6 degrees C temperature increase, rapid population growth, urbanization, and massive changes in land use and water use. Considerable future changes are also projected until the mid-21st century. However, little is known about the impacts on biodiversity and ecosystem services so far, and this in turn hampers future projections of such effects. Therefore, we urge scientists to explore interdisciplinary approaches designed to investigate change in multiple drivers, underlying mechanisms, and interactions over time, including assessment and analysis of matching-scale data from several disciplines. Such a perspective is needed for science to contribute to adaptive governance by constantly improving the understanding of linked change complexities and their impacts.
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| 5. |
- Hylander, Kristoffer, et al.
(författare)
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Microrefugia : Not for everyone
- 2015
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44, s. s60-S68
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Tidskriftsartikel (refereegranskat)abstract
- Microrefugia are sites that support populations of species when their ranges contract during unfavorable climate episodes. Here, we review and discuss two aspects relevant for microrefugia. First, distributions of different species are influenced by different climatic variables. Second, climatic variables differ in the degree of local decoupling from the regional climate. Based on this, we suggest that only species limited by climatic conditions decoupled from the regional climate can benefit from microrefugia. We argue that this restriction has received little attention in spite of its importance for microrefugia as a mechanism for species resilience (the survival of unfavorable episodes and subsequent range expansion). Presence of microrefugia will depend on both the responses of individual species to local climatic variation and how climate-forcing factors shape the correlation between local and regional climate across space and time.
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| 6. |
- König, Malin A. E., et al.
(författare)
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Timing of flowering and intensity of attack by a butterfly herbivore in a polyploid herb
- 2015
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 5:9, s. 1863-1872
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Tidskriftsartikel (refereegranskat)abstract
- Timing of plant development both determines the abiotic conditions that the plant experiences and strongly influences the intensity of interactions with other organisms. Plants and herbivores differ in their response to environmental cues, and spatial and temporal variation in environmental conditions might influence the synchrony between host plants and herbivores, and the intensity of their interactions. We investigated whether differences in first day of flowering among and within 21 populations of the polyploid herb Cardamine pratensis influenced the frequency of oviposition by the butterfly Anthocharis cardamines during four study years. The proportion of plants that became oviposited upon differed among populations, but these differences were not related to mean flowering phenology within the population in any of the four study years. Attack rates in the field were also not correlated with resistance to oviposition estimated under controlled conditions. Within populations, the frequency of butterfly attack was higher in early-flowering individuals in two of the four study years, while there was no significant relationship in the other 2years. Larger plants were more likely to become oviposited upon in all 4years. The effects of first flowering day and size on the frequency of butterfly attack did not differ among populations. The results suggest that differences in attack intensities among populations are driven mainly by differences in the environmental context of populations while mean differences in plant traits play a minor role. The fact that within populations timing of flowering influenced the frequency of herbivore attack only in some years and suggests that herbivore-mediated selection on plant phenology differs among years, possibly because plants and herbivores respond differently to environmental cues.
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| 7. |
- Navarro-Cano, Jose A., et al.
(författare)
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Climate change, phenology, and butterfly host plant utilization
- 2015
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44:S!, s. S78-S88
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of how species interactions are influenced by climate warming is paramount to understand current biodiversity changes. We review phenological changes of Swedish butterflies during the latest decades and explore potential climate effects on butterfly-host plant interactions using the Orange tip butterfly Anthocharis cardamines and its host plants as a model system. This butterfly has advanced its appearance dates substantially, and its mean flight date shows a positive correlation with latitude. We show that there is a large latitudinal variation in host use and that butterfly populations select plant individuals based on their flowering phenology. We conclude that A. cardamines is a phenological specialist but a host species generalist. This implies that thermal plasticity for spring development influences host utilization of the butterfly through effects on the phenological matching with its host plants. However, the host utilization strategy of A. cardamines appears to render it resilient to relatively large variation in climate.
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| 8. |
- Posledovich, Diana, et al.
(författare)
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Latitudinal variation in diapause duration and post-winter development in two pierid butterflies in relation to phenological specialization
- 2015
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 177:1, s. 181-190
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Tidskriftsartikel (refereegranskat)abstract
- Diapause plays a central role in insect life cycles by allowing survival during adverse seasonal conditions as well as synchronizing life cycles with the period of mate and food availability. Seasonal timing is expected to be particularly important for species that are dependent on resources available during a short time window-so-called phenological specialists-and latitudinal clines in seasonality are expected to favor local adaptation in phenological timing. However, to what degree latitudinal variation in diapause dynamics and post-winter development due to such local adaptation is influenced by the degree of phenological specialization is not well known. We experimentally studied two pierid butterfly species and found that the phenological specialist Anthocharis cardamines had shorter diapause duration than the phenological generalist Pieris napi along a latitudinal gradient in Sweden. Moreover, diapause duration increased with latitude in P. napi but not in A. cardamines. Sensitivity of the two species to winter thermal conditions also differed; additional cold temperature during the winter period shortened diapause duration for P. napi pupae but not for A. cardamines pupae. In both species, post-winter pupal development was faster after longer periods of cold conditions, and more southern populations developed faster than northern populations. Post-winter development was also invariably faster at higher temperatures in both species. We argue that the observed differences in diapause dynamics between the two species might be explained by the difference in phenological specialization that influences the costs of breaking diapause too early in the season.
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| 9. |
- Posledovich, Diana, et al.
(författare)
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The developmental race between maturing host plants and their butterfly herbivore – the influence of phenological matching and temperature
- 2015
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 84:6, s. 1690-1699
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Tidskriftsartikel (refereegranskat)abstract
- Interactions between herbivorous insects and their host plants that are limited in time are widespread. Therefore, many insect-plant interactions result in a developmental race, where herbivores need to complete their development before plants become unsuitable, while plants strive to minimize damage from herbivores by outgrowing them. When spring phenologies of interacting species change asymmetrically in response to climate warming, there will be a change in the developmental state of host plants at the time of insect herbivore emergence. In combination with altered temperatures during the subsequent developmental period, this is likely to affect interaction strength as well as fitness of interacting species. Here, we experimentally explore whether the combined effect of phenological matching and thermal conditions influence the outcome of an insect-host interaction. We manipulated both developmental stages of the host plants at the start of the interaction and temperature during the subsequent developmental period in a model system of a herbivorous butterfly, Anthocharis cardamines, and five of its Brassicaceae host plant species. Larval performance characteristics were favoured by earlier stages of host plants at oviposition as well as by higher developmental temperatures on most of the host species. The probability of a larva needing a second host plant covered the full range from no influence of either phenological matching or temperature to strong effects of both factors, and complex interactions between them. The probability of a plant outgrowing a larva was dependent only on the species identity. This study demonstrates that climatic variation can influence the outcome of consumer-resource interactions in multiple ways and that its effects differ among host plant species. Therefore, climate warming is likely to change the temporal match between larval and plant development in some plant species, but not in the others. This is likely to have important implications for host plant use and possibly influence competitive relationships.
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