Chromosome studies in Chiropotes satanas utahicki hershkovitz, 1985 (cebidae,platyrrhini): A comparison with Chiropotes satanas chiropotes

Karyological characterizations of C. s. utahicki (2n = 54) and C. s. chiropotes (2n = 54) showed that these two subspecies are chromosomally very similar. In a single, isolated specimen of C s. utahicki, however, a derived, biarmed, chromosome 14 was found in the heterozygous condition. This variant chromosome was identical with pair 10 in C. s. chiropotes in which this chromosome type was apparently fixed. Chromosome differences between these subspecies might be transitional, leading to the establishment of two different karyomorphic populations derived from a once uniform karyotypic group that split into separate allopatric subspecies. © 1992 Wiley-Liss, Inc.     

Does habitat fragmentation promote climate‐resilient phenotypes?

Understanding how individual differences in physiological performance modify behavioral responses to environmental variability and its fitness consequences is key to predicting the vulnerability of species and populations to environmental change. For many species, summit metabolic rate (M_SUM; the upper limit to heat production) and basal metabolic rate (BMR; the lower limit related to energy acquisition and processing) often constrain aspects of physiological performance and behavioral activity. We examined the relationship between metabolic phenotypes, foraging behavior, and survival in overwintering black‐capped chickadees Poecile atricapillus inhabiting contiguous and fragmented forested landscapes. We found that birds with lower summit metabolic rates were generally more sensitive to winter weather and increased their use of supplemental feeding stations as ambient temperatures decreased. In highly fragmented forests, this relationship may have incurred strong survival consequences, as birds with lower summit metabolic rates were less likely to survive the winter season. Additionally, we found that chickadee populations persisting in fragmented landscapes were characterized by slightly higher thermogenic capacity (M_SUM) and lower maintenance metabolic costs (BMR). We suggest that habitat loss and fragmentation present unique selection pressures that alter the relationships between environmental variability, behavior and physiology, and result in context‐specific fitness consequences.     

Locomotor behavior and skeletal morphology of two sympatric pitheciine monkeys,Pithecia pithecia and Chiropotes satanas

Field observations of two sympatric pitheciine species reveal that the positional repertoire of the white-faced saki, Pithecia pithecia, is dominated by leaping behaviors, whereas the bearded saki, Chiropotes satanas, is predominantly quadrupedal. Examination and comparison of the postcranial skeletal morphologies and limb proportions of these species display numerous features associated with their respective locomotor behaviors. These observations accord with associations found in other primate and mammalian groups and with predictions based on theoretical and experimental biomechanics. Preliminary observations of the skeletal morphology of Cacajao calvus demonstrate a marked similarity to that of Chiropotes. The fossil platyrrhine Cebupithecia sarmientoi displays greater similarity to Pithecia, suggesting that its positional repertoire also included significant leaping and clinging behaviors.     

生境破碎化对植物-昆虫及昆虫之间相互关系的影响

生境破碎化对生物多样性和生态系统功能影响是当前国内外生态学家研究的热点问题之一。文章针对生境破碎化的内涵、量度指标进行介绍,着重分析生境破碎化对植物-昆虫关系的影响,包括植物与植食性昆虫的关系、植物与传粉昆虫的关系、种子与种子捕食者的关系,植物及其分解者的关系,还分析生境破碎化对昆虫-昆虫关系的影响,包括昆虫及其拟寄生物的关系、捕食者与猎物的关系。通过对上述方面的阐述,旨在更好地理解生境破碎化对动植物群落相互关系产生的深刻影响,并提出今后研究中应注意的问题和研究热点。     

景观生态学:两栖动物生态学研究的新途径

全球两栖动物正以远超过自然灭绝的高速率灭绝,这与生境丧失和景观破碎化有着直接关系。生境丧失导致两栖动物的生存空间减少,使局部种群消失,而景观破碎化则导致两栖动物种群之间的隔离度增加,不利于动物的繁殖和扩散。但两者往往是同时出现,相互作用。复合种群、景观连接度、景观遗传学及景观模型模拟等理论和方法的发展,为在生境丧失与破碎化景观下两栖动物的种群结构、组成和动态变化研究提供了理论基础和技术方法。同时景观生态学中特别重视研究的尺度,生境破碎化是发生在景观尺度下的生境变化过程,因此对生境破碎化的影响应该从现有的主要集中在斑块尺度和斑块-景观尺度转变到景观尺度上来。     

Comparison of environmental,biological and anthropogenic causes of wildlife–vehicle collisions among three large herbivore species

Wildlife–vehicle collisions are of increasing concern with regards to the continuous and accelerating anthropogenic development. Preventing and mitigating collisions with wildlife will require a better understanding of the environmental and biological drivers of collision risks. Because species of large mammals differ in terms of food requirements, habitat selection and movement behaviors we tested, at the management unit level, if the density of collisions with red deer, roe deer and wild boar differed in terms of spatial distribution and explanatory factors. From 20,275 documented collisions in France between years 1990 and 2006, we found marked differences in the most influential environmental factors accounting for the density of collisions among the three large herbivore species. The effect of road density was higher for the red deer than for the two other species and did not level off at our spatial-scale of observation. As expected, the annual hunting harvest—interpreted as a proxy of population abundance—was positively associated with the density of collisions for all species, being the strongest for red deer. While the collision density decreased with the proportion of forest in a management unit for wild boar, it increased with the fragmentation of forest for red deer that commute among forest patches between day and night. To reduce the number of wildlife–vehicle collisions, our results suggest to generalize road fencing and/or a control of abundance of large herbivore populations. Mitigation measures should target units where the collision risk is the highest for the most problematic species.