LITZGUS, J.D.*; MOUSSEAU, T.A.: Geographic variation in clutch frequency in the spotted turtle (Clemmys guttata)

We examined the reproductive output of spotted turtles (Clemmys guttata) from a population in South Carolina, near the southern extreme of the species’ range. We used radio telemetry, palpation, and x-rays to monitor the reproductive condition of females over two field seasons. We present the first evidence for multiple clutching in a wild population of spotted turtles. Of 12 females with radio transmitters that became gravid, five produced second clutches and one produced a third clutch. Average annual clutch frequency was 1.2 per female. Clutch frequency was not dependent upon body size. We compared reproductive output among three populations: Ontario, Pennsylvania, South Carolina. Individual clutch sizes varied with latitude. Clutch size was largest in the north (mean = 5.3 eggs), mid-sized in the central population (mean = 3.9), and smallest in the south (mean = 2.9). We suggest that this pattern is related to seasonality differences which result in different selective pressures on body size of females. Total annual egg production (the sum of all clutches within a reproductive season) by gravid females did not differ statistically between the Ontario (mean = 5.3 eggs) and South Carolina populations (mean = 4.6). These data indicate that although individual clutch sizes differ between northern and southern spotted turtles, total annual reproductive output is consistent at the extremes of the species’ range.