bluuebunny/crossref_metadata_2025 huggingface dataset:
Phenotypic plasticity in Phlox. III. Variation among natural populations of P. drummondii
Authors: Schlichting Carl D. , Levin Donald A.
Published: March 2003

Amounts and patterns of phenotypic plasticity were measured for seven populations of the Texas annual Phlox drummondii. Individuals from each population were grown in a factorial greenhouse experiment involving five treatments: control, low water, leaf removal, low nutrients, and small pots. Ten traits, representing aspects of biomass, shape, reproduction, and allocation, were measured for each plant. Results of two‐way ANOVA (population by treatment interaction) indicated variation in plasticity for 6 of the 10 traits. Pairwise two‐way ANOVAs on these traits allowed identification of the particular populations responsible for the overall population by treatment interactions. Five populations had relatively similar plastic responses, while two populations differed substantially from the others. The patterns of plasticity of certain traits (e.g. root/shoot ratio) showed very little divergence among populations compared to other traits. Divergence among populations based on the plasticities of traits differed substantially from the pattern of divergence based on trait means, indicating that the plastic responses of traits are able to evolve independently of the traits themselves.
Can transposable element copy number distribution parameters be estimated from natural populations of Drosophila melanogaster?
Authors: Quesneville Hadi , Katz Mariano , Anxolabéhère Dominique
Published: March 2003

The copy frequency distribution of a transposable element family in a Drosophila melanogaster natural population is generally characterised by the values of the Charlesworths' model parameters α and β (Charlesworth & Charlesworth, 1983). The estimation of these parameters is made using the observed distribution of the occupied sites in a population sample. Several results have been interpreted as due either to the influence of stochastic factors or to deterministic factors (transposition, excision, selection…). The accuracy of this method was tested by estimations performed on samples from simulated populations. The results show that with the sample size usually used for natural population studies, the confidence intervals are too large to reasonably deduce either the element copy number distribution or the values of transposition and excision rate and selective coefficients.
Phenotypic selection on morphology at independence in the Chinstrap penguin Pygoscelis antarctica
Authors: Moreno  , Barbosa  , León  , Fargallo
Published: March 2003

Every year, shortly after the emancipation of chicks at our study colony (Deception Island, South Shetlands), hundreds of carcasses of presumably starved Chinstrap penguin Pygoscelis antarctica chicks are washed on the shore. In 1997 we measured the flippers of fresh carcasses and compared their lengths with those of live chicks about to become independent. There was a highly significant difference of 6.5 mm between both distributions, which suggests strong directional phenotypic selection on skeletal size operating through its association with body reserves at independence. Given that heritabilities of flipper length and body weight measured on 36 families are 0.73(± 0.32) and 0.075(± 0.081), and that both characters show a genetic correlation of 0.44(± 0.14), we can expect an evolutionary response to this selection episode. Assuming that the target of selection is weight at emancipation (heavier chicks carry proportionally larger reserves), and that flipper length changes as a consequence of its genetic correlation with weight, we can predict a response of 1.32–2.87 mm or 0.23–0.51 standard deviation units for flipper length. This substantial evolutionary response may be countered by other selective pressures affecting other life stages of these birds. Selection on reserve storage capacity at independence may affect morphological traits also in other species.
Evolution of mimicry in the New World Dysdercus (Hemiptera: Pyrrhocoridae)
Authors: Zrzavý J. , Nedvěd O.
Published: March 2003

Evolution of mimicry rings is reconstructed for the New World species of cotton-stainer bugs (Dysdercus, Hemiptera: Pyrrhocoridae). Using a cladistic analysis of 43 species (including D. silaceus Doesburg, 1968 stat. nov. and D. modestus Doesburg, 1968 stat. nov.), evolution of colour patterns and biogeographical history of the clade are hypothesized. Three probable mimicry rings are obtained from the analysis, together with data about their possible model–mimic or comimic–comimic structures: (a) ‘Yellow’ species in north-western South America and in the Andes (several possible models, D. rusticus, D. mimus part., D. imitator part., and D. collaris part. as mimics); (b) ‘Median Yellow–Black’ species with a median-forewing black pattern in north-western South America and Central America (several possible models, D. basialbus as a mimic); (c) ‘Median Red–Black’ species with a median-forewing black pattern in the Caribbean islands (D. andreae, D. discolor, D. neglectus–D. sanguinarius clade, and D. jamaicensis–D. fervidus–D. ocreatus clade as comimics). A few additional, less supported rings are also identified. Two highly polymorphic species (D. obscuratus, D. mimus) seem to enter different mimicry rings in different regions.
Do females adjust the sex of their offspring in relation to the breeding sex ratio?
Authors: Bensch  , Westerdahl  , Hansson  , Hasselquist
Published: March 2003

