Department of Anthropology, University of Victoria, Victoria, British Columbia, Canada.
Department of Mathematics and Statistics, University of Victoria, Victoria, British Columbia, Canada.
Am J Primatol. 2020 Apr;82(4):e23095. doi: 10.1002/ajp.23095. Epub 2020 Jan 30.
Habitat fragmentation is an increasingly serious issue affecting primates in most regions where they are found today. Populations of Lemur catta (ring-tailed lemur) in Madagascar's south-central region are increasingly restricted to small, isolated forest fragments, surrounded by grasslands or small-scale agriculture. Our aim was to evaluate the potential for population viability of L. catta in nine forest fragments of varying sizes (2-46 ha, population range: 6-210 animals) in south-central Madagascar, using a set of comparative, quantitative ecological measures. We used Poisson regression models with a log link function to examine the effects of fragment size, within-fragment food availability, and abundance of matrix resources (food and water sources) on L. catta population sizes and juvenile recruitment. We found a strong association between overall population size and (a) fragment size and (b) abundance of key food resources Melia azedarach and Ficus spp. (per 100 m along transect lines). Juvenile recruitment was also associated with fragment size and abundance of the two above-mentioned food resources. When the largest population, an outlier, was removed from the analysis, again, the model containing fragment size and abundance of M. azedarach and Ficus spp. was the best fitting, but the model that best predicted juvenile recruitment contained only fragment size. While our results are useful for predicting population presence and possible persistence in these fragments, both the potential for male dispersal and the extent of human disturbance within most fragments play crucial roles regarding the likelihood of long-term L. catta survival. While seven of the nine fragments were reasonably protected from human disturbance, only three offered the strong potential for male dispersal, thus the long-term viability of many of these populations is highly uncertain.
生境破碎化是一个日益严重的问题，影响着当今大多数有灵长类动物分布的地区。马达加斯加中南部地区的环尾狐猴（Lemur catta）数量越来越多地局限于小而孤立的森林碎片中，周围是草原或小规模农业区。我们的目标是评估中南部九个不同大小（2-46 公顷，种群范围：6-210 只）的森林碎片中 L. catta 的种群生存潜力，使用一组比较的、定量的生态措施。我们使用具有对数链接函数的泊松回归模型来检查碎片大小、碎片内食物供应和基质资源（食物和水源）丰度对 L. catta 种群大小和幼体补充的影响。我们发现总体种群大小与（a）碎片大小和（b）关键食物资源楝树（Melia azedarach）和榕属植物（Ficus spp.）的丰度之间存在很强的关联（每 100 米沿样线）。幼体补充也与上述两种食物资源的碎片大小和丰度有关。当从分析中去除最大的种群（异常值）时，再次包含碎片大小和楝树（Melia azedarach）和榕属植物（Ficus spp.）丰度的模型是拟合度最好的，但最佳预测幼体补充的模型仅包含碎片大小。虽然我们的结果有助于预测这些碎片中的种群存在和可能的持续存在，但雄性扩散的潜力和大多数碎片内人类干扰的程度对于 L. catta 的长期生存的可能性至关重要。虽然九个碎片中有七个相对免受人类干扰，但只有三个提供了雄性扩散的强大潜力，因此这些种群中的许多种群的长期生存能力高度不确定。
