Graham Sean P, Earley Ryan L, Hoss Shannon K, Schuett Gordon W, Grober Matthew S
Center for Behavioral Neuroscience, Georgia State University, 33 Gilmer Street, S.E., Unit 8, Atlanta, GA 30303-3088, USA.
Gen Comp Endocrinol. 2008 Nov-Dec;159(2-3):226-35. doi: 10.1016/j.ygcen.2008.09.002. Epub 2008 Sep 14.
To better understand the proximate causation of the two major types of mating seasons described for North American pitvipers, we conducted a field study of the cottonmouth (Agkistrodon piscivorus) in Georgia from September 2003 to May 2005 that included an extensive observational regime and collection of tissues for behavioral, anatomical, histological, and hormone analysis. Enzyme immunoassays (EIA) of plasma samples and standard histological procedures were conducted on reproductive tissues. Evidence from the annual testosterone (T) and sexual segment of the kidney (SSK) cycle and their relationship to the spermatogenic cycle provide correlative evidence of a unimodal mating pattern in this species of pitviper, as these variables consistently predict the mating season in all snake species previously examined under natural conditions. In most reptiles studied to date, high plasma levels of T and corticosterone (CORT) coincide during the mating period, making the cottonmouth an exception to this trend; we suggest two possible explanations for increased CORT during spring (regulation of a spring basking period), and decreased CORT during summer (avoiding reproductive behavioral inhibition), in this species.
为了更好地理解北美蝰蛇所描述的两种主要交配季节的直接原因，我们于2003年9月至2005年5月在佐治亚州对水腹蛇（食鱼蝮）进行了一项野外研究，其中包括广泛的观察机制以及收集用于行为、解剖、组织学和激素分析的组织样本。对生殖组织进行了血浆样本的酶免疫分析（EIA）和标准组织学程序。来自年度睾酮（T）和肾性节段（SSK）周期的证据以及它们与精子发生周期的关系，为这种蝰蛇的单峰交配模式提供了相关证据，因为这些变量始终能预测此前在自然条件下研究的所有蛇类物种的交配季节。在迄今为止研究的大多数爬行动物中，交配期间血浆中高浓度的T和皮质酮（CORT）是同时出现的，水腹蛇是这一趋势的例外；我们针对该物种春季CORT升高（春季晒太阳期的调节）和夏季CORT降低（避免生殖行为抑制）提出了两种可能的解释。
