bluuebunny/crossref_metadata_2025 huggingface dataset:
Using a phenomenological research technique to examine student nurses' understandings of experiential teaching and learning: a critical review of methodological issues
Authors: Green Anita J. , Holloway David G.
Published: December 2004

This paper provides a report of the usage of a phenomenological research methodology to investigate the influence on clinical practice of pre‐ and post‐registration nurse education which makes explicit use of experiential teaching and learning approaches. The primary aim of the research was to explore the use of a phenomenological research methodology to examine the students'understanding of experiential teaching and learning. The claims made for the use of experiential teaching and learning approaches in both pre‐ and post‐registration nurse courses and how clinical practice is influenced by the experiential learning elements of pre‐ and post‐registration nurse education were also examined. The first stage of the enquiry involved focused non‐directive interviews with members of BSc Nursing Studies and MSc Mental Health Branch programmes. Both programmes claim to make use of experiential teaching and learning. The data were analysed using a technique developed by Giorgi. Previous experiences of experiential teaching and learning were probed, student interpretations differentiated, and the relationship between course‐based learning using experiential approaches and the implications for it's influence on practice were examined. The second stage of the enquiry has followed up the initial findings, exploring the students'experience of experiential approaches on their courses both in the classroom and in work‐based learning situations. The findings are presented and discussed in the context of other studies from both nurse and higher education. Throughout the paper methodological concerns arising are discussed. The paper concludes with the identification of methodological problems arising from the research strategy: the implications of the power nexus created when teachers research students, and issues relating to the use of a phenomenological methodology in a longitudinal study.
Professional caring: a contradiction in terms?
Authors: Woodward Vivien M.
Published: December 2004

The caring activities which are traditionally associated with the nursing and midwifery professions comprise two essential and inseparable elements: the instrumental and expressive. Yet the former appears to be attracting an emphasis which threatens the integrity of the whole. In this paper, the reduction in altruistic values in society is identified as one possible cause, and examples of practice which fall short of the ideal are identified. Also, the ways in which current educational, professional and organizational goals appear detrimental to expressive caring, while endorsing the instrumental component, are discussed. It is argued that in order for caring, in its traditional sense, to be perpetuated in practice, there is need for increased educational focus, the ability of practitioners to identify the implications of current changes in the United Kingdom for practice and the commitment to maintain caring as a central value.
A ‘bonding between strangers’: a palliative model of clinical supervision
Authors: Jones Alun
Published: December 2004

This paper examines the role of clinical supervision in relation to the work of palliative care nurses. Through a single ‘paradigm’ case study illustration the author explores a phenomenologically guided palliative method of supervision. It is suggested that such means of supervized clinical practice forge a bond between patients, families, nurse and colleagues. The discussion explores ethical issues related to supervisory relationships including language, power and gender. The paper concludes with the central recommendation that, aside from methodological considerations, constructing a safe working environment for clinical supervision is important.
Use of the QSR.NUD.IST computer program to identify how clinical midwife mentors view their work
Authors: Davis Catherine , Davis Bryn D. , Burnard Philip
Published: December 2004

This paper looks at the use of a computer program (QSR.NUD.IST) to analyse qualitative data. The data are derived from interviews with clinical midwife mentors as part of an evaluation of a midwifery educational programme. An account is given of the content analysis of the data with reference to the literature, and then the way the programme was used to analyse the data a second time. A description is given of the way this programme in particular functions using the textual data as an example. The use of computers in general for analysing qualitative data is discussed in terms of their advantages and disadvantages. The results of the study are described briefly showing how the mentors view their role and responsibilities.
Elements of psychological support in nursing care
Authors: Motyka Marek , Motyka Helena , Wsołek Romana
Published: December 2004

The paper presents the results of a pilot study which involved 50 nurses from several departments of internal medicine of The State Clinical Hospital of the Collegium Medicum, Jagiellonian University in Cracow. The results are based on the Statement Response Questionnaire. They show that the most common responses of the nurses in the face of anxiety expressed by patients are cheering up the patient, collecting information about the symptom, and offering explanation of the symptom. The least common responses included expressing one's own positive emotions and showing empathy towards the patient.
Critical care nurses, ethical decision‐making and stress
Authors: Erlen Judith A. , Sereika Susan M.
Published: December 2004

Considerable attention has focused on describing ethical issues that critical care nurses face in their practice; however, less attention has been directed at describing the process of ethical decision‐making. Systematic research linking aspects of ethical‐decision making and stress is lacking. This cross‐sectional study examines the relationship between selected aspects of ethical decision‐making, stress and selected nurse characteristics. Sixty‐one critical care nurses completed the Nurse's Ethical Decision Making—ICU Questionnaire and the Health Professions Stress Inventory. Findings revealed that nurses who selected the patient advocacy model had significantly higher nurse autonomy scores, that perceived anxiety had a negative association with nurse autonomy, and that workplace restrictions and stress were related.
Raphidascaris acus (Bloch, 1779) larvae infections of the stone loach, Barbatula barbatula (L.), from the River Haná, Czech Republic
Authors: Koubková B , Baruš V , Prokeš M , Dyková I
Published: December 2004

The stone loach, Barbatula barbatula (L.), is a typical and dominant intermediate host of Raphidascaris acus in lowland streams of Central Europe. The prevalence of infection of R. acus in B. barbatula from the River Haná ranged throughout the year from 73.3 to 100%. The abundance and the mean intensity of infection also varied throughout the year with a peak in September. Larvae were located mainly in the liver parenchyma. High numbers of larvae and their migration through the tissue caused cyst‐ or abscess‐like formations in the host parenchyma. The severity of the disease condition ranged from mild to severe. We speculate that the infection of stone loach by R. acus larvae regulates the population density and abundance of the intermediate host in lowland streams where natural predators are absent.
Adverse effects of summer amongst people with learning disabilities: neuroleptic malignant syndrome
Authors: Fitzgerald B. , Middleton J. K. , Cooper S.‐A.
Published: December 2004

The existing literature regarding neuroleptic malignant syndrome (NMS) amongst people with learning disabilities is limited. We describe three case reports of people with learning disabilities from the same geographical area who developed NMS within 3 weeks of each other. This was during the hottest part of a very hot summer. The presentation of NMS is discussed. The importance of carers attending to adequate hydration for people with learning disabilities and poor communication skills during the summer months is stressed.
Behaviour disorder in an adolescent with terminal deletion of chromosome 3
Authors: Davies J. L. , Mathew G.
Published: December 2004

Individuals with terminal deletion of the long arm of chromosome 3 are rare and survival into adulthood has not been previously reported. A 15‐year‐old with this condition was studied and the difficulties in management of the manifest behaviours are described. This chromosomal abnormality