荒漠草原马粪中粪金龟子组成及分解作用

2007年4-10月,采用野外和室内实验相结合的方法,研究了荒漠草原马粪中的粪金龟子群落组成和对马粪分解的影响.共捕获粪金龟子13528头,隶属于3科4属26种,优势种为符号蜉金龟(Aphodius comma),占总捕获量的88.5%,不同季节粪金龟子群落组成明显不同;在鲜马粪中活动的粪金龟子以粪居型蜉金龟为主,在鲜马粪堆置3d时种数和个体数达到最高,6d后全部离开;马粪经过136 d分解,残留率为52.5%,残留粪样中氮和磷释放较慢,钾释放较快;结合室内分解实验的结果,认为粪金龟子主要通过在马粪中活动对其分解产生影响,并与风蚀作用成为荒漠草原马粪块破碎的重要动因,主要发生在春季和秋季.     

放牧对内蒙古典型草原粪金龟子群落的影响

为阐明放牧对粪金龟子群落的影响, 于2004年5-9月, 选择内蒙古典型草原不同放牧强度 (无放牧、 适度放牧和过度放牧) 草地为样地, 采用诱捕法采集粪金龟子标本, 分析了放牧对粪金龟子群落的影响。结果表明： 共捕获粪金龟子60 839头, 隶属于3科5属24种。放牧影响下, 粪金龟子群落个体数、 种数和生物量均发生显著变化, 不同粪金龟子对放牧的敏感性不同, 并具有明显的季节特征。Pearson相关分析表明, 春季粪金龟子群落个体数、 生物量、 种数以及符号蜉金龟Aphodius comma和马粪蜉金龟Aphodius subterraneus个体数与放牧强度提高之间存在显著负相关关系; 夏季粪金龟子群落种数和叉角粪金龟Ceratophyus polyceros个体数与放牧强度提高也呈显著负相关; 秋季粪金龟子群落生物量和种数以及费氏粪金龟Ceratophyus fischeri、 墨侧裸蜣螂Gymnopleurus mopsus和小驼嗡蜣螂Onthophagus gibbulus个体数与放牧强度提高之间存在显著正相关关系。依据体长、 体重和行为特征, 将粪金龟子划分为4个功能群, 放牧对体型较小的功能群Ⅲ和Ⅳ的影响较显著。指示值计算结果表明, 费氏粪金龟、 毛蜉金龟Aphodius scofa和马粪蜉金龟可以作为不同放牧强度草地的特征指示种。     

Asymmetric competition in cattle dung between two species of Onthophagus dung beetle and the bush fly, Musca vetustissima

Abstract.

• 1 Competition in cattle dung pads between two dung beetles, Onthophagus ferox Harold and Onthophagus binodis Thunberg, and the bush fly, Musca vetustissima Walker, was investigated in laboratory experiments, to determine why spring fly abundance in the field did not fall following the introduction of O. binodis.
• 2 At low beetle densities, the number of eggs laid by each species was reduced by the second species. A similar amount of dung was buried by each species alone or by both together.
• 3 At high beetle densities O. binodis egg production was substantially affected by each additional O.ferox, but O.ferox egg production was not affected by each additional O.binodis. Asymmetric competition occurred because O.ferox buried more dung than O.binodis, and a greater proportion in day 1 (pre-emptive dung burial).
• 4 O.ferox caused greater M. vetustissima egg-puparia mortality than O. binodis. Mortality mostly occurred in young M. vetustissima larvae less than 1 day old. Total egg-puparia fly mortality was correlated better with the dung buried on day 1 than dung buried on day 8 (pre-emptive dung burial). O.binodis did not add to fly mortality by O.ferox at high densities because of asymmetric competition between the beetles.

