Reproductive Cycle of Male Chinese Green Tree Vipers, Trimeresurus s. stejnegeri, in Northern Taiwan (original) (raw)

Abstract

-We studied the reproductive cycle of male Chinese green tree vipers, Trimeresurus s. stejnegeri, in northern Taiwan by examining seasonal changes in the morphology and histology of their reproductive organs from May 1996 to August 1997. A total of 144 mature males was examined. Based on a histological examination of the seminiferous epithelium, we classified spermatogenesis into five stages: early recrudescence, late recrudescence, spermiogenesis, early regression, and late regression. Testis recrudescence began in the spring. Sperm started to appear in summer and reached a peak in fall. In the winter, testes of most snakes were regressed and sperm disappeared in the lumina of the seminiferous tubules. Throughout the year, sperm were present in the vas deferens. Testis mass peaked in summer, then regressed in winter and early spring. Monthly changes in seminiferous tubule diameter, seminiferous epithelium height, and fat body mass revealed a similar pattern as that of testis. These three parameters were significantly correlated with each other and with temperature and rainfall. Monthly changes in testis and fat body mass were followed by changes in kidney mass. Hypertrophy of the renal sexual segment of T. s. stejnegeri occurred from late summer to winter and might be related to mating activities observed in the same period. As with other viperids, male Chinese green tree vipers exhibited a postnuptial spermatogenesis cycle, which may be confusing when judging from mating activities alone. We proposed another criterion to distinguish postnuptial from prenuptial spermatogenesis. rnal of Herpet logy, Vol. 34, No. 3, pp. 24-43 , 2000 right 2 0 Society for the Study of Amphibians and Reptiles roductive Cycle of Male Chinese Green Tree Vipers, i eresurus s. stejn ger , in Northern Taiwan Reproductive cycles of snakes have been reviewed by many researchers (Fitch, 1970; Aldridge, 1979a; Saint Girons, 1982; Seigel and Ford, 1987; Schuett, 1992). These studies, however, focused primarily on the families Colubridae and Viperidae and mainly on snakes from North America, Europe, and Japan (Slip and Shine, 1988; Schuett, 1992). Seigel and Ford (1987) noted it is inaccurate to suggest that the reproductive patterns of temperate-zones snakes are representative of the world's snakes. However, research on the reproductive cycles of tropical and subtropical snakes are limited. FurCorresponding Author. thermore, previous investigators have typically used museum specimens from various geographic regions and different years (Saint Girons, 1982; Seigel and Fitch, 1985). Only a few studies have used continuous sampling in restricted areas (Seigel and Ford, 1987). Consequently, additional studies are needed to get a better understanding of the reproductive cycles of snakes from tropical and subtropical areas. The Chinese green tree viper, Trimeresurus s. stejnegeri, is distributed widely throughout southeast Asia (Zhao and Adler, 1993), and is one of the most abundant snakes in Taiwan. Nevertheless, there are only a few reports on its life history (Fitch, 1970; Huang et al., 1987, 1991; Lue et al., 1989; Tsai and Tu, 1998). Whether the , revious investigators have typically speci ens from various geoio s and different years (Saint Gi; Seigel and Fitch, 1985). Only a few e used continuous sampling in reeas (Seigel and Ford, 1987). Conse, itional studies are n eded to get a erstanding of the reproductive cycles o tropical and subtropical areas. i se green tr e viper, Trimeresurus s. i, is distributed widely throughout sia (Zhao and Adler, 1 93), and is 424 This content downloaded from 207.46.13.146 on Tue, 23 Aug 2016 05:06:08 UTC All use subject to http://about.jstor.org/terms MALE REPRODUCTIVE CYCLE OF TRIMERESURUS