Spatial and temporal variation in species composition of dung beetle assemblages in southern Ireland

Abstract. 1. This study attempts to identify the main community characteristics that contribute to variability in dung beetle assemblage composition and structure across a range of spatial and temporal scales.
2. Dung beetle assemblages ( Aphodius , Sphaeridium, and Geotrupes species) were monitored by dung-baited pitfall trapping at 10-day intervals during the seasonally active period at eleven sites in southern Ireland. Three of the sites were monitored over at least 2 years between 1991 and 1996.
3. Although the species composition of the above taxonomic groups was comparable among sites and years, relative abundances of component species varied considerably. Detrended correspondence analysis ordinations indicated a similar level of variability in dung beetle assemblage structure among years, and among sites ≈1–180 km apart.
4. Processes that may contribute to spatio-temporal variability in dung beetle assemblages are discussed, and strategies for future research are suggested.     

Intra- and interspecific aggregation of north temperate dung beetles on standardised and natural dung pads: the influence of spatial scale

Abstract.  1. The spatial distribution of north temperate dung beetles ( Aphodius , Sphaeridium , and Margarinotus ) was investigated at three spatial scales (scale  a between all pads – large spatial scale, small patch size; scale  b between block – large spatial scale, large patch size; scale  c within block – small spatial scale, small patch size) in the field using standardised and naturally dropped dung pads that varied in size and volume.
2. Results indicated that all the major colonising species of dung beetle expressed strong intraspecific aggregation, while interspecific aggregation, though present, was of a lesser magnitude.
3. In both controlled and natural dung treatments, intra- and interspecific aggregation decreased with increasing patch size (from pad to block) and also decreased with decreasing spatial scale (from whole plot to within-block scale).
4. The data also suggested that intraspecific aggregation was more important than interspecific aggregation in the distribution of adult dung beetles in natural and standardised dung pads and hence has the potential to facilitate coexistence.
5. Intra- and interspecific aggregation was greater in the natural dung compared with that of the standardised dung, and the effect of pad size partly explains this phenomenon.
6. The within-patch spatial distribution of dung beetles observed in the natural and standardised dung was possibly mediated through within-patch differences between the two treatments. Six confounding factors could explain this difference and these factors are discussed in relation to resource utilisation by north temperate dung beetles.     

A functional classification for analysis of the structure of dung beetle assemblages

Abstract. 1. Regional scarabaeid dung beetle assemblages in southern Africa may contain over 100 species, ranging in live weight from 10 mg to 10 g. These show a wide variety of dung-use and reproductive strategies.
2. To facilitate analysis of these diverse assemblages, a system of classification analogous to guilds is proposed. Scarabaeid dung beetle species are allocated to one of seven functional groups (FGs) according to the way they use and disrupt dung. Each group therefore contains a set of species which are functional analogues of each other. This classification provides a conceptual framework within which to analyse the structure of dung beetle assemblages and the interactions between dung beetles and other dung-breeding species such as coprophagous flies.
3. There is a clear hierarchy of functional groups in their ability to compete for dung. Competitively dominant groups such as the large ball rollers (FG I) and fast-burying tunnellers (FG III) are mostly large, aggressive beetles which rapidly remove dung from the pad. The smaller ball rollers (FG II) are also effective competitors for dung. Subordinate groups are those which bury dung slowly over many days (FG IV and V) and those which breed inside the pad (FG VII, endocoprids). Kleptocoprids (FG VI) breed in dung buried by other beetles and so are not part of the hierarchy.
4. The use of this classification is illustrated by reference to three contrasting assemblages of dung beetles in a summer rainfall region of southern Africa. The potential of these beetles for biological control of dung-breeding flies is discussed.     

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.     

The importance of sward architectural complexity in structuring predatory and phytophagous invertebrate assemblages