     

Altitudinal variation of dung beetle (Scarabaeidae: Scarabaeinae) assemblages in the Colombian Andes

Aim We describe the changes in species richness, rarity and composition with altitude, and explore whether the differences in Scarabaeinae dung beetle composition along five altitudinal transects of the same mountain range are related to altitude or if there are interregional differences in these altitudinal gradients. Location Field work was carried out on the eastern slope of the eastern Cordillera, Colombian Andes, between Tamá Peak to the north, in the Tamá National Park (07°23′ N, 72°23′ W) and the San Miguel River (00°28′ N, 77°17′ W) to the south. Methods Sampling was carried out between February 1997 and November 1999 in five regions spanning elevation gradients. In each gradient, six sites were chosen at 250 m intervals between 1000 and 2250 m a.s.l. Results We found a curvilinear relationship between altitude and mean species richness, with a peak in richness at middle elevations. However, the diversity of dung beetle assemblages does not seem to be related to the interregional differences in environmental conditions. The number of geographically restricted species is negatively and significantly related to altitude, with geographically restricted species more frequent at low altitude sites. Ordination delimited the two main groups according to altitude: one with all the highest sites (1750–2250 m a.s.l.) and a second group with the remaining sites (< 1750 m a.s.l.). Analysis of species co‐occurrence shows that these dung beetle assemblages seem to be spatially structured when all sites have the same probability of being chosen. In contrast, the spatial structure of species assemblages seems to be random when the probability of choosing any site is proportional to its altitude. Main conclusions The altitude of sites is the main factor that influences the diversity of these dung beetle assemblages. The peak in species richness at middle elevations, the higher number of geographically restricted species at lower altitudinal levels, and the compositional differences along these mountain gradients seem to result from the mixing at these altitudes of dung beetle assemblages that have different environmental adaptations and, probably, different origins. The relevance of altitude in these assemblages is related to the limited role of these Neotropical high altitude environments as centres of refuge and vicariance for a monophyletic group of warm‐adapted species, for which the vertical colonization of these high mountain environments by lineages distributed at lower altitudes would have been very difficult.     

内蒙古典型草原家畜粪中的粪金龟子群落特征

2008年6月-2009年9月,在内蒙古典型草原放牧区,分析了马、牛和羊鲜粪中粪金龟子的物种多样性、群落结构、功能群和取食偏好.共捕获粪金龟子7805头,隶属于3科4属32种,优势种为符号蜉金龟(Aphodius comma)、游荡蜉金龟(Aphodius erraticus)和泥蜉金龟(aphodius sordec...     

Preliminary investigations of Aphodius species activity in cattle faeces treated with ivermectin

Abstract. A.sphacelatus at densities of 0.5 and 1.0 beetle/g faeces caused significantly greater median percentage reductions (65.2% and 87.4% respectively) of Pilobolus sporangia than 0.1 beetle/g faeces (31 %) in untreated cattle faeces. The median percentage reduction in sporangia due to beetle activity (48.4%) was significantly lower (P < 0.02) in faeces mixed with ivermectin at l.Oppm (wet weight) than in untreated faeces (88.4%). After treating a bullock with ivermectin (Ivomec^R Pour-On), the median percentage reduction in sporangia caused by beetles was significantly less (P < 0.05) on days 9 (78.9%) and 10 (76.9%) than in pre-dose faeces (86.5% and 93.8% respectively). In microcosms without beetles, sporulation of Pilobolus in cattle faeces from a heifer treated with ivermectin was significantly less on days 5,10 and 15 after dosing. However, this difference was not apparent for days 5 and 10 after storage of faeces at 4^oC for 55 and 50 days respectively.     

Experimental warming alters the relative survival and emigration of two dung beetle species from an Australian dung pat community

To preserve insect‐mediated ecosystem services under ongoing climate change, it is necessary to first understand the impact that warming will have on the insects that provide or mediate these services. Furthermore, because responses of a species may be modified by interactions with competitors, it is informative to examine warming effects on organisms and service provision under competition. Dung beetles provide numerous services to agriculture by burying the manure of other animals. To understand the potential impacts of climate warming on ecosystem service provision, we exposed two dung beetle species (Sisyphus rubrus and Euoniticellus fulvus (Coleoptera: Scarabaeidae)), occurring together in the same experimental pats, to warming and measured reproduction (dung ball production and burial, brood production, and egg laying), pat departure behaviour and survival of both species. These two species are likely competitors in pastures in northern New South Wales. To simulate climate warming, we used custom‐built chambers to add offsets (+0, +2 or +4°C) to field recorded, diurnally fluctuating baseline temperatures. There was no direct effect of increased temperature on any measured trait in either species. We did find however that the relative survival of the two species depended on temperature; S. rubrus had a higher probability (resulting in greater odds) of surviving than E. fulvus in the +0 and +4°C offset chambers, but not in the +2°C offset chambers. Likewise, the relative likelihood of the different species leaving a dung pat was temperature dependent; in the +2°C offset chambers, E. fulvus were more likely to leave than S. rubrus, but not in the +0 and +4°C offsets chambers. Our results highlight that it may be important for future studies to consider warming effects on relative survival and emigration because such effects could potentially lead to changes in dung beetle species composition.     

