nvtb 2008 jaap van der meer

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Seasonal timing of reproduction in the bivalve Macoma balthica : a model study of fitness consequences. NVTB 2008 Jaap van der Meer. Question. Timing of reproduction: Make sure the larvae can grow up under optimal food conditions Spawn just before the spring bloom Many species don’t do this - PowerPoint PPT Presentation

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  • *QuestionTiming of reproduction: Make sure the larvae can grow up under optimal food conditionsSpawn just before the spring bloom

    Many species dont do this

    An why should they? Alternative rule: Make sure the bloom occurs at the size of maximum growth

  • *SystemSemi-chemostat

    Seasonal pattern in food concentration of inflowing waterSeasonal pattern in temperature

    Standard DEB modelMacoma balthica parameters as estimated by Van der Veer et al. (2006)R extremely small: 0.012%; background mortalityOne spawning event per year

  • *60 days after

  • *110 days after

  • *160 days after

  • *Spawning date: bifurcation analysis

  • *160 days after

  • *Adaptive dynamicsIntroduce a mutant that has no effect on the (food) environment, and see whether it can invadeIn a k-year cycle of the resident, mutants are introduced during each of k succeeding yearsIn one run, three types of mutants were introduced: the first group spawns slightly earlier, the second group does as the residents, the last group spawns slightly later

  • Mutants*

  • *Invadability

  • *140 days before the plankton peak

  • *140 days before the plankton peak

  • *60 days after the plankton peak

  • *60 days after the plankton peak

  • *Individual state

  • *Invadability

  • *Preliminary conclusionStable strategy: spawn exactly half a year before the food peak

  • *Next stepsPresent survival rule: [E]/[Em] > L/Lm Resorption of reproductive material

    Low RA-symmetric interference, which decreases the competitive ability of the youngsters

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