When the adult sex ratio differs between years in local populations, but still is predictable between adjacent years, it has been proposed that the best strategy would be to bias the offspring sex ratio in favour of the rare sex. We tested this hypothesis using a data set of great reed warbler offspring, sexed by molecular techniques, that were collected over 11 breeding seasons at two adjacent reed marshes. Three important assumptions for this hypothesis are fulfilled in the studied great reed warbler population. First, a substantial proportion of great reed warblers are living in small local populations where sex ratio distortions would be sufficiently large and common. Second, breeding adults and their offspring return to breed in the local population to a high degree. Third, females have a possibility to assess the breeding sex ratio before laying their eggs. At our study site, the breeding sex ratio was positively correlated between successive years. However, contrary to our prediction, female great reed warblers seemed not to adjust their offspring sex ratio in relation to the local breeding sex ratio.
Effects of competition on lifetime estimates of inbreeding depression in the outcrossing plant Crepis sancta (Asteraceae)
Authors: Cheptou  , Imbert  , Lepart  , Escarre
Published: March 2003

Inbreeding depression was studied in two populations of a Mediterranean allogamous colonizing species Crepis sancta. In order to test the hypothesis that the magnitude of inbreeding depression can be modified by successional processes, the growth and survival of individuals resulting from two generations of inbred crosses including selfing were analysed with interspecific competition (in natural vegetation) and without interspecific competition (by removing natural vegetation). Inbreeding depression was weak for seed production. Germination was little affected by inbreeding but mortality and the number of capitula showed inbreeding depression, especially in the presence of competition. This suggests that inbreeding depression is very sensitive to variations in environmental conditions such as interspecific competition. As a consequence, inbreeding depression cannot be considered as constant in natural conditions.
Split sex ratios and virginity in a gall-inducing thrips
Authors: Kranz  , Schwarz  , Giles  , Crespi
Published: March 2003

Split sex ratios have been predicted in haplodiploid populations with high proportions of reproductive virgins, but there has been little empirical support. We found such split sex ratios in the gall-inducing thrips, Kladothrips rugosus. Sex ratios of juveniles from 96 galls were determined using chaetotaxy over two consecutive summers. The population-wide sex ratio was unbiased, but bimodal. Twenty-four per cent of galls only contained male juveniles. These galls were induced by a female that was probably a virgin. The mean sex ratio of all other galls was 0.36 ± 0.02, which is not significantly different from the theoretical evolutionarily stable sex ratio of 0.34, calculated from a previous model ( Godfray, H.C.J. 1990. J. Evol. Biol. 3: 3–17) for 24% constrained females in a panmictic population. These data provide the first empirical support for the constrained sex allocation model of Godfray.
Evolutionary transition to a semelparous life history in the socially parasitic ant Acromyrmex insinuator
Authors: Bekkevold  , Boomsma
Published: March 2003

The recently discovered social parasite Acromyrmex insinuator ( Schultz, Bekkevold & Boomsma 1998) exploits colonies of the leafcutter ant A. echinatior. We document that A. insinuator represents a rare early stage in the evolution of social parasitism, because a worker caste is still partially present and mating phenology has remained at least partially similar to that of the host. A. insinuator is tolerant of host queens, and sexual offspring produced in parasitized colonies can be either exclusively A. insinuator or a mix of A. insinuator and A. echinatior. The remarkably high abundance of A. insinuator in nests of the investigated Panamanian host population and the fact that A. insinuator colonies readily reproduce under laboratory conditions allowed us to test evolutionary predictions on reproductive life history evolution that are not possible in most other socially parasitic ants. We show that (1) A. insinuator has a semelparous ‘big bang’ reproductive life history which exploits host colonies without leaving reserves for survival; (2) social parasite sexuals are significantly smaller than A. echinatior host sexuals, but still large compared to host workers, confirming an evolutionary scenario of gradual size reduction and loss of the worker caste after transition towards a socially parasitic life history; (3) major changes in the life history of ants can evolve relatively quickly compared to adaptations in morphology, caste differentiation and mating phenology.
Fertility selection, genetic selection and evolution
Authors: Campbell
Published: March 2003

The relationship between fertility selection as measured by the correlation in progeny number between parents and offspring, and selection at individual loci is investigated in humans. Estimates for the magnitude of fertility selection (0.1) and the rate of gene substitution (0.5 gene substitutions per generation per genome) are used in various mathematical models for selection. It is found that the observed magnitude of fertility selection cannot be explained by non-epistatic directional selection at individual loci. A symmetric quantitative directional selection model is consistent with the observed data. But it is possible that fertility selection does not have a genetic basis.
Contrasting population genetic structures using allozymes and the inversion polymorphism in Drosophila buzzatii
Authors: Rodriguez C. , Piccinali R. , Levy E. , Hasson E.
Published: March 2003

