Costs of Reproduction in Subarctic Ranunculus acris: A Five-Year Field Experiment

Hemborg, Åsa M.

doi:10.2307/3546838

Cited by 15 publications

(11 citation statements)

References 57 publications

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“…An alternative explanation could be that soil nutrient availability is lower than at warmer sites (Chapin and Shaver 1985). As a result, the production of reproductive meristems may be less frequent (Hemborg 1998;Hemborg and Karlsson 1998). Producing an extra¯ower might be possible only after nutrient accumulation (ThoreÂ n et al 1996).…”

Section: Discussionmentioning

confidence: 98%

“…Producing an extra¯ower might be possible only after nutrient accumulation (ThoreÂ n et al 1996). If producing multiple¯owers at these high-altitude sites implies higher costs of reproduction in terms of reduced future reproductive success or survival (Davis 1981;Hemborg 1998), in the long term, single¯owers may be more favourable. We would therefore explain the distribution of multiple¯owers as being enforced by environmental factors, rather than by interactions between¯ies and their host plants, because seed predation only very rarely resulted in a skewed relationship to the disadvantage of the host.…”

Section: Discussionmentioning

confidence: 98%

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Oviposition by mutualistic seed-parasitic pollinators and its effects on annual fitness of single- and multi-flowered host plants

Hemborg

Després

1999

Oecologia

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The balance of intimate relationships between plants and seed-eating pollinators can depend on pollinator behaviour in relation to floral characters, such as flower size and flower number. Here, we examined how pollinator oviposition in relation to these traits affected annual fitness (seed output) of single- and multi-flowered Trollius europaeus along altitudinal gradients in subarctic Sweden and the French Alps. Small flies (Chiastocheta spp.) pollinate T. europaeus and their larvae feed on developing seeds. Assuming that late flowers in multi-flowered plants attracted flies to the earliest flower on the same plant, we expected more eggs and higher seed predation in early multiple flowers than in single flowers. Relative seed predation would thereby increase with flower number. Both in Sweden and the Alps, more eggs were placed on large flowers. Early multiple flowers were slightly larger than single flowers, and about twice the size of secondary flowers. As a result, and possibly combined with the effects of secondary flowers, early multiple flowers attracted more ovipositing flies and experienced relatively higher seed predation. However, this did not generally result in higher seed predation of multi-flowered hosts. Multiple flowers had greater seed output than single flowers at all altitudes, also in the high alpine and subarctic sites, where single flowers were more abundant. We hypothesise that the distribution of multiple flowers generally is enforced by environmental factors, rather than by fly-host plant interactions, because only very rarely (in triple-flowered alpine plants) was seed predation disproportionate, and the relationship skewed to the disadvantage of the host. The outcome of the mutualistic interaction was often similar in alpine and subarctic populations, but the underlying factors were different. Subarctic flowers had high abortion and low predation rates, while alpine flowers experienced the reversed situation. The higher fly abundance in the Alps suggests a more intense mutualistic interaction than in Sweden. Despite varying ecological and environmental conditions at these sites, the mutualistic relationship was generally in balance. However, when it was unbalanced, this could be explained by fly behaviour in response to floral traits, and by differences in fly abundance.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 98%

Oviposition by mutualistic seed-parasitic pollinators and its effects on annual fitness of single- and multi-flowered host plants

Hemborg

Després

1999

Oecologia

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“…Are their single flowers the result of lower nutrient availability at these sites (Sørensen 1941;Chapin and Shaver 1985)? Or is flower production suppressed by architectural constraints (Diggle 1995(Diggle , 1997; for example, meristem availability (Watson and Casper 1984;Geber 1990;Hemborg 1998a)? The level of phenotypic plasticity can be genetically determined (Schmid and Weiner 1993;Clauss and Aarssen 1994;Redbo-Torstensson 1994), and restricted in some genotypes, if subjected to strong selection in their natural environments (Schmid and Bazzaz 1992).…”

Section: Introductionmentioning

confidence: 98%

Floral phenotypic plasticity as a buffering mechanism in the globeflower–fly mutualism

