cerrado ecology, either directly, by influencing plant growth and reproduction, or indirectly,
by the interaction with abiotic factors (Marquis et al. 2002). Herbivory restricts plant
distribution, acting as an environmental filter (Harley 2003). Environmental filters tend to
select species with similar traits that allow them to survive certain pressures (Fukami et al.
2005). We expect, then, herbivory to be a strong environmental filter in cerrado, selecting
species with high investment on defense traits.
Functional traits generally present phylogenetic conservatism on plant lineages (Ackerly
2003). If so, phylogenetic proximity allows two species to respond similarly to environmental
processes, due to traits inherited from common ancestry (Webb et al. 2002, Núñez-Farfán et
al. 2007). However, strong selection pressure can also lead two less related species to respond
similarly due to adaptative convergence (Webb et al. 2002, Núñez-Farfán et al. 2007). At
higher phylogenetic scales, defense traits seem to be more conserved, whereas, at lower
scales, they seem to be convergent (Agrawal and Fishbein 2006, Fine et al. 2006). For
example, different genera tend to present different suites of defense traits, indicating
phylogenetic clustering (Fine et al. 2006). However, in the genus Asclepias, defense traits are
not congruent to phylogeny, indicating “phylogenetic overdispersion” (Agrawal and Fishbein
2006). We expect, then, at community level, defense syndromes to be conserved.
Although there are studies on defense syndromes at genus level (Agrawal and Fishbein
2006, Becerra 2007) and among pairs of genera in forest communities (Fine et al. 2006), there
are no studies at community level. Particularly in the Brazilian cerrado, herbivory surveys are
restricted to only one species (e.g., Varanda and Pais 2006) or only a defense trait, such as
presence of extra-floral nectaries to ant association (e.g., Oliveira 1997, Oliveira and Freitas
2004) or latex presence (e.g., Diniz et al. 1999). Field mensurative experiments of defense
syndromes in cerrado plant communities could test the extrapolation of syndrome theory, as
well as relate defense traits to ecological and evolutionary constraints of savanna areas.