bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative fluorescence resonance energy transfer (FRET) measurement with acceptor photobleaching and spectral unmixing
Authors: GU Y. , DI W. L. , KELSELL D. P. , ZICHA D.
Published: July 2004

Fluorescence resonance energy transfer (FRET) by acceptor photobleaching is a simple but effective tool for measurements of protein–protein interactions. Until recently, it has been restricted to qualitative or relative assessments owing to the spectral bleed‐through contamination resulting from fluorescence overlap between the donor and the acceptor. In this paper, we report a quantitative algorithm that combines the spectral unmixing technique with FRET by acceptor photobleaching. By spectrally unmixing the emissions before and after photobleaching, it is possible to resolve the spectral bleed‐through and retrieve the FRET efficiency/interaction distance quantitatively. Using a human keratinocyte cell line transfected with cyan fluorescent protein (CFP)‐ and yellow fluorescent protein (YFP)‐tagged Cx26 connexins as an example, FRET information at homotypic gap junctions is measured and compared with well‐established methods. Results indicate that the new approach is sensitive, flexible, instrument independent and solely FRET dependent. It can achieve FRET estimations similar to that from a sensitized emission FRET method. This approach has a great advantage in providing the relative concentrations of the donor and the acceptor; this is, for example, very important in the comparative study of cell populations with variable expression levels.
Five‐colour in vivo imaging of neurons in Caenorhabditis elegans
Authors: HUTTER H.
Published: July 2004

In the last few years variants of the ‘green fluorescent protein’ (GFP) with different spectral properties have been generated. This has greatly increased the number of possible applications for these fluorochromes in cell biology. The significant overlap of the excitation and emission spectra of the different GFP variants imposes constraints on the number of variants that can be used simultaneously in a single sample. In particular, the two brightest variants, GFP and YFP, are difficult to separate spectrally. This study shows that GFP and YFP can be readily separated with little spectral overlap (cross‐talk) with the use of a confocal microscope equipped with an acusto‐optical beam splitter and freely adjustable emission windows. Under optimal recording conditions cross‐talk is less than 10%. Together with two other fluorescent proteins and the lipophilic dye DiD a total of five different colours can now be used simultaneously to label in vivo distinct anatomical structures such as neurons and their processes. Spatial resolution of the confocal microscope is sufficient to resolve the relative position of labelled axons within a single axon bundle. The use of five distinct marker dyes allows the in vivo analysis of the Caenorhabditis elegans nervous system at unprecedented resolution and richness in detail at the light microscopic level.
Silver deposition on freeze‐dried cells allows subcellular localization of cholesterol with imaging TOF‐SIMS
Authors: NYGREN H. , MALMBERG P.
Published: July 2004

Imaging time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) was used for characterization and subcellular localization of organic ions in leucocytes adhering to glass surfaces. The cells were fixed by freeze drying in 0.15 m ammonium formate buffer at pH 7.2–7.4. The freeze‐dried cells were sputter‐coated with silver, and the silver surface was analysed with imaging TOF‐SIMS. TOF‐SIMS spectra were recorded by scanning the primary ion beam over the analysis area and acquiring positive mass spectra of the ions leaving the surface. The relative brightness of each pixel within the analysis area reflects the signal intensity of a selected ion in that pixel. Data were collected separately at high mass resolution m/Δm > 7000 and at high lateral resolution (= 0.5 µm). The images were analysed by principal component analysis (PCA).

The glass‐adhering cells showed a well defined attachment area with a diameter of up to 20 µm, and an equally well defined cell body, containing the nucleus, with a diameter of 8–10 µm. On the raw data images, the obtained cholesterol distributions were consistent with a higher cholesterol content of the cell membrane in the attachment area than in the cell body. Using PCA analysis, silver‐cationized molecular cholesterol was found localized mainly in the attachment area of the cells. Cholesterol was also seen at higher concentration in circular spots of ≤ 1 µm in diameter, probably representing caveolae.
Pre‐ and post‐thaw assessment of intracellular ice formation
Authors: ACKER J. P. , CROTEAU I. M.
Published: July 2004

Intracellular ice formation (IIF) refers to the formation of ice crystals within cells during rapid freezing. To develop an understanding of the means by which intracellular ice forms and the mechanisms by which it damages cells and tissues requires techniques that combine real‐time assessment of ice nucleation and ice crystal growth with detailed assessments of cell structure and function. Intracellular ice formation has been detected in live samples using light scattering, freeze substitution and fluorescent detection. In this study we develop a method to correlate IIF with post‐thaw structural analyses by combining low temperature microscopy and freeze substitution. V79‐4 hamster fibroblasts were frozen on a low temperature microscope at various temperatures, IIF was visualized using the nucleic acid‐specific fluorophore SYTO 13™, then the samples were fixed (10% formaldehyde, 85% ethanol, 5% acetic acid) while still frozen. The monolayers were then thawed and stained with routine histological stains haematoxylin and eosin and assessed. Fixation allowed for the post‐thaw assessment of IIF and for subsequent histological processing to examine in detail the structural consequences of IIF. The post‐thaw identification of cells that form intracellular ice during freezing is a significant improvement to current methods used in low temperature biology.
Fine‐scale spatial patterns in populations of the clonal moss Hylocomium splendens partly reflect structuring processes in the boreal forest floor
Authors: Økland Rune Halvorsen , Bakkestuen Vegar
Published: July 2004

