Ideal free distribution and natal dispersal in female roe deer
Ideal free distribution and natal dispersal in female roe deer
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雌性狍的理想自由分布和产后扩散
作者：
L. Kjell Walhström;P. Kjellander
我们调查了成年（102年）女性roedeer Capreolus capreolus是否符合理想的自由或理想的专制分布，以了解是否纳塔尔分散是“自愿”或社会强制。这项研究是在1989年至1994年期间在瑞典斯德哥尔摩附近的高密度、自由放养的种群中进行的。除了年龄分布之外，还在附近的两个区域（“田野”和“森林”）获得了有关种群密度、栖息地质量、雌性生殖和身体状况的五个参数以及年龄分布的数据，这两个区域代表了对比鲜明的栖息地。人口密度估计粪便颗粒组计数除了总计数的扑杀动物后，一个主要的鹿收获。在“实地"的密度是在”森林区“的两倍（66对33鹿/平方公里）。栖息地的质量进行了测定，通过分析量的粪便中收集的粪便样品中的氮，在这两个领域，并通过比较大小的夏季家庭范围的成年人的性别与遥测的帮助。这两项估计表明，较高的营养质量和资源丰度，分别在“领域”，粪便氮含量较高（2.96比2.43%），范围较小（12.9比20.9公顷）。从淘汰的雌性动物中获得的任何生殖或身体状况参数（即黄体数量）均无显著差异（1.8 vs 1.8），有后代的雌性比例（71 vs 56%）、体重（16.9 vs 17.3 kg）、肾脂肪指数（91.9 vs 98.5）和下颌骨长度（152.8 vs 151.4 mm）。根据牙齿磨损情况确定的女性年龄分布在不同地区之间也没有差异。这些结果与理想自由假设的预测是一致的。这反过来又表明，在这个物种中的女性分散是“自愿的”，潜在的近因是最大化的资源收益。
We investigated whether adult (≧ 2 years) female roe deer Capreolus capreolus conform to an ideal free or an ideal despotic distribution, in order to understand whether natal dispersal is ‘voluntary’ or socially enforced. The study was undertaken in a high-density, free-ranging population close to Stockholm, Sweden, during 1989–1994. Data on population density, habitat quality, and five parameters on female reproduction and body condition, in addition to age distribution, were obtained in two nearby located areas, the ‘field’ and the ‘forest’, representing contrasting habitats. Population density was estimated by faecal pellet group counting in addition to total counts of culled animals after a major deer harvest. Density in the ‘field area’ was twice that in the ‘forest area’ (66 vs 33 deer/km2). Habitat quality was determined by analysing the amount of faecal nitrogen from samples of faeces collected in the two areas, and by comparing size of summer home ranges for adults of both sexes with the aid of telemetry. Both estimates indicated a higher nutritional quality and resource abundance, respectively, in the ‘field area’, with faecal nitrogen content being higher (2.96 vs 2.43%), and ranges being smaller (12.9 vs 20.9 ha). No significant differences were found in any of the parameters on reproduction or body condition obtained from culled females, i.e. number of corpora lutea (1.8 vs 1.8), proportion of females with offspring (71 vs 56%), body mass (16.9 vs 17.3 kg), kidney fat index (91.9 vs 98.5), and length of the lower mandible (152.8 vs 151.4 mm). Neither did the age distribution among females, as determined from tooth wear, differ between the areas. These results are consistent with the prediction of the ideal free hypothesis. This, in turn, suggests that female dispersal in this species is ‘voluntary’, the underlying proximate cause being maximization of resource gain.