Second chromosome inversion and genotypic frequencies at seven allozyme loci, differentially associated with inversions, were determined in seven natural populations of Drosophila buzzatii. The patterns of variation of allozymes and the inversion polymorphisms were significantly different, indicating the role of adaptive differentiation for the latter. Moreover, the patterns of population structure varied among allozyme loci, suggesting the operation of diversifying selection for certain loci. Differentiation was negligible for Leucyl-amino peptidase (Lap) and Peptidase-2 (Pep-2), low to moderate for Aldehyde oxidase (Aldox), Peptidase-1 (Pep-1) and Esterase-1 (Est-1) and high for Esterase-2 (Est-2) and Xanthine dehydrogenase (Xdh). Significant linkage disequilibria were detected between inversions and Aldox, Est-1, Est-2 and Xdh. Multiple regression analyses of inversion and allele frequencies on environmental variables revealed the existence of clines for inversions, Est-1, Est-2, Xdh and Aldox along altitudinal, latitudinal and/or climatic gradients. Tests using conditional allele frequencies showed that Est-1 and Aldox clines could be accounted for by hitchhiking with inversions, whereas natural selection should be invoked to explain the clines observed for Est-2 and Xdh.
Direct and correlated responses to selection on age at physiological maturity in Drosophila simulans
Authors: Promislow D. E. L. , Bugbee M.
Published: March 2003

Biologists who study the timing of development in insects have focused on variation in duration of pre-adult stages almost without exception. However, development is not complete until adults are not only morphologically mature, but also reproductively mature. Here we describe an experiment in the fruit fly, Drosophila simulans, in which we used artificial selection to create lines with shortened and lengthened duration from eclosion to the age when the first egg was laid. We found significant genetic variation for this trait. The response to selection on age when the first egg was laid was due to variation among females. Delayed adult development was correlated with rapid pre-adult development and longer life span in females. The approach we use here resolves some difficulties with previous approaches used to study the genetics of senescence, and provides an opportunity to study the hitherto unexamined predictions derived from classic models for the evolution of senescence.
Female polyandry affects their sons’ reproductive success in the red flour beetle Tribolium castaneum
Authors: Bernasconi G. , Keller L.
Published: March 2003

A potential benefit to females mating with multiple males is the increased probability that their sons will inherit traits enhancing their pre- or post-mating ability to obtain fertilizations. We allowed red flour beetle (Tribolium castaneum) females to mate on three consecutive days either repeatedly to the same male or to three different males. This procedure was carried out in 20 replicate lines, 10 established with wild-type, and 10 with the Chicago black morph, a partially dominant phenotypic marker. The paternity achieved by the sons of females from polyandrous vs. monandrous lines of contrasting morph was assessed in the F1, F2 and F3 generation by mating wild-type stock females to two experimental males and assigning the progeny to either sire based on phenotype. The sons of polyandrous wild-type females achieved significantly higher paternity when mating in the second male role than the sons of monandrous wild-type females. By contrast, when mating in the first male role, males produced by females from polyandrous lines tended to have lower paternity than males from monandrous lines. Both effects were independent of the number of mates of the black competitor’s mother, and interacted significantly with the number of progeny laid by the female. These results provide the first evidence that manipulating the number of mates of a female can influence her sons’ mating success and suggest a potential trade-off between offence and defence in this species.
Evolutionary convergence of body shape and trophic morphology in cichlids from Lake Tanganyika
Authors: RÜber L. , Adams D. C.
Published: March 2003

A recent phylogenetic analysis of mitochondrial DNA sequences from eretmodine cichlids from Lake Tanganyika indicated independent origins of strikingly similar trophic specializations, such as dentition characters. Because genetic lineages with similar trophic morphologies were not monophyletic, but instead were grouped with lineages with different trophic phenotypes, raises the question of whether trophic morphology covaries with additional morphological characters. Here, we quantified morphological variation in body shape and trophically associated traits among eretmodine cichlids using linear measurements, meristic counts and landmark-based geometric morphometrics. A canonical variates analysis (CVA) delineated groups consistent with dentition characters. Multivariate regression and partial least squares analyses indicated that body shape was significantly associated with trophic morphology. When the phylogenetic relationships among taxa were taken into account using comparative methods, the covariation of body shape and trophic morphology persisted, indicating that phylogenetic relationships were not wholly responsible for the observed pattern. We hypothesize that trophic ecology may be a key factor promoting morphological differentiation, and postulate that similar body shape and feeding structures have evolved multiple times in independent lineages, enabling taxa to invade similar adaptive zones.
Genetic structure of Polytrichum formosum in relation to the breeding system as revealed by microsatellites
Authors: Van Der Velde M. , Van De Zande L. , Bijlsma R.
Published: March 2003

