西双版纳地区小型哺乳动物群落结构及其季节变动

2008年10月—2009年6月,选择云南西双版纳地区7个不同类型生境,分别在旱季、雾凉季和雨季,采用铗夜法对小型哺乳动物群落展开调查。共布2100铗日,捕得小型哺乳动物3科10种127只,其中啮齿目(Rodentia)鼠科(Muridae)8种,食虫目(Instectivo-ra)鼩鼱科(Soricidae)和猬科(Erinaceidae)各1种,平均捕获率为6%。社鼠(Niviventer con-fucianus)是该地区小型哺乳动物群落中的优势种,其捕获率在季节之间的差异达到显著水平(P=0.023),在生境之间的差异不显著(P0.05)。在所调查的7个生境中,以生境最原始的热带雨林中的小型哺乳动物物种多样性指数最高(1.91);热带山地常绿阔叶林物种均匀度最高(0.95);热带季节性湿润林物种优势度最高(0.94)。人工橡胶林中未捕获到小型哺乳动物。3个季节中以旱季捕获小型哺乳动物数量最多。对不同生境内群落相似性指数进行聚类分析,6个生境在相似性指数0.21处全部聚合在一起。本研究结果表明,不同生境中小型哺乳动物物种多样性的丰富度与人类干扰程度有关,在人类干扰越小的生境中,小型哺乳动物种类越丰富,生物多样性指数越高;人为干扰频繁的生境物种多样性较低。     

Diversity patterns of small mammals in the Zambales Mts., Luzon, Philippines

In 2004 and 2005, we conducted a survey of the small mammals on Mt. Tapulao (=Mt. High Peak, 2037 m) in the Zambales Mountains, Luzon Island, Philippines in order to obtain the first information on the mammals of this newly discovered center of endemism. We also tested two hypotheses regarding the relationship of species richness with elevation and the impact of alien species on native mammals. The survey covered five localities representing habitats from regenerating lowland rain forest at 860 m to mossy rain forest near the peak at 2024 m. We recorded 11 species, including 1 native shrew, 1 alien shrew, 8 native rodents, and 1 alien rodent. Two species of Apomys and one species of Rhynchomys are endemic to Zambales; this establishes the Zambales Mountains as a significant center of mammalian endemism. Species richness of native small mammals increased with elevation, from five species in the lowlands at 925 m to seven species in mossy forest at 2024 m; total relative abundance of native small mammals increased from 925 to 1690 m, then declined at 2024 m. Alien small mammals were restricted to highly disturbed areas. Our results support the prediction that maximum species richness of small mammals would occur in lower mossy forest near the peak, not near the center of the gradient. Our results also support the hypothesis that when a diverse community of native Philippine small mammals is present in either old-growth or disturbed forest habitat, “invasive” alien species are unable to penetrate and maintain significant populations in forest.     

Scaling coexistence and assemblage patterns of desert small mammals

Scaling biodiversity patterns has been recognized lately as a very important issue in the search of global processes; however coexistence and assemblage patterns are typically approached at a single spatial scale. Here, we examined coexistence and co-occurrence patterns of desert small mammal communities across different spatial scales in the search of general community patterns. We sampled small mammals in Monte desert (Argentina, South America) for small spatial scales and reviewed published papers from other worldwide deserts for large spatial scale analyses. We used classic community estimators (Shannon, Richness), rank abundance curves and fitting distributions to analyze species coexistence and co-occurrence patterns. Assemblage patterns were analyzed evaluating nestedness across spatial scales and among deserts. Worldwide desert small mammal assemblages are characterized mainly by low species richness and high variation in species composition. The central Monte desert of Argentina showed a consistent assemblage pattern across spatial scales, with a generalist species being the most abundant and widely distributed, accompanied by other subordinate and more narrowly distributed species. All Monte desert communities were significantly nested, with nestedness increasing with scale from patch to regional. Assemblage and coexistence patterns were similar when comparing worldwide deserts despite differences in total richness and faunal singularity. The degree of nestedness varied among worldwide deserts; however all of them showed a consistent nested pattern. Differences in the degree of nestedness could be a result of different regulating factors depending on the desert and scale. These results highlight the importance of including multiscale approaches when dealing with processes that structure desert communities.     

