PMC

Scatterplots showing the correlation between surface microplankton biomass (A) and surface productivity (B, estimated by fluorescence) against benthic trophic parameters: community niche width (TA, filled circles) and food sources diversity (dCR, open circles).

Eco-evolutionary dynamics of a four-trophic-level food chain model with negative prey mass scaling (functional response gests shallower with prey size). Abundances at each trophic level (left column) are shown for non-evolution ODE solutions (dashed lines) in the presence (yellow) or absence (purple) of a trophic cascade. Shaded areas show middle 50% of GEM simulations. Trophic levels are arranged from the apex predator (top) to the producer (bottom). Body mass (centre column) and body mass fitness gradients (right column) show selection and the potential for selection during trophic cascades. Negative values in fitness gradients indicate selection for smaller size and a positive number indicates selection for larger size. (Online version in colour.)

Simulated prey (green solid) and predator biomass (blue dashed) (top), mean trait values, (green solid) and (blue dashed) and food-suitability (red dotted) (middle) and variances of the trait values, (green solid) and (blue dashed) (bottom, only shown when ), after a spin-up of 1000 days in (i) a model run with constant trait values for predator and prey, (ii) a model run with variation in , but not , i.e., only the prey trophic level has the potential for trait variation, (iii) a model run with variation in , but not , i.e., only the predator trophic level has the potential for trait variation, and (iv) a model run with variation in and in , i.e., both the prey and the predator level have the potential for trait variation. Constants as in . Initial conditions for all runs were: , , , , . and represent the mean values of d). For runs without trait variation and were set to zero.

How much a trophic cascade alters the abundance and size of organisms differs when evolution (dotted yellow line) is incorporated. Trophic levels are arranged from apex predator (left) to producer (right). Negative scaling scenario (functional response gets shallower with prey size; top row) and positive scaling scenario (functional response gets steeper with prey size; bottom row) prey scaling scenarios are depicted (see text). Each line depicts the change in body size and abundance from systems without trophic cascades (blue dot) caused by a trophic cascade in the absence (dashed line) or presence (dotted line) of evolution. For the dotted line, dots are shown at regular time intervals to illustrate rates of change in body size and abundance (e.g. increasing distance between dots indicates accelerating change). (Online version in colour.)