Microsatellite variation was determined for three Danish and three Dutch populations of the haploid moss species Polytrichum formosum to gain insight into the relative importance of sexual vs. asexual reproduction for the amount and structure of genetic variation. In general, low levels of microsatellite variation were observed within this species. Even when estimated for polymorphic loci only, the levels of microsatellite variability (P=90.6, A=4.3 and HS=0.468) within populations were on average lower than those reported for most other plant species. In contrast, genotypic diversity was high within each of the examined populations, indicating that sexual reproduction is a very important determinant of the genetic structure of P. formosum within populations. In agreement with previous findings for allozyme data, no significant genetic differentiation (FST=0.028, RST=0.015) was observed neither between populations nor between regions approximately 450 km apart (Denmark vs. the Netherlands). These low levels of population differentiation observed for both types of genetic markers are probably best explained by a high level of effective spore dispersal (gene flow) between populations. Therefore, also on a large geographical scale sexual reproduction is the most important determinant of the genetic structure of P. formosum, despite the high potential to reproduce clonally.
Female- and male-specific signals of quality in the barn owl
Authors: Roulin A. , Dijkstra C. , Riols C. , Ducrest A.-L.
Published: March 2003

Most bird studies of female signalling have been confined to species in which females display a male-ornament in a vestigial form. However, a great deal of benefit may be gained from considering phenotypic traits that are specific to females. This is because (1) sex-specific traits may signal sex-specific qualities and (2) females may develop a male-ornament not because they are selected to do so, but because fathers transmit to daughters the underlying genes for its expression (genetic correlation between the sexes). We investigated these two propositions in the barn owl Tyto alba, a species in which male plumage is lighter in colour and less marked with black spots than that of females. Firstly, we present published evidence that female plumage spottiness reflects parasite resistance ability. We also show that male plumage coloration is correlated with reproductive success, male feeding rate and heart mass. Secondly, cross-fostering experiments demonstrate that plumage coloration and spottiness are genetically correlated between the sexes. This implies that if a given trait value is selected in one sex, the other sex will indirectly evolve towards a similar value. This prediction is supported by the observation that female plumage coloration and spottiness resembled that of males, in comparisons at the level of Tyto alba alba populations, Tyto alba subspecies and Tyto species. Our results therefore support the hypothesis that sex-specific traits signal sex-specific qualities and that a gene for a sex-specific trait can be expressed in the other sex as the consequence of a genetic correlation between the sexes.
Predicting the evolution of sexual size dimorphism
Authors: Reeve J. P. , Fairbairn D. J.
Published: March 2003

Lande’s (1980b, Evolution34: 292–305) equations for predicting the evolution of sexual size dimorphism (SSD) through frequency-dependent sexual selection, and frequency-independent natural selection, were tested against results obtained from a stochastic genetic simulation model. The SSD evolved faster than predicted, due to temporary increases in the genetic variance brought about by directional selection. Predictions for the magnitude of SSD at equilibrium were very accurate for weak sexual selection. With stronger sexual selection the total response was greater than predicted. Large changes in SSD can occur without significant long-term change in the genetic correlation between the sexes. Our results suggest that genetic correlations constrain both the short-term and long-term evolution of SSD less than predicted by the Lande model.
Adaptive radiation versus intraspecific differentiation: morphological variation in Caribbean Anolis lizards
Authors: Knox A. K. , Losos J. B. , Schneider C. J.
Published: March 2003

Lizards in the genus Anolis have experienced adaptive radiation in the Greater Antilles, producing a suite of species morphologically adapted to use different parts of the environment. In the Lesser Antilles, adaptive radiation has not occurred, but on some islands, interpopulational variation is high and represents adaptation to different habitats. We compared the extent of morphological differentiation among Greater Antillean habitat specialists with that exhibited among populations of two species, Anolis marmoratus and A. oculatus, from the Lesser Antillean islands of Guadeloupe and Dominica. Although extensive, intraspecific divergence in the Lesser Antilles is substantially less in magnitude than the differences among habitat specialists in the Greater Antilles. All populations of A. marmoratus are most similar to Greater Antillean trunk-crown habitat specialists, but populations of A. oculatus differ in their affinities: some are similar to trunk-crown anoles, but others are more similar to trunk-ground habitat specialists.
Cryptic male choice: sperm allocation strategies when female quality varies
Authors: Reinhold K. , Kurtz J. , Engqvist L.
Published: March 2003

We examined evolutionary stable sperm allocation and included stochastic variation in male mating frequency, not included in previous models examining sperm allocation strategies. We assumed sperm mixing and variation in female quality and used a genetic algorithm to analyse the evolution of male sperm allocation. Our results show that males should invest more sperm in initial copulations than in subsequent copulations as a male might fail to mate again. The inclusion of variation in female fecundity had no influence on the evolutionary stable sperm allocation strategy if males were unable to recognize female quality. If males were assumed to allocate sperm in response to female quality, the proportion of sperm allocated was positively correlated with female quality. Moreover, with increasing variance in female quality, males conserved more sperm for later copulations. Literature data on sperm allocation from diverse taxa show a good fit with the predictions given by our model.
Different mate preferences by parasitized and unparasitized females potentially reduces sexual selection
Authors: Pfennig K. S. , Tinsley R. C.
Published: March 2003

