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Re: [beemonitoring] Why plants mass flower?

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  • David Inouye
    Burd, M. (1998). Excess flower production and selective fruit abortion: a model of potential benefits. Ecology 79 (6): 2123-2132. Flowering plants often
    Message 1 of 2 , Jan 30, 2012
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      Burd, M. (1998). ""Excess" flower production and selective fruit abortion:  a model of potential benefits." Ecology 79(6): 2123-2132.
               Flowering plants often produce more flowers than fruits. An initial "excess" of flowers, although making no numerical contribution to fruit set, may indirectly increase female reproductive success by allowing selective maturation of fruits of superior quality. I use a framework based on order statistics to assess the potential fitness benefit from this "wider choice" mechanism. The analysis shows that a floral surplus with subsequent selective abortion can generate large increases in mean female fitness. However, marginal fitness returns always diminished as the floral surplus increased (i.e., the fitness gain curve was always saturating), and imperfect selectivity of abortion could severely mute the advantages of surplus flowers. If the mating environment creates low variance in quality among developing fruits, then little benefit is derived from surplus flowers, while a high variance allows large fitness gains but with rapidly saturating benefits. The results imply that selection on flower number due to wider choice could be very strong in some circumstances, but that selection through this mechanism may often favor only a modest number of excess flowers.

      Bos, M. M., D. Veddeler, et al. (2007). "Caveats to quantifying ecosystem services: Fruit abortion blurs benefits from crop pollination." Ecological Applications 17(6): 1841-1849.
               The recent trend to place monetary values on ecosystem services has led to studies on the economic importance of pollinators for agricultural crops. Several recent studies indicate regional, long-term pollinator declines, and economic consequences have been derived from declining pollination efficiencies. However, use of pollinator services as economic incentives for conservation must consider environmental factors such as drought, pests, and diseases, which can also limit yields. Moreover, excessis a well-known reproductive strategy of plants as insurance against unpredictable, external factors that limit reproduction. With three case studies on the importance of pollination levels for amounts of harvested fruits of three tropical crops (passion fruit in Brazil, coffee in Ecuador, and cacao in Indonesia) we illustrate how reproductive strategies and environmental stress can obscure initial benefits from improved pollination. By interpreting these results with findings from evolutionary sciences, agronomy, and studies on wild-plant populations, we argue that studies on economic benefits from pollinators should include the total of ecosystem processes that (1) lead to successful pollination and (2) mobilize nutrients and improve plant quality to the extent that crop yields indeed benefit from enhanced pollinator services. Conservation incentives that use quantifications of nature's services to human welfare will benefit from approaches at the ecosystem level that take into account the broad spectrum of biological processes that limit or deliver the service.

      Torres, C. and L. Galetto (1999). "Factors constraining fruit set in Mandevilla pentlandiana (Apocynaceae)." Botanical Journal of the Linnean Society 129(3): 187-205.
               The reproductive success of Mandevilla pentlandiana was studied to disclose its reproductive strategy, and to determine the links between nectar production, breeding system, fruit set and inflorescence size. The plant produces many inflorescences with a large number of flowers but initiates few fruits (9%). This vine is self-compatible but not autogamous. Given that no significant differences could be detected considering many traits (ripe and abortive fruit sets, fruit quality, and seedling survival) between the pollination treatments (self-, cross-and natural-), the low natural fruit set was not related to pollen limitation. Fruits were not distributed at random within inflorescences (earlier fruits had the highest probability of maturation) but there were no significant differences in fruit quality according to different fruit positions. Conversely, the time of fruit initiation influenced most of the fruit-traits. Many developing fruits were aborted (20%). An increase in the probability of abortion was detected when the whole inflorescence was hand pollinated. In addition, a positive correlation was detected between the abortions and the number of ripe fruits which developed before them. Looking at our data from an evolutionary perspective, we argue that a theoretical inflorescence size, corresponding to the intersection point between the mean values of fruit number and fruit set per inflorescence, can be assumed to indicate the optimum inflorescence size that maximizes equally both female and male functions. Comparison between the theoretical and the observed mean inflorescence size suggests, that for M. pentlandiana, pollen donation may be the primary evolutionary factor behind excess flowers.



      At 05:44 AM 1/30/2012, Asif Sajjad wrote:
       

      Hello All,
                     I am student of plant-pollinator interactions at B Z University Multan, Pakistan. I need some help regarding this statement:

      "many mass-flowering plants mass-flower to increase floral display and abort most of their flowers and may not have enough resources to develop fruits from all these flowers"

      I need any supportive reference for this statement if it's true.

      Thank you
      --
      Asif Sajjad
      PhD scholar
      B Z university Multan,
      Pakistan

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