bluuebunny/crossref_metadata_2025_split huggingface dataset:
A hierarchical model for estimating density in camera‐trap studies
Authors: Royle J. Andrew , Nichols James D. , Karanth K. Ullas , Gopalaswamy Arjun M. 
Published: November 2008

Summary

Estimating animal density using capture–recapture data from arrays of detection devices such as camera traps has been problematic due to the movement of individuals and heterogeneity in capture probability among them induced by differential exposure to trapping.
We develop a spatial capture–recapture model for estimating density from camera‐trapping data which contains explicit models for the spatial point process governing the distribution of individuals and their exposure to and detection by traps.
We adopt a Bayesian approach to analysis of the hierarchical model using the technique of data augmentation.
The model is applied to photographic capture–recapture data on tigers Panthera tigris in Nagarahole reserve, India. Using this model, we estimate the density of tigers to be 14·3 animals per 100 km2 during 2004.
Synthesis and applications. Our modelling framework largely overcomes several weaknesses in conventional approaches to the estimation of animal density from trap arrays. It effectively deals with key problems such as individual heterogeneity in capture probabilities, movement of traps, presence of potential ‘holes’ in the array and ad hoc estimation of sample area. The formulation, thus, greatly enhances flexibility in the conduct of field surveys as well as in the analysis of data, from studies that may involve physical, photographic or DNA‐based ‘captures’ of individual animals.
Succession of floodplain grasslands following reduction in land use intensity: the importance of environmental conditions, management and dispersal
Authors: Bischoff Armin , Warthemann Guido , Klotz Stefan 
Published: November 2008

Summary

Classical ecological theory predicts a succession towards plant communities that are determined by environmental conditions. However, in ecological restoration, species composition often remains different from the predicted target community, compromising the success of restoration measures.
We analysed the relative importance of environmental conditions, management and distance to source populations for floodplain grassland succession following re‐conversion from intensive to traditional use. The study was established at 33 grassland sites in central German river valleys. Species composition, environmental variables, past and current management, and the distance to source populations of characteristic species of traditional management (indicator species) were recorded and compared using multivariate statistics. We further tested the speed of colonization by two indicator species, Silaum silaus and Serratula tinctoria, along transects from source populations into unoccupied fields.
The species composition of the successional grassland was mainly determined by elevation, total soil nitrogen, distance to remnant species‐rich grasslands and frequency of mowing or grazing. Elevation and distance were negatively, and frequency was positively related to the occurrence of late successional species.
Colonization by indicator species was only dependent on the distance to source populations; other explanatory variables were not significant. Migration from adjacent source sites of S. silaus and S. tinctoria into re‐converted grasslands was slow, reaching only 40 m and 15 m after 15 years.
Synthesis and applications. The results demonstrated the limitations of the deterministic view on plant succession and the high relative importance of propagule availability in grassland restoration. Natural colonization will only be successful if source populations of the target species are adjacent to the restoration sites. Artificial introduction techniques are recommended to overcome dispersal barriers.
Prevalence of hypertension in adults with intellectual disability in the Netherlands
Authors: Van De Louw J. , Vorstenbosch R. , Vinck L. , Penning C. , Evenhuis H. 
Published: November 2008

AbstractBackground  Literature on the prevalence of hypertension in people with intellectual disability (ID) is mostly based on file studies or on measurements limited to the age group below 50 years. We measured and calculated the prevalence of hypertension in adults with ID and studied the distribution of hypertension in relation to age, gender, diagnosis of Down's syndrome and level of ID.Methods  In an observational cross‐sectional study, standardized blood pressure measurements were obtained from 258 randomly selected adult clients of three Dutch care providers for people with ID. Hypertension was defined as a mean systolic blood pressure above 140 mm Hg on repeated measurements.Results  The overall prevalence rate of hypertension was 17.4% (95% CI 12.28–22.46). This was comparable to the prevalence in the general Dutch population. No accurate blood pressure measurement could be performed in 28.4% of people with severe and profound ID owing to repetitive physical activity or resistance. Hypertension was significantly related to older age and absence of Down's syndrome; no correlation with gender or level of ID could be shown.Recommendation  The risk factor hypertension should be detected and treated in the same manner as in the general population following national guidelines.
Polyploid evolution and plastid DNA variation in the Dactylorhiza incarnata/maculata complex (Orchidaceae) in Scandinavia
Authors: HEDRÉN MIKAEL , NORDSTRÖM SOFIE , STÅHLBERG DAVID 
Published: November 2008

