Reproductive traits of the gray ratsnake Ptyas korros from three geographically distinct populations

• Main Author: Long-Hui LIN, Fei MAO, Ce CHEN, Xiang JI
• Format: Article
• Language: English
• Published: Oxford University Press 2012-06-01
• Series: Current Zoology
• Subjects: Colubridae; Life-history; Reproductive output; Egg size; Clutch size; Geographical variation; Egg-laying date
• Online Access: http://www.currentzoology.org/paperdetail.asp?id=12148

We collected gravid gray rat snakes Ptyas korros from three geographically distinct populations in China, Chenzhou (CZ), Jiangshan (JS) and Dinghai (DH), to study geographical variation in female reproductive traits. Egg-laying dates differed among the three populations such that at the most northern latitude egg-laying was latest, and earliest at the most southern latitutde. Clutch size, clutch mass, egg mass, egg shape, within clutch variability in egg sizes and relative clutch mass differed among the three populations, whereas post-oviposition body mass did not. Except for egg-laying date, none of the traits examined varied in a geographically continuous trend. CZ and DH females, although separated by a distance of approximately 1100 km as the crow flies, were similar in nearly all traits examined. JS females were distinguished from CZ and DH females by their higher fecundity (clutch size), greater reproductive output (clutch mass) and more rounded eggs. Our data do not validate the prediction that larger offspring should be produced in colder localities. The absence of an egg size-number trade-off in each of the three populations presumably suggests that P. korros is among species where eggs are well optimized for size within a population [Current Zoology 58 (6): 820–827, 2012].