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

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1.
  • Sherman, Danielle A., et al. (författare)
  • Sex and the cost of reproduction through the life course of an extremely long-lived herb
  • 2019
  • Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 191:2, s. 369-375
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite being central concepts for life history theory, little is known about how reproductive effort and costs vary with individual age once plants have started to reproduce. We conducted a 5-year field study and estimated age-dependent reproductive effort for both sexes in the extraordinarily long-lived dioecious plant Borderea pyrenaica. We also evaluated costs of reproduction on vital rates for male and female plants, both by examining effects of differences in individual reproductive effort under natural conditions, and by conducting a flower removal experiment, aimed at decreasing reproductive effort. Reproductive effort was fairly constant and independent of age for males, which may reflect a strategy of adjusting overall reproductive output by spreading reproduction over the life course. Females had a higher total effort, which first increased and then decreased with age. The latter may be a response to an increasing reproductive value-an inverse of a terminal investment-or a sign of reproductive senescence due to an age-related physiological decline. Seed production was lower in plants with higher previous reproductive effort and this effect increased with age. We found no evidence for costs of reproduction on other vital rates for either sex. Experimental flower removal only resulted in progressively more negative effects on flower production in older male plants, whereas female vital rates were unaffected. Overall, this study demonstrates that not only sex, but also age influences resource allocation trade-offs and, thus, plant life history evolution.
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2.
  • Fogelström, Elsa, 1986- (författare)
  • Plant phenology in seasonal environments
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Phenology, or the seasonal timing life-history events such as emergence, reproduction and senescence will determine the outcome of interactions between plants and both abiotic and biotic aspects of the environment. Such timing is therefore of utmost importance for plants in seasonal environments. In this thesis, I first investigated the factors determining the start, end and length of the growing season for a perennial herb. Secondly, I estimated phenotypic selection on flowering time and investigated to which extent it corresponded to genotypic selection in a natural field setting. Thirdly, I estimated population differentiation in flowering time in a common garden and in the field. Lastly, I experimentally manipulated the synchrony of a perennial herb and its main herbivore to investigate the effects of herbivore phenological preference and plant-herbivore synchrony on the direction of selection on flowering time.I found that flowering individuals emerged earlier in spring than non-flowering individuals and that large individuals senesced later in autumn, suggesting that the length of the growing season is linked to individual condition and resource demands. Phenotypic selection favoured early-flowering individuals, but there was no genotypic selection. I found evidence for genetic population differentiation in flowering time in a common garden but not in the field. This suggests that, although flowering time has a genetic component, the observed variation in flowering time was mainly plastic under natural field conditions. Lastly, I show that constant herbivore preferences of plant phenology, in combination with environmentally driven variation in relative synchrony of the plant and the herbivore, leads to among-year variation in natural selection on flowering time. With this thesis, I contribute to identifying the factors affecting plant phenology as well as of the mechanisms shaping selection on flowering time in perennial plants. Such knowledge is essential for predicting species responses to climate change.
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3.
  • Karlsson, Konrad, 1983- (författare)
  • Local adaptation in life history traits and population size estimation of aquatic organisms
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Human society is dependent on healthy aquatic ecosystems for our basic needs and well-being. Therefore, knowledge about how organisms respond and interact with their environments is pivotal. The Baltic Sea is highly affected by human activity and future populations living in its catchment area will have to respond to multiple set of changing abiotic and biotic predictors.The first two papers of this thesis focus on local adaptation, adaptive capacity, and the response to changing temperature, salinity, and food conditions of different Eurytemora affinis populations, a ubiquitous zooplankton species in the Baltic Sea. Development time of zooplankton is an important trait and relates to how fast a population can increase in number. Common garden experiments showed that E. affinis populations from warmer southern areas had shorter development time from nauplii to adult at high temperature compared to populations from colder areas, which indicates an adaptation to temperature. The adaptation was explained by a correlation in development time between higher temperatures, 17 and 22.5 °C, while development between a colder temperature, 12 °C, and the two higher temperatures was uncorrelated. This implies that adaption to short development time at high temperature is unlikely for populations originating from cold temperatures. Hence, global warming will be disadvantageous for northern, compared to southern populations. However, development time is heritable and may change under selection, and may improve the competitive advantage of northern populations. The population with the shortest development time had comparably lower survival at high temperature and low food quality. This represents a cost of fast development, and emphasizes the importance of including multiple stressors when investigating potential effects of climate change.E. affinis inhabits a broad range of habitats from an epi-benthic life in freshwater lakes and river mouths, to pelagic life in estuaries. Paper III aims to link the morphology of different populations to habitat and resource utilization. Results showed that the individuals of a pelagic population were smaller in size and more slender, compared to a littoral population of larger and more fecund individuals. In experimentally constructed benthic and pelagic algae communities, the littoral population produced less offspring than the pelagic population when filamentous benthic diatoms were included. This suggests that filaments disturb their feeding and that littoral populations of E. affinis stay epi-benthic. As pelagic fish typically select larger prey, living close to the bottom probably allows the littoral population to grow larger than the pelagic. These results link morphology to habitat specialization, and show contrasting ecological effects of two E. affinis populations.Paper IV focuses on the recreational angler’s potential role as a citizen scientist. The pike Esox lucius has a stabilizing role in ecosystems as a top consumer and is highly valued by recreational anglers in European lakes and estuaries. Results showed that recreational angling could be used to estimate population size and connectivity of E. lucius in spatial capture-recapture models. The only prerequisite is that anglers practice catch and release, retain spatial data, and take photos of their caught fish. These results show that data from recreational angling can be of potential use for fisheries managers and researchers.
