Community Ecology Processes, Models, and Applications

R’

S’ C’

R’’

S’’ C’’

R

S C

1 2 3

Competition subnetworks within

functional groups/ trophic

levels:

Mutualism networks:

Trophic networks:

S¢ C¢

R¢¢

S¢¢ C¢¢

R

S C

1 2 3

levels:

Mutualism networks:

(a)

Trophic networks:

R¢

Balanus

Thais

Balanus

Thais

(b)

PisasterPisaster

MytilusMytilus

ChitonsChitons LimpetsLimpets

MitellaMitella

Mytilus Algae

Pollicipes

L.

strigatella

Oyster -

catchers

Gulls

Mytilus Algae

Pollicipes

L.

strigatella

Oyster

Gulls catchers

(c)

L.

digitalis

L.

digitalis

L.

pelta

L.

pelta

Figure 14.4What would an idealized unified network of local community interactions look like? (a) Ovals correspond to
idealized trophic levels, and species within trophic levels interact via intransitive competitive interactions, indicated by
dashed lines. Predator—prey links between trophic levels are indicated by solid lines. Mutualistic interactions are
indicated by dotted lines, and mutualists may compete and interact with other species as prey or predators. Examples for
small subwebs from the literature are shown in (b) for data from Paine (1966) and in (c) for data from Wootton (1992).

200 FUTURE DIRECTIONS