寒温带牧林交错区生境复杂度对啮齿类物种多样性的影响

采用铗日法对嫩江流域牧林交错区5个生境梯度中啮齿动物的多样性水平进行了研究,以探讨栖息地复杂程度对地面啮齿类物种多样性的影响.结果表明,黑线姬鼠、黑线仓鼠和大林姬鼠是嫩江流域牧林交错区中的优势种和常见种,不同物种在不同生境类型中呈明显的不均匀分布,反映了它们对不同生境的选择倾向性.同时,地面草本植物的覆盖度和丰富度对地面活动的小型哺乳动物的物种组成和群落结构具有较大的影响,啮齿动物的捕获率和生物量与草本植物的多样性水平呈现出显著的相关性关系,其物种丰富度随草本植物多样性指数的增加呈递增的趋势.此外,各生境中啮齿动物的物种多样性指数与草本植物多样性的相关关系并不显著,可能是因为灌丛区和林-灌交错区内大量的低矮灌丛与萌生丛改善了生境的隐蔽条件与食物资源,为更多物种的共存创造了良好的微环境,使得两生境中啮齿动物的物种多样性水平尤为突出.研究表明,小型啮齿动物的物种组成与栖息地的复杂程度有关,但地面植被对小型兽类生物量和物种多样性的影响力度并不是等同的,对地面小型兽类物种多样性影响的研究,统计生境复杂度或异质性时应考虑不同植被型/生境类型距地面的高度,不同植被型对小型兽类物种多样性的贡献程度随其距地面高度的增加而降低.     

Population dynamics of large and small mammals

We offer an evaluation of the Caughley and Krebs hypothesis that small mammals are more likely than large mammals to possess intrinsic population regulating mechanisms. Based on the assumption that intrinsic regulation will be manifest via direct density-dependent feedbacks, and extrinsic regulation via delayed density-dependent feedbacks, we fit autoregressive models to 30 time series of abundance for large and small mammals to characterize their dynamics. Delayed feedbacks characterizing extrinsic mechanisms, such as trophic-level interactions, were detected in most time series, including both small and large mammals. Spectral analyses indicated that the effect of such delayed feedbacks on the variability in population growth rates differed with body size, with large mammals exhibiting predominantly reddened and whitened spectra in contrast with predominantly blue spectra for small mammals. Large mammals showed less variance and more stable dynamics than small mammals, consistent with, among other factors, differences in their potential population growth rates. Patterns of population dynamics in small versus large mammals contradicted those predicted by the Caughley and Krebs hypothesis.     

Biomechanics and energetics in aquatic and semiaquatic mammals: platypus to whale

A variety of mammalian lineages have secondarily invaded the water. To locomote and thermoregulate in the aqueous medium, mammals developed a range of morphological, physiological, and behavioral adaptations. A distinct difference in the suite of adaptations, which affects energetics, is apparent between semiaquatic and fully aquatic mammals. Semiaquatic mammals swim by paddling, which is inefficient compared to the use of oscillating hydrofoils of aquatic mammals. Semiaquatic mammals swim at the water surface and experience a greater resistive force augmented by wave drag than submerged aquatic mammals. A dense, nonwettable fur insulates semiaquatic mammals, whereas aquatic mammals use a layer of blubber. The fur, while providing insulation and positive buoyancy, incurs a high energy demand for maintenance and limits diving depth. Blubber contours the body to reduce drag, is an energy reserve, and suffers no loss in buoyancy with depth. Despite the high energetic costs of a semiaquatic existence, these animals represent modern analogs of evolutionary intermediates between ancestral terrestrial mammals and their fully aquatic descendants. It is these intermediate animals that indicate which potential selection factors and mechanical constraints may have directed the evolution of more derived aquatic forms.     

