高海拔地区爬行动物的繁殖受多种选择压力的限制，如低温、缺氧和强紫外线等。为了提高幼体存活率，多数高海拔地区的爬行动物选择在食物丰富和气候适宜的春夏季产子，这种繁殖模式有助于新生幼体在越冬前获得充足的生长和能量储存时间。日前，中科院成都生物所傅金钟课题组，以生活在高海拔地区的一种青海沙蜥为研究对象，结合解剖学与行为学手段，探讨了青海沙蜥的繁殖模式。相关成果发布于《生态与进化》。

科研人员研究发现，青海沙蜥的繁殖模式属于高海拔地区比较稀少的形式，即幼体在越冬前集中出生，而越冬存活率却高达84.4%。目前数据揭示，成体主要通过以下三个方面来提高幼体的存活率。其一，与其他低海拔地区的沙蜥物种相比，青海沙蜥显著推迟了成体的性成熟时间，从而提高了幼体出生时的体形大小；其二，卵子在雌性怀孕期停止发育，从而确保了胚胎发育有足够的能量供给。此外，幼体在越冬季节与成体共享洞穴，从而有效降低极端寒冷天气对幼体的威胁。

该研究揭示了高海拔胎生爬行动物繁殖模式的适应性机理，对于了解动物“卵生—胎生”繁殖模式的进化研究提出了新的见解。（来源：中国科学报 彭科峰）

An atypical reproductive cycle in a common viviparous Asia Agamid Phrynocephalus vlangalii

Abstract  Viviparous lizards living in cold climate of high altitude often exhibit atypical reproductive cycles, in which mating and fertilization occur synchronously and annually with parturition occurring at the end of the year. Nevertheless, detailed case studies on atypical reproductive cycles are few. Using anatomical data combined with behavioral observations, we examined the reproductive cycle of a common Asian agamid, Phrynocephalus vlangalii, from a high-elevation area in Sichuan, China. Male spermiation of P. vlangalii occurred in May, and spermatogenesis began in June and reached a maximum in October. For females, ovulation and fertilization occurred in May, and females developed gestation and pregnancy in 3 months from June to August, without vitellogenesis during this period. Females gave birth synchronously in late August, then vitellogenesis began and lasted until May of the next year. All adult males and females were synchronized in the same reproductive condition each month. The synchronous and annual reproductive cycle of P. vlangalii clearly represents an atypical cycle. The male courtship and mating behaviors were concordant with gonadal cycle and mainly happened in May and June. Despite the short growth period for neonates, they had a high over-winter survival rate of 84.4%, suggesting that autumn parturition did not generate high costs to this reproductive cycle. We propose that the high over-winter survival rate of neonates is likely linked with female delayed sexual maturity, female asynchronous vitellogenesis and gestation, large relative clutch mass (RCM), and adult-offspring burrow sharing behavior during hibernation.

原文链接：http://onlinelibrary.wiley.com/doi/10.1002/ece3.1783/full