Parasite-mediated models of sexual selection predict that females should avoid parasitized mates, thereby generating selection on male traits revealing health. The strength of this selection, however, may depend on the prevalence of parasitism among females if their infection status alters their mate preferences. We evaluated the effects of a socially transmitted parasite on male traits and female behaviour in spadefoot toads. Parasitized males were larger and in better condition than unparasitized males. Moreover, better condition males produced longer calls. Unparasitized females preferred longer calls indicative of good-condition males that are more likely parasitized. By contrast, parasitized females as a group possessed no preference for call duration. Presumably because of reduced selection by these parasitized females, male mating success was not associated with any measured traits. Thus, when females are parasitized, sexual selection on condition-dependent traits is potentially reduced.
Evolutionary responses of Drosophila melanogaster to selection at different larval densities: changes in genetic variation, specialization and phenotypic plasticity
Authors: Pérez A. , García C.
Published: March 2003

We studied the evolutionary response to novel environments by applying artificial selection for total progeny biomass in populations of Drosophila melanogaster maintained at three different larval population densities. We found the relative amount of genetic variability for characters related with biomass to be lower and the correlation between them more negative at the intermediate density, and that selection resulted in changes in phenotypic plasticity and in patterns of resource allocation between traits. We found some evidence for tradeoffs between densities, which suggests that populations living at heterogeneous densities might be subject to disruptive selection. Our results show that adaptation to new environments may be a complex process, involving not only changes in trait means, but also in correlations between traits and between environments.
Evolution of the distribution of dispersal distance under distance-dependent cost of dispersal
Authors: Rousset F. , Gandon S.
Published: March 2003

We analyse the evolution of the distribution of dispersal distances in a stable and homogeneous environment in one- and two-dimensional habitats. In this model, dispersal evolves to avoid the competition between relatives although some cost might be associated with this behaviour. The evolutionarily stable dispersal distribution is characterized by an equilibration of the fitness gains among all the different dispersal distances. This cost-benefit argument has heuristic value and facilitates the comprehension of results obtained numerically. In particular, it explains why some minimal or maximal probability of dispersal may evolve at intermediate distances when the cost of dispersal function is an increasing function of distance. We also show that kin selection may favour long range dispersal even if the survival cost of dispersal is very high, provided the survival probability does not vanish at long distances.
Genetics of wing size asymmetry in Drosophila buzzatii
Authors: Santos M.
Published: March 2003

Contemporary approaches that use fluctuating asymmetry (FA) as a possible target for natural and sexual selection are based on the premise that FA is a quantifiable expression of developmental instability (DI) that is inherited. Previous work with Drosophila buzzatii found that male mating success was correlated positively to body size (wing length) and negatively to FA, but these relationships seem to be environmentally induced. Heritability of FA was low and not significantly different from zero, but statistical power was also estimated to be very low and, hence, no conclusive evidence could be obtained. A large half-sib mating design is used here to examine the relationships of different aspects of development for wing size. Consistently with previous findings, I found high heritabilities for wing length (WL) and wing width (WW), and positive correlations between both traits.  Heritabilities of FA (FAWL, FAWW) were low (0.037) but significantly different from zero, and the genetic correlation between FAWL and FAWW was estimated as −1 because the absolute value for the genetic covariance was similar in magnitude or even larger than the estimated genetic variances of both traits. This suggests that these two traits should be considered to be the same character. The between-trait phenotypic correlation in FA, which reduces to the repeatability in this situation, was positive and statistically significant thus rendering an estimate of heritability for DI in D. buzzatii of . Nevertheless, the fact that left/right wing sizes were found to be determined by the same set of genes is difficult to reconcile with the presence of special genetic mechanisms that stabilize left/right development in this species. A qualitatively different pattern for asymmetry was observed when the nonlinear composite character wing area (WA ≈ WL × WW) was used, and . Although the results could be made compatible with the existence of a diallelic locus with antagonistic pleiotropic effects on FAWL and FAWW that combine multiplicatively to produce overdominance for FAWA, the available evidence is extremely weak at best. Finally, a test to the null hypothesis of a nongenetic basis of FA, particularly relevant to those situations when directional asymmetry may be heritable, is suggested.
Selection experiments and the study of phenotypic plasticity
Authors: Scheiner S. M.
Published: March 2003