AbstractThe Dactylorhiza incarnata/maculata complex (Orchidaceae) was used as a model system to understand genetic differentiation processes in a naturally occurring polyploid complex with much of ongoing diversification and wide distribution in recently glaciated areas in northern Europe. Data were obtained for 12 hypervariable regions in the plastid DNA genome. A total of 166 haplotypes were found in a sample of 1099 plants. Allopolyploid taxa have inherited their plastid genomes from D. maculata s.l. Overall haplotype diversity of the combined group of allopolyploid taxa was comparable to that of maternal D. maculata s.l., but populations of allopolyploids were also more strongly differentiated from each other and contained lower numbers of haplotypes than populations of D. maculata s.l. In addition to haplotypes found in extant D. maculata s.l., the allopolyploids also contained several distinct and widespread haplotypes that were not found in any of the parental lineages. Some of these haplotypes were shared between widespread allopolyploids. Divergent allopolyploids with small distributions did not seem to originate from local polyploidization events, but rather as segregates of already existing allopolyploids. Genetic diversification of allopolyploid Dactylorhiza is the result of repeated polyploid formation, secondary hybridization and introgression between already existing polyploids and extant representatives of parental lineages, hybridization between independently derived polyploid lineages, and phyletic diversification in the group of allopolyploids. Although some polyploid taxa must have evolved after the last glaciation, genetic material from the parental lineages has been transferred continuously for longer periods of time. This combination of processes may explain the taxonomic complexity encountered in Dactylorhiza and other polyploid complexes distributed in previously glaciated parts of Europe.
Airborne‐pollen pool and mating pattern in a hybrid zone betweenPinus pumilaandP. parvifloravar.pentaphylla
Authors: ITO MEGUMI , SUYAMA YOSHIHISA , OHSAWA TAKESHI A. , WATANO YASUYUKI 
Published: November 2008

AbstractThe reproductive isolation barriers and the mating patterns amongPinus pumila,P. parvifloravar.pentaphyllaand their hybrids were examined by flowering phenology and genetic assays of three life stages: airborne‐pollen grains, adults and seeds, in a hybrid zone on Mount Apoi, Hokkaido, Japan. Chloroplast DNA composition of the airborne‐pollen was determined by single‐pollen polymerase chain reaction. Mating patterns were analysed by estimating the molecular hybrid index of the seed parent, their seed embryos and pollen parents. The observation of flowering phenology showed that the flowering ofP. pumilaprecedes that ofP. parvifloravar.pentaphyllaby about 6 to 10 days within the same altitudinal ranges. Although this prezygotic isolation barrier is effective, the genetic assay of airborne‐pollen showed that the two pine species, particularlyP. pumila, still have chances to form F1hybrid seeds. Both parental species showed a strong assortative mating pattern; F1seeds were found in only 1.4% of seeds fromP. pumilamother trees and not at all inP. parvifloravar.pentaphylla. The assortative mating was concluded as the combined result of flowering time differentiation and cross‐incompatibility. In contrast to the parental species, hybrids were fertilized evenly by the two parental species and themselves. The breakdown of prezygotic barriers (intermediate flowering phenology) and cross‐incompatibility may account for the unselective mating. It is suggested that introgression is ongoing on Mount Apoi through backcrossing between hybrids and parental species, despite strong isolation barriers between the parental species.
Comparative phylogeography of two sibling species of forest‐dwelling rodent (Praomys rostratus and P. tullbergi) in West Africa: different reactions to past forest fragmentation
Authors: NICOLAS V. , BRYJA J. , AKPATOU B. , KONECNY A. , LECOMPTE E. , COLYN M. , LALIS A. , COULOUX A. , DENYS C. , GRANJON L. 
Published: November 2008