Abstract.  1. Although the importance of plant community assemblages in structuring invertebrate assemblages is well known, the role that architectural complexity plays is less well understood. In particular, direct empirical data for a range of invertebrate taxa showing how functional groups respond to plant architecture is largely absent from the literature.
2. The significance of sward architectural complexity in determining the species richness of predatory and phytophagous functional groups of spiders, beetles, and true bugs, sampled from 135 field margin plots over 2 years was tested. The present study compares the relative importance of sward architectural complexity to that of plant community assemblage.
3. Sward architectural complexity was found to be a determinant of species richness for all phytophagous and predatory functional groups. When individual species responses were investigated, 62.5% of the spider and beetle species, and 50.0% of the true bugs responded to sward architectural complexity.
4. Interactions between sward architectural complexity and plant community assemblage indicate that the number of invertebrate species supported by the plant community alone could be increased by modification of sward architecture. Management practices could therefore play a key role in diversifying the architectural structure of existing floral assemblages for the benefit of invertebrate assemblages.
5. The contrasting effects of sward architecture on invertebrate functional groups characterised by either direct (phytophagous species) or indirect (predatory species) dependence on plant communities is discussed. It is suggested that for phytophagous taxa, plant community assemblage alone is likely to be insufficient to ensure successful species colonisation or persistence without appropriate development of sward architecture.     

Intraspecific female brood parasitism in the dung beetle Onthophagus taurus

Abstract.  1. Brood parasitism occurs when individuals parasitise each others' investment into parental care, and has been documented primarily as an interspecific interaction. Intraspecific brood parasitism, in contrast, is often difficult to detect and quantify, and evidence for it is comparatively scarce. The present study documents the occurrence of intraspecific brood parasitism by females of the tunnelling dung beetle Onthophagus taurus , and investigates the contributions of two variables to the propensity of female brood parasitism: female body size and dung desiccation rate.
2. Female O. taurus were found to routinely utilise brood balls made by conspecific females as food provisions for their own offspring.
3. Contrary to expectations, large and small females did not differ in the likelihood of engaging in brood-parasitic behaviour.
4. Dung desiccation rate appeared to influence likelihood of brood parasitism. Females that were given access to rapidly drying dung were significantly more likely to detect and utilise brood balls produced by conspecific females.
5. While interspecific brood parasitism has been documented in dung beetles before, the present study is among the first to present evidence for intraspecific brood parasitism as an alternative reproductive tactic of female dung beetles. Results are discussed in the context of the evolutionary ecology of onthophagine beetles.     

Resource quality and the colonisation and succession of coprophagous dung beetles

In order to examine the degree of resource selectivity in a north temperate dung beetle assemblage und to identify major parameters that influence such selectivity, the occurrence of adult dung beetles ( Aphodius. Geotrupes and Sphaeridium ) in up to five different types of dung over a period of up to 25 d was examined in a series of field experiments using standardised dung pats. There were significant physical and chemical differences in dung quality between dung types and over time during succession. Dung beetle species showed distinct preferences for particular types of dung which were generally similar in data sets from both pitfall traps and dung pat samples. Species also showed distinct patterns of successional occurrence. Ordinations produced by Canonical Correspondence Analysis, based on species occurrences in dung types and over time, usually selected dung pat age as the most important environmental variable influencing dung beetle assemblages. Dung quality parameters contributed a significant element of structure to the species ordinations but ordinations using dung types or dung quality parameter values as the environmental variables were very similar in terms of sample and species placement within the ordination for each data set. Most importantly the CCA ordinations clearly grouped species according to their breeding behaviour. Early-successional species laid eggs in the soil, or in silken egg cocoons, which allowed them to exploit wet dung. Mid and late-successional species laid eggs in the dung pat: late-successional species could exploit normally wetter dung types than mid-successional species, probably due to increased crust formation and drying as the dung pat ages. Thus, species appear to be differentially adapted to exploit varying types of dung microhabitats. Therefore, where two or more species of large herbivores are present, dung quality preferences probably constitute an important niche dimension.     

Acorn removal and dispersal by the dung beetle Thorectes lusitanicus: ecological implications

Abstract.  1. Plant–animal interactions, and in particular the processes of seed predation and dispersal, are crucial for tree regeneration and forest dynamics. A novel and striking case of interaction between a dung beetle ( Thorectes lusitanicus ) and two Quercus species ( Q. suber and Q. canariensis ) in forests of southern Spain is presented here.
2. During the autumn, T. lusitanicus beetles (endemic to the southern Iberian Peninsula) bury and feed on single-seeded fruits (acorns) of Quercus , with important ecological implications.
3. Field experiments found differences in the removal rate of acorns by T. lusitanicus , depending on the type of microsite within the forest, the species of oak, the exclosure of large herbivores, and the forest site.
4. Acorn consumption by T. lusitanicus was studied under laboratory conditions, confirming for the first time that this dung beetle is a legitimate seed predator.
5. In addition, some buried acorns can be abandoned partially predated or even intact, and emerge as seedlings; thus, T. lusitanicus also has a potential role as secondary seed disperser.     