Effect of dung beetle species richness and chemical perturbation on multiple ecosystem functions

1. The relationship between biodiversity and ecosystem functioning is typically positive but saturating, suggesting widespread functional redundancy within ecological communities. However, theory predicts that apparent redundancy can be reduced or removed when systems are perturbed, or when multifunctionality (the simultaneous delivery of multiple functions) is considered. 2. Manipulative experiments were used to test whether higher levels of dung beetle species richness enhanced individual functions and multifunctionality, and whether these relationships were influenced by perturbation (in this case, non‐target exposure to the veterinary anthelmintic ivermectin). The four ecosystem functions tested were dung removal, primary productivity, soil faunal feeding activity and reduction in soil bulk density. 3. For individual functions, perturbation had limited effects on functioning, with only dung removal significantly (negatively) affected. Species richness did not, on its own, explain significant variation in the delivery of individual functions. In the case of primary productivity, an interaction between richness and perturbation was found: species‐rich dung beetle assemblages enhanced forage growth in the unperturbed treatment, relative to the perturbed treatment. 4. Using a composite ‘multifunctionality index’ it was found that species‐rich dung beetle assemblages delivered marginally higher levels of multifunctionality in unperturbed conditions; however, this benefit was lost under perturbation. Using a relatively new and robust method of assessing diversity–multifunctionality relationships across a range of thresholds, no significant effect of species richness on multifunctionality was found.     

A review of competition in north temperate dung beetle communities

Abstract. 1. Studies of north temperate dung beetle communities frequently invoke competition as an influential ecological process. In this review, the evidence for competition in north temperate dung beetle communities is evaluated and the role of competition as a factor affecting community structure is assessed.
2. Resource limitation and the evidence for interspecific competition are assessed by collating the available experimental and observational evidence for both the adult and larval stages of the dung beetle life cycle. The role of competition as a structuring force in dung beetle communities is discussed under the following headings: niche dynamics, migration to and from individual pats, the aggregation model of co-existence, and metapopulations.
3. Some of the main conclusions are that competition for space is much more likely to occur than competition for food; the effects of competition on community structure are poorly understood; several of the influential studies of competition in north temperate dung beetle communities need to be evaluated carefully. The differences in ecology between tropical and temperate dung beetle communities are clarified.
4. As priorities for future research, resource utilisation and competition should be researched experimentally: density-dependent relationships should be investigated, particularly for the larval stages, as should competitive interactions with other dung fauna. If such experimental approaches establish convincingly the occurrence of competition, then the extent of competition in the field and under real world conditions needs to be established. A functional group classification of dung beetles and other dung fauna is described, which may improve the generality of interpretation from individual, site-specific results.     

Role of dung beetle feeding mechanisms in limiting the suitability of species as hosts for the nematode Spirocerca lupi

Various species of dung beetle serve as intermediate hosts after ingesting the embryonated eggs (11–15 × 30–37 µm) of Spirocerca lupi (Spirurida: Spirocercidae) in dog faeces. The feeding mechanisms of coprophagous dung beetles restrict the size of the food particles they can ingest and hence may determine which species can be efficient vectors for S. lupi. In this study, we aimed to exclude certain dung beetle species as possible hosts of S. lupi based on whether or not they ingested latex beads of known diameters mixed into fresh cattle dung. We found that the majority (11/14) of species tested can potentially serve as intermediate hosts of S. lupi because their mouthparts allow the passage of food particles larger than the minimum size range of the eggs of this parasite.     

