bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trade‐off between male and female allocation in the simultaneously hermaphroditic flatworm Macrostomum sp.
Authors: Schärer L. , Sandner P. , Michiels N. K. 
Published: February 2005

AbstractSex allocation theory for simultaneous hermaphrodites assumes a direct trade‐off between the allocation of resources to the male and female reproductive functions. Empirical support for this basic assumption is scarce, possibly because studies rarely control for variation in individual reproductive resource budgets. Such variation, which can have environmental or genetic sources, can generate a positive relationship between male and female investment and can thus obscure the trade‐off. In this study on the hermaphroditic flatworm Macrostomum sp. we tried to control for budget effects by restricting food availability in a standardized way and by using an inbred line. We then manipulated mating group size in a two‐way design (two group sizes × two enclosure sizes) in order to induce phenotypic variation in male allocation, and expected to find an opposing correlated response in female allocation. The results suggest that we only managed to control the budget effects under some conditions. Under these the sex allocation trade‐off emerged. Under the other conditions we found a strongly positive correlation between male and female allocation. We discuss possible causes for the observed differences.
Crossing the taxonomic divide: conflict and its resolution in societies of reproductively totipotent individuals
Authors: HART A. G. , RATNIEKS F. L. W. 
Published: February 2005

AbstractReproduction in groups may be unequal, with one or a few individuals monopolizing direct reproduction assisted by nonbreeding helpers. In social insects this has frequently led to a pronounced queen‐worker dichotomy and a loss of reproductive totipotency among workers. However, in some invertebrate and all vertebrate societies, all or most individuals remain reproductively totipotent. In these groups, conflicts of interest over reproduction are potentially greatest. Here, we synthesize previous analyses of reproductive conflict, aggression and breeder replacement in haplodiploid societies of totipotent individuals and extend them to cover diploid (vertebrate) examples. We test predictions arising from this approach using the best‐studied invertebrate (Dinoponeraqueenless ants) and vertebrate (naked mole‐rat,Heterocephalus glaber) examples, although in principle our analysis applies to all similar groups. We find that premature replacement of a parent breeder by nonbreeders (overthrow) is rare. Dominant coercive control of nonbreeders by the breeder is often unnecessary and honest signalling of breeder vitality can maintain group stability and resolve conflicts over reproduction. We hope that by providing an explicit transfer of social theory between ants and naked mole‐rats we will stimulate further cross‐taxonomic studies that will greatly broaden our understanding of sociality.
Hybrid incompatibility is consistent with a hybrid origin ofHeliconius heurippaHewitson from its close relatives,Heliconius cydnoDoubleday andHeliconius melpomeneLinnaeus
Authors: Salazar C. A. , Jiggins C. D. , Arias C. F. , Tobler A. , Bermingham E. , Linares M. 
Published: February 2005

AbstractShared ancestral variation and introgression complicates the reconstruction of phylogenetic relationships among closely related taxa. Here we use overall genomic compatibility as an alternative estimate of species relationships in a group where divergence is rapid and genetic exchange is common.Heliconius heurippa, a butterfly species endemic to Colombia, has a colour pattern genetically intermediate betweenH. cydnoandH. melpomene: its hindwing is nearly indistinguishable from that ofH. melpomeneand its forewing band is an intermediate phenotype between both species. This observation has lead to the suggestion that the pattern ofH. heurippaarose through hybridization. We present a genetic analysis of hybrid compatibility in crosses between the three taxa.Heliconius heurippa × H. cydnoand femaleH. melpomene × maleH. heurippayield fertile and viable F1hybrids, but maleH. melpomene × femaleH. heurippacrosses yield sterile F1females. In contrast, Haldane's rule has previously been detected betweenH. melpomeneandH cydnoin both directions. Therefore,H. heurippais most closely related toH. cydno, with some evidence for introgression of genes fromH. melpomene.The results are compatible with the hypothesis of a hybrid origin forH. heurippa. In addition, backcrosses using F1hybrid males provide evidence for a large Z(X)‐chromosome effect on sterility and for recessive autosomal sterility factors as predicted by Dominance Theory.
The geographic selection mosaic for squirrels, crossbills and Aleppo pine
Authors: MEZQUIDA E. T. , BENKMAN C. W. 
Published: February 2005