Monkey and dung beetle activities influence soil seed bank structure

In Neotropical forests, dung beetles act as efficient secondary dispersers of seeds that are dispersed primarily by red howler monkeys. Here, we investigated the origins of soil seed bank variability in relation to monkey and dung beetle activity, to assess the impact of dung beetles on seed fate, and their adaptability to resource availability. This question is important to better understand the process of tree regeneration, and is especially timely in the current context of threat to primates. We characterized soil seed bank structures in sites differing in monkey frequentation, and conducted field experiments with artificial beads to monitor bead fate. We also conducted experiments on specific roller and tunneller beetle species to examine bead processing behavior and its variability among and within species. We found that seed number and diversity increased with monkey frequentation, but seed viability was optimal under moderate monkey frequentation. We showed for the first time that dung provisioning yielded higher beetle activity in sites more often visited by monkeys, which calls for further investigation to understand the mechanisms of attraction to resource and potential spatial structuration of beetle populations. Although all beetle species involved in the experiments actively excluded beads from dung reserves, selectivity was higher for small than large beetle species, and for large compared to small bead sizes. It also increased when per-capita dung resource decreased, suggesting that intraspecific competition could alter seed fate. Altogether, our results support a major role of dung beetles in soil seed bank structure and dynamics. They reveal interesting interspecific variability within the dung beetle community and a complex interplay with primary dispersal.     

Predator-mediated coexistence in laboratory communities of mycophagous Drosophila (Diptera: Drosophilidae)

Abstract. 1. This laboratory experiment examined the effects of interspecific competition and predation by Ontholestes cingulatus Gravenhorst (Coleoptera: Staphylinidae) on three species of mycophagous Drosophila (Diptera: Drosophilidae): D.tripunctata Loew, D.falleni Wheeler and D.putrida Sturtevant.
2. Single-species and three-species assemblages were exposed to single commercial mushrooms on wet pine shavings in 200 ml culture bottles. A predacious rove beetle (Ontholestes cingulatus) was present in half of the three-species replicates. The stocked adult flies and beetles were removed after 4 days, and the number, biomass and mean mass of emerging progeny was recorded.
3. For all three species the abundance and biomass of the progeny emerging in the 'no predator' communities' was significantly less than for the progeny emerging in single-species replicates, suggesting an interspecific competitive effect. D.tripunctata was the competitive dominant; it emerged in abundance from all seven three-species 'no predator' communities while D.putrida and D.falleni were often excluded.
4. The decrease in production was attributed to strong interspecific competition among larva and not interference among ovipositing adults.
5. Predation on ovipositing adults significantly reduced the number and biomass of D.tripunctata progeny emerging, and indirectly facilitated the number and biomass of emerging D.falleni and D.putrida.Predation on adults reduced larval recruitment, relaxed larval competition, and released the inferior competitors.     

Effects of land usage on dung beetle assemblage structure: Kruger National Park versus adjacent farmland in South Africa

Little quantitative evidence exists regarding how effective protected areas are for preserving species. We compared dung beetle assemblages (Coleoptera: Scarabaeidae: Scarabaeinae) inside and outside of the Kruger National Park, which protects indigenous flora and fauna over a large area of savanna in the northeast lowlands of South Africa. Although it is contiguous with other reserves in South Africa, Zimbabwe and Mozambique, parts of its border abut onto farmland. Some effects of differing land usage either side of this border were studied at the South African Wildlife College (24.541° S 31.335° E) and the nearby farming village of Welverdiend using dung beetle assemblage structure (Coleoptera: Scarabaeidae: Scarabaeinae) as indicators. Samples were taken from gabbro-derived and granite-derived soils in open woody vegetation, both within the reserve and on adjoining farmland, using composite pig, elephant and cattle dung baits in the early rainy season (November 2009) and separate pig and elephant dung baits in the late rainy season (March 2010). Despite much higher large mammal density around Welverdiend, significantly greater species richness, abundance, and biomass of dung beetles were recorded in the reserve where mammal species diversity is greater and elephants produce much larger droppings than any mammal in the farmland. Assemblage structure also differed strongly between dung types, weather conditions on sample days, and season, but weakly between sampled soil types. These differences in assemblage structure were recorded over short distances as the sites in the reserve were only 3?C4?km from those in farmland at Welverdiend.     

