Author: Guillaume  Le Gland,  Postodoctoral researcher (ICM - CSIC)

Designation: 

Description:
Diversity plays a key role in the ability of marine ecosystems to adapt to environmental changes. However, modelling the adaptive dynamics of phytoplankton functional traits remains challenging due to the competitive exclusion of sub-optimal phenotypes. Trait diffusion (TD) is a recently developed approach to sustain diversity in plankton models by allowing the adaptive evolution of traits to occur at ecological timescales. SPEAD (Simulating Plankton Evolution with Adaptive Dynamics) is an eco-evolutionary model where phytoplankton phenotypes compete for a nutrient. Phytoplankton in SPEAD are characterized by two traits, nitrogen half-saturation constant and optimal temperature, which can mutate using the TD mechanism. SPEAD does not resolve the different phenotypes as discrete entities, using instead six statistical moments as state variables: total biomass, mean trait values, trait variances and inter-trait covariance. SPEAD is coupled to a vertically resolved (1D) physical model of the Sargasso Sea, and therefore its dynamics are controlled by seasonal variations in temperature, irradiance and vertical mixing. The simulated bulk properties of SPEAD 1.0 are validated against observations from BATS in the Sargasso Sea. The results of SPEAD 1.0 show very good agreement with those of a classical discrete multi-phenotype model and it has a computational cost two orders of magnitude lower. The effect on adaptive dynamics of a range of realistic mutation rate values is evaluated through a sensitivity analysis and the results are discussed in a plankton ecology context.

Category: Scientific Program Abstract > Special Sessions > SS44 Modelling the ecology & evolution of plankton