AbstractThe interactions between many species are structured in a geographic mosaic of populations among which selection is divergent. Here we tested the hypothesis that such a geographic selection mosaic arises for common crossbills (Loxia curvirostra) feeding on seeds in the cones of Aleppo pine (Pinus halepensis) because of geographic variation in the occurrence of European red squirrels (Sciurus vulgaris). On the Iberian Peninsula, Sciurus exerted directional selection favouring larger cones with larger scales, which has caused cones there to be larger than in the Balearic Islands where Sciurus are absent. Moreover, cones on the Iberian Peninsula are so large that they are apparently little used by the relatively small‐billed crossbills on the Peninsula; selection by Sciurus seems to have made the cones so difficult to feed on that crossbills rely mostly on the seeds of other conifers. Where crossbills are present but Sciurus are absent (Mallorca Island), cones were smaller as a result of relaxation of selection by Sciurus. However, cones on Mallorca had proportionally thicker scales in comparison to where both Sciurus and crossbills are absent (Ibiza Island), presumably as an adaptation against crossbill predation. Here crossbills specialize on Aleppo pine, have relatively large bills and have apparently coevolved in an arms race with Aleppo pine. These results suggest that Sciurus has influenced both the geographic selection mosaics for crossbills and conifers and the adaptive radiation of crossbills in Eurasia much like Tamiasciurus has done in the North America.
The evolution of generalization? Parasitoid flies and the perils of inferring host range evolution from phylogenies
Authors: STIREMAN J. O. 
Published: February 2005

AbstractIt is widely assumed that high resource specificity predisposes lineages toward greater likelihood of extinction and lower likelihood of diversification than more generalized lineages. This suggests that host range evolution in parasitic organisms should proceed from generalist to specialist, and specialist lineages should be found at the ‘tips’ of phylogenies. To test these hypotheses, parsimony and maximum likelihood methods were used to reconstruct the evolution of host range on a phylogeny of parasitoid flies in the family Tachinidae. In contrast to predictions, most reconstructions indicated that generalists were repeatedly derived from specialist lineages and tended to occupy terminal branches of the phylogeny. These results are critically examined with respect to hypotheses concerning the evolution of specialization, the inherent difficulties in inferring host ranges, our knowledge of tachinid‐host associations, and the methodological problems associated with ancestral character state reconstruction. Both parsimony and likelihood reconstructions are shown to provide misleading results and it is argued that independent evidence, in addition to phylogenetic trees, is needed to inform models of the evolution of host range and the evolutionary consequences of specialization.
The evolutionary genetics of egg size plasticity in a butterfly
Authors: STEIGENGA M. J. , ZWAAN B. J. , BRAKEFIELD P. M. , FISCHER K. 
Published: February 2005

AbstractThe evolution of phenotypic plasticity requires that it is adaptive, genetically determined, and exhibits sufficient genetic variation. For the tropical butterfly Bicyclus anynana there is evidence that temperature‐mediated plasticity in egg size is an adaptation to predictable seasonal change. Here we set out to investigate heritability in egg size and genetic variation in the plastic response to temperature in this species, using a half‐sib breeding design. Egg size of individual females was first measured at a high temperature 4 days after eclosion. Females were then transferred to a low temperature and egg size was measured after acclimation periods of 6 and 12 days respectively. Overall, additive genetic variance explained only 3–11% of the total phenotypic variance, whereas maternal effects were more pronounced. Genotype–environment interactions and cross‐environmental correlations of less than unity suggest that there is potential for short‐term evolutionary change. Our findings strengthen the support for the adaptive nature of temperature‐mediated plasticity in egg size.
Evolutionary traction: the cost of adaptation and the evolution of sex
Authors: HADANY L. , FELDMAN M. W. 
Published: February 2005

AbstractThe advantage of sexual reproduction remains a puzzle for evolutionary biologists. Everything else being equal, asexual populations are expected to have twice the number of offspring produced by similar sexual populations. Yet, asexual species are uncommon among higher eukaryotes. In models assuming small populations, high mutation rates, or frequent environmental changes, sexual reproduction seems to have at least a two‐fold advantage over asexuality. But the advantage of sex for large populations, low mutation rates, and rare or mild environmental changes remains a conundrum. Here we show that without recombination, rare advantageous mutations can result in increased accumulation of deleterious mutations (‘evolutionary traction’), which explains the long‐term advantage of sex under a wide parameter range.
Identification of discriminant factors after treatment of resistant and susceptible banana leaves with Fusarium oxysporum f. sp. cubense culture filtrates
Authors: Companioni B. , Mora N. , Díaz L. , Pérez A. , Arzola M. , Espinosa P. , Hernández M. , Ventura J. , Pérez M. C. , Santos R. , Lorenzo J. C. 
Published: February 2005

