| Much of evolution is driven by reciprocal selection caused by ecological and behavioral interactions between individual organisms. Reciprocal selection occurs at a phenotypic interface linking traits that determine fitness outcomes of an interaction. Species interactions, however, vary from one locality to another, ultimately, making the ecological and evolutionary outcomes, as well as the adaptive processes that drive them, geographically structured. This dissertation provides an integrative approach in light of the Geographic Mosaic Theory of Coevolution. It considers the geographic structure of the antagonistic relation between Attalea phalerata (Arecaceae) and Pachymerus cardo (Chrysomelidae) across the Bolivian lowlands. Using a nested sampling scheme in combination with exclusion experiments, it shows that seed predation varies across a hierarchy of spatial scales. Traits such as seed number promote scale-dependent seed predation and modulate reciprocal selective pressures in a hierarchical manner. In addition, morphological differences in fruits (i.e., seed number, endocarp to endosperm ratio) and differences in mandible asymmetry of beetle larvae are related to fitness across populations generating a selection mosaic. Fitness of A. phalerata trees and consequently selection on fruit traits depends on the geographical distribution of the phenotypes of P. cardo. Finally, reciprocal transplant experiments provide evidence for variable local adaptation to a coevolutionary partner. Fitness-trait relations were different between local and transplanted populations. In conclusion, regional interaction outcomes depend on local outcomes and any potential reciprocal evolutionary change will occur primarily at the scale of populations before it is translated into species-level patterns. These results are in accordance with recent coevolutionary theory. |