Impacts of large mammals on movements of the pouched mouse (Saccostomus mearnsi) in central Kenya

Populations of large wild mammals are declining worldwide, while the abundance of livestock is increasing. The absence of large mammals frequently leads to increases in the abundance of small mammals such as rodents, but little is known about how the loss of large mammals affects the behaviour of small mammals. To investigate this question, we analysed long‐term data collected at the Kenya Long‐term Exclosure Experiment, which excludes different combinations of large mammals from a savannah ecosystem in central Kenya. We investigated the effects of excluding large mammals, both wild and domestic, on the movements of the pouched mouse (Saccostomus mearnsi), the most common species of small mammal in this habitat. Mice moved ~20% more in the presence of wildlife, but their movements were not significantly affected by the presence of cattle. An index of intraspecific contacts between mice was higher at higher mouse densities, and these high densities were more likely when wildlife and cattle were absent. The results suggest that the absence of large mammals led to higher densities of small mammals, which resulted in a greater probability of intraspecific contacts, despite lower average movement distances.     

中国中生代哺乳类化石

本文对迄今所知的中国中生代哺乳类的化石地点、层位、时代、化石材料和系统分类位置作了总结和讨论。     

Muscle mass scaling in primates: an energetic and ecological perspective

Body composition is known to vary dramatically among mammals, even in closely related species, yet this issue has never been systematically investigated. Here, we examine differences in muscle mass scaling among mammals, and explore how primate body composition compares to that of nonprimate mammals. We use a literature-based sample of eutherian and metatherian mammals, and combine this with new dissection-based data on muscularity in a variety of strepsirrhine primates and the haplorhine, Tarsius syrichta. Our results indicate an isometric scaling relationship between total muscle mass and total body mass across mammals. However, we documented substantial variation in muscularity in mammals (21-61% of total body mass), which can be seen both within and between taxonomic groups. We also found that primates are under-muscled when compared to other mammals. This difference in body composition may in part reflect the functional consequences of arboreality, as arboreal species have significantly lower levels of muscularity than terrestrial species.     

A Model for Chagas Disease with Oral and Congenital Transmission

This work presents a new mathematical model for the domestic transmission of Chagas disease, a parasitic disease affecting humans and other mammals throughout Central and South America. The model takes into account congenital transmission in both humans and domestic mammals as well as oral transmission in domestic mammals. The model has time-dependent coefficients to account for seasonality and consists of four nonlinear differential equations, one of which has a delay, for the populations of vectors, infected vectors, infected humans, and infected mammals in the domestic setting. Computer simulations show that congenital transmission has a modest effect on infection while oral transmission in domestic mammals substantially contributes to the spread of the disease. In particular, oral transmission provides an alternative to vector biting as an infection route for the domestic mammals, who are key to the infection cycle. This may lead to high infection rates in domestic mammals even when the vectors have a low preference for biting them, and ultimately results in high infection levels in humans.     

Comparative research on the cerebroside and sulfocerebroside content of the mammalian brain

Data are presented on cerebroside and sulfocerebroside content of the brain for 31 mammalian species from 8 orders. The increase in concentration of both glycolipids in the brain of mammals in phylogenesis was demonstrated. Low levels of cerebrosides and sulfocerebrosides were found in the brain of lower mammals (Insectivora, Chiroptera) and high ones--in the brain of higher mammals (Carnivora, Primates). Irrespectively from taxonomic position and ecological factors, in the brain of all mammals investigated higher content of cerebrosides with hydroxy acids was found as compared to the content of cerebrosides with normal fatty acids. The ratio of these cerebrosides in the brain of terrestrial mammals is 2-3 times higher than in aquatic and semi-aquatic ones. The data obtained are discussed in relation to the development of the brain of mammals during their phylogenesis.     