AbstractAmong the most important crops in developing countries are banana and plantain. However, the production is threatened by increasingly virulent forms of Fusarium wilt, and therefore, intensive breeding programmes are being carried out worldwide. As conventional field studies of banana resistance to this disease are time‐consuming and destructive, an easy‐to‐do procedure was previously developed to differentiate field‐grown resistant and susceptible banana cultivars at leaf level. Such a procedure involved the in vitro treatment of fungal culture filtrates on to field‐grown adult leaves and the measurement of lesion areas 48 h later. The present report includes measurements of other indicators such as biochemical compounds. The cultivar ‘Gross Michel’ (susceptible) and cv. ‘FHIA‐01’ (resistant) leaves were treated with Fusarium oxysporum f. sp. cubense race 1 culture filtrates. Evaluations were performed 48 h after leaf treatment. Compared with culture medium‐treated leaves (control treatment), fungal metabolites produced leaf lesions, decreased freephenolic contents and increased protein levels in both cultivars. In ‘FHIA‐01’, the culture filtrate increased contents of cell wall‐linked phenolics and the pool of aldehydes (except malondialdehyde). Fungal metabolites did not cause variations in peroxidase activity, chlorophyll pigment contents or malondialdehyde level in any cultivar. The use of Fisher's linear discriminant analysis to differentiate resistant and susceptible banana cultivars in breeding programmes is also a novel aspect of this report. Such an estimation was performed from a data matrix that included the effects of the fungal metabolites (leaf lesion area and levels of free and cell wall‐linked phenolics, aldehydes, except malondialdehyde, and proteins) on banana leaves of seven cultivars (four susceptible and three resistant).
Genetic variation, heritability and genetic correlations for forage quality and yield traits of Mediterranean tall fescue germplasm
Authors: Annicchiarico P. , Romani M. 
Published: February 2005

AbstractHigher ruminant intake potential and in vivo digestibility as indicated by lower neutral and acid detergent fibre (NDF and ADF), respectively, and higher crude protein (CP), may be valuable targets in tall fescue breeding. Some 105 full‐sib families from a diallel cross of Mediterranean parent germplasm were grown in a heated greenhouse simulating the temperature pattern of a Mediterranean environment, to estimate genetic parameters for NDF, ADF, CP and dry matter (DM) yield in one autumn and one winter harvest. Family x harvest interaction was large for NDF and ADF, moderate for CP and absent for DM yield. Additive genetic variance was mostly larger than specific genetic variance, and tended to be small for quality traits and large for DM yield. Narrow‐sense heritability was low for CP and ADF in autumn and moderate to fairly high in the remaining cases. Predicted gains per selection cycle never exceeded 5% for quality traits while being greater than 10% for DM yield. An inverse genetic correlation between DM yield and any quality trait emerged in the presence of sizeable genetic variation.
Combining ability of non‐adapted sources for male‐fertility restoration in Pampa CMS of hybrid rye*
Authors: Miedaner T. , Wilde P. , Wortmann H. 
Published: February 2005

AbstractHybrid rye breeding and seed production relies on the cytoplasmic male sterility‐inducing Pampa (P)‐Cytoplasm. High levels of restoration were recently found in non‐adapted rye accessions from Argentina (Pico Gentario, Pastoreo Massaux) and Iran (IRAN IX). To analyse their relative superiority, five seed‐parent lines in P cytoplasm were crossed with five inbred lines of these sources and four adapted restorer lines. The 45 F1 hybrids were tested for male‐fertility restoration in three locations. Significant (P = 0.01) general and specific combining ability (GCA and SCA respectively) for male‐fertility restoration were found. The non‐adapted restorer lines were able to restore all seed‐parent lines similarly, resulting in hybrids with 55‐90% pollen shedding (mean 78%) compared with 2‐74% pollen shedding (mean 44%) when adapted restorer lines were used. Significant (P = 0.05) SCA effects were detected in 11 of 45 combinations, nine of them were crosses with adapted pollinator lines. Non‐adapted restorer lines showed a high phenotypic stability of male‐fertility restoration across locations. Introgression of these exotic sources into the adapted restorer gene pool by repeated backcrossing should result in environmentally stable male fertility in Pampa‐based rye hybrids.
Isozyme electrophoretic characterization of 29 related cultivars of lily (Lilium spp.)
Authors: Arzate‐Fernandez A.‐M. , Mejía‐González C.‐O. , Nakazaki T. , Okumoto Y. , Tanisaka T. 
Published: February 2005

