RICH AND SPECIALIZED PLANT-INSECT ASSOCIATIONS IN A MIDDLE–LATE PALEOCENE (58–60 MA) NEOTROPICAL RAINFOREST (BOGOTÁ FORMATION, COLOMBIA)

Abstract

Plant predation by insects is a major driver of high plant diversity in modern tropical forests. Previous reports of leaf damage in middle–late Paleocene Neotropical rainforests of Cerrejón, Colombia, show that leaf herbivory was abundant but of low diversity, mainly inflicted by generalized feeders. Here, we present and describe plant-insect associations in leaf fossils from the middle–late Paleocene Bogotá Formation, central Colombia, to test whether the high abundance and low richness of insect damage typified early evolving Neotropical rainforests. The Bogotá flora records the highest richness and frequency of insect-damage associations among comparable Paleocene floras in North America, Patagonia, and Europe, as well as the highest number of leaf mines and galling associations. These results indicate that by the middle–late Paleocene, plant-insect herbivore interactions were much more intense and host-specialized in Neotropical rainforests of the Bogotá region than elsewhere. The rich and frequent galling associations, a distinctive feature of the Bogotá flora, are consistent with the preferential use of canopy leaves by galling insects seen in modern Neotropical rainforests. Our results also indicate differences in plant-insect associations among Paleocene Neotropical rainforests, perhaps reflecting a geographically heterogeneous ecological recovery from the end-Cretaceous ecological crisis. Plant-insect associations in the Bogotá flora also suggest a deep historical context for negative density-dependence as a potential driver (and maintainer) of the high plant diversity observed in modern Neotropical rainforests.