Authors' contributions
ACE and MMH conceived and designed this study, performing
some preliminary assays. ACE contributed to the
acquisition of field and experimental data, and carried out
the analytical work. ACE initiated data interpretation, and
drafted and revised the manuscript. MMH and CFA
offered analytical suggestions, assisted with the interpretation
of results, and made critical revisions to the manuscript
suggesting details for the final draft. SSC
contributed to statistical analyses and interpretation of
data. All authors read and approved the final manuscript
before submission.