A late Pleistocene Wood Turtle (Glyptemys insculpta) from Iowa, USA: response of the taxon to glaciation and formation of the current range

The partial shell of a Wood Turtle (Glyptemys insculpta) was collected from the West Branch of the East Nishnabotna River in southwestern Iowa, near Malvern. By direct accelerator mass spectrometry, it radiocarbon dates to the late Pleistocene (10 220 ± 30 years before present [BP], 11 975–11 813 calibrated years [cal] BP). Other subfossil evidence indicates that Wood Turtles moved far south of their current range, into the southeastern United States, in response to late Pleistocene glaciation. The specimen suggests that the species also moved south and west, into a previously undocumented western range, where favourable habitat and, in particular, somewhat cooler summer temperatures prevailed until ~10 200 cal BP. My assessment of the Holocene subfossil record suggests that establishment of the western portion of the current range may have occurred within the past 1000 years. Phylogenetic analysis and direct radiometric dating of subfossil specimens are needed to determine additional details about the late Pleistocene dispersal of Wood Turtle and the postglacial formation of their current range.