Abundance patterns and coexistence processes in communities of fleas parasitic on small mammals

The abundance of a given species in a community is likely to depend on both the total abundance and diversity of other species making up that community. A large number of co-occurring individuals or co-occurring species may decrease the abundance of any given species via diffuse competition; however, indirect interactions among many co-occurring species can have positive effects on a focal species. The existence of diffuse competition and facilitation remain difficult to demonstrate in natural communities. Here, we use data on communities of fleas ectoparasitic on small mammals from 27 distinct geographical regions to test whether the abundance of any given flea species in a community is affected by either the total abundance of all other co-occurring flea species, or the species richness and/or taxonomic diversity of the flea community. At all scales of analysis, i.e. whether we compared the same flea species on different host species, or different flea species, two consistent results emerged. First, the abundance of a given flea species correlates positively with the total abundance of all other co-occurring flea species in the community. Second, the abundance of any given flea species correlates negatively with either the species richness or taxonomic diversity of the flea community. The results do not support the existence of diffuse competition in these assemblages, because the more individuals of other flea species are present on a host population, the more individuals of the focal species are there as well. Instead, we propose explanations involving either apparent facilitation among flea species via suppression of host immune defenses, or niche filtering processes acting to restrict the taxonomic composition and abundance of flea assemblages.     

Effects of grassland succession on communities of small mammals in Illinois, USA

Native grasslands are among the most imperiled of the North American ecosystems, with only ∼4% of their pre-settlement area remaining, but some grassland habitats are being restored and maintained through such methods as prescribed burning and mowing, which may provide habitat for animal species endemic to this ecosystem. I determined how succession of the plant community, due to a four-year rotational burn in 16 grassland fragments, influenced species richness and local abundances of small mammals in Illinois, USA. Species richness was relatively low in grasslands that were recently burned and highest in older successional grasslands. The most abundant species, Microtus ochrogaster, M. pennslyvanicus, Peromyscus maniculatus, P. leucopus, and Reithrodontomys megalotis showed very different responses to succession; Microtus spp. were most abundant in older successional grasslands, preferring areas with more cover of bunchgrasses, whereas the other three species were relatively abundant in grasslands of all successional ages. P. maniculatus was most abundant in any habitat that had ample open ground. The grasslands at my study site are a mixture of restored and non-restored grasslands. Overall, adding additional time between burns and restoring more of the grasslands by planting bunchgrasses that are native to this area may increase abundances of most mammal species at my study site.     

Spatio-temporal activity patterns of mammals in an agro-ecological mosaic with seasonal recreation activities

Recreation activities in developed landscapes may add additional stressors that affect wildlife spatial and temporal activity patterns. We assessed medium to large mammal species response to a tourist scenic route in an agro-ecological mosaic landscape of the Shikma region, Israel. We placed 60 camera traps in an agro-ecological matrix and recorded mammals during three seasons between 2015 and 2017. We used N-mixture models to estimate mammal activity in relation with proximity to the scenic route and additional anthropogenic related factors such as traffic volume and land use. Anthropogenic development and activities had negative effects on large, endangered species, and none or positive on smaller, commensal species. Our results suggest an expansion of human recreation activity may have adverse outcomes on apex predators, which can cause a chain reaction and lead to meso-predator release, ultimately affecting prey species. The results emphasize the need for land managers to be extra cautious when attempting to add additional stressors (i.e., recreation activity) to developed landscapes such as the study area. Such landscapes can function as healthy ecosystems and provide suitable habitats for wildlife given that land managers are aware and account for wildlife-limiting factors in future development plans.     