Laboratory selection experiments are powerful tools for establishing evolutionary potentials. Such experiments provide two types of information, knowledge about genetic architecture and insight into evolutionary dynamics. They can be roughly classified into two types: (1) artificial selection in which the experimenter selects on a focal trait or trait index, and (2) quasi-natural selection in which the experimenter establishes a set of environmental conditions and then allows the population to evolve. Both approaches have been used in the study of phenotypic plasticity. Artificial selection experiments have taken various forms including: selection directly on a reaction norm, selection on a trait in multiple environments, and selection on a trait in a single environment. In the latter experiments, evolution of phenotypic plasticity is investigated as a correlated response. Quasi-natural selection experiments have examined the effects of both spatial and temporal variation. I describe how to carry out such experiments, summarize past efforts, and suggest further avenues of research.
Host choice promotes reproductive isolation between host races of the larch budmoth Zeiraphera diniana
Authors: Emelianov I. , Simpson F. , Narang P. , Mallet J.
Published: March 2003

The chances for sympatric speciation are improved if ecological divergence leads to assortative mating as a by-product. This effect is known in parasites that find mates using host cues, but studies of larch- and pine-feeding races of the larch budmoth (Zeiraphera diniana, Lepidoptera: Tortricidae) suggest it may also occur when mate attraction is via sex pheromones that are independent of habitat. We have previously shown that females releasing pheromones on or near their own host attract more males of their own race than if placed on the alternative host. This host effect would enhance assortative mating provided adults preferentially alight on their native hosts. Here we investigate alighting preferences in natural mixed forest using a novel likelihood analysis of genotypic clusters based on three semidiagnostic allozyme loci. Both larch and pine females show a realized alighting preference for their own host of 86%. The equivalent preferences of males were 79% for the larch race and 85% for the pine race. These preferences are also detectable in small-scale laboratory experiments, where alighting preferences of larch and pine races towards their own hosts were, respectively, 67 and 66% in females and 69 and 63% in males. Pure larch race moths reared in the laboratory had alighting choice similar to moths from natural populations, while hybrids were intermediate, showing that alighting preferences were heritable and approximately additive. The field estimates of alighting preference, coupled with earlier work on mate choice, yield an estimated rate of natural hybridization between sympatric host races of 2.2–3.8% per generation. Divergent alighting choice enhances pheromone-mediated assortative mating today, and is likely to have been an important cause of assortative mating during initial divergence in host use. Because resources are normally ‘coarse-grained’ in space and time, assortative mating due to ecological divergence may be a more important catalyst of sympatric speciation than generally realized.
Rapid detection of antibodies to immunoglobulin A molecules by using the particle gel immunoassay
Authors: Salama A. , Schwind P. , Schönhage K. , Genth R. , Cotting C. , Hustinx H. , Krieg R. , Nydegger U. , Aebischer I.
Published: March 2003

Background and Objectives

Antibodies to immunoglobulin A (IgA) molecules are thought to be frequently responsible for anaphylactic reactions in transfusion medicine, but practical tests for the detection of antibodies to IgA are not yet available.

Material and Methods

Red, high‐density polystyrene beads were coated with purified IgA molecules and then used to test serum samples collected from unselected healthy blood donors (n = 105) and patients with common variable immunodeficiency and/or IgA deficiency (n = 44). For testing, the standard gel‐agglutination technique (ID‐Micro Typing System) was employed.

Results

None of the normal serum samples were reactive with IgA‐coated beads and samples from only 10 patients were positive (titre range 1 : 2 to 1 : 256). Only one out of all patients studied had a history of an anaphylactic reaction and this was related to the administration of Rh(D) prophylaxis (anti‐D immunoglobulin). The beads did not show non‐specific agglutination and could be used repeatedly for longer than 6 months. The results were reproducible in all patients tested.

Conclusion

The new test allows a specific and rapid detection of antibodies to IgA molecules. In order to evaluate the clinical relevance of the test, analysis is required of a wider range of antibodies that produce anaphylactic reactions.
Molecular characterization of weak D phenotypes by site‐directed mutagenesis and expression of mutant Rh–green fluorescence protein fusions in K562 cells
Authors: Kamesaki T. , Iwamoto S. , Kumada M. , Omi T. , Okuda H. , Tanaka M. , Takahashi J. , Obara K. , Seno T. , Tani Y. , Kajii E.
Published: March 2003

Background and Objectives

Mutations detected in 161 weak D samples from Caucasians have been classified into 16 types. Because flow cytometry using monoclonal anti‐D antibodies (mAbs) has shown that weak D red cells display type‐specific antigen density, these mutations in transmembranous regions have been assigned weak D phenotypes. The present study attempts to confirm or refute this assignment.

Materials and Methods

We amplified DNA from four Japanese weak D samples using the polymerase chain reaction (PCR), and directly sequenced the amplified DNA. Using site‐directed mutagenesis, we constructed three vectors expressing mutantRHDs – G212C, V270G (weak D type 1) and G358A (type 2) – in K562 cells. The expression of RhD antigens was examined by flow cytometry using mAbs.