Variations in dung beetle assemblages across a gradient of hunting in a tropical forest

Populations of large mammals are severely depleted by hunting in tropical forests, with direct effects on plant regeneration. But indirect consequences on commensal taxa depending on them for food resources, like coprophagous beetles, are less documented. Cascading effects of species loss across Scarabaeinae are expected, with likely significant negative implications for ecosystem functions. We examined dung beetle assemblages using pitfall traps at three rain forest sites in French Guiana ranging from intact mammalian fauna (Nouragues) to moderate (Kaw) and heavy (Matoury) defaunation. The site with the most depauperate mammalian fauna showed significantly lower dung beetle species richness than the two other two sites, which were not different from each other. Mean abundance and biomass per trap were not different across sites whereas community composition strongly differed among sites. A positive correlation was observed between body size and the individual contribution to dissimilarity between Nouragues and Kaw. The species contributing the most to dissimilarity were large. By contrast, one medium-sized species, dominant in Matoury, contributed the most to dissimilarity between Matoury and other sites. Diurnal genera of large tunnellers showed a higher diversity and abundance in Nouragues compared to other sites, whereas a nocturnal genus showed no differences. Large rollers were more abundant in Kaw compared to other sites. None of the groups of small beetles but one were affected by defaunation. Our results suggest that loss of large mammal populations affects dung beetle assemblage structure and causes decreasing abundance or disappearance of large tunnellers species that have a major impact on several dung beetle-mediated ecological processes.     

Metacommunity patterns of highly diverse stream midges: gradients,chequerboards, and nestedness,or is there only randomness?

Abstract.  1. Several non-random patterns in the distribution of species have been observed, including Clementsian gradients, Gleasonian gradients, nestedness, chequerboards, and evenly spaced gradients. Few studies have examined these patterns simultaneously, although they have often been studied in isolation and contrasted with random distribution of species across sites.
2. This study examined whether assemblages of chironomid midges exhibit any of the idealised distribution patterns as opposed to random distribution of species across sites within the metacommunity context in a boreal drainage system. Analyses were based on stream surveys conducted during three consecutive years. Analytical approaches included ordinations, cluster analysis, null models, and associated randomisation methods.
3. Midge assemblages did not conform to Clementsian gradients, which was evidenced by the absence of clearly definable assemblage types with numerous species exclusive to each assemblage type. Rather, there were signs of continuous Gleasonian variability of assemblage composition, as well as significant nested subset patterns of species distribution.
4. Midge assemblages showed only weak relationships with any of the measured environmental variables, and even these weak environmental relationships varied among years.
5. Midge assemblages did not appear to be structured by competition. This finding was somewhat problematic, however, because the two indices measuring co-occurrence provided rather different signs of distribution patterns. This was probably a consequence of how they actually measure co-occurrence.
6. Although midge assemblages did not show a perfect match with any of the idealised distribution patterns, they nevertheless showed a resemblance to the empirical patterns found previously for several plant and animal groups.     

Diversity, distinctiveness and conservation status of the Mediterranean coastal dung beetle assemblage in the Regional Natural Park of the Camargue (France)

The Mediterranean region as a whole has the highest dung beetle species richness within Europe. Natural coastal habitats in this region are among those which have suffered severe human disturbance. We studied dung beetle diversity and distinctiveness within one of the most important coastal protected areas in the west Euro‐Mediterranean region (the regional Park of Camargue, southern France) and made comparisons of dung beetle assemblages with other nearby Mediterranean localities, as well as with other coastal protected area (Doñana National Park, Spain). Our finding showed that: (1) The species richness of coastal habitats in the Camargue is low and only grasslands showed a similar level of species richness and abundance to inland habitats of other Mediterranean localities. The unique habitats of the coastal area (beaches, dunes and marshes) are largely colonized by species widely distributed in the hinterland. (2) In spite of their low general distinctiveness, dune and marsh edges are characterized by the occurrence of two rare, vulnerable, specialized and large roller dung beetle species of the genus Scarabaeus. As with other Mediterranean localities, current findings suggest a recent decline of Scarabaeus populations and the general loss of coastal dung beetle communities in Camargue. (3) The comparison of dung beetle assemblages between the Camargue and Doñana shows that, in spite of the low local dung beetle species richness in the Camargue, the regional dung beetle diversity is similar between both protected areas. Unique historical and geographical factors can explain the convergence in regional diversity as well as the striking divergence in the composition of dung beetle assemblages between both territories.     

Temporal changes in replicated experimental stream fish assemblages: predictable or not?

