Vasey Natalie
Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Am J Phys Anthropol. 2002 Jun;118(2):169-83. doi: 10.1002/ajpa.10054.
Based on a year-long field study in northeastern Madagascar, I summarize annual patterns of niche use (food patch size, diet, forest height, and forest site) in two sympatric lemurs, Varecia variegata rubra and Eulemur fulvus albifrons. Furthermore, I examine intraspecific patterns of niche use according to sex, season, and reproductive stage in these two lemurs that differ in terms of energetic investment in reproduction. Lemurs as a group provide a special opportunity to test hypotheses concerning sex differences in niche use. Due to their body size monomorphism and seasonal, synchronous pattern of breeding, it is possible to directly evaluate whether sex differences in diet reflect high energetic investment in reproduction by females. Results confirm the hypothesis that intraspecific variation in niche use (e.g., sex differences, seasonal differences) would be more pronounced in V. v. rubra than in E. f. albifrons, due in large measure to the former's relatively high energetic investment in reproduction: 1a) Dietary sex differences in V. v. rubra are most pronounced during costly reproductive stages and involve acquisition of low-fiber, high-protein plant foods. Females of both species consume more seasonally available low-fiber protein (young leaves, flowers) relative to conspecific males during the hot dry season, but only in V. v. rubra females is this pattern also evident during gestation and lactation. 1b) The diets of female V. v. rubra and female E. f. albifrons are more similar to each other than are the diets of conspecific males and females in the case of V. v. rubra. This is not uniformly the case for female E. f. albifrons. This finding confirms a hypothesis put forward in Vasey ([2000] Am J Phys Anthropol 112:411-431) that energetic requirements of reproductive females drive niche separation more than do the energetic requirements of males. 1c) Both species synchronize most or all of lactation with seasonal food abundance and diversity. E. f. albifrons shows a more protracted period of synchrony, and this may contribute to its wide biogeographic distribution in Madagascar. 2) Sex differences and seasonal differences in microhabitat use reflect intraspecific patterns of thermoregulation, predator avoidance, and in the case of V. v. rubra, reproduction. One important factor selecting for body size monomorphism in lemurs appears to be the tight synchrony between lactation and periods of food abundance afforded by annual, seasonal breeding.
基于在马达加斯加东北部进行的为期一年的实地研究，我总结了两种同域狐猴——红领狐猴（Varecia variegata rubra）和白额狐猴（Eulemur fulvus albifrons）的生态位利用年度模式（食物斑块大小、饮食、森林高度和森林地点）。此外，我还研究了这两种狐猴在繁殖能量投入方面存在差异的情况下，根据性别、季节和繁殖阶段的种内生态位利用模式。狐猴群体为检验有关生态位利用性别差异的假设提供了一个特殊机会。由于它们体型单一且繁殖具有季节性、同步性模式，因此有可能直接评估饮食中的性别差异是否反映了雌性在繁殖方面的高能量投入。结果证实了这一假设：种内生态位利用的变化（例如性别差异、季节差异）在红领狐猴中比在白额狐猴中更为明显，这在很大程度上是由于前者在繁殖方面相对较高的能量投入：1a）红领狐猴的饮食性别差异在代价高昂的繁殖阶段最为明显，涉及获取低纤维、高蛋白的植物性食物。在炎热干燥季节，两种狐猴的雌性相对于同种雄性都消耗更多季节性可得的低纤维蛋白质（嫩叶、花朵），但只有红领狐猴的雌性在怀孕和哺乳期这种模式也很明显。1b）红领狐猴中，雌性红领狐猴和雌性白额狐猴的饮食彼此之间比同种雄性和雌性的饮食更为相似。白额狐猴的雌性情况并非始终如此。这一发现证实了瓦西（[2000]《美国体质人类学杂志》112:411 - 431）提出的一个假设，即繁殖期雌性的能量需求比雄性的能量需求更能推动生态位分离。1c）两种狐猴的大部分或全部哺乳期都与季节性食物的丰富度和多样性同步。白额狐猴的同步期更长，这可能有助于其在马达加斯加广泛的生物地理分布。2）微生境利用中的性别差异和季节差异反映了种内的体温调节、避敌模式，对于红领狐猴来说，还反映了繁殖模式。在狐猴中选择体型单一性的一个重要因素似乎是哺乳期与年度季节性繁殖所带来的食物丰富期之间的紧密同步。