Results

A new mutation resulting in a conversion at amino acid residue 212 (Gly to Cys) was detected in a Japanese weak D sample. K562 cells transduced with mutantRhDcDNA reacted weakly in a type‐specific manner with mAbs.

Conclusions

The mutations – G212C (new weak D type), V270G (weak D type 1) and G358A (type 2) – in transmembranous regions had obvious effects on the D epitopes recognized by mAbs. The results of this study provide direct evidence that these mutations can account for weak D phenotypes.
Anti‐U‐like: a common antibody in Black individuals
Authors: Janvier D. , Lam Y. , Maury J.
Published: March 2003

Background and Objectives Anti‐Uz, a scarce antibody, defines a glycophorin B high‐incidence antigen, which is protease‐sensitive. In a few years, we have encountered 12 antibodies of similar specificity, made by Black individuals of the S− s+ U+ phenotype.

Materials and Methods Antibodies were characterized by serological methods, with common and rare MNS types, as well as red cells treated with various proteases.

Results Anti‐U‐like, mostly an autoantibody, was of IgG class and reacted optimally by indirect antiglobulin test at 20 °C. The corresponding antigen was destroyed by several proteases. Tests with papain‐treated or Dantu+ cells suggested the existence of several subspecificities.

Conclusion Anti‐U‐like is common in the African population, though its reactions are often misinterpreted. The fact that antibody producers are always Black patients remains unexplained. No relationship with a pathological state could be established.
Prestorage leucocyte reduction of red cell components prevents release of bactericidal permeability increasing protein and defensins
Authors: Fransen E. J. , Rombout‐Sestrienkova E. , Van Pampus E. C. M. , Buurman W. A. , Reutelingsperger C. P. M. , Maessen J. G.
Published: March 2003

Background and Objectives In this study we examined whether prestorage leucocyte reduction prevents the accumulation of bioreactive substances in red cell units.

Materials and Methods Measurements were performed in the supernatants of buffy‐coat‐depleted (standard red cells) and leucocyte‐reduced (filtered red cells) red cell units. The effect of storage was evaluated by taking repetitive samples up to 35 days after donation. We determined the concentrations of polymorphonuclear neutrophil (PMN)‐derived bactericidal permeability increasing protein (BPI), defensins and annexin A5. In addition, leucocyte counts (using nageotte chamber) were performed on days 0 and 35.

Results During storage, the concentrations of BPI, defensins and annexin A5 in standard red cells gradually increased. However, in the filtered red cells BPI and defensins were found in only a few samples, whereas the annexin A5 concentration in these units did not change during storage. Haemolysis data in both types of red cell components were similar at all time‐points, except prestorage. Significant correlations were found between the release of BPI, defensins and annexin A5 into red cell units and the loss of leucocytes during storage.

Conclusions PMNs lose their membrane integrity during cold storage and release their contents into red cell components. Prestorage leucocyte reduction of red cell components prevents the accumulation of BPI, defensins and annexin A5.
Cytokine levels as performance indicators for white blood cell reduction of platelet concentrates
Authors: Wadhwa M. , Krailadsiri P. , Dilger P. , Gaines Das R. , Seghatchian M. J. , Thorpe R.
Published: March 2003

Background and ObjectivesWith the implementation of universal white blood cell (WBC) reduction in the UK, in‐process WBC‐reduction filters for pooled buffy coat (BC)‐derived platelet concentrates (PCs) and apheresis methods are used routinely for the production of WBC‐reduced PCs. While these strategies meet the specification for WBC reduction (< 5 × 106WBCs/unit), the products from these processes may differ depending on the process employed and its performance. The aim of this study was therefore to investigate whether PCs prepared using various WBC‐reduction processes are sufficiently depleted of WBCs to limit cytokine accumulation during storage and to assess if cytokine levels detected in platelet products can serve as indicators of acceptable platelet activation as a result of the WBC‐reduction process.

Materials and MethodsWe measured the levels of cytokines predominantly derived from WBCs [e.g. interleukin‐8 (IL‐8)] and platelets [e.g. regulated on activation, normal, T‐cell expressed, and secreted (RANTES) and transforming growth factor‐β1(TGF‐β1)] under the present experimental conditions in different WBC‐reduced PCs, i.e. PCs prepared from three different WBC‐reduction filters and control non‐filtered PCs using pooled BCs from the same donors and three apheresis types. Supernatant plasma was collected at the beginning (day 1) and end (day 5) of the shelf life of each PC, and the cytokine content was determined using appropriate enzyme‐linked immunosorbent assays (ELISAs). Process efficiency was assessed by platelet yield and residual WBC count.

