种群密度对高原鼠兔类固醇激素水平的影响

本研究于2003 年在野外条件下,通过比较不同密度种群间高原鼠兔的种群增长、4 种类固醇激素水平和肾上腺重量的变化,探讨种群密度与其内分泌水平间的相互关系。结果表明,在最高密度的种群内高原鼠兔种群密度增长最大,在最低密度种群内种群密度增长最小。繁殖盛期时高密度种群内雄性高原鼠兔血浆皮质酮水平显著高于低密度种群内个体,肾上腺重量在不同密度种群间也有显著差异,而血浆雌二醇、睾酮、皮质醇水平均未表现出种群密度间的显著变化。整个繁殖期内,高密度和低密度种群间高原鼠兔的皮质酮水平和肾上腺重量呈现不一致的季节变化模式,高密度种群内繁殖盛期和中期显著高于其它繁殖时期,低密度种群内则无明显变化。不同密度种群内高原鼠兔的雌二醇、睾酮、皮质醇水平的季节性变化具有相似的模式。本研究结果表明,在当前种群密度相对较低的自然情况下,高种群密度不能使高原鼠兔产生强烈的社群应激,从而限制其种群增长。

Effect of population density on the steroid hormone levels of plateau pika (Ochotona curzoniae)

This research investigated differences in population increases, plasma concentrations of four steroid hormones, and paired adrenal masses of plateau pika(Ochotona curzoniae) at different population densities under field conditions in 2003, to test the relationship between population density and endocrine level. Population density increased the most the in population with the highest density. In contrast, the population with the lowest density increased the least. There were some differences significant in plasma corticosterone levels and adrenal masses between or among population densities. Furthermore, throughout the reproductive period, the variation patterns of corticosterone levels and adrenal masses were different between higher and lower density populations. This change was more obvious in the higher density population than in the lower density population. However, there were no significant differences in the estradiol, testosterone and cortisol levels between or among population densities, and the different seasonal patterns were not observed. We concluded an intense social stress was not elicited by the high population density, and subsequently limited the population increase of plateau pika in the current nature with a low population density.