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A. Merico, G. Brandt, S.L. Smith, and M. Oliver,
Sustaining diversity in trait-based models of phytoplankton communities,
Front. Ecol. Evol. 2 (2014), 59, doi:10.3389/fevo.2014.00059.
Abstract:
It is well-established that when equilibrium is attained for two
species competing for the same limiting resource in a stable, uniform
environment, one species will eliminate the other due to competitive
exclusion. While competitive exclusion is observed in laboratory
experiments and ecological models, the phenomenon seems less common in
nature, where static equilibrium is prevented by the fluctuating
physical environment and by other factors that constantly change
species abundances and the nature of competitive
interactions. Trait-based models of phytoplankton communities appear
to be useful tools for describing the evolution of large assemblages
of species with aggregate group properties such as total biomass, mean
trait, and trait variance, the latter representing the functional
diversity of the community. Such an approach, however, is limited by
the tendency of the trait variance to unrealistically decline to zero
over time. This tendency to lose diversity, and therefore adaptive
capacity, is typically "solved" by fixing the variance or by
considering exogenous processes such as immigration. Exogenous
processes, however, cannot explain the maintenance of adaptive
capacity often observed in the closed environment of chemostat
experiments. Here we present a new method to sustain diversity in
adaptive trait-based models of phytoplankton communities based on a
mechanism of trait diffusion through subsequent generations. Our
modeling approach can therefore account for endogenous processes such
as rapid evolution or transgenerational trait plasticity.