Smithsonian National Museum of Natural History

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Carboniferous

 

 

Conrad C. Labandeira
Ph.D. University of Chicago
M.S. University of Wisconsin
B.S. California State University

 

Research Focus:

 

Plant-insect associations in the fossil record (see: Damage Type Field Guide)


Insect paleoecology and the evolution of terrestrial ecosystems


Early Devonian ecosystems and the origin of arthropod terrestriality

The fundamental question that encompasses my research is the following: How is it that insects and vascular plants have come to dominate virtually all land and freshwater environments? Specifically, how is this 420-million-year-old pattern of terrestrial monopolization reflected in the historical record of plants, insects, and their associations? The answer involves a fossil record that provides valuable information for long-term trends regarding feeding (trophic) structure in fossil assemblages, associational trends among trophically linked plant and insect lineages, the development of component communities (that is, a plant host and all of its dependent species), and ultimately ecosystem evolution. However, this line of investigation is quite new and is rooted in two different, albeit complementary, approaches. The first is examination of the evolutionary biology among extant plants and their associates, either at the ecological level of examining trophic interactions, or at the evolutionary level of documenting phylogenetic patterns in associated lineages of plant and insect species. Such actualistic studies have made considerable strides in revealing long-term evolutionary processes and often have generated insights into processes inherent in true coevolution.

Alternatively, one can assess the fossil record directly and document what has happened among co-occurring plants and insects, focusing on their associations. In this regard, I view the geochronologic history of these two hyperdiverse groups as consisting of three distinctive fossil records: the body-fossil record of plants, the body-fossil of insects, and importantly, the trace-fossil record of their associations. This latter archive of associations is based on five types of fossil evidence, depending on the type of preservation and whether the plant or insect component is better represented. They are, stressing first the plant evidence: (1) features of plant reproductive biology indicating insect association, (2) insect-mediated plant damage, (3) insect gut contents that contain plant material, (4) dispersed insect coprolites, and (5) the plant-related structure of insect mouthparts and ovipositors. All five elements constitute a matrix that in any one deposit may be variously present or absent, and whose assembly is essential for the reconstruction and interpretation of plant-insect associations within a bygone community. It should be noted that all three fossil records are important, but it is the associational record that provides the ecological dimension for understanding not only the spectrum from looser detritivorous to more intricate herbivorous relationships, but also the evolution of trophic webs at the local community and broader ecosystem levels.

My research has taken four major directions, although other, related projects are being pursued as well now and into the future.

Research Themes:

Document the expansion of herbivory during the Late Carboniferous to Middle Permian of Euramerica.

Document the role that the end-Permian extinction had on plant-insect associations in Gondwana.

Investigate the role that the end-Cretaceous extinction had on plant-insect associations of North America.

Evaluate vegetational turnover and shifting strategies of insect herbivory resulting from the Early Cenozoic Thermal Maximum (ECTM).

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