乌鲁木齐市小型兽类群落特征与分布格局初步研究

根据2002年7月的调查资料对乌鲁木齐市养禽场鼠类群落进行了研究。结果表明：该地区分布的鼠类可划分为2种群落,(1)褐家鼠 小家鼠群落;(2)小家鼠 灰仓鼠群落。同时对鼠类群落的多样性,均匀度等进行了初步研究。     

Effects of macroparasites on the energy allocation of reproducing small mammals

Reproduction,including lactation,is the most costly activity in terms of energy expenditure in female mammals.Consequently,the energy requirements of the reproducing female may not be met at this time,especially if other energy demanding activities are occurring concomitantly.Such activities could be the activation and maintenance of an immune system in response to parasitic infestation.These protective processes are energetically demanding and require trade-off decisions among competing energy demands.In the case of a reproducing mammal,the trade-offs occur mainly between defence against parasites and reproductive costs of the host.In this paper,I discuss the effects of macroparasites on the energy allocation of reproducing small mammals.     

Effects of macroparasites on the energy allocation of reproducing small mammals

Reproduction, including lactation, is the most costly activity in terms of energy expenditure in female mammals. Consequently, the energy requirements of the reproducing female may not be met at this time, especially if other energy demanding activities are occurring concomitantly. Such activities could be the activation and maintenance of an immune system in response to parasitic infestation. These protective processes are energetically demanding and require trade-off decisions among competing energy demands. In the case of a reproducing mammal, the trade-offs occur mainly between defence against parasites and reproductive costs of the host. In this paper, I discuss the effects of macroparasites on the energy allocation of reproducing small mammals.     

Effects of small mammals and vertebrate predators on vegetation in the Chilean semiarid zone

 We monitored the cover and seed bank response of shrubs, perennial herbs, and ephemeral plants to experimental exclusion of both the principal rodent herbivore, Octodon degus, and its vertebrate predators from 1989 to 1994 in a semiarid Chilean mediterranean site. Although both richness and species composition of the plant community at the study site were largely determined by abiotic factors (mainly rainfall and soil nutrients), predator and herbivore exclusion had significant effects on the relative abundance of several plant species. Experimental exclusion of herbivores was associated with increased cover of some shrubs and a perennial grass, and decreased cover and seed densities of several ephemerals, especially those exotic or restricted to areas underneath shrubs. Herbivores apparently reduced shrubs through browsing and indirectly affected herb cover and seed densities by opening up areas under shrubs and/or modifying physical and chemical conditions of the soil. Plant responses to predator exclusion were less clear. Nevertheless, higher cover of some shrubs and ephemerals in the presence of predators suggests tritrophic effects through changes in small mammal densities and/or foraging behavior. Received: 22 April 1996 / Accepted: 14 August 1996     

Phase shift in leaf movements of xanthium attributed to age and rhythm patterns

Leaves of cockelbur (Xanthium strumarium L.) have been reported to be in either an upright or downward position during the dark span (night) of a 24-hour cycle. Results from our studies clearly indicate that such differences in leaf position are not related to differences in ecotypes but can be attributed to age of the leaf, pattern of the waveform of the rhythm at various stages of the light-dark synchronizer regimen, and the statistical model used for the analysis of the waveform. Younger leaves reached a maximum upright position closer to the middle of the dark span, whereas older leaves reached this position closer to the end of the dark span. A phase shift of up to 6 to 10 hours may occur as the leaf ages. Results from the examination of the pattern of the waveform at four different times showed that the pattern of a younger leaf was different from that of an older leaf during the middle of the dark span, during the light-to-dark transition, and during the middle of the light span, but not during the dark-to-light transition. Linear regression, statistical analyses, and the fitting of harmonics clearly indicate that it is the trough, more than the peak, that differs with the age of the leaf.     

Melatonin circadian rhythm in the retina of mammals

Melatonin has been traditionally considered to be derived principally from the pineal gland. However, several investigations have now demonstrated that melatonin synthesis occurs also in the retina (and in other organs as well) of several vertebrate classes, including mammals. As in the pineal, melatonin synthesis in the retina is elevated at night and reduced during the day. Since melatonin receptors are present in the retina and retinal melatonin does not contribute to the circulating levels, retinal melatonin probably acts locally as a neuromodulator. Melatonin synthesis in the retinas of mammals is under control of a circadian oscillator located within the retina itself, and circadian rhythms in melatonin synthesis and/or release have been described for several species of rodents. These rhythms are present in vivo, persist in vitro, are entrained by light, and are temperature compensated. The recent cloning of the gene responsible for the synthesis of the enzyme arylalkylamine N-acetyltransferase (the only enzyme unique to the melatonin synthetic pathway) will facilitate localizing the cellular site of melatonin synthesis in the retina and investigating the molecular mechanism responsible for the generation of retinal melatonin rhythmicity. Melatonin has been implicated in many retinal functions, and the levels of melatonin and dopamine appear to regulate several aspects of retinal physiology that relate to light and dark adaptation. In conclusion, it seems that retinal melatonin is involved in several functions, but its precise role is yet to be understood.     

