bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cladistic analysis of blue‐green procaryote interrelationships and chloroplast origin based on 16S rRNA oligonucleotide catalogues
Authors: Bremer Birgitta , Bremer K»re 
Published: March 2003

AbstractOligonucleotide catalogues from 16S rRNA have been a major source of information for phylogenetic reconstruction among procaryotes. Several large procaryote groups have been analyzed and phylogenies presented. Catalogues are also available for many chloroplasts. The hypotheses of phylogeny are derived mainly from similarity (phenetic) comparisons of the catalogues and the extent of the homoplasy (parallelisms and reversals) involved has not been estimated properly. Although catalogues are currently being superseded by complete sequence data, an evaluation of the strength of catalogue data, and hence of the strength of the extensive phylogenetic hypotheses derived from them, is in order. Cladistic analysis of 16S rRNA oligonucleotide catalogues from three blue‐green procaryotes, Prochloron, and chloroplasts of a red alga, Euglena, a green alga and two flowering plants shows that there is extensive homoplasy in the catalogues and several phylogenetic trees are possible. The corresponding consensus trees indicate that little or nothing can be said about interrelationships and chloroplast origin on the basis of these particular catalogues, except that Prochloron may be more closely related to the blue‐greens than to chloroplasts.
Phenotypic plasticity in Phlox. III. Variation among natural populations of P. drummondii
Authors: Schlichting Carl D. , Levin Donald A. 
Published: March 2003

AbstractAmounts 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

AbstractThe 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.