Summary 1. Natural aquatic communities or habitats cannot be fully replicated in the wild, so little is known about how initially identical communities might change over time, or the extent to which observed changes in community structure are caused by internal factors (such as interspecific interactions or traits of individual species) versus factors external to the local community (such as abiotic disturbances or invasions of new species).
2. We quantified changes in seven initially identical fish assemblages, in habitats that were as similar as possible, in seminatural artificial streams in a 388-day trial (May 1998 to May 1999), and compared the change to that in fish assemblages in small pools of a natural stream during a year. The experimental design excluded floods, droughts, immigration or emigration. The experimental fish communities diverged significantly in composition and exhibited dissimilar trajectories in multivariate species space. Divergence among the assemblages increased from May through August, but not thereafter.
3. Differences among the experimental assemblages were influenced by differences that developed during the year in algae cover and in potential predation (due to differential survival of sunfish among units).
4. In the natural stream, fish assemblages in small pools changed more than those in the experimental units, suggesting that in natural assemblages external factors exacerbated temporal variation.
5. Our finding that initially identical assemblages, isolated from most external factors, would diverge in the structure of fish assemblages over time suggests a lack of strong internal, deterministic controls in the assemblages, and that idiosyncratic or stochastic components (chance encounters among species; vagaries in changes in the local habitat) even within habitat patches can play an important role in assemblage structure in natural systems.     

Optimising Bait for Pitfall Trapping of Amazonian Dung Beetles (Coleoptera: Scarabaeinae)

The accurate sampling of communities is vital to any investigation of ecological processes and biodiversity. Dung beetles have emerged as a widely used focal taxon in environmental studies and can be sampled quickly and inexpensively using baited pitfalls. Although there is now a wealth of available data on dung beetle communities from around the world, there is a lack of standardisation between sampling protocols for accurately sampling dung beetle communities. In particular, bait choice is often led by the idiosyncrasies of the researcher, logistic problems and the dung sources available, which leads to difficulties for inter-study comparisons. In general, human dung is the preferred choice, however, it is often in short supply, which can severely limit sampling effort. By contrast, pigs may produce up to 20 times the volume. We tested the ability of human and pig dung to attract a primary forest dung beetle assemblage, as well as three mixes of the two baits in different proportions. Analyses focussed on the comparability of sampling with pig or human-pig dung mixes with studies that have sampled using human dung. There were no significant differences between richness and abundance sampled by each bait. The assemblages sampled were remarkably consistent across baits, and ordination analyses showed that the assemblages sampled by mixed dung baits were not significantly different from that captured by pure human dung, with the assemblages sampled by 10% and 90% pig mixes structurally most similar to assemblages sampled by human dung. We suggest that a 10:90 human:pig ratio, or similar, is an ideal compromise between sampling efficiency, inter-study comparability and the availability of large quantities of bait for sampling Amazonian dung beetles. Assessing the comparability of assemblage samples collected using different baits represents an important step to facilitating large-scale meta-analyses of dung beetle assemblages collected using non-standard methodology.     

Co‐declining mammal–dung beetle faunas throughout the Atlantic Forest biome of South America

The millennial–scale evolutionary relationships between mammals and dung beetles have been eroded due to several drivers of contemporary biodiversity loss. Although some evidence of co‐decline has been shown for mammals and dung beetles at some Neotropical sites, a biome‐scale analysis for the entire Atlantic Forest of South America would strengthen our understanding of how relictual sets of mammal species can affect dung beetle co‐occurrences and co‐declines. We therefore collated hundreds of assemblages of both dung beetles and medium‐ to large‐bodied mammals throughout the world's longest tropical forest latitudinal gradient to examine to what extent mammal assemblages may exert a positive influence on dung beetle species composition and functional assembly, and whether this relationship is scale dependent. We also collated several climatic and other environmental variables to examine the degree to which they shape mammal–dung beetle relationships. The relationships between local mammal and dung beetle faunas were examined using regression models, variation partitioning, dissimilarity indices and ecological networks. We found a clear positive relationship between mammal and dung beetle species richness across this forest biome, indicating an ongoing process of mammal–dung beetle niche‐mediated co‐decline. We found a strong relationship between the species composition of both taxa, in which dung beetle species dissimilarity apparently track changes in mammalian dissimilarity, typically in 80% of all cases. Co‐variables such as phytomass and climatic variables also influenced mammal–dung beetle patterns of co‐decline along the Atlantic Forest. We conclude that dung beetle diversity and community assembly are shaped by the remaining co‐occurring mammal assemblages and their functional traits, and both groups were governed by environmental features. We emphasize that ecosystem‐wide effects of mammal population declines remain poorly understood both quantitatively and qualitatively, and curbing large vertebrate defaunation will ensure the persistence of co‐dependent species.     