Spatial patterns of important population or individual characteristics are expected to reflect structuring ecosystem processes to the extent that populations with strikingly different spatial patterns most likely have been structured by different processes. Few studies of spatial pattern in plant assemblages, bryophyte assemblages in particular, still exist and pattern has only vaguely been linked with process. In this study we describe fine‐scale spatial variation in size and the occurrence of terminated (non‐branching) segments in 21 Norwegian populations of the dominant boreal forest moss Hylocomium splendens, in search for general patterns of spatial structure.

All Hylocomium splendens segments in the investigated plots were followed for a 10‐year period; their size (dry mass, estimated from in situ measurements) and fate (terminated or ramifying) were recorded annually. The spatial structure of size and terminating segments at scales from 0.5 to 16 cm was described for each population as fractal dimension profiles, derived from semi‐variograms. For about one half of the populations size and terminating segments could be assigned to a specific spatial pattern, the predicted outcome of one of three main structuring processes: (i) negative spatial dependence (fractal dimension F>3.0) on the scale of individuals (below 2 cm), indicative of negative interactions; (ii) positive spatial dependence (F<3.0) on the scale of individuals, indicative of positive interactions; and (iii) positive spatial dependence on broader (4–8 cm) scales, indicative of structuring by environmental factors or patchy disturbance. Patterns (i) and (iii) were observed both for size and terminated segments more often than expected. Fractal dimension profiles for size obtained separately for each year revealed temporal patterns of spatial structure that tended to be invariant over years. Negative spatial dependence of size, possibly due to large size difference between buried segments and other segments during self thinning, was typical of populations rapidly growing in number. Positive spatial dependence with a range of influence by the spatial process of 4–8 cm was observed in plots with sparse bryophyte cover and high cover of deciduous litter, probably due to accumulation of litter in depressions between shoots or groups of shoots. The main finding of this study is that different populations of the same species in the same type of ecosystem can be spatially structured in different ways. This accords with a model for the studied system as consisting of a mosaic of cells, of spatial extent of a few cm or larger, intergrading in space and temporally dynamic, the population characteristics of each cell being shaped by several structuring processes that vary, temporally and spatially, in their relative importance.
The impact of short‐term predator removal on vole dynamics in an arctic‐alpine landscape
Authors: Ekerholm Per , Oksanen Lauri , Oksanen Tarja , Schneider Michael
Published: July 2004

During 1991–95, mammalian predators (weasel, Mustela nivalis, stoat, M. erminea, mink, M. vison, and red fox, Vulpes vulpes) were excluded in late summers from a 2 ha piece of a north Norwegian mountain slope. The exclosure extended from an outpost of luxuriant sub‐arctic birch forest to a typical arctic–alpine habitat complex, including productive willow scrublands, tundra heaths, dry ridges and snow‐beds. The exclosure thus encompassed the entire range of habitat conditions encountered in a typical north Fennoscandian mountain and tundra landscapes. During 1991–95, the exclosure was predator‐proof from late July to late September. In wintertime and in early summer, the exclosure was accessible to mammalian predators. Vole dynamics in the short‐term exclosure were compared to dynamics in five reference areas with similar habitat conditions.

In 1991, when vole densities were rising in the area, neither collective vole densities nor densities of individual vole species differed significantly between the exclosure and the replicated controls. Spring densities of voles were never significantly different between the exclosure and the controls. With respect to autumnal densities of voles, however, the exclosure was a statistical outlier in the peak year 1992 and throughout the gradual decline phase of 1993–95. In the peak year, the difference in collective vole densities was modest (30%), but increased to two‐fold during the first two decline years and was almost four‐fold in the crash year of 1995. The strongest response was displayed by field voles (Microtus agrestis), hypothesized to be the pivotal prey species of weasels, especially by females and young individuals, i.e. by the functional categories especially sensitive to mammalian predation. These results are consistent with the hypothesis that predation plays a pivotal role for the regulation of herbivorous mammals in relatively productive arctic–alpine habitats.
Conspicuousness, not colour as foraging cue in plant–animal signalling
Authors: Schmidt Veronika , Martin Schaefer Hinrich , Winkler Hans
Published: July 2004

The global prevalence of red and black fruits has still not been explained. Hypotheses based on innate consumer preferences have been tested and rejected. Though colour itself plays an important role in animal foraging, it is only one component of signals. Another major component are colour contrasts against background achieving the conspicuousness of signals. In order to evaluate which signal component determines consumers behaviour, we measured fruit colour and colour contrasts of 43 species against their natural background under ambient light conditions. Red and black fruits exhibit stronger contrasts and are therefore more conspicuous to consumers than fruits of other colours. Subsequently, trials were carried out to determine whether colour or conspicuousness influences avian food choice. Four bird species strongly preferred contrasting red–green or black–green over uni‐coloured red, green, or black fruit displays, while no preference for particular hues was found. We therefore hypothesize that conspicuousness determines avian food selection and define the contrast hypothesis: Diurnal dispersers select fruit colours based on their conspicuousness and not their colour itself.