Introduced species: domestic mammals are more significant transmitters of parasites to native mammals than are feral mammals

The study of parasitism related to biological invasion has focused on attributes and impacts of parasites as invaders and the impact of introduced hosts on endemic parasitism. Thus, there is currently no study of the attributes of hosts which influence the invasiveness of parasites. We aimed to determine whether the degree of domestication of introduced mammalian species – feral introduced mammals, livestock or pets, hereafter ‘D’ – is important in the spillover of introduced parasites. The literature on introduced parasites of mammals in Chile was reviewed. We designed an index for estimating the relevance of the introduced host species to parasite spillover and determined whether the D of introduced mammals predicted this index. A total of 223 introduced parasite species were found. Our results indicate that domestic mammals have a higher number of introduced parasites and spillover parasites, and the index indicates that these mammals, particularly pets, are more relevant introducers than introduced feral mammals. Further analyses indicated that the higher impact is due to higher parasite richness, a longer time since introduction and wider dispersal, as well as how these mammals are maintained. The greater relevance of domestic mammals is important given that they are basically the same species distributed worldwide and can become the main transmitters of parasites to native mammals elsewhere. This finding also underlines the feasibility of management in order to reduce the transmission of parasites to native fauna through anti-parasitic treatment of domestic mammals, animal-ownership education and the prevention of importing new parasite species.     

The Zoogeography of Mammalian Basal Metabolic Rate

Zoogeographical effects on the basal metabolic rate (BMR) of 487 mammal species were analyzed using conventional and phylogenetically independent ANCOVA. Minimal BMR variance occurred at a "constrained body mass" of 358 g, whereas maximum variance occurred at the smallest and largest body masses. Significant differences in BMR were identified for similar-sized mammals from the six terrestrial zoogeographical zones (Afrotropical, Australasian, Indomalayan, Nearctic, Neotropical, and Palearctic). Nearctic and Palearctic mammals had higher basal rates than their Afrotropical, Australasian, Indomalayan, and Neotropical counterparts. Desert mammals had lower basal rates than mesic mammals. The patterns were interpreted with a conceptual model describing geographical BMR variance in terms of the influence of latitudinal and zonal climate variability. Low and high basal rates were explained in unpredictable and predictable environments, respectively, especially in small mammals. The BMR of large mammals may be influenced in addition by mobility and predation constraints. Highly mobile mammals tend to have high BMRs that may somehow facilitate fast running speeds, whereas less mobile mammals are generally dietary specialists and are often armored. The model thus integrates physiological and ecological criteria and makes predictions concerning body size and life-history evolution, island effects, and locomotor energetics.     

Heterothermy,body size,and locomotion as ecological predictors of migration in mammals

1. Migration is ubiquitous among animals and has evolved repeatedly and independently. Comparative studies of the evolutionary origins of migration in birds are widespread, but are lacking in mammals. Mammalian species have greater variation in functional traits that may be relevant for migration. Interspecific variation in migration behaviour is often attributed to mode of locomotion (i.e. running, swimming, and flying) and body size, but traits associated with the evolutionary precursor hypothesis, including geographic distribution, habitat, and diet, could also be important predictors of migration in mammals. Furthermore, mammals vary in thermoregulatory strategies and include many heterothermic species, providing an alternative strategy to avoid seasonal resource depletion.
2. We tested the evolutionary precursor hypothesis for the evolution of migration in mammals and tested predictions linking migration to locomotion, body size, geographic distribution, habitat, diet, and thermoregulation. We compiled a dataset of 722 species from 27 mammalian orders and conducted a series of analyses using phylogenetically informed models.
3. Swimming and flying mammals were more likely to migrate than running mammals, and larger species were more likely to migrate than smaller ones. However, heterothermy was common among small running mammals that were unlikely to migrate. High-latitude swimming and flying mammals were more likely to migrate than high-latitude running mammals (where heterothermy was common), and most migratory running mammals were herbivorous. Running mammals and frugivorous bats with high thermoregulatory scope (greater capacity for heterothermy) were less likely to migrate, while insectivorous bats with high thermoregulatory scope were more likely to migrate.
4. Our results indicate a broad range of factors that influence migration, depending on locomotion, body size, and thermoregulation. Our analysis of migration in mammals provided insight into some of the general rules of migration, and we highlight opportunities for future investigations of exceptions to these rules, ultimately leading to a comprehensive understanding of the evolution of migration.

