Escaping senescence: demographic data from the three-toed box turtle (Terrapene carolina triunguis)

Two criteria have been proposed for the demonstration of negligible senesce nce. These include (1) no increase in age-related mortality and (2) negligi ble functional impairments with age. Although researchers have suspected tu rtles to exhibit negligible senescence, this has been largely based on the former rather than the latter criteria for which scant evidence is availabl e. Using a long-term study on a population of three-toed box turtles (Terra pene carolina triunguis) in Cole County, Missouri, I combine known minimum age ranges and reproductive evidence to demonstrate their apparent escape f rom senescence. During 1998 and 1999, eight females > 60 years of age were found gravid. The oldest of these is estimated to be at least 65-74 years o f age. Of females > 60 years, the mean clutch size and the proportion gravi d were greater, although not significantly different, when compared to fema les < 60 years. These findings indicate that the reproductive function in t hese turtles does not become impaired with age, thus supporting the second criteria for demonstrating negligible senescence. (C) 2001 Elsevier Science Inc. All rights reserved.