AbstractIsozyme banding patterns (IBPs) were studied for cultivars of lily (Lilium spp.) by means of horizontal starch‐gel electrophoresis (SGE). An array of continuous histidine‐citrate buffer systems at eight ranges of pH and four extraction buffers were tested. On the basis of this survey, the extraction buffer two (Eb‐2) and the buffer system E at pH 7.7 were found to be suitable for detection of lily isozymes. Using the SGE technique, IBP in catalase (CAT; EC 1.11.1.6), esterase (EST; EC 3.1.1.1), malate dehydrogenase (MDH; EC 1.1.1.37), malic enzyme (MAL; EC 1.1.1.40), peroxidase (POX; EC 1.11.1.7), phosphoglucomutase (PGM; EC 2.7.5.1), phosphoglucose isomerase (PGI; EC 5.3.1.9) and 6‐phosphogluconate dehydrogenase (PGD; EC 1.1.1.44) were assayed. In total 29 cultivars were tested in this study: nine were analysed for all eight enzyme systems, 16 cultivars for seven systems, three for six, and one for five enzyme systems. Some IBP were identified as section‐specific biochemical markers. Eight enzymes systems were analysed by constructing a dendogram using the unweighted pair group method, arithmetic average (UPGMA) cluster analysis. The analysis indicated that the lily cultivars could be separated from other Lilium species, except for two L. x formonlogi cultivars:‘Hakuba’ and ‘Hakuko’ which could not be distinguished from each other by the isozyme patterns assayed here. This study shows that isozymes can provide useful biochemical markers for lily cultivar identification and to estimate the phylogenetic relationships among those cultivars.
Mapping QTL involved in powdery mildew resistance of the apple clone U 211
Authors: Stankiewicz‐Kosyl M. , Pitera E. , Gawronski S. W. 
Published: February 2005

AbstractScab and powdery mildew, caused by Venturia inaequalis (Cke.) Wint. and Podosphaera leucotricha (Ellis et Ev.) Salm. are the most important apple diseases. The apple clone U 211 is resistant to scab and is also highly resistant to powdery mildew under field conditions. The interval mapping method was applied for the identification of genomic regions conferring U 211 resistance to powdery mildew. The genetic maps of the ‘Idared’ and U 211 genome sectors were constructed using amplified fragment lenght polymorphism and simple sequence repeat markers and 98 individuals from the progeny of the cross ‘Idared’× U 211. On the basis of the phenotypic and molecular marker data 10 powdery mildew resistance quantitative trait loci (QTL) were identified in U 211 and ‘Idared’. One of the QTL in the clone U 211 explained 48‐72% of the phenotypic variation and its effect was stable over years.
Mapping of QTL controlling tocopherol content in winter oilseed rape
Authors: Marwede V. , Gul M. K. , Becker H. C. , Ecke W. 
Published: February 2005

AbstractTocopherols are natural antioxidants in vegetable oils and are important dietary nutrients. Enhanced tocopherol content has become an important objective in oilseed rape breeding. A segregating DH population was tested for 2 years at two locations in replicated field trials. Genotypic differences occurred for α‐, γ‐ and total tocopherol content as well as α/γ‐tocopherol ratio, but highly significant genotype x environment interactions resulted in low heritabilities. Using a mixed‐model composite interval mapping approach between one and five QTL with additive and/or additive x environment interaction effects could be mapped for α‐, γ‐ and total tocopherol content and α/β‐tocopherol ratio. In addition, one to six locus pairs with epistatic interaction effects were identified, indicating a strong contribution of epistasis to trait variation. In total, the additive and epistatic effects explained between 28% (α‐tocopherol content) and 73% (total tocopherol content) of the genotypic variance in the population, with individual QTL and locus pairs contributing between 7.5 and 29.2% of variance. Considering the low heritabilities of the tocopherol traits, the results of this study indicate that marker‐assisted selection may be an efficient strategy in a breeding program for enhanced tocopherol content in rapeseed.
Histological and inheritance studies of partial resistance in the Brassica napus–Albugo candida host‐pathogen interaction
Authors: Bansal V. K. , Tewari J. P. , Stringam G. R. , Thiagarajah M. R. 
Published: February 2005

