環境科学院 植物生態学セミナー   2012-07-10 (Tue) 10:30
(Room: A809 )

Differences in reproductive traits between endangered species Drosera anglica and common congener D. rotundifolia

Yuri Hoyo

It is an essential to understand their life history traits and important factors to regulate their life history for making appropriate decision for the protection and restoration of an endangered species. Drosera anglica, which adapts to poor-nutrient boreal bogs, is reported to decrease on several habitats in the world and is concerned to accelerate the disappearance rate of local population. Reproductive traits, e.g. seed set and reproductive mode (the balance between the sexual and vegetative reproduction), have previously been shown to be critical for reproductive success and persistence of endangered species. In this study, I compared the reproductive traits of D. anglica with a closely related but more common sympatric congener D. rotundifolia to determine whether D. anglica is more vulnerable than D. rotundifolia in their life history traits related to reproduction, growth and survival. I asked following two questions, 1) does D. anglica have low productivity in sexual and vegetative reproduction?, and 2) do the differences of reproductive traits affect abundance in microhabitat of D. anglica? In this seminar, I answer about the question 1). The study was conducted in the Sarobetsu mire, northern Hokkaido where the two Drosera species co-occurred. Five permanent plots were placed from 2009-2011, and shoot size and reproductive status were recorded for all shoots. The sexual and vegetative productions were respectively quantified by number of flowers and new ramet. Number of produced flowers per shoot was larger on D. rotundifolia however number of produced new ramets per shoot was larger on D. anglica. Both the proportion of flowering and vegetative reproduction in all mature shoots was higher on D.anglica than on D. rotundifolia. Flowering and vegetative reproduction were size-dependent and threshold size of reproduction was larger on D. anglica. Occasionally, both sexual and vegetative reproduction were continuously seen for two or three years on a shoot, especially for D. anglica. Flowering affected next year’s survival of the shoot but vegetative reproduction did not. Based on these results, D. anglica seems to be more reliance on vegetative reproduction, and to keep stable reproductive productivity if only the shoot could grow, although the number of flowers is less than D. rotundifolia.


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