Sagittal otolith growth patterns in regularly and irregularly spawning burbot,Lota lota,in northern Finland

Synopsis Sagittal otolith growth patterns were compared among three burbot,Lota lota, populations in northern Finland. Coastal burbot off Simo on the northern coast of the Bothnian Bay and lake burbot from Lake Kemijärvi represented populations with about 30% non-spawning adult individuals, while the river burbot from the River Kitinen spawned regularly. Irregular growth patterns i.e. crenulations on the dorsal edge of the sagitta and pointed extensions in the rostrum region and cloudy appearance of the sagittal otoliths, as observed by light, scanning and transmission microscopy, occurred significantly more often in the coastal and lake burbot than in the river burbot. This could not be explained by differences in age or size. Its possible relationship to supposed reproduction disorder is discussed.     

Mobility, growth patterns and substrate in some fossil and Recent corals

The article analyses the relationships between mobile corals, the associated benthic fauna and the physical character of their substrates. Different types of coral mobility are here classified under three headings: (1) Passive rotation by water movement or by intervention of infaunal, benthic or nektic organisms. (2) Lifelong towing by a symbiotic sipunculid worm. (3) Auto-mobility, defined as self-induced movement which allows unburial, righting and lateral migration. In each case the morphology of the skeleton reflects the type of mobility, which can therefore be traced in the fossil record. Two examples of auto-mobile corals, Cycloseris (Recent) and Chomatoseris (= Anabacia) (Jurassic) are reviewed in detail; their main common architectural features are concentric growth and lack of epitheca. Both genera prefer loose, muddy sands. Mobility in corals allows them to flourish under circumstances unfavourable for sedentary forms. They are good indicators of loose, soft, sand substrates ranging from lagoonal through peri-reefal to deeper water environments. Though relatively few in species at any given time, mobile corals are geographically widespread and may be locally extremely abundant (>1500 per m²). World distribution maps are given for the Recent Cycloseris cyclolites, Diaseris distorta, Heteropsammia, Heterocyathus and Manicina areolata and for the Jurassic Chomatoseris. Cet article analyse Ies relations entre les coraux mobiles, la faune benthique associée et les propriétés physiques de leur substrat. On peut classer les différents types de mobilité chez les coraux selon trois catégories: (1) Rotation passive due aux mouvements de l'eau, à l'intervention de l'endofaune, d'organismes benthoniques ou nectoniques. (2) Remorquage par un ver Sipunculide symbiotique. (3) Auto-mobilité, définie comme mouvements propres, permettant au polypier de s'extraire du sédiment, de se retourner et de se déplacer latéralement. Dans tous les cas la morphologie du squelette est liée au type de mobilité qui peut done être reconnu chez les fossiles. Deux exemples de coraux auto-mobiles sont ici revus en détail: Cycloseris (actuel) et Chomatoseris (=Anabacia) (Jurassique); les traits communs entre ces deux formes sont la croissance concentrique et l'absence d'épithèque. Les deux genres préfèrent les sables boueux meubles. La mobilité chez les coraux permet leur épanouissement dans des circonstances défavorables aux formes sédentaires. Ce sont de bons indicateurs de fond meuble (sable ou sable vaseux). On les trouve dans les lagons, les zones péri-récifales et jusque dans des eaux plus profondes. Les genres mobiles, dont le nombre connu est encore faible, ont cependant une large distribution géographique et peuvent localement être représentés par de nombreux individus (>1500 par m²). Des cartes de répartition mondiale sont établies pour les coraux actuels Cycloseris cyclolites, Diaseris distorta, Heteropsammia, Heterocyathus, Manicina areolata et pour le genre jurassique Chomatoseris.