     

Cephalopagus conjoined twins in a leopard cat (Prionailurus bengalensis)

Case reports of conjoined twins ("Siamese twins") in wild mammals are scarce. Most published reports of conjoined twins in mammals concern cases in man and domestic mammals. This article describes a case of cephalopagus conjoined twins in a leopard cat (Prionailurus bengalensis) collected on the island of Sumatra, Indonesia, in the period 1873-76. A review of known cases of conjoined twinning in wild mammals is given.     

Flea (Siphonaptera) species richness in the Great Basin Desert and island biogeography theory

Numbers of flea (Siphonaptera) species (flea species richness) on individual mammals should be higher on large mammals, mammals with dense populations, and mammals with large geographic ranges, if mammals are islands for fleas. I tested the first two predictions with regressions of H. J. Egoscue's trapping data on flea species richness collected from individual mammals against mammal size and population density from the literature. Mammal size and population density did not correlate with flea species richness. Mammal geographic range did, in earlier studies. The intermediate‐sized (31 g), moderately dense (0.004 individuals/m²) Peromyscus truei (Shufeldt) had the highest richness with eight flea species on one individual. Overall, island biogeography theory does not describe the distribution of flea species on mammals in the Great Basin Desert, based on H. J. Egoscue's collections. Alternatively, epidemiological or metapopulation theories may explain flea species richness.     

小相岭山系大熊猫大中型伴生兽类

本文总结了小相岭山系与大熊猫同域分布的大中型兽类的种类、主要遗留痕迹的鉴别特征以及对大熊猫的影响;统计了大熊猫伴生动物的样线遇见率,反映了不同伴生动物的相对数量。本文对进一步研究小相岭山系大熊猫的伴生动物,更好地保护大熊猫具有一定的参考价值。     

Of mice and wrens: the relation between abundance and geographic range size in British mammals and birds

We examine the relation between population size and geographic range size for British breeding birds and mammals. As for most other assemblages studied, a strong positive interspecific correlation is found in both taxa. The relation is also recovered once the phylogenetic relatedness of species has been controlled for using an evolutionary comparative method. The slope of the relation is steeper for birds than for mammals, but this is due in large part to two species of mammals that have much higher population sizes than expected from their small geographic ranges. These outlying mammal species are the only ones in Britain to be found only on small offshore islands, and so may be exhibiting density compensation effects. With them excluded, the slope of the abundance–range size relation for mammals is not significantly different to that for birds. However, the elevation of the relation is higher for mammals than for birds, indicating that mammals are approximately 30 times more abundant than birds of equivalent geographic range size. An earlier study of these assemblages showed that, for a given body mass, bats had abundances more similar to birds than to non-volant mammals, suggesting that the difference in abundance between mammals and birds might be due to constraints of flight. Our analyses show that the abundance–range size relation for bats is not different for that from other mammals, and that the anomalously low abundance of bats for their body mass may result because they have smaller than expected geographic extents for their size. Other reasons why birds and mammals might have different elevations for the relation between population size and geographic range size are discussed, together with possible reasons for why the slopes of these relations might be similar.     

中国兽类遗传与进化研究进展与展望

中国兽类物种丰富,且具有150个特有种。本文综述了60年来中国兽类遗传与进化的研究进展,内容涵盖系统发育关系重建、遗传多样性评估、种群遗传结构、适应性进化以及趋同进化的分子机制。本文重点概述了食肉目（大、小熊猫）、有蹄类、翼手目、灵长目、小型兽类以及海兽类等重要类群的研究进展,为中国兽类的物种保护提供了重要资料。另外,本文还对中国兽类遗传与进化研究未来的研究方向提出几点建议,包括运用各种组学技术、筛选新型遗传标记和候选基因（调控序列）、结合表观遗传学并借助进化发育生物学研究方法,以期全面深入地理解中国兽类分类地位、起源以及特异表型产生和独特适应的发育遗传学机制等,进而实现“天人合一”保护生物学的新理念和新愿景。     