ResultsWe found that products from the apheresis process involving a filtration step (Haemonetics MCS+) showed a lower cytokine content on both day 1 and day 5 in comparison with the fluidized bed (COBE Spectra) or elutriation (Amicus) processes. WBC reduction of BC‐PCs of the same origin using three different filters showed comparable levels of cytokines on day 1 in all units. After storage for 5 days, the levels of IL‐8 remained essentially unchanged in filtered BC‐PCs but increased by more than threefold in control non‐filtered BC‐PCs, suggesting IL‐8 release by residual WBCs present in the control PCs. The concentration of platelet‐derived cytokines such as RANTES and TGF‐β1, however, increased significantly in all filtered and control non‐filtered PCs during the storage period.

ConclusionThese results show that markers of cytokine release from both WBCs and platelets are useful indicators of the performance and efficacy of the WBC‐reduction process and of platelet quality.
Purification of human immunoglobulin G: a new approach to plasma fractionation
Authors: Li G. , Stewart R. , Conlan B. , Gilbert A. , Roeth P. , Nair H.
Published: March 2003

Background and Objectives Currently, plasma fractionation involves multiple processing steps using established methods such as ethanol precipitation and column chromatography. The known limitations associated with conventional purification techniques, combined with strict regulations on safety and high demand for particular plasma proteins, have resulted in a shortage of plasma‐derived therapeutics such as intravenous immunoglobulin G (IgG).

Materials and Methods In this study, IgG was purified from human plasma using Gradiflow technology, an electrophoresis‐based separation technology.

Results IgG was isolated from plasma to high purity, with 94 ± 5% recovery in a short processing time.

Conclusions The technology has been shown to be linearly scalable and has the capacity to contribute to increased production of important plasma fraction therapeutics.
Inactivation of viral and prion pathogens by γ‐irradiation under conditions that maintain the integrity of human albumin
Authors: Miekka S. I. , Forng R.‐Y. , Rohwer R. G. , MacAuley C. , Stafford R. E. , Flack S. L. , MacPhee M. , Kent R. S. , Drohan W. N.
Published: March 2003

Background and Objectives The administration of therapeutic plasma protein concentrates has been associated with the real risk of transmitting viral diseases and the theoretical risks of prion transmission. Our objective was to determine if γ‐irradiation can inactivate viral or prion infectivity without damaging a protein biotherapeutically.

Materials and Methods Human albumin 25% solution, spiked with four model viruses (including porcine parvovirus) or with brain homogenate from scrapie‐infected hamsters, was γ‐irradiated at constant low‐dose rates and assayed for viral and prion infectivity or for albumin integrity.

Results At a radiation dose of 50 kGy, viruses were inactivated by ≥ 3·2 to ≥ 6·4 log10 and scrapie by an estimated 1·5 log10, whereas albumin was only moderately aggregated and fragmented.

Conclusions γ‐Irradiation can preferentially inactivate viral and prion pathogens without excessive damage to albumin structure.
Pharmacological approaches to reducing allogeneic blood exposure
Authors: Kovesi T. , Royston D.
Published: March 2003

This article discusses evidence for the role of pharmacological interventions such as the protease inhibitor aprotinin (Trasylol®), lysine analogue anti‐fibrinolytics [tranexamic acid (Cyclokapron®) and epsilon aminocaproic acid (Amicar®)], DDAVP (Desmopressin®) and recombinant Factor VIIa (NovoSeven®), in preventing the need for blood and blood‐component therapies after major (cardiac, hepatic and orthopaedic/trauma) surgery. The data show that aprotinin is consistently effective in reducing globally the transfusion burden in cardiac and hepatic surgical procedures. However, there are little data to support its use in routine elective orthopaedic surgery. Multiple studies have failed to show an increased risk for myocardial ischaemia or infarction with aprotinin, and there may even be a reduced incidence of perioperative stroke in patients undergoing cardiac surgery. An increased probability of a hypersensitivity reaction when the drug is readministered within a 6‐month period remains a significant issue. The data for the lysine analogue anti‐fibrinolytics show no evidence of efficacy in reducing the transfusion burden for epsilon aminocaproic acid and inconsistent results with tranexamic acid in cardiac and hepatic surgery. As with aprotinin therapy, there is a paucity of data to support their use in routine elective orthopaedic surgery. There are no data to support the routine use of DDAVP to reduce the transfusion burden. Limited data suggest that this drug may be effective when a defect in platelet function is demonstrated. This aspect deserves further investigation. Recombinant activated Factor VII (rFVIIa) has proven benefit for its licensed indication to reduce bleeding in haemophiliacs with inhibitors to Factors VIII and IX. Reports of benefit in other instances are largely anecdotal. Hence, at this time it is therefore speculative and premature to suggest whether there is a place for this agent in routine clinical practice. No adequately powered, placebo‐controlled prospective studies are available to investigate the safety of the lysine analogues, DDAVP or rFVIIa in cardiac, hepatic or orthopaedic surgery.