Opposing Selective Pressures Imposed by Pollinators and Seed Predators on Succisa pratensis

Janovský, Z. (1), Říhová, D. (1,2), Vosolsobě, S. (1,3), Ponert, J.H. (3,4), Mikát, M. (1,2) & Pavlíková, A. (5)

1) Department of Botany, Charles University Prague, Czech Republic
2) Department of Zoology, Charles University Prague
3) Department of Experimental Plant Biology, Charles University Prague
4) Prague Botanical Garden
5) Department of Zoology, University of South Bohemia, České Budějovice

Established plants of many perennial species often do not flower each year. This may be caused often by nutrient limitation, however it might also represent a plant’s “decision” optimising the fitness. We investigated, what plant traits attract pollinators and seed predators, which of these two groups has greater influence on plant fitness and whether this is being reflected by the “flowering strategy” of individual plants over two years.

The pollinators and seed predators are being attracted by virtually the same set of plant traits, connected with plant’s conspicuousness. However, the occurrence of pollinators was much more predictable. The overall effect of seed predators was approximately twice as important compared to pollinators. We suppose, that this is caused by the fact, that even a small plant attracts some pollinators, whereas approximately half of the plants suffer no or negligible seed predation, with the other half receiving minor to very serious seed predation (sometimes even 100%). This is in line also with the results of the comparison of plants, that flowered only once or in both years. When controlled on their reproductive investment, the plants flowering twice (and thus with comparably smaller inflorescence) nursed more seeds.

We conclude that in our system with quite predictable pollinators and rather lottery-like occurrence of seed predators it is better for plants to flower twice and hedge the bets. We presume, however, that in a system with rare pollinators the model “once every several years” would be more advantageous.

Presentováno na konferenci populačně biologické sekce Německé ekologické společnosti (GfÖ) konané v Oxfordu ve dnech 2.-4.6.2011.

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