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4.
  • Inouye, Brian D., et al. (författare)
  • Phenology as a process rather than an event : from individual reaction norms to community metrics
  • 2019
  • Ingår i: Ecological Monographs. - : Wiley. - 0012-9615 .- 1557-7015. ; 89:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Measures of the seasonal timing of biological events are key to addressing questions about how phenology evolves, modifies species interactions, and mediates biological responses to climate change. Phenology is often characterized in terms of discrete events, such as a date of first flowering or arrival of first migrants. We discuss how phenological events that are typically measured at the population or species level arise from distributions of phenological events across seasons, and from norms of reaction of these phenological events across environments. We argue that individual variation in phenological distributions and reaction norms has important implications for how we should collect, analyze, and interpret phenological information. Regarding phenology as a reaction norm rather than one year's specific values implies that selection acts on the phenologies that an individual expresses over its lifetime. To understand how climate change is likely to influence phenology, we need to consider not only plastic responses along the reaction norm but changes in the reaction norm itself. We show that when individuals vary in their reaction norms, correlations between reaction norm elevation and slope make first events particularly poor estimators of population sensitivity to climate change, and variation in slopes can obscure the pattern of selection on phenology. We also show that knowing the shape of the distribution of phenological events across the season is important for predicting biologically important phenological mismatches with climate change. Last, because phenological events are parts of a continuous developmental process, we suggest that the approach of measuring phenology by recording developmental stages of individuals in a population at a single point in time should be used more widely. We conclude that failure to account for phenological distributions and reaction norms may lead to overinterpretation of metrics based on single events, such as commonly recorded first event dates, and may confound meta-analyses that use a range of metrics. Rather than prescribing a single universal approach to studying phenology, we point out limitations of inferences based on single metrics and encourage work that considers the multivariate nature of phenology and more tightly links data collection and analyses with biological hypotheses.
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5.
  • Toftegaard, Tenna, et al. (författare)
  • Butterfly-host plant synchrony determines patterns of host use across years and regions
  • 2019
  • Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 128:4, s. 493-502
  • Tidskriftsartikel (refereegranskat)abstract
    • Variation in the degree of synchrony among host plants and herbivores can disrupt or intensify species interactions, alter the strength of natural selection on traits associated with phenological timing, and drive novel host plant associations. We used field observations from three regions during four seasons to examine how timing of the butterfly herbivore Anthocharis cardamines relative to six host plant species (Arabis hirsuta, Cardamine pratensis, Arabis glabra, Arabidopsis thaliana, Thlaspi caerulescens and Capsella bursa-pastoris) influenced host species use and the choice of host plant individuals within populations. Butterflies laid a larger fraction of their eggs on species that were closer to the butterfly's preferred stage of development than on other host species. Within host plant populations, butterflies showed a stronger preference for individuals with a late phenology when plants within the population were on average more developed at the time of butterfly flight. Our results suggest that changes in synchrony between herbivores and their host plants are associated with changes in both host species use and the choice of host plant individuals differing in phenology within populations. This is likely to be an important mechanism generating variation in interaction intensities and trait selection in the wild, and therefore also relevant for understanding how anthropogenic induced changes, such as global warming, will influence natural communities.
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6.