First discovery of fossil dung beetle brood balls and nests in the Chadian Pliocene Australopithecine levels

The Pliocene continental formations of the paleo-lake Chad system are known because of the recent discovery of the first australopithecine known west of the Rift Valley. The structures under study are found in sandstone levels associated with a rich fauna, including mammals, birds, reptiles and fishes. Analysis of the depositional environment and fauna indicates a mosaic landscape of gallery forest, savannah, grassland and ephemeral rivers interrupted by lacustrine episodes. This sandstone facies contains bioturbation in the form of sandstone balls 4-12 cm in diameter, slightly flattened at the poles. These structures are characterized by an external husk or crust and by a decimetric cavity in the upper part of the ball. Between the husk and the cavity are a number of concave laminae similar to those of a bulb, whose concavity is directed toward the upper cavity. The comparison between these structures and the brood balls of modern Scarabaeidae shows great similarity, especially in the external husk, the concave internal laminae and the chamber of the grub in the upper part of the structures. This bioturbation is interpreted as fossil brood balls of dung beetles (Coleoptera, Scarabaeidae). Fossil dung beetle brood balls are generally rare, but have been known since the 1940s. They can be very abundant in any series, as described by several authors in South America. The first fossil dung balls were described in this area in 1938 by Frenguelli and by Roselli. These authors describe elementary spherical forms of 35 mm in diameter on average, flattened at the poles and with an upper cavity. The fossil dung beetle brood balls discovered in Chad are the first in which all the internal characteristic structures are preserved. Many of them are connected by a remarkably large net of tunnels which has no parallel in the past or the present.     

Dung pad residence time covaries with male morphology in the dung beetle Onthophagus taurus

1. The immigration and emigration behaviours of Onthophagus taurus were investigated in a combination of field and laboratory experiments to examine patterns of dispersal in this species. 2. On average, the mean proportion of major males immigrating to baited pitfall traps decreased significantly with time. In contrast, the mean proportion of minor males and females did not change with time. 3. The time taken to emigrate from a dung pad differed significantly among major males, minor males, and females. This difference arose because major males spent a significantly shorter period of time residing within the dung pad. On average, more than 50% of major males had emigrated from the dung pads after 30 h, some 4 h earlier than minor males and females. 4. When the effects of body size were controlled, major males with longer horns were shown to have longer wings. Because major males spend more time in flight, longer wings may be an adaptation to more frequent dispersal. Alternatively, longer wings in major males may compensate for the production of aerodynamically costly horns.     

Species turnover, community boundaries and biogeographical composition of dung beetle assemblages across an altitudinal gradient in South Africa

Aim To identify biogeographical boundaries which are obscured by faunal overlap and habitat modification. Location KwaZulu-Natal in south-east, South Africa beyond the southern tip of the Moçambique Coastal Plain. Methods Species abundance data for dung beetles (Scarabaeidae: Scarabaeinae) were collected at six levels from the coastal escarpment (30°16′S – 500 m) to the top of the nearby Drakensberg (29°35′S – 2850 m). Cross-altitudinal boundaries were identified using clustering techniques, beta-diversity indices, and range edge analysis. Biogeographical data for the species were drawn from an extensive reference collection and used to classify the biogeographical affinities of the assemblages. Results Three discrete communities are defined (<10% similarity) from species abundance distributions. These communities occur in coastal forest (500 m), coastal to highveld grassland (500–1500 m), and montane grassland (1900–2850 m). Two of these communities are biogeographically homogeneous comprising >89% east coast endemics (coastal forest) or >84% South African montane endemics (montane grassland) in terms of abundance. The third community in coastal to highveld grassland is biogeographically more heterogeneous. Predominant biota of this community comprise both South African highveld endemics and elements with distributions extending into the tropics. At highveld levels (1500 m), there are proportionately more highveld endemics whereas at lowland levels (500 m), there are proportionately more tropical elements. At 1000 m, there was a change in the balance between these two groups across an anthropogenic gradient due to a decline in the proportion of endemics in favour of temperate/tropical generalists. This gradient from a natural grassland fragment to improved pastures of Kikuyu grass also parallels a decline in species richness and abundance. Species turnover analyses showed three different cross-altitudinal patterns. Range-edge analysis showed a trimodal pattern of species turnover (peaks in forest and the Drakensberg foothills as in the community analysis but also at 1000 m). Five beta-diversity indices showed either a bimodal pattern of turnover (forest/grassland and foothills/middle Drakensberg slopes) or a trimodal turnover pattern (forest/grassland, highveld/Drakensberg foothills, Drakensberg peaks). Main conclusions Clear altitudinal zonation is revealed by community and biogeographical analysis but one natural biogeographical boundary may be obscured by the process of habitat modification. This boundary at 1000 m is revealed by range-edge analysis and is supported by findings for plant communities. Beta-diversity, species turnover patterns diverged slightly from those suggested by the community and range-edge analyses.     

