| 1. |
- von Euler, Tove, 1976-, et al.
(författare)
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A demographic assessment of local adaptation in a grassland perennial herb
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The importance of local adaptation to the distribution and performance of plants is well recognized. Several studies have documented local adaptation among populations of perennial plant species based on assessments of one or a few fitness components. However, natural selection does not act on fitness components but on life-time fitness. Assessments of local adaptation should therefore ideally be based on integrated measures of the performance during the entire life cycle. We transplanted seedlings and adult plants reciprocally among four populations of the perennial herb Primula farinosa separated by up to 6.2 km in alvar grasslands in SE Sweden, and recorded survival, growth, flowering and fruit production during two-three consecutive years (2009-2011). We used integral projection models to quantify variation in total fitness, estimated as population growth rate. Transplant site had large effects on most aspects of plant performance, and there were also significant effects of population of origin on survival, growth, flowering propensity and fruit production. However, no evidence of local adaptation expressed through single fitness components or total fitness was detected. The results suggest that at the spatial scale examined genetic differentiation among alvar populations of P. farinosa is not related to current selection regimes. Furthermore, this study illustrates how total fitness can be estimated to assess local adaptation in long-lived species.
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| 2. |
- von Euler, Tove, 1976-, et al.
(författare)
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Environmental context influences the impact of pre-dispersal seed predation on host plant population dynamics in multiple ways
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Environmental heterogeneity influences species distributions as well as population dynamics within species. Effects of the environment can be both direct and indirect, altering the outcome of biotic interactions. Although it is well known that biotic interactions may strongly affect several vital rates, few studies have investigated how the effect of biotic interactions on life-time fitness and population dynamics depends on environmental context. We studied how the effect of pre-dispersal seed predation on host plant population growth rates varied with soil conditions and vegetation height, monitoring 24 populations of the perennial herb Primula farinosa during three consecutive years. First, we investigated how reductions in population growth rate due to seed predators were related to predation intensity and the sensitivity of population growth rate to predation, respectively. Second, we examined how predation intensity and sensitivity were related to environmental context in terms of soil depth, soil moisture, soil nutrient composition and vegetation height. Both seed predation intensity and sensitivity of population growth rate to seed predation varied considerably among populations, and both contributed to variation in the effects of seed predation on population growth rate. Soil moisture influenced population growth rate in three different ways; via direct effects on potential growth rate, via effects on predation intensity and via effects on the sensitivity of population growth rates to seed predation. We conclude that, in our study system, environmental context influences how biotic interactions affect population dynamics, and that a given environmental parameter can influence population growth rate in different directions through effects on potential growth rate, intensity of biotic interactions, and the sensitivity of population growth rate to these biotic interactions.
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| 3. |
- von Euler, Tove, 1976-
(författare)
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Environmental heterogeneity, population dynamics and life-history differentiation in Primula farinosa
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Allocation to reproduction is a key life-history trait. Optimal allocation to reproduction depends on environmental conditions because of their effects both on costs and benefits of reproduction and on patterns of growth, fecundity, and mortality. In this thesis, I studied 24 populations of the perennial herb Primula farinosa in the northern part of the Great Alvar on Öland, SE Sweden, and in an experimental garden at Stockholm University to investigate how plant allocation patterns and population dynamics vary along environmental gradients. In the first study, I performed experimental manipulations of reproduction to study costs of reproduction in relation to water availability. In the second study, I performed a demographic survey to investigate the effects of pre-dispersal seed predation on host-plant population dynamics in relation to environmental context. In the third study, I used a common garden experiment to investigate whether environmental variation among natural populations was correlated with genetic differentiation in reproductive effort, and in the fourth study, I performed reciprocal transplantations among four populations to investigate whether genetically based adaptive differentiation among local populations could be detected. The results showed that under natural conditions, plant reproductive costs, intensity of pre-dispersal seed predation, population growth rate and reproductive effort varied with water availability and vegetation height. Costs of reproduction were detected at high and low water availability but not under intermediate soil moisture conditions (paper I). Population dynamics of P. farinosa were affected by environmental conditions both directly, through effects on potential population growth rate (in the absence of seed predation) and indirectly, through effects on seed predation intensity and sensitivity to seed predation (paper II). Among-population genetic differentiation in reproductive allocation was documented in the common-garden experiment (paper III). However, reciprocal transplantations among populations separated by up to 6.2 km provided no evidence of local adaptation to current environmental conditions. Moreover, large differences in the performance of individuals transplanted to different study sites suggest that the study populations display considerable phenotypic plasticity (paper IV). Taken together, the results of these studies suggest that environmental variation has important direct and indirect effects on population dynamics and life history trade-offs in P. farinosa, and that differences in reproductive effort partly reflect genetic differentiation, but that phenotypic variation observed among natural populations does not reflect adaptations to current environmental conditions.
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| 4. |
- von Euler, Tove, 1976-, et al.
(författare)
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Floral display and habitat quality affect cost of reproduction in Primula farinosa
- 2012
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 121:9, s. 1400-1407
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Tidskriftsartikel (refereegranskat)abstract
- Costs of reproduction should depend on resource availability and on reproductive effort, which in turn may depend on traits influencing reproductive success. Therefore, variation in both habitat quality and reproductive traits should be considered when assessing reproductive costs. We investigated the effect of habitat quality and floral display on the costs of reproduction in the perennial herb Primula farinosa. In the study area, P. farinosa occurs in habitats that differ in water availability, which strongly influences plant performance. Furthermore, it displays a scape length dimorphism, with two distinct scape morphs differing in attractiveness to pollinators and reproductive success. To test the hypothesis that the cost of fruit production is higher in the long-scaped than in the short-scaped morph, and depends on water availability, we manipulated reproductive investment in eight P. farinosa populations along a gradient of soil moisture. Fruit set was higher in long-scaped individuals, and prevention of fruit set increased flower production in the following year among long-scaped, but not among short-scaped plants. Furthermore, costs of fruit production were evident at low and high moisture levels but not at intermediate levels. The results demonstrate an association between a genetically determined difference in floral display and cost of reproduction, and suggest that costs of reproduction are non-linearly related to water availability. They thus indicate links between the evolution of plant reproductive traits and plant life histories, and between habitat quality and optimal life history.
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| 5. |
- von Euler, Tove, 1976-, et al.
(författare)
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Genetic differentation in reproductive effort in the perennial herb Primula farinosa is related to vegetation height
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Spatial variation in abiotic and biotic environmental factors influences vital rates and selection on reproductive strategies. Environmental factors that increase plant mortality, reduce competition and create gaps favorable for seedling recruitment should favor high reproductive effort in plants. To determine whether reproductive effort was negatively related to vegetation height and water availability, we quantified variation in age at first reproduction and relative allocation to flower production in flowering plants in field surveys and in a common-garden experiment that included twenty populations of Primula farinosa in calcareous alvar grasslands in SE Sweden. Reproductive effort of flowering plants varied significantly among populations both at the sites of origin and in the common-garden experiment, whereas there were no differences in age at first reproduction. Both in the field and in the common garden, reproductive effort decreased with increasing vegetation height at the sites of origin, and in the field it also tended to decrease with increasing soil moisture. The results indicate that observed variation in reproductive effort represent both genetic differentiation and phenotypic plasticity, that genetic differences in reproductive effort may have evolved in response to divergent selection associated with among-population differences in vegetation height, and that water availability is one determinant of plastic variation in reproductive effort.
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