Dawley E M, Crowder J
Department of Biology, Ursinus College, Collegeville, Pennsylvania 19426, USA.
J Comp Neurol. 1995 Aug 28;359(3):382-90. doi: 10.1002/cne.903590303.
Sexually dimorphic behaviors often are associated with sexually dimorphic neural structures. Perinatal hormonal levels influence structural sexual dimorphism, and seasonal structural changes also can be the result of seasonal hormonal fluctuations. We compared the volume of vomeronasal organs of male and female red-backed salamanders (Plethodon cinereus) throughout the year. Odorants are delivered to vomeronasal receptors through nasolabial grooves when salamanders touch the bases of these grooves to objects (nose tapping). Males may locate and identify potential mates through nose tapping during the prolonged breeding season that lasts from October through May. We compared vomeronasal organ data through multiple regression by using total body size, sex, and season as variables that may influence vomeronasal organ volume. Gonads also were examined as an indicator of reproductive status. Total body size and sex significantly affect vomeronasal organ volume; as body size increases, so does vomeronasal organ volume, and males have significantly larger vomeronasal organs than females at all times of the year. During the summer, both males and females have larger vomeronasal organs than at any other time of the year. Summer also is a period of intense foraging and the initiation of a new cycle of gametogenesis. Previous studies of circulating hormone levels in amphibians have shown that the initial stages of gametogenesis correspond to a period of low estradiol and testosterone levels but high gonadotropin-releasing hormone levels. The functional significance of sexual and seasonal differences in the vomeronasal organs of P. cinereus may relate to the neurogenesis of specialized receptors for courtship and mating.
两性异形行为通常与两性异形的神经结构相关。围产期激素水平影响结构上的两性异形，而且季节性的结构变化也可能是季节性激素波动的结果。我们比较了雄性和雌性红背蝾螈（灰红背无肺螈）全年犁鼻器的体积。当蝾螈用鼻轻触鼻唇沟基部的物体时，气味剂通过鼻唇沟传递到犁鼻器受体（鼻轻敲）。在从10月持续到5月的漫长繁殖季节中，雄性可能通过鼻轻敲来定位和识别潜在配偶。我们以总体体型、性别和季节作为可能影响犁鼻器体积的变量，通过多元回归比较犁鼻器数据。性腺也作为生殖状态的一个指标进行了检查。总体体型和性别显著影响犁鼻器体积；随着体型增大，犁鼻器体积也增大，并且在一年中的所有时间里，雄性的犁鼻器都明显大于雌性。在夏季，雄性和雌性的犁鼻器都比一年中的其他任何时候都大。夏季也是觅食激烈和新的配子发生周期开始的时期。此前对两栖动物循环激素水平的研究表明，配子发生的初始阶段对应于雌二醇和睾酮水平较低但促性腺激素释放激素水平较高的时期。灰红背无肺螈犁鼻器的性别和季节性差异的功能意义可能与求偶和交配的特殊受体的神经发生有关。