The role of habitat and daily activity patterns in explaining the diversity of mountain Neotropical dung beetle assemblages

The interaction between land use and climate change is expected to strongly affect species distributions along high elevation landscapes. We aimed to test the effect of climatic variables on community metrics among five types of land use in a high elevation landscape. We described dung beetle spatial and temporal taxonomic and functional diversity patterns, and partitioned β‐diversity into turnover and nestedness components. The interaction between land use and daily period of activity mostly drives abundance, functional richness and functional diversity, but not dung beetle species richness. Unlike Neotropical lowlands, species richness and abundance in open environments are similar to those existing in forests. Temperature is an important predictor of abundance and functional divergence. There is a higher spatial component of the taxonomic β‐diversity, which is highly driven by species turnover. The temporal component of the taxonomic β‐diversity was strongly driven by nestedness, where night assemblages are sub‐sets, although not entirely, of diurnal assemblages. For functional diversity, the temporal β‐diversity was much higher than the spatial β‐diversity, but both were similarly represented by functional group turnover and nestedness. The composition of nocturnal and diurnal assemblages is clearly different, even more than the differences observed between habitats. However, taxonomic turnover is the dominant force between sampling sites while nestedness dominates the daily pattern. This means that forest habitats are unlikely to act as shelters for grassland species under a scenario of rising temperature.     

Spatial analyses of intertidal assemblages on sheltered rocky shores

Abstract Understanding processes in complex assemblages depends on good understanding of spatial and temporal patterns of structure at various spatial scales. There has been little quantitative information about spatial patterns and natural temporal changes in intertidal assemblages on sheltered rocky shores in temperate Australia. Natural changes and responses to anthropogenic disturbances in these habitats cannot be accurately measured and assessed without quantitative data on patterns of natural variability in space and through time. This paper describes some suitable quantitative methods for examining spatial and temporal patterns of diversity and abundances of highshore, midshore and lowshore intertidal assemblages and the important component species for a number of shores in a bay that has not been severely altered by human disturbance. Despite a diverse flora and fauna on these shores, the midshore and lowshore assemblages on sheltered shores were characterized by a few species which were also the most important in discriminating among assemblages on a shore and, for each assemblage, among different shores. The same set of species was also important for measuring small-scale patchiness within each assemblage (i.e. between replicate sites on a shore). Therefore, these data provide a rationale for selecting species that are useful for measuring differences and changes in abundance among places and times at different scales and, hence, can be used in the more complex sampling designs necessary to detect environmental impacts. There was considerable spatial variability in all assemblages and all species (or taxa) examined at scales of metres, tens of metres and kilometres. There were no clear seasonal trends for most measures, with as much or more variability at intervals of 3 months as from year to year. Most interactions between spatial and temporal measures were at the smallest scale, with different sites on the same shore generally showing different changes from time to time. The cause(s) of this apparently idiosyncratic variability1 were not examined, but some potential causes are discussed. These data are appropriate for testing hypotheses about the applicability of these findings to other relatively undisturbed sheltered shores, about effects of different anthropogenic disturbances on sheltered intertidal assemblages and to test hypotheses about differences in intertidal assemblages on sheltered versus wave-exposed shores.     

