Eco-evolutionary Dynamics of Individual-Based Food Webs - Advances in Ecological Research - page 256

that best predict the data fluctuate broadly, like in the fish community, across
all the environmental gradients sampled (see Table 2 ).
E. Effect of Intraspecific Variability on Species Level
Food Web Connectance
We study the effect of the intraspecific variation in the number of prey or
connectivity for the species-level food web connectance. The empirical spe-
cies-level connectance given by the 'minimal sampling threshold' decays
faster than the neutral expectation in all the environmental situations, for
which per-individual predation rates are equivalent ( Figure 13 ). Connectance
values for the empirical data collapse for a small change in the sampling
threshold within the stomach contents of the individual predators in all the
environmental situations ( Figure 13 , insets). This pattern remains the same
for the whole Guadalquivir estuary food web with approximately 10 5 sam-
pled individual prey and predators and 65 species in all the environmental
situations ( Figure 14 ). This high sensitivity of connectance to sampling effort
is driven by the large intraspecific variance observed in the number of prey
items per predator ( Figures 5 and 6 ). Interestingly, regardless of the sampling
threshold (i.e. one or two prey items in the stomach content of the predator),
food webs from the random encounter model require twice the sampling
effort to entirely disconnect the network (i.e. approximately from 60 to 120
individuals, see Figure 14 ).
IV. SUMMARY AND DISCUSSION
A. Models of Eco-evolutionary Dynamics as a
General Framework
This study has been strongly motivated by two main findings (1) the large
intraspecific variance in the use of resources and reproduction mode that
occur during individuals' life cycle ( Ar´ujo et al., 2010; Bolnick et al., 2002;
Cohen et al., 2005; Polis, 1991; Roughgarden, 1972 ) and (2) the strong
convergence between ecological and evolutionary dynamics ( Fussmann
et al., 2007; Hairston et al., 2005; Thompson, 1998 ). Despite the rise of
high resolution datasets, a general framework to analyse and test from
individual-level processes the convergence between ecological and evolution-
ary dynamics, and its implications for patterns of biodiversity in food webs
have been particularly lacking. Similarly, the combination of hypothesis
testing combining experiments, theory and large datasets to detect the main
mechanisms that drive the link between intraspecific variance and the speed