Plant-herbivore interactions and secondary metabolites of plants: Ecological and evolutionary perspectives

Abstract

<p><strong>Abstract</strong></p><p><strong>Background: </strong>Throughout disciplines including paleontology and molecular biology, hence using the fossil record or DNA sequences, ancestral and current plant-herbivore associations mediated by secondary compounds have been assessed. The coevolutionary model of “escape and radiation” predicts adaptive patterns at micro- and macro-evolutionary scale, resulted from the plant-herbivore interaction.</p><p><strong>Questions:</strong>  The study of plant-herbivore interaction and secondary metabolites, has been bias for two main reasons: (1) the interdisciplinary study of the interaction has “atomized" the field. (2) The conceptual framework of coevolution favored analysis either within populations or across taxa.</p><p><strong>Methods</strong>:<strong> </strong>I review the evolutionary history of the interaction and secondary metabolites, from paleontological and palebiochemical data. Then, based on empirical evidence of quantitative genetics and comparative methods, I examine the main assumptions of micro- and macro-evolutionary postulates of the coevolutionary model. Further, I overview the analytical approach for the study of plant defense within-species and across phylogeny.<strong> </strong></p><p><strong>Results:  </strong>Within species, (1) the coevolutionary dynamics shaping plants and herbivore phenotypes, and (2) the role of plant chemistry to constraint ecological interactions, are the most stressed patterns. Across phylogeny, (1) the role of plant chemistry to constraint insect host shifts, and (2) the implications of, and mechanism behind the evolutionary novelties, are more recently assessed.</p><strong>Conclusion: </strong>I suggest that future research should integrate both conceptual and analytical perspectives of micro- and macro-evolutionary approaches. One promising direction relies in modern molecular techniques that may open new research avenues by providing evidence for the function of complex genetic and genomic machineries behind biotic interactions.