CHAPTER 11
Evolutionary processes in
community ecology
Jacintha Ellers
11.1 Introduction
Community ecology examines the distribution,
abundance, demography and interactions among
populations of coexisting species at a particular
site or in a specific area. In past decades, it has
been extremely successful in describing and ex-
plaining patterns of species diversity, food web
structure, invasion, etc. However, at the same time
community ecology has been under fire for lack of
two important attributes. First, community ecology
is short of general, mechanistic principles leading to
quantitative predictions (Lawton 1999). Mechanis-
tic approaches in ecology try to functionally link
traits of individuals to higher level processes such
as multispecies interactions and community struc-
ture. Yet in an effort to reduce the inherent com-
plexity of biological communities, most studies
have grouped species according to their trophic
positions while disregarding differences in traits
within these functional groups. Such simplification
of community structure facilitates the study of eco-
logical community properties, but it overlooks the
species-specific contribution to multiple species in-
teractions in the community. Analysis of functional
traits is one way to quantitatively predict the im-
pact of local species loss or biological invasions on
ecosystems. Second, community ecology has al-
ways assumed homogeneous populations that are
impervious to evolutionary change, thereby exclud-
ing any evolutionary community dynamics result-
ing from selection on traits of individuals. For a
long time, it was assumed that the relatively slow
timescale of evolutionary changes rendered an
evolutionary perspective unnecessary. However,
evolutionary biology has produced compelling evi-
dence that strong selection pressures and fast (co-)
evolution are commonplace in nature (Thompson
2005). Hence, local adaptation of populations to
community context may significantly affect com-
munity functioning. A growing number of commu-
nity ecologists have come to realize the value of an
evolutionary perspective for addressing ecological
questions.11.1.1 Bridging the gap between evolutionary biology and community ecology
Several recent papers have explored the possibili-
ties for a synthesis between community ecology
and evolutionary biology (Agrawalet al. 2007; John-
son and Stinchcombe 2007). Evolutionary biology
studies how ecological factors regulate genetic var-
iation and evolution, and can thus provide commu-
nity ecology with a more mechanistic, quantitative
insight into how genetic and phenotypic diversity
can shape community processes. On the other
hand, most evolutionary studies perform experi-
ments with the single species in isolation, or only
in direct interaction with another species such as
studies on coevolution. Including community com-
position as an ecological context for evolution may
increase our understanding of the maintenance of
genetic and phenotypic variation in the field.
However, part of the difficulty in bringing to-
gether the community perspective with the151