Because colour vision is an ancient trait, the entire heterogeneous group of frugivorous birds most likely perceives conspicuousness uniformly over evolutionary time spans. Conspicuousness has thus the potential to explain the global prevalence of red and black fruits.
Kin structure and shoal composition dynamics in the guppy,Poecilia reticulata
Authors: T. Russell Stephen , L. Kelley Jennifer , A. Graves Jefferson , E. Magurran Anne
Published: July 2004

Although kin associations between fish can develop in the laboratory, the importance of kin structure in natural social groups remains uncertain. Guppies (Poecilia reticulata) possess many behavioural and life‐history traits that promote kin structure, and so constitute ideal candidates for testing its general significance amongst fish. We collected 25 adult only shoals from ∼150 m stretches along two Trinidadian rivers. The 272 sampled fish were genotyped from a pool of seven hypervariable microsatellite loci. Although mark‐recapture experiments have previously detected male‐biased dispersal, which is predicted from the guppy mating system and which may have important implications for population differentiation, we found no sex‐biases in dispersal between shoals. Because sex‐biased dispersal was not evident, males and females were pooled in analyses of kin structure. Relatedness levels within each shoal did not differ significantly from zero, indicating that kin selection does not contribute to gross structure. Instead, our data is more consistent with the hypothesis that individual‐level selection underlies shoal composition dynamics. These dynamics have important implications for the evolution of cooperative behaviour in guppies.
Cannibalism‐mediated life history plasticity to combined time and food stress
Authors: Block Marjan De , Stoks Robby
Published: July 2004

There is increasing awareness that combinations of biotic and time stress interact in shaping life history plasticity. Despite being widespread and abundant, the role of cannibalism in linking both types of constraints to life history plasticity has been largely neglected. Moreover, no studies disentangled direct (due to the extra meal) and indirect (due to the elimination of the competitor) life history effects of cannibalism, and little is known about their differential dependency on these constraints. We studied effects of cannibalism on the life history of the damselflyLestes viridisunder combinations of time stress (by manipulating the perceived time available in the growth season) and food stress. We reared larvae per two and disentangled direct and indirect effects of cannibalism by preventing cannibalism in half of the cups and by manipulating the per capita food increase after cannibalism. Cannibalism was more frequent under both time stress and food stress and our results show it may help cannibals to compensate for the negative effects of these constraints imposed on life history. Both direct and indirect benefits of cannibalism (increased development and growth rates, larger mass at emergence) were dependent on the timing of cannibalism, being more pronounced or only present when cannibalism occurred early. Moreover, we found that the ecological constraints (time stress and food stress) also differentially shaped some of the direct and indirect effects. Given the differential context‐dependency of direct and indirect effects and the fact that direct and indirect life history effects may be both important in shaping life history, disentangling these effects is critical to mechanistically understand under which conditions cannibalism is expected to be adaptive or not.
No evidence for a role of pollinator discrimination in causing selection on flower size through female reproduction
Authors: Totland Ørjan
Published: July 2004

The preference for certain floral phenotypes by flower visiting animals may fuel the evolution of floral traits because variation in flower visitation rates may lead to fitness variation within a population. Here, I examine the importance of flower size for pollinator visitation rate, seed set, and seed mass in two alpine populations of the insect‐pollinated herb Ranunculus acris L. during two seasons. There was no pollen limitation of seed set or mass. Pollinators discriminated strongly against flowers experimentally reduced in size. Despite this, there were no signs of any significant impact of flower size on female reproductive success. The results show that although pollinators discriminate strongly among floral phenotypes, this may not always result in female fitness differences within a population because seed set or mass is not limited by pollen availability alone. Probably abiotic environmental constraints prevent plants with high pollinator visitation from capitalizing on the high pollen deposition.
Differential habitat use promotes sustainable coexistence between the specialist otter and the generalist mink
Authors: Bonesi Laura , W. Macdonald David
Published: July 2004

Optimal foraging and habitat selection theories predict that heterogeneous environments should favour the coexistence of competitors, especially when the dominant competitor is a specialist and the sub‐ordinate is a generalist. In this paper, we analysed differential habitat use as a potential mechanism for the coexistence of two competing riparian mammals, the specialist and dominant Eurasian otter (Lutra lutra) and the generalist and sub‐ordinate American mink (Mustela vison). We tested three hypotheses: H1: mink coexist with otters for longer in areas with abundance of habitats hosting terrestrial prey because, by not relying on aquatic prey, mink can segregate from its competitor. H2: the characteristics of the habitat closer to the riverbank will affect the length of time the two species coexist, because mink are still tied to the water even in the presence of otters. H3: denser vegetative cover along the bank increases the duration of coexistence of mink and otters because it reduces the frequency of their encounters. The first hypothesis was supported by the data and we found that in areas where terrestrial prey was abundant mink coexisted for longer with otters. The second hypothesis was also supported by the data and the characteristics of the habitat closer to the riverbank were the most important in determining coexistence time. Finally, we did not find supporting evidence for the third hypothesis. This study provides strong evidence that habitat heterogeneity plays an important role in determining the likelihood of coexistence of American mink with Eurasian otters. This result is particularly important from a conservation standpoint. Mink are invasive and a threat to endangered species in parts of their range. The knowledge that mink have a higher chance to persist in the presence of otters when terrestrial prey is abundant should be used to target areas for preferential mink management.
Species and sex biases in ectoparasitism of dragonflies by mites
Authors: J. Lajeunesse Marc , R. Forbes Mark , P. Smith Bruce
Published: July 2004

