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Understand the fitness consequences of seasonal reproduction timing in Macoma balthica bivalves. Explore the impact of spawning before the spring bloom and alternative timing rules on larval growth and survival. Utilize a semi-chemostat system for seasonal pattern analysis in food concentration and temperature. Investigate invadability of mutants to determine adaptive reproductive strategies.
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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 • An why should they? • Alternative rule: Make sure the bloom occurs at the size of maximum growth
System • Semi-chemostat • Seasonal pattern in food concentration of inflowing water • Seasonal pattern in temperature • Standard DEB model • Macoma balthica parameters as estimated by Van der Veer et al. (2006) • R extremely small: 0.012%; background mortality • One spawning event per year
Adaptive dynamics • Introduce a mutant that has no effect on the (food) environment, and see whether it can invade • In a k-year cycle of the resident, mutants are introduced during each of k succeeding years • In 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
Preliminary conclusion • Stable strategy: spawn exactly half a year before the food peak
Next steps • Present survival rule: [E]/[Em] > L/Lm • Resorption of reproductive material • Low R • A-symmetric interference, which decreases the competitive ability of the youngsters