Hemborg

Després

2011

Plant Ecol

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A buffering mechanism in co-evolutionary relationships could be to display phenotypic plasticity in response to environmental changes. In the nursery pollination mutualism between the European globeflower and its exclusive fly pollinators, adults feed and mate in flowers, and larvae develop feeding on seeds. Flower number and size influence fitness for both partners, and large flowers attract more flies. We tested floral plasticity in plants from two contrasting environments: a high-altitude heath and low-and intermediate-altitude meadow forests. High-altitude plants have single flowers, while meadow-forest plants sometimes have multiple flowers. Plants were grown for 3 years in a garden and supplied with eight times more nutrients than available in natural soils, given to controls. During the experiment, over 90% of all plants with excess nutrients flowered, while in controls, 40% (highaltitude) to 75-78% (meadow-forest) plants flowered. Excess nutrients stimulated 30% larger flowers, and in meadow-forest plants flower number increased 4.5-5 times. Flower number was only doubled in high-altitude plants. High-altitude plants displayed less plasticity, and possibly, a different genetic strategy involving meristem limitation.

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“…In fact, clipping of flower stalks and removal of developing flowers are treatments sometimes used to manipulate the current reproductive investment in order to test how the reduced reproductive effort affects future reproductive success in perennial plants (e.g. Tolvanen and Laine 1997;Hemborg 1998;Houle 2001;Obeso 2002;Knight 2003). If the plants do postpone their reproductive investment in response to flower removal, their improved future reproductive success would indicate the costs of reproduction.…”

Section: Introductionmentioning

confidence: 98%

Tolerance of a perennial herb, Pimpinella saxifraga, to simulated flower herbivory and grazing: immediate repair of injury or postponed reproduction?

Huhta

Rautio²,

Hellström

et al. 2008

Plant Ecol

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Perennial, polycarpic herbs can respond to herbivory either by (1) regrowth in the same season in order to compensate for lost reproductive structures or by (2) postponing reproduction until the following growing season. We tested these response patterns with the perennial umbellifer Pimpinella saxifraga by simulating flower herbivory and shoot grazing both in the field and in a common garden experiment. In the field, both simulated flower herbivory and grazing effectively suppressed current reproduction, whereas no statistically significant effects of previous-year treatments on growth or reproduction were found in the following year. In the common garden, in the first year the species fully compensated for simulated flower herbivory in vegetative parameters but seed set was reduced by 26%. After 2 years of flower removal, the plants overcompensated in shoot and root biomass by 47 and 46%, respectively, and compensated fully in reproductive performance. Simulated grazing resulted in 21% lower shoot biomass in the first season, but the root biomass was not affected. In the second season the root biomass increased by 43% as compared to the control plants. However, regrowth following simulated grazing resulted in a significant delay in flowering with the consequence that the seed yield of fertile plants was reduced by 55% as compared to the control plants. These results suggest that in resource-rich garden conditions P. saxifraga may immediately repair injuries caused by flower herbivory, but repairs more extensive shoot injury less successfully. Delayed phenology decreases the benefits of immediate repair. In resource-poor conditions, the benefits of regrowth can be negligible. Accordingly, in our field population, the plants postponed their reproduction until the following year in response to simulated grazing and frequently in response to flower removal. When the plants gain very little from regrowth, the costs of reproduction would select for postponed reproduction in response to injury.

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Costs of Reproduction in Subarctic Ranunculus acris: A Five-Year Field Experiment

Cited by 15 publications

References 57 publications

Oviposition by mutualistic seed-parasitic pollinators and its effects on annual fitness of single- and multi-flowered host plants

Oviposition by mutualistic seed-parasitic pollinators and its effects on annual fitness of single- and multi-flowered host plants

Floral phenotypic plasticity as a buffering mechanism in the globeflower–fly mutualism

Tolerance of a perennial herb, Pimpinella saxifraga, to simulated flower herbivory and grazing: immediate repair of injury or postponed reproduction?

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