AbstractTwo sibling species of the rodent genus Praomys occur in West African forests: P. tullbergi and P. rostratus. By sampling across their geographical ranges (459 individuals from 77 localities), we test the hypothesis that climatic oscillations during the Quaternary made an impact on the observed pattern of cytochrome b sequence variation. We show that, although these two species have parapatric geographical distributions, their phylogeographical histories are dissimilar, which could be related to their distinct ecological requirements. Since the arid phases of the Pleistocene were characterized by isolated forest patches, and intervening wetter periods by forest expansion, these changes in forest cover may be the common mechanism responsible for the observed phylogeographical patterns in both of these species. For example, in both species, most clades had either allopatric or parapatric geographical distributions; however, genetic diversity was much lower in P. tullbergi than in P. rostratus. The genetic pattern of P. tullbergi fits the refuge hypothesis, indicating that a very small number of populations survived in distinct forest blocks during the arid phases, then expanded again with forest recovery. In contrast, a number of populations of P. rostratus appear to have survived during the dry periods in more fragmented forest habitats, with varying levels of gene flow between these patches depending on climatic conditions and forest extent. In addition, historical variations of the West African hydrographic network could also have contributed to the pattern of genetic differentiation observed in both species.
Genetic patterns across multiple introductions of the globally invasive crab genus Carcinus
Authors: DARLING JOHN A. , BAGLEY MARK J. , ROMAN JOE , TEPOLT CAROLYN K. , GELLER JONATHAN B. 
Published: November 2008

AbstractThe European green crab Carcinus maenas is one of the world's most successful aquatic invaders, having established populations on every continent with temperate shores. Here we describe patterns of genetic diversity across both the native and introduced ranges of C. maenas and its sister species, C. aestuarii, including all known non‐native populations. The global data set includes sequences from the mitochondrial cytochrome c oxidase subunit I gene, as well as multilocus genotype data from nine polymorphic nuclear microsatellite loci. Combined phylogeographic and population genetic analyses clarify the global colonization history of C. maenas, providing evidence of multiple invasions to Atlantic North America and South Africa, secondary invasions to the northeastern Pacific, Tasmania, and Argentina, and a strong likelihood of C. maenas × C. aestuarii hybrids in South Africa and Japan. Successful C. maenas invasions vary broadly in the degree to which they retain genetic diversity, although populations with the least variation typically derive from secondary invasions or from introductions that occurred more than 100 years ago.
Dispersal in the spiny damselfish,Acanthochromis polyacanthus, a coral reef fish species without a larval pelagic stage
Authors: MILLER‐SIMS V. C. , GERLACH G. , KINGSFORD M. J. , ATEMA J. 
Published: November 2008

AbstractThe spiny damselfish,Acanthochromis polyacanthus, is widely distributed throughout the Indo‐Australian archipelago. However, this species lacks a larval dispersal stage and shows genetic differentiation between populations from closely spaced reefs. To investigate the dispersal strategy of this unique species, we used microsatellite markers to determine genetic relatedness at five dispersal scales: within broods of juveniles, between adults within a collection site (~30 m2), between sites on single reefs, between nearby reefs in a reef cluster, and between reef clusters. We sampled broods of juveniles and adults from seven reefs in the Capricorn‐Bunker and Swain groups of the Great Barrier Reef. We found that extra‐pair mating is rare and juveniles remain with their parents until fledged. Adults from single sites are less related than broods but more related than expected by chance. However, there is no evidence of inbreeding suggesting the existence of assortative mating and/or adult migration. Genetic differences were found between all of the reefs tested except between Heron and Sykes reefs, which are separated only by a 2‐km area of shallow water (less than 10 m). There was a strong correlation between genetic distance, geographical distance and water depth. Apparently, under present‐day conditions spiny damselfish populations are connected only between sites of shallow water, through dispersal of adults over short distances. Assuming that dispersal behaviour has not changed, the broad distribution ofA. polyacanthusas a species is likely based on historical colonization patterns when reefs were connected by shallow water at times of lower sea levels.
A unique family of proteins associated with internalized membranes in protein storage vacuoles of the Brassicaceae
Authors: Gillespie Jane , Rogers Sally W. , Deery Mike , Dupree Paul , Rogers John C. 
Published: November 2008

