Ecological and evolutionary responses of terrestrial arthropods to Middle-Late Pennsylvanian environmental change

The Middle-Late Pennsylvanian Subperiod was marked by recurrent glacial-interglacial cycles superimposed on a longer-term trend of increasing aridity. Wetland and drought-tolerant floras responded with repeated migrations in the tropics, and a major plant turnover occurred in swamp ecosystems in parts of Euramerica near the Middle-Late Pennsylvanian boundary. However, the corresponding ecological and evolutionary responses of insects and other terrestrial arthropods are poorly understood. Here, we review the record of plant-arthropod interactions and analyse origination and extinction rates of insects during the Middle-Late Pennsylvanian. Although preliminary, plant-arthropod associations broadly persist through the Middle-Late Pennsylvanian boundary, and new damage types and host-plant associations first appear in the Late Pennsylvanian, possibly related to increased availability of accessible vascular and foliar tissues associated with the shift from arborescent lycopsid to tree and seed fern dominance in Euramerican wetlands. Likewise, our analysis of the insect body fossil record does not suggest especially high rates of origination or extinction during this interval. Together, these results suggest that insects did not suffer major extinctions during the Middle-Late Pennsylvanian, despite short- and long-term changes in climate and environmental conditions.