Eco-evolutionary Dynamics of Individual-Based Food Webs - Advances in Ecological Research - page 226

we describe the sampling methods of the empirical data (i.e. individual diets
and independent estimations of abundance) and the model (i.e. rarefaction
and fit to the data), how we connect the observed data with the outputs from
the model and the analysis of resolution in the data to understand some
macroscopic descriptors of interest in food webs. In the last part of the study,
we present the main results emphasizing the biological meaning obtained
from the deviations between the observed and expected trophic diets within
and between the sampled populations and species diversity for all the
environmental situations, We finally discuss the usefulness and limitations
of the approach and we give some perspectives to improve the approach here
presented.
II. MATERIAL AND METHODS
A. The Models
We combine the original neutral theory of biodiversity with a DNA-
sequence-based individual model that uses genetic-distance-based speciation,
sexual reproduction and trophic behaviour to produce a model that simulta-
neously generates the number of individual preys per predator, species
abundance and the species-level food web connectance. Despite these set of
combinations, the model just adds one parameter to the previous neutral
theory, so we then proceed to fit parameters of the model and test the model's
predictions using observations of individual connectivities of a community of
predators and estimates of abundance in a predator-prey food web in a range
of environmental conditions.
Figure 1 summarizes the steps taken to integrate a DNA-sequence-based
individual model that uses genetic-distance-based speciation within an indi-
vidual-based food web model. In order to link the classical neutral metacom-
munity model with a population genetics model, we first describe the basic
metacommunity framework from the neutral biodiversity theory ( Hubbell,
2001 ). In this model, an implicit parameter of speciation that adds a new
species to the community, dispersal limitation and ecological drift are the
main drivers of the population and community dynamics ( Figure 1 A). We
then describe the link between the neutral metacommunity model and a
mechanistic model of genetic drift, accomplished by tracking each indivi-
dual's genome. Third, we add genetic-distance-based speciation assuming
assortative mating driven by a minimum genetic similarity threshold that
limits reproductive compatibility between each pair of individuals ( Higgs and
Derrida, 1992; Meli´n et al., 2010 ). We note that assortative mating occurs in
the absence of dispersal limitation, and thus we assume that genetic similari-
ty, and not spatial structure, is the main factor constraining mating in the