SummaryThe protein storage vacuole (PSV) is a specialized organelle in plant seeds that accumulates storage proteins and phytate during seed development. In many plant species, such as tomato and tobacco, the PSV contains two types of microscopically visible intra‐organellar inclusions: a large crystalline lattice of membranes and proteins, the crystalloid, and one or a few large phytate crystals, the globoids. In seeds of the family Brassicaceae, the PSVs lack visible crystalloids and have many small globoids dispersed throughout. We biochemically fractionated PSVs from Brassica napus and defined a crystalloid‐like fraction that contained integral membrane protein markers found in crystalloids of other plants. Protein analyses identified a previously undescribed family of proteins, the Brassicaceae PSV‐embedded proteins (BPEPs), associated with ‘crystalloid’ and globoid fractions. The defining characteristics of the BPEPs are an N‐terminal signal peptide and tandem MATH domains, which may mediate protein–protein interactions. Database analyses indicated that the BPEPs are unique to Brassicaceae. Immunofluorescence studies using anti‐BPEP antibodies and antibodies to other biochemical markers to label B. napus and Arabidopsis thaliana seed sections localized the BPEPs to structures within the PSVs, whose appearance was consistent with a diffuse network of internalized membranes and globoids. These results demonstrate that Brassicaceae PSVs contain internalized membranes, and raise the possibility that BPEPs modify these internal membrane structures to yield a PSV morphology different from that of tomato or tobacco.
X‐ray diffraction structure of a plant glycosyl hydrolase family 32 protein: fructan 1‐exohydrolase IIa ofCichorium intybus
Authors: Verhaest Maureen , Ende Wim Van den , Roy Katrien Le , De Ranter Camiel J. , Laere André Van , Rabijns Anja 
Published: November 2008

SummaryFructan 1‐exohydrolase, an enzyme involved in fructan degradation, belongs to the glycosyl hydrolase family 32. The structure of isoenzyme 1‐FEH IIa fromCichorium intybusis described at a resolution of 2.35 Å. The structure consists of an N‐terminal fivefoldβ‐propeller domain connected to two C‐terminalβ‐sheets. The putative active site is located entirely in theβ‐propeller domain and is formed by amino acids which are highly conserved within glycosyl hydrolase family 32. The fructan‐binding site is thought to be in the cleft formed between the two domains. The 1‐FEH IIa structure is compared with the structures of two homologous but functionally different enzymes: a levansucrase fromBacillus subtilis(glycosyl hydrolase family 68) and an invertase fromThermotoga maritima(glycosyl hydrolase family 32).
Cell‐specific regulation of a Brassica napus CMS‐associated gene by a nuclear restorer with related effects on a floral homeotic gene promoter
Authors: Geddy Rachel , Mahé Laetitia , Brown Gregory G. 
Published: November 2008

SummaryCytoplasmic male sterility (CMS) is a maternally inherited defect in pollen production specified by novel mitochondrial genes. It can be suppressed by nuclear restorer (Rf) genes which normally downregulate expression of a CMS‐associated novel mitochondrial gene. Two forms of Brassica napus CMS, nap and pol, are associated with related chimeric genes, orf222 and orf224, respectively. We show that in pol and nap CMS, anther locule development is asynchronous and asymmetric, that one or more locules within each anther may fail to develop entirely and that CMS anthers display polarity in locule development. We show, by in situ hybridization, that orf222 transcripts accumulate in sterile anthers prior to development of morphological differences between CMS and restored stamens, and remain preferentially localized to microsporangia. In fertility‐restored anthers, however, orf222 transcript levels remain low throughout development. Some sporogenous and meiotic cells differentiate within CMS anthers and form functional pollen despite retaining high orf222 transcript levels, suggesting that the effect of orf222 expression in blocking pollen development is limited to an early and specific stage. Transcripts of other mitochondrial genes, exemplified by atp6 and cob, and of the nuclear‐encoded ATP synthase gamma subunit, accumulate preferentially in the microsporangia of both sterile and fertile anthers. Thus nuclear fertility restoration reduces orf222 transcript levels in a gene and tissue‐specific manner. We observe differences between CMS and fertile plants in the timing and patterning of APETALA3 promoter activity that suggest a possible basis for the developmental abnormalities of CMS flowers.
A two‐component high‐affinity nitrate uptake system in barley
Authors: Tong Yiping , Zhou Jing‐Jiang , Li Zhensheng , Miller Anthony J. 
Published: November 2008