秦岭南北近地面水汽时空变化特征

利用秦岭南北地区47个气象站1960-2011年的观测资料,借助Spline空间插值、Pettitt突变点检验、Morlet小波分析等方法对水汽的空间分布、时空演变、突变特征和周期特征及其可能影响因素进行分析.结果表明:①秦岭南北近地面水汽呈南高北低、东高西低的空间分布格局,各子区水汽由南向北递减,季节分布规律与年尺度基本一致,以夏季最大,冬季最小.②近52年平均水汽压呈上升趋势,秦岭南坡和汉水流域上升速率较快,巴巫谷地呈下降趋势;③53％的站点冬季水汽压发生突变,集中分布于秦岭以南的部分地区,突变集中发生在1985-1988年间,与冬季气温突变时间一致,其余季节突变现象不明显.④水汽在21a时间尺度下经历了4次干湿交替变化,各季节水汽变化规律与年尺度基本一致,未来一段时间该地区仍然处于相对干旱状态.⑤水汽压受到包括气温、风速、日照在内的多种气象因素的综合作用,影响力大小排序为气温＞降水量＞日照时数＞相对湿度.     

Local and regional ecological morphology of dung beetle assemblages across four biogeographic regions

Aim Niche partitioning within species assemblages is thought to influence species packing and/or total niche space occupied. The evolution of dung beetles (Scarabaeinae) is likely to have been strongly influenced by inter‐specific competition, leading to niche partitioning. We consider whether local‐scale processes leave a signature in regional patterns of functional diversity in dung beetle assemblages, and investigate the correlation between total exploited ecomorphological space and density of species packing with increased species richness. We test whether ecomorphological space occupied by local assemblages reflects that of their regional species pool, and the extent to which ecomorphological space is convergent or divergent within functional groups across regional pools. Location Neotropics, Africa, Australia and Madagascar. Methods Dung beetle assemblages were collected in a standardized manner from four biogeographic regions. Ecomorphological similarity among the assemblages was assessed by multivariate analysis of 19 linear measurements for 300 species and three functional nesting types (roller, tunneller or dweller), firstly on a local level within the Neotropics and Afrotropics, and then between the regional species pools. Results Key body measurements, in particular the hind tibia, separated rollers and tunnellers into largely non‐overlapping entities along the first three axes of the shape analysis. Three Neotropical assemblages, which vary widely in species numbers, each harboured a similar amount of morphometric variation, resulting in increasingly dense species packing with greater species richness. Similar findings were obtained in two South African assemblages. Assemblages in the four biogeographic regions showed largely similar distributions of ecomorphological variation, including the separation of rollers and tunnellers, despite their distant phylogenetic relationships. Ecomorphological similarity among regions was particularly high in tunnellers, whilst the rollers exhibited greater regional differentiation. Main conclusions Local assemblages evidently represent the full diversity of functional groups available in the regional pool, even in species‐poor assemblages. There is a strong trend towards convergence in morphology separating tunnellers and rollers in phylogenetically independent lineages. The ecomorphological similarity of regional assemblages suggests that morphological convergence is the result of common selective forces active within the assemblages themselves. This lends support to the widely hypothesized effect of inter‐specific interactions and niche partitioning in determining assemblage composition and lineage evolution in the Scarabaeinae.     

喀斯特山区洼地表层土壤水分的时空变异

研究用地统计学方法在桂西北典型喀斯特洼地研究了表层土壤水分（0～15cm）的时空变异特征及其分布格局。结果表明在取样时段内洼地表层土壤水分总体不高（15．0％～27．5％）,呈现弱至中等变异特征,并且中等变异一般与含水量较低相对应。洼地表层土壤水分的半变异函数参数及其影响因素产生一定的季节变化;块金值、基台值和变程的变化范围分别是0．01～2．74,2．04～7．52和6．0～36．8。块金值和基台值的变化大致与平均含水量呈相反变化趋势;变程在采样初期和中期与土壤水分的变化趋势相反,在后期变化趋势相同,结果说明平均含水量对表层土壤水分的时空变异具有持续主导作用,结合研究目标可以有效指导后续的土壤采样。在剔除趋势效应后,表层土壤水分呈明显的斑块或条带状分布,样块土壤水分不仅具有空间分布的差异而且具有明显季节变化,其中旱、雨季的土壤水分分布特征明显不同。在喀斯特山区特殊地貌中,土壤平均含水量、地形、微地貌（石丛）和人为管理等因素是造成洼地表层土壤水分时空变异及其分布差异的主要影响因素。