AbstractTraditional and doubled haploid (DH) genotypes of oilseed Brassica spp. resistant, partially resistant, moderately susceptible, and susceptible to Albugo candida were compared for phenotypic development of host‐pathogen interaction and histology of host‐pathogen interaction. The partially resistant genotype showed pinhead‐size pustules, mainly on the upper surface of cotyledonary leaves. Relatively less mycelium was observed in the partially resistant genotype compared with the susceptible genotype. In resistant B. napus genotypes, there was neither pustule development nor any mycelial growth. In the moderately susceptible genotype, the pustules were similar to those in the partially resistant genotype in being of pinhead‐size and occasionally coalescing. However, ample mycelial growth in the mesophyll tissue in the moderately susceptible genotype was similar to that in the susceptible control B. rapa cv. ‘Torch’. The susceptible genotype B. rapa cv. ‘Torch’ also showed large coalescing pustules. In the non‐host B. juncea cv. ‘Commercial Brown’, no pustules were formed although some mycelial growth was observed beneath the epidermal cell layer and in the mesophyll cell layer of the cotyledonary leaf tissue. For inheritance studies, two partially resistant B. napus genotypes were crossed with a resistant B. napus genotype. Various generations viz., F1, F1(reciprocal), F2, and DHs produced from the crosses were inoculated with a zoospore suspension of race 7v of A. candida. The partially resistant phenotype appeared to be controlled by a single recessive gene designated as wpr with variable expression. The simple inheritance of partial resistance has implications for disease resistance breeding against white rust, as this type of resistance can be easily incorporated into elite breeding lines through conventional and DH breeding methods.
Statin therapy improves brachial artery vasodilator function in patients with Type 1 diabetes and microalbuminuria
Authors: Dogra G. K. , Watts G. F. , Chan D. C. , Stanton K. 
Published: February 2005

AbstractAims  Type 1 diabetes mellitus patients with microalbuminuria have endothelial dysfunction associated with the degree of albuminuria but not with LDL‐cholesterol levels. Lipid‐lowering agents such as statins may still be of benefit as they can correct endothelial dysfunction by both lipid and non‐lipid mechanisms. We therefore examined the effects of atorvastatin on brachial artery endothelial dysfunction in these patients.Methods  In a double‐blind, randomized crossover study, 16 Type 1 diabetes mellitus patients with microalbuminuria received 6 weeks of atorvastatin 40 mg/day or placebo, separated by a 4‐week washout. Brachial artery, endothelium‐dependent, flow‐mediated dilatation (FMD) and endothelium‐independent, glyceryl trinitrate‐mediated dilatation (GTNMD) were measured.Results  Compared with placebo, atorvastatin produced a significant decrease in apolipoprotein B (34.2%), LDL‐cholesterol (44.1%) (all P < 0.001), and oxidized‐LDL (35.7%, P = 0.03). There was a non‐significant increase in plasma cGMP (P = 0.13) on atorvastatin. FMD and GTNMD increased significantly on atorvastatin (FMD: atorvastatin +1.8 ± 0.4%; placebo +0.2 ± 0.4%, P = 0.007); (GTNMD: atorvastatin +1.3 ± 0.9%; placebo −1.2 ± 0.6%, P = 0.04). An increase in cGMP was independently correlated with an increase in FMD on atorvastatin (adjusted R2 0.41, P = 0.02).Conclusion  Atorvastatin improves endothelium‐dependent and independent vasodilator function of the brachial artery in Type 1 diabetes mellitus patients with microalbuminuria. This may relate to pleiotropic effects of statins, in particular reduced oxidative stress and increased availability of nitric oxide.