SummaryThe analysis of genome databases for many different plants has identified a group of genes that are related to one part of a two‐component nitrate transport system found in algae. Earlier work using mutants and heterologous expression has shown that a high‐affinity nitrate transport system from the unicellular green algae, Chlamydomonas reinhardtii required two gene products for function. One gene encoded a typical carrier‐type structure with 12 putative trans‐membrane (TM) domains and the other gene, nar2 encoded a much smaller protein that had only one TM domain. As both gene families occur in plants we investigated whether this transport model has more general relevance among plants. The screening for nitrate transporter activity was greatly helped by a novel assay using 15N‐enriched nitrate uptake into Xenopus oocytes expressing the proteins. This assay enables many oocytes to be rapidly screened for nitrate transport activity. The functional activity of a barley nitrate transporter, HvNRT2.1, in oocytes required co‐injection of a second mRNA. Although three very closely related nar2‐like genes were cloned from barley, only one of these was able to give functional nitrate transport when co‐injected into oocytes. The nitrate transport performed by this two‐gene system was inhibited at more acidic external pH and by acidification of the cytoplasm. This specific requirement for two‐gene products to give nitrate transport function has important implications for attempts to genetically manipulate this fundamental process in plants.
The benefits of male ejaculate sex peptide transfer in Drosophila melanogaster
Authors: FRICKE C. , WIGBY S. , HOBBS R. , CHAPMAN T. 
Published: November 2008

AbstractThe accessory gland protein (Acp) ejaculate molecules of male Drosophila melanogaster mediate sexual selection and sexual conflict at the molecular level. However, to date no studies have comprehensively measured the timing and magnitude of fitness benefits to males of transferring specific Acps. This is an important omission because without this information it is not possible to fully understand the strength and form of selection acting on adaptations such as Acps. Here, we measured the fitness benefits to males of ejaculate sex peptide (SP) transfer. SP is of interest because it is a candidate for mediating sexual conflict: its frequent receipt reduces female fitness. In single matings with virgin females SP is known to increase egg laying and decrease receptivity. Hence, we predicted that SP could: (i) boost a male’s absolute paternity by increasing offspring production and delaying female remating and/or (ii) boost relative paternity share. We tested these predictions using two different lines of SP‐lacking males, in both two‐mating and free‐mating assay conditions. SP transfer conferred higher absolute, but not relative, male reproductive success. In matings with virgin females, SP transfer increased mating productivity and delayed remating and hence the onset of sperm competition. In already mated females, SP transfer did not elevate absolute progeny production, but did increase intermating intervals and hence the period over which a male could gain paternity. Consistent with this, under free‐mating conditions over an extended period, we detected a ‘per‐mating’ fitness benefit for males transferring SP. These benefits are consistent with a role for SP in mediating conflict, with SP acting to maximize short‐term fitness benefits for males.
Evidence of restoration cost in the annual gynodioecious Phacelia dubia
Authors: DEL CASTILLO R. F. , TRUJILLO S. 
Published: November 2008

AbstractA negative pleiotropic effect on fitness of nuclear sex‐determining genes (cost of restoration) could explain nuclear–cytoplasmic gynodioecy but rarely has been demonstrated empirically. In a gynodioecious Phacelia dubia population, maternal lineages produce only hermaphroditic progenies irrespective of the pollen parent (N) or can segregate females (S). Natural progenies of N maternal plants had lower seed viability than that of S. Full‐sib progenies of unrelated hermaphrodites from all possible matings between N and S lineages had similar pollen filling but differed in sporophyte performance, mainly at seed germination stage. A discrete multivariate analysis reveals that the performance of N♀ × S♂ progeny at early stages of development was significantly lower than that of the other three types of mating in agreement with the silent‐cost‐of‐restoration hypothesis, affecting the sporophyte. The restoration cost and male sterility appear to be dominant and consequence of nuclear–cytoplasmic incompatibilities that may maintain nuclear–cytoplasmic polymorphism by frequency‐dependent selection.