Is the diatom sex clock a clock?

Area of Science:

• Marine biology
• Mathematical modeling
• Cellular dynamics

Background:

• Diatoms exhibit a unique life cycle with continuous cell size decrease and restoration.
• This size fluctuation has been considered a multi-annual biological clock.
• Understanding long-term diatom population dynamics requires robust mathematical models.

Purpose of the Study:

• To investigate mathematical models describing diatom population oscillations.
• To determine the mechanisms behind long-lasting rhythms in diatom populations.
• To analyze the role of cell size distribution in population dynamics.

Main Methods:

• Algebraic and numerical analysis of generic mathematical models.
• Simulations of diatom proliferation dynamics incorporating a limited cell wall lifetime.
• Inclusion of seasonal perturbation events in population models.

Main Results:

• Simple proliferation models fail to sustain oscillations due to size distribution broadening.
• A limited cell wall lifetime significantly slows relaxation to equilibrium over many generations.
• The proposed model, with limited lifetime and seasonal perturbations, explains long-term diatom rhythms.

Conclusions:

• Diatom population dynamics are not a simple limit cycle oscillator.
• The life cycle acts like a pendulum clock, requiring periodic "winding" by seasonal events.
• A limited cell wall lifespan is crucial for maintaining long-term, non-equilibrium oscillations.