An important problem in understanding the evolution of parasite host range is determining the extent to which parasite fitness varies among host species and the factors affecting that fitness variation. We present a detailed investigation on the patterns of host use and successful parasitism of two dragonfly species by the ectoparasitic water mite, Limnochares americana Lundblad. In our field surveys, we found both species biases and sex biases in parasitism by mites, which appear explained by differences in exposure. Differential habitat use by dragonflies helped explain male biases in parasitism in both host species, but was not useful in explaining species biases in parasitism. Species biases in parasitism may be explained by more subtle variation in habitat use not explored in this study, or perhaps by differences in timing of emergence, as we found for the two dragonfly species. Despite species differences in parasitism in nature, we found that mites attached equally successfully to both dragonfly species during experimental infestations. However, mites failed to engorge more often on the dragonfly species less often used as a host in nature. This host species also was more likely to have dead mites in natural infestations as compared to the other host species, which was more often and more heavily parasitized. Our results are consistent with previous research suggesting parasites are less successful on less often used hosts. Such research has implications for understanding determinants of host range for animal parasites.
Balanced dispersal or source–sink–do both models describe wood mice in farmed landscapes?
Authors: H. Tattersall F. , W. Macdonald D. , J. Hart and W. Manley B.
Published: July 2004

To test two models of how wood mouse Apodemus sylvaticus populations in different patches might interact, we estimated parameters from capture‐mark‐recapture data in four habitats (set‐aside, crop, boundary and woodlot) at two sites in arable farmland. In the source–sink model, populations in ‘source’ patches have fitness>1, while in ‘sink’ patches fitness is<1; dispersal is constrained so there is a net flow of individuals from sources to sinks. In the balanced dispersal model, patches may vary in quality and carrying capacity, but there are no sinks and no constraints on dispersal; fitness is equal across patches. Our results broadly support balanced dispersal. Patches close together were more likely to exchange individuals than those far apart, there was no evidence of density‐dependent dispersal and little evidence for directionality of movement. Overall population growth rates were similar in all patches (range: 0.99–1.05). Times when no animals were known to be alive occurred in some patches and could be attributed to stochastic events. On one crop patch, however, extinction followed high abundance, and coincided with poor recruitment, suggesting sink dynamics. Recruitment rates were highest in boundary and crop, but surprisingly, the proportion of individuals in reproductive condition, timing of breeding and pregnancy rates did not vary between habitats. Apparent survival rates were lowest in crop, although recapture rates were high. While female body size in December did not vary between habitats, males on set‐aside were smaller than elsewhere. In general, the balanced dispersal model best described arable wood mouse populations, but dynamics on one patch suggested an ‘attractive’ sink. Our results demonstrate that more than one model for dispersal dynamics between populations may apply within the same landscape, for the same species.
Consumer–resource matching in a food chain when both predators and prey are free to move
Authors: Jackson Andrew L. , Ranta Esa , Lundberg Per , Kaitala Veijo , Ruxton Graeme D.
Published: July 2004

The classical theory of the ideal free distribution (IFD) predicts that the spatial distribution of consumers should follow the distribution of the resources they depend on. Here, we study consumer–resource matching in a community context. Our model for the community is a food chain with three levels. We study whether the primary consumers are able to match resources both under predation risk and in its absence. Both prey and predators have varying degrees of knowledge of the global and local resource distribution. We present two versions of the model. In the “resource maximising” model, the consumers consider the availability of their resource only. In the “balancing” model, individual consumers minimise predation risk per unit of resource that they can gain access to. We show that both models can lead to perfect matching of consumers on resources and predators on consumers, assuming that individuals have full knowledge of the whole environment. However, when the consumers’ information and freedom of movement are greater than those of the predators, then the predators generally undermatch the consumers. In the opposite case, we observe overmatching and high consumer movement rates. Furthermore, undermatching of predators on consumers tends to induce overmatching of consumers on resources.
State‐dependent parental care in the Antarctic petrel: responses to manipulated chick age during early chick rearing
Authors: Varpe Øystein , Tveraa Torkild , Folstad Ivar
Published: July 2004