The applicability of metapopulation theory to large mammals

Metapopulation theory has become a common framework in conservation biology and it is sometimes suggested that a metapopulation approach should be used for management of large mammals. However, it has also been suggested that metapopulation theory would not be applicable to species with long generations compared to those with short ones. In this paper, we review how and on what empirical ground metapopulation terminology has been applied to insects, small mammals and large mammals. The review showed that the metapopulation term sometimes was used for population networks which only fulfilled the broadest possible definition of a metapopulation, i.e. they were subpopulations connected by migrating individuals. We argue that the metapopulation concept should be reserved for networks that also show some kind of metapopulation dynamics. Otherwise it applies to almost all populations and loses its substance. We found much empirical support for metapopulation dynamics in both insects and small mammals, but not in large mammals. A possible reason is the methods used to confirm the existence of metapopulation dynamics. For insects and small mammals, the common approach is to study population turnover through patch occupancy data. Such data is difficult to obtain for large mammals, since longer temporal scales need to be covered to record extinctions and colonizations. Still, many populations of large mammals are exposed to habitat fragmentation and the resulting subpopulations sometimes have high risks of extinction. If there is migration between the subpopulations, the metapopulation framework could provide valuable information on their population dynamics. We suggest that a metapopulation approach can be interesting for populations of large mammals, when there are discrete breeding subpopulations and when these subpopulations have different growth rates and demographic fates. Thus, a comparison of the subpopulations’ demographic fates, rather than subpopulation turnover, can be a feasible alternative for studies of metapopulation dynamics in large mammals.     

A preliminary study of resource overlap between howling monkeys (Alouatta palliata) and other arboreal mammals in the tropical rain forest of Los Tuxtlas,Mexico

Potential resource overlap between howling monkeys and other arboreal mammals was studied in the rain forest of Los Tuxtlas, Veracruz, Mexico. Eight species of mammals belonging to the orders Primates, Carnivora, Rodentia, and Marsupialia were found to share the canopy and to overlap trophically with howling monkeys. These mammals made up 77% and Alouatta 23% of the arboreal mammalian biomass under consideration. The arboreal porcupine and spider monkey were the only mammals that also fed on leaves. However, in this feeding niche, Alouatta is the only important mammalian folivore in Los Tuxtlas, and resource depression derived from leaf-eating insects is more important. The eight arboreal mammals may exert more pressure upon fruit resources, for they consumed 75% of the estimated total dry weight of fruit/ha/yr consumed by arboreal mammals.     

Use of fibrous diets by small herbivores: How far can the rules be 'bent'?

Allometric considerations suggest that small mammals should be unable to eat highly fibrous diets. A combination of the selective and more rapid passage of fibrous material through the gut, together with changes in gut capacity when energy requirements increase, may allow small mammals to escape these allometric constraints. Recent evidence that birds can absorb essential amino acids from the caecum (which has hitherto been considered insignificant in mammals) suggests that birds and mammals have evolved very different ways to be a herbivore.     

A dynamic similarity hypothesis for the gaits of quadrupedal mammals

The dynamic similarity hypothesis postulates that different mammals move in a dynamically similar fashion whenever they travel at speeds that give them equal values of a dimensionless parameter, the Froude number. Thus, given information about one species, it could be possible to predict for others relationships between size, speed and features of gait such as stride length, duty factor, the phase relationships of the feet and the patterns of force exerted on the ground.
Data for a diverse sample of mammals have been used to test the hypothesis. It is found to be tenable in many cases when comparisons are confined to quadrupedal mammals of the type described by Jenkins (1971) as "cursorial". Most mammals of mass greater than 5 kg are of this type. Although the hypothesis applies less successfully to comparisons between cursorial and non-cursorial mammals it is shown to be a reasonable approximation even for such comparisons and for comparisons between quadrupedal mammals and bipedal mammals and birds.