  • Valdés, Alicia, et al. (författare)
  • Resource overlap and dilution effects shape host plant use in a myrmecophilous butterfly
  • 2019
  • Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 88:4, s. 649-658
  • Tidskriftsartikel (refereegranskat)abstract
    • The effects of consumers on fitness of resource organisms are a complex function of the spatio-temporal distribution of the resources, consumer functional responses and trait preferences, and availability of other resources. The ubiquitous variation in the intensity of species interactions has important consequences for the ecological and evolutionary dynamics of natural populations. Nevertheless, little is known about the processes causing this variation and their operational scales. Here, we examine how variation in the intensity of a consumer-resource interaction is related to resource timing, resource density and abundance of other resources. Using the butterfly consumer Phengaris alcon and its two sequential resources, the host plant Gentiana pneumonanthe and the host ants Myrmica spp., we investigated how butterfly egg-laying depended on focal host plant phenology, density and phenology of neighbouring host plants and host ant abundance. Butterflies preferred plants that simultaneously maximized the availability of both larval resources in time and space, that is, they chose early-flowering plants that were of higher nutritional quality for larvae where host ants were abundant. Both the probability of oviposition and the number of eggs were lower in plant individuals with a high neighbour density than in more isolated plants, and this dilution effect was stronger when neighbours flowered early. Our results show that plant-herbivore interactions simultaneously depend on the spatio-temporal distribution of a focal resource and on the small-scale spatial variation in the abundance of other herbivore resources. Given that consumers have negative effects on fitness and prefer certain timing of the resource organisms, this implies that processes acting at the levels of individuals, populations and communities simultaneously contribute to variation in consumer-mediated natural selection.
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7.
  • Fogelström, Elsa, et al. (författare)
  • Phenotypic but not genotypic selection for earlier flowering in a perennial herb
  • 2019
  • Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 107:6, s. 2650-2659
  • Tidskriftsartikel (refereegranskat)abstract
    • 1. Timing of reproduction affects the outcome of interactions between plants and their pollinators, grazers and seed predators, as well as with their local abiotic environment. In seasonal environments, phenotypic selection has often been shown to favour early flowering. Yet, we still know little about the agents driving selection in natural populations and whether observed phenotypic selection corresponds to genotypic selection – a prerequisite for evolutionary change.2. In this study, we experimentally assessed phenotypic and genotypic selection for flowering time in a natural population of the perennial herb Lathyrus vernus. We transplanted sibling individuals, obtained through controlled crosses, to their source population and found net phenotypic selection for earlier flowering in the field.3. Despite a higher susceptibility to roe deer grazing, early‐flowering plants had higher fruit set and more seeds per fruit than late‐flowering plants. We found no support for genotypic selection on flowering time, and heritability for first flowering day was very low.4. Synthesis: Our results suggest that commonly observed patterns of higher fitness in early‐flowering plants do not always correspond to selection on genotypic values and are thus not necessarily expected to result in evolutionary change even if the relationship between flowering time and fitness is causal. This finding should be important to understand how species phenology might respond to changing environmental conditions.
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8.
  • Valdés, Alicia, et al. (författare)
  • A natural heating experiment : Phenotypic and genotypic responses of plant phenology to geothermal soil warming
  • 2019
  • Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 25:3, s. 954-962
  • Tidskriftsartikel (refereegranskat)abstract
    • Under global warming, the survival of many populations of sedentary organisms in seasonal environments will largely depend on their ability to cope with warming in situ by means of phenotypic plasticity or adaptive evolution. This is particularly true in high‐latitude environments, where current growing seasons are short, and expected temperature increases large. In such short‐growing season environments, the timing of growth and reproduction is critical to survival. Here, we use the unique setting provided by a natural geothermal soil warming gradient (Hengill geothermal area, Iceland) to study the response of Cerastium fontanum flowering phenology to temperature. We hypothesized that trait expression and phenotypic selection on flowering phenology are related to soil temperature, and tested the hypothesis that temperature‐driven differences in selection on phenology have resulted in genetic differentiation using a common garden experiment. In the field, phenology was related to soil temperature, with plants in warmer microsites flowering earlier than plants at colder microsites. In the common garden, plants responded to spring warming in a counter‐gradient fashion; plants originating from warmer microsites flowered relatively later than those originating from colder microsites. A likely explanation for this pattern is that plants from colder microsites have been selected to compensate for the shorter growing season by starting development at lower temperatures. However, in our study we did not find evidence of variation in phenotypic selection on phenology in relation to temperature, but selection consistently favoured early flowering. Our results show that soil temperature influences trait expression and suggest the existence of genetically based variation in flowering phenology leading to counter‐gradient local adaptation along a gradient of soil temperatures. An important implication of our results is that observed phenotypic responses of phenology to global warming might often be a combination of short‐term plastic responses and long‐term evolutionary responses, acting in different directions.
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