Life histories are state‐dependent, and an individual's reproductive decisions are determined by its available resources and the needs of its offspring. Here we test how a chick's needs for food and protection influence parental decisions in the Antarctic petrel,Thalassoica antarctica, where the parents, due to their long breeding lifespan, are expected to give priority to their own needs before those of the young. We exchanged one‐day‐old chicks with four‐day‐old chicks and studied how the parents subsequently provided care to the chick. The duration of the guarding period was adjusted, and parents left older chicks earlier and younger chicks later compared to controls. Three mechanisms were responsible for the adjustments. 1) Parents with an older chick co‐ordinated fewer guarding spells whereas parents with a younger chick co‐ordinated more guarding spells. 2) At the last guarding spell, i.e. where a parent left the chick alone before the partner returned, less time was spent with older chicks, and more time with younger chicks. 3) Foraging trip duration was shortened by parents given older chicks and prolonged by parents given younger chicks, probably in response to the chick's food demand. Hence, the parents responded quickly to the altered needs of the chick. Parents with high body mass guarded longer and were better able to co‐ordinate the guarding spells compared to lighter parents. In conclusion, Antarctic petrels adjust reproductive decisions to their own, their mate's, and their chick's state, and they seem to respond to the chick's needs for both food and protection.
Plant species identity and diversity effects on different trophic levels of nematodes in the soil food web
Authors: De Deyn Gerlinde B. , Raaijmakers Ciska E. , Van Ruijven Jasper , Berendse Frank , Van Der Putten Wim H.
Published: July 2004

Previous studies on biodiversity and soil food web composition have mentioned plant species identity, as well as plant species diversity as the main factors affecting the abundance and diversity of soil organisms. However, most studies have been carried out under limitations of time, space, or appropriate controls. In order to further examine the relation between plant species diversity and the soil food web, we conducted a three‐year semi‐field experiment in which eight plant species (4 forb and 4 grass species) were grown in monocultures and mixtures of two, four and eight plant species. In addition there were communities with 16 plant species. We analyzed the abundance and identity of the nematodes in soil and roots, including feeding groups from various trophic levels (primary and secondary consumers, carnivores, and omnivores) in the soil food web.

Plant species diversity and plant identity affected the diversity of nematodes. The effect of plant diversity was attributed to the complementarity in resource quality of the component plant species rather than to an increase in total resource quantity. The nematode diversity varied more between the different plant species than between different levels of plant species diversity, so that plant identity is more important than plant diversity. Nevertheless the nematode diversity in plant mixtures was higher than in any of the plant monocultures, due to the reduced dominance of the most abundant nematode taxa in the mixed plant communities. Plant species identity affected the abundances of the lower trophic consumer levels more than the higher trophic levels of nematodes. Plant species diversity and plant biomass did not affect nematode abundance. Our results, therefore, support the hypothesis that resource quality is more important than resource quantity for the diversity of soil food web components and that plant species identity is more important than plant diversity per se.
Cryptospore Assemblages from the Ordovician/silurian Boundary in the Puna Region, North‐west Argentina
Authors: Rubinstein Claudia V. , Vaccari Norberto E.
Published: July 2004

Palynomorph assemblages have been recovered from deposits believed to straddle the Ordovician/Silurian boundary, from the upper member of the Salar del Rincón Formation, in the Puna region of north‐west Argentina. The palynomorph assemblages are dominated by terrestrial cryptospores, but also contain marine elements (acritarchs, prasinophycean algae and chitinozoans). The cryptospore assemblages are similar in composition to those described from coeval deposits worldwide, suggesting that the producers were cosmopolitan and tolerated a wide range of climatic conditions. They are correlated with the Imperfectotriletes spp. Interval Biozone (sub‐biozone α) of the Imperfectotriletes spp.‐Laevolancis divellomedia Assemblage Biozone, indicating a Hirnantian (latest Ordovician) age. Acritarchs include late Ordovician species such as Eupoikilosusa striata and Villosacapsula cf. setosapellicula, that coexist with the Llandovery species Dactylofusa estillis. Based on lithological and palynological evidence, an early Llandovery, or a late Hirnantian (post‐glacial) age is proposed for the basal part of the upper member of the Salar del Rincón Formation.
Revision of the Athyrisininae, Siluro‐devonian Brachiopods from China and Russia
Authors: Jia‐Yu Rong , Alvarez Fernando , Modzalevskaya Tatyana L. , Yan Zhang
Published: July 2004

Athyrisinine brachiopods from the Upper Silurian of Russia and the Lower–Middle Devonian of China and north Vietnam include over 70 species belonging to Athyrisina and Parathyrisina; generic and subfamilial diagnoses are emended. Five genera are considered synonyms of Athyrisina and three of Parathyrisina. A neotype is selected and illustrated for Athyrisina squamosa, the type species of Athyrisina. Four nomina nova, Athyrisinaxui, Parathyrisina wani, P. minima, and P. cheni, are suggested as new substitute names for Athyrisina tumida Wang, in Xu et al. 1978 (primary homonymy), Athyrisinoides ganxiensis Wan, in Xu et al. 1978, Parathyrisina minor Zhang, in Zhang and Fu 1983, and Athyrisinoides tudilingensis Chen, 1979 (secondary homonyms) respectively. A new genus, Bruntosina, is described from the Emsian to Eifelian of the Qinling region. A new subfamily, Homeathyridinae, is erected within the Athyrididae with Homeathyris, Pseudohomeospira, and Squamathyris included, revised and their diagnoses emended. Homeathyris incisus sp. nov. is described from the Ludfordian of Novaya Zemlya. Ikella is revised and excluded from the athyrisinins. The origin and dispersal of the homeathyridins and the athyrisinins are discussed.
A New Eurypterid (Chelicerata: Eurypterida) from the Upper Devonian Gogo Formation of Western Australia, With A Review of the Rhenopteridae
Authors: Tetlie O. Erik , Braddy Simon J. , Butler Piers D. , Briggs Derek E. G.
Published: July 2004

