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

Abstract

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].

Measuring Annual Variation in Reproductive Output Reveals a Key Role of Maternal Body Condition in Determining the Size of Eggs in Snakes

“…We did not detect the egg size number trade-off in L. rufozonatum . This affirms the results reported for three colubrid snakes of the genus Ptyas , P. mucosus [ 53 ], P. korros [ 54 ], and P. dhumnades [ 29 ], where females do not trade off egg size against number. By contrast, the egg size number trade-off is significant in the king ratsnake Elaphe carinata [ 42 ] and the Chinese cobra Naja atra [ 37 ] but, in both species, there is a fixed upper limit (~1.4 times greater that the population mean egg size) to egg size not set by the maternal body volume [ 15 , 16 ].…”

Altitudinal variation in life-history features of a Qinghai-Tibetan Plateau lizard

“…As a result of the lower ambient temperatures, embryos in high latitudes or altitudes grow at a slower rate than those at lower latitudes or altitudes ( Mathies and Andrews 1995 ), and our results follow this rule. On the other hand, at lower altitudes, the date of emergence from hibernation is earlier for reptiles, and the time between emergence and ovulation can influence their egg-laying or parturition dates ( Ji and Wang 2005 ; Lin et al 2012 ). In this study, we also noticed that low-altitude lizards emerged from hibernation around mid-April, while high-altitude lizards emerged around mid-May, which is consistent with the above situation.…”

First report on the reproduction of captive Chinese many-toothed snake (Sibynophis chinensis) in Jeju Island, South Korea

“…Our observation revealed that the female of S. chinensis oviposits at mid-June and hatched out at the end of July (i.e., summer season). Marques and Pizzatto (2002), Lin et al (2012), and SantoshKumar and Kannan (2016) have reported similar patterns of egg laying and hatching of Oxyrhopus guibei, P. korros, and Xylophis perroteti, respectively. This captive egg laying in summer might be the result of two mating seasons (i.e., autumn and spring).…”