Dung beetle community composition affects dung turnover in subtropical US grasslands

1. An important service in many ecosystems is the turnover and degradation of dung deposited by cattle. Dung beetles are the primary group of insects responsible for dung turnover, and factors affecting their abundance and distribution thus impact dung degradation. Lands lost to grazing due to dung buildup and pasture contamination total millions of acres per year in US pastures.
2. We evaluated the structural differences in dung beetle assemblages in natural grasslands versus a managed agroecosystem in subtropical southeastern Florida (USA). We measured the direct effect of dung longevity when dung beetle fauna normally inhabiting dung pats were excluded.
3. Our results indicate dung beetle abundance, functional diversity, and species richness have a substantial impact on the rate of dung turnover in subtropical pastoral lands with ~70% of dung removed from the soil surface after three months. Functional diversity and evenness did not have a significant positive effect on dung removal in managed, versus natural grasslands demonstrating a strong relationship between dung beetle assemblage composition and delivery of a key ecological process, dung degradation.
4. We suggest the importance of trees, which provide a thermal refuge for beetles, should be dispersed within matrixes of open pasture areas and within proximity to adjacent closed‐canopy hammocks to facilitate the exchange of dung beetles between habitats and therefore maintain the provisioning of dung degradation services by dung beetle assemblages.

     

Late Pleistocene beetle faunas of Beringia: where east met west

Aim   To examine the issue of Beringian steppe-tundra from an entomological standpoint, using fossil beetle data collected from late Pleistocene sites.
Location   North-eastern Siberia (Western Beringia), the Bering Land Bridge (Central Beringia), and Alaska and the Yukon Territory (Eastern Beringia).
Methods   Analysis of habitat preferences of beetle species found in fossil assemblages, leading to classification of major habitat types characterized by the faunal assemblages.
Results   Fossil beetle assemblages indicative of steppe-tundra are found mainly in the interior regions of Eastern Beringia, whereas these assemblages dominate nearly all late Pleistocene fossil sites in Western Beringia. Eastern Beringian faunas contain a much larger proportion of mesic to hygrophilous species and very few arid-habitat species. In contrast to this, the habitat requirements of the Western Beringian faunas are more evenly spread across the moisture spectrum.
Main conclusions   The taxonomic patterns of the two sets of fossil assemblages are remarkably different. Eastern Beringian faunal assemblages contain substantial numbers of mesic tundra and riparian rove beetles (Staphylinidae); this element is almost entirely lacking in the Western Beringian fossil assemblages. Taphonomic bias tends to overemphasize moisture-loving species at the expense of dry, upland species in the fossil record. Both Western and Eastern Beringian landscapes undoubtedly contained mosaics of habitats ranging from dry uplands (steppe-tundra) through mesic tundra to bogs and riparian corridors.     

Are ball-rolling (Scarabaeini,Gymnopleurini, Sisyphini) and tunnelling scarabaeine dung beetles equally choosy about the size of ingested dung particles?

Abstract.  1. The maximum size of ingested particles was determined in 11 species of ball-rolling, adult dung beetle (Scarabaeidae: Scarabaeinae) by mixing small latex or glass balls of known diameter into their food. The tribes Scarabaeini, Gymnopleurini, and Sisyphini (four, four, and three species respectively) were represented, with mean body sizes ranging from 0.33 to 4.0 g fresh weight.
2. Only particles with maximum diameters of 4–85 µm were ingested. Hence rollers, like other known beetles feeding on fresh dung, filter out larger, indigestible plant fragments and confine ingestion to small particles of higher nutritional value.
3. The maximum diameter of ingested particles increased significantly with body weight, whereas taxon (tribe) had no additional effect. Because big rollers accept larger particles than do tunnellers (which make dung stores for feeding and breeding in the soil immediately below the pat) of similar weight, the slope of the diameter-against-weight regression for rollers was significantly higher than that found earlier for tunnellers.
4. An explanation could be that a typical food ball made by a roller is considerably smaller than the amount of dung available to a feeding tunneller of the same size. If the roller were as choosy about particle size as the tunneller, it might not get enough food. This applies to large rollers in particular because their food balls contain a higher proportion of coarse fibres than those made by small species.