A new eurypterid, Rhenopterus waterstoni sp. nov., is described from the Gogo Formation (Frasnian, Upper Devonian) of Western Australia. This species is distinguished from related forms by the tuberculation of the anteriormost tergite and crenulated posterior margins of the carapace and opisthosomal segments. It is the only eurypterid specimen known from the Gogo Formation, the most complete eurypterid from Australia, and also the youngest representative of Rhenopterus in the fossil record. Structures retrieved from between the prosomal‐opisthosomal juncture comprise polygonal tubes 30–40 μm in diameter, which are interpreted as sarcomeral sheaths of muscular tissue. Rhenopterus is reviewed: R. latus Størmer, 1936 is synonymized with R. diensti Størmer, 1936 as it is here recognized as a female sexual dimorph; R. maccarthyi (Kjellesvig‐Waering, 1934) is an orthocone nautiloid.
The Problematic Paralbunea Hu and Tao, 1996: Homonymy, Generic Nom. Nov., and Correct Taxonomic Placement
Authors: Boyko Christopher B.
Published: July 2004

The fossil genus Paralbunea Hu and Tao, described as an anomuran albuneid, is a junior homonym of Paralbunea Serène and a possible synonym of either the brachyuran raninid Ranilia H. Milne Edwards, 1837, or Cosmonotus Adams and White, 1848. The type series of P. taipeiensis Hu and Tao is composed of at least two species belonging to two raninid genera and appears (in part) assignable to the genus Ranilia and (in part) to Cosmonotus grayi Adams and White, 1848. However, due to both limited availability and poor quality of the holotype of Paralbunea taipeiensis, and destruction of the paratypes, this taxon cannot be unequivocally synonymized with any particular raninid taxon and a new name is proposed to replace Hu and Tao's preoccupied generic name. Caution is urged when describing purported albuneid fossils, due to strong convergence with raninid crabs, which are far more common in the fossil record.
A Rich and Highly Endemic Decapod Crustacean Fauna from the Middle Jurassic of North‐east France
Authors: Crônier Catherine , Courville Philippe
Published: July 2004

Decapod crustaceans are relatively widespread in Jurassic deposits of Europe and a small number have been collected from the north‐east of France. A new fossil of a macrurous decapod assigned to Eryma burgundiaca sp. nov., an erymid lobster, is described from this area and comparisons are made with closely allied species from Europe. Probable pagurid anomurous decapods are represented by Orhomalus magnificus sp. nov., Palaeopagurus acutus sp. nov. and Palaeopagurus neraudeaui sp. nov. No brachyurous decapods are presently known from the fauna. Based on the associated ammonites, the material is considered to be Callovian in age.
Siluro‐devonian Conodonts from the Camelford Limestone, Wellington, New South Wales, Australia
Authors: Farrell John R.
Published: July 2004

Conodont data have been utilized to identify the Silurian/Devonian boundary within the Camelford Limestone near Wellington, NSW. Conodont faunas are documented from the eosteinhornensis Zone to early delta Zone with one new species of Walliserodus (W. multistriatus) and two new species of Ozarkodina (O. brocki and O. camelfordensis) described. An apparatus reconstruction of Belodella anomalis is also presented.
The Jurassic Belemnite Suborder Belemnotheutina
Authors: Doyle Peter , Shakides Emma V.
Published: July 2004

The Belemnotheutina is a monophyletic group of mostly late Jurassic belemnites that possess largely plesiomorphic characters of ten subequal arms with hooks, a simple, conical, rostrum, a narrow breviconic phragmocone and a spatulate pro‐ostracum. Although some of the best‐preserved belemnites with soft parts have been described from this group, until recently, its status has been in question. A new genus from the Upper Jurassic of Antarctica, Antarctiteuthis is described which, like Acanthoteuthis (= Belemnotheutis of authors), possesses unique rostral surface morphology of raised ridges with accompanying grooves unknown in other true belemnites. This is an important apomorphy for the group, which is considered to be a monophyletic suborder of the Belemnitida.
The Trilobite Subfamily Monorakinae (Pterygometopidae)
Authors: Holloway David J.
Published: July 2004

The Monorakinae is a subfamily of the Pterygometopidae characterised by the fusion of L2 and L3 in the glabella. The resulting bicomposite lobe is expanded backwards to reach the occipital furrow, displacing L1 from contact with the axial furrow and causing the realignment of S1 to a markedly oblique orientation. The bicomposite lobe is commonly bounded adaxially by a longitudinal furrow containing three pairs of apodemal pits. The Monorakinae was probably derived from the Pterygometopinae, and includes the genera and subgenera Monorakos, Carinopyge, Ceratevenkaspis, Elasmaspis, Evenkaspis (Evenkaspis) and E. (Parevenkaspis), of which Carinopyge, Elasmaspis and Evenkaspis (Parevenkaspis) are known only from limited parts of the exoskeleton. Monorakines have a stratigraphical range of Caradoc–Ashgill. Their known geographical distribution in the Siberian Platform, Taimyr, the Russian Far East, and the Seward Peninsula of Alaska is restricted to areas that in the Ordovician were part of the palaeocontinents of Siberia and Arctida, which must have been connected or situated close together at that time. The occurrence of monorakines in the Taimyr Peninsula but their absence from Baltica does not support the suggestion of some workers that Taimyr was part of Baltica in the Ordovician.
F.A. Quenstedt's Trinominal Nomenclature of Jurassic Ammonites
Authors: Callomon John H. , Donovan Desmond T. , Howarth Michael K.
Published: July 2004

In an early attempt to incorporate infraspecific, varietal categories into conventional, morphodescriptive Linnaean taxonomy, Quenstedt in 1845 introduced an idiosyncratic trinominal nomenclature that has bedevilled ammonite taxonomy ever since. The trinomina consist of ordinary binomina to which were added third names in the same adjectival form as the specific epithets themselves. The problem has been whether these third names should be construed as of subspecific rank, governed by the International Code of Zoological Nomenclature, or of infra‐subspecific varietal rank, which is not. Quenstedt's exposition of the difference in principle between natural species and their variants was entirely clear, but its recognition in fossils has in practice to be subjective. Intended to be varietal, he used the same third names repeatedly, making no attempt to avoid homonymy under the generic name Ammonites. Subsequent revisers, judging Quenstedt's trinominally named taxa to be specifically distinct, have been faced with unending problems of homonymy. Two comprehensive solutions present themselves. The first, put forward by H. Ho¨lder in 1958, is to declare all of Quenstedt's third names to be of infrasubspecific rank and hence not available in formal Linnaean nomenclature. The second, proposed here, is to declare all the trinomina to be in principle available at subspecific rank. We present the case for this solution as the basis for an application for its ratification to the International Commission on Zoological Nomenclature (ICZN).
A New Method for Finding Small Vertebrate Fossils: Ultraviolet Light At Night
Authors: Croft Darin A. , Kaye Tom , Panko Laura
Published: July 2004

Vertebrate fossils from many different formations fluoresce when exposed to ultraviolet (UV) light. In this paper field observations and controlled experiments in the Chadron Formation (White River Group, late Eocene) of Wyoming are used to assess the utility of searching for fossils at night using ultraviolet light. The results indicate that, especially for very small teeth and egg‐shell fragments, searching with ultraviolet light at night can result in significantly more specimens than searching during daylight hours. This method has the potential to increase sample sizes for small vertebrate specimens that are often overlooked when using standard collecting techniques.
A New Pterosaur from the Jurassic of Cuba
Authors: Gasparini Zulma , Fernández Marta , Fuente Marcelo de la
Published: July 2004

Cacibupteryx caribensis gen. et sp. nov. is a new pterosaur of the family Rhamphorhynchidae found in western Cuba, in rocks of the Jagua Formation (Middle–Upper Oxfordian). The holotype, a skull and part of the left wing, is one of the few Jurassic pterosaurs that is well preserved in three dimensions. The new taxon shares characters with early and late Jurassic pterosaurs, and is one of the few late Jurassic taxa from western Laurasia and Gondwana. Furthermore, Cacibupteryx joins Nesodactylus hesperius Colbert from Cuba, and Sordes pilosus Sharov, from Kazakhstan as the most complete pterosaur recorded from the Middle–Upper Oxfordian. Cacibupteryx caribensis is one of the largest Jurassic pterosaurs known, and its skull possesses several distinct characters, including relatively broad roof elements (mainly frontal and parietal bones), a jugal with a prominent recess, occipital table trapezoidal in shape with the maximum width between the quadrate bones, and a small fenestra located in the posterior part of the pterygoid bones. In the Oxfordian, the Caribbean Corridor separated Laurasia and western Gondwana. The diversity of the marine herpetofauna found in the Jagua Vieja Member (Jagua Formation), and of teleostean fish, confirms that the corridor was an effective seaway over which flew at least Nesodactylus and Cacibupteryx.
Can the assumption of a non‐random search improve our prediction of butterfly fluxes between resource patches?
Authors: Kindlmann Pavel , Aviron Stephanie , Burel Francoise , Ouin Annie
Published: July 2004

Abstract.  1. Understanding dispersal patterns that enable small, spatially isolated populations to survive in fragmented landscapes has become an important issue in conservation biology and landscape management. However, for most of the species of interest it is not known whether dispersing individuals navigate or follow systematic search strategies, as opposed to moving randomly.

2. Recently it was shown that individuals of the butterfly species Maniola jurtina do not seek resources by means of random flight. If true, this may be problematic for existing metapopulation models, including those based on the evolution of dispersal rates in metapopulations.

3. The study tested to what extent the non‐random dispersal patterns described in the literature can explain M. jurtina fluxes in its natural habitat.

4. A model based on literature assumptions of M. jurtina movements is presented in the work reported here, and its predictions are compared with 2 years of capture–recapture data on its fluxes in two landscapes.

5. The model provides a good fit to the data and gives better predictions than the model based only on patch sizes and distances between patches.

6. Thus, if data are available about the actual landscape under consideration, the model should be preferred to simpler approaches; however, in general theoretical considerations the simple approach based on patch size and the degree of its isolation will retain its value.
Foraging in nature: foraging efficiency and attentiveness in caterpillars with different diet breadths
Authors: Bernays E. A. , Singer M. S. , Rodrigues D.
Published: July 2004

Abstract.  1. Seventy‐seven individual last‐instar caterpillars foraging in the field were examined for 6 h each. They represented four species of Arctiidae of similar size and habitat use. Two, Hypocrisias minima and Pygarctia roseicapitis, are specialists restricted to particular plant genera. The other two, Grammia geneura and Estigmene acrea, are extreme generalists that use many host plant species from multiple plant families.

2. Parameters of behavioural efficiency were monitored. Generalists spent more time walking, rejected more potential host plants, took longer to decide to feed after inspecting a plant, and took relatively more small feeding bouts compared with specialists.

3. This is the first test of differential foraging efficiency in the field in relation to diet breadth of insects and the data indicate that generalists are less efficient in their foraging activities and may suffer from divided attention. The need for attentiveness to enhance efficiency and thereby reduce ecological risk is discussed.
Effects of parental body condition and size on reproductive success in a tenebrionid beetle with biparental care
Authors: Heg Dik , Rasa O. Anne E.
Published: July 2004

Abstract.  1. The beetle Parastizopus armaticeps (Coleoptera: Tenebrionidae) inhabits the Kalahari desert of southern Africa, constructs breeding burrows after rainfall, and shows extensive biparental care. Previous work has shown that it is predominantly male size, not female size, that determines breeding success; however, in the field these beetles show size assortative mating. This might obscure or override effects of female size on reproduction. Moreover, the inaccessibility of the breeding burrows makes it impossible to test effects of female and male size on offspring development and survival before adulthood.

2. To disentangle the effects of male and female length, body mass, and body condition on reproductive success, males and females were paired randomly in small breeding cages in the laboratory (n = 887 breeding pairs). The construction of the breeding cages allowed a clear view of the brood chamber contents at each stage in offspring development. Larva, pupa, and imago numbers and development were monitored daily, and imago mass at hatching from the pupa (hatchlings), offspring mass, and offspring body length at complete exoskeleton melanisation (juveniles) were determined.

3. There was a weak positive correlation between body condition and body length for females only. Breeding chronology was related to male body condition: males in better condition were fast to start and finish a breeding bout. Males in better condition produced heavier hatchlings and juveniles, and larger‐sized males produced larger‐sized juveniles. In contrast, numbers of larvae and juveniles produced were determined mainly by female length and body condition: larger females in better condition hatched more larvae and produced more offspring.

4. The results suggest that male size and condition will be the most important determinant of reproductive success under relatively dry conditions, when burrow length is critical for reproductive success. Female size might be more important for the pair's reproductive success under wet breeding conditions, when burrow length is less critical for successful reproduction.
The control of reproductive diapause in Nebria salina (Coleoptera: Carabidae)
Authors: Telfer G. , Butterfield J. E. L.
Published: July 2004

Abstract.  1. Adult male and female Nebria salina were collected in summer, when in reproductive diapause, and subjected to three different photoperiod regimes, LD 18:6 h, LD 12:12 h, and LD 6:18 h, to assess the role of light regimes on sexual development.

2. Two alternative hypotheses were tested: (i) development rates increase in response to time restriction and (ii) development rate is at a maximum on the day length approximating to that in the field during reproduction.

3. Gonad development was assessed after 1 and 2 months' exposure to the experimental day lengths. In female N. salina, photoperiod and length of time of exposure both influenced reproductive development. Females required at least 2 months' exposure to photoperiods of ≤ LD 12:12 h to mature. Development of the ovary did not take place on LD 18:6 h, irrespective of the length of exposure. Sexual development occurred in all the males after 2 months, irrespective of photoperiod.

4. At the end of the study the activity of the remaining beetles was measured and compared. Significantly higher activity levels were measured in periods of darkness, and consequently beetles exposed to the two shorter day lengths were found to be more active than those kept on the longest photoperiod. Comparing the 3‐h period 06.00 – 09.00, the last 3 h of darkness for all three regimes, activity was significantly higher on LD 12:12 h and LD 6:18 h than on the LD 18:6 h regime.

5. In order to place the experimental studies in context with the life cycle under natural conditions, pitfall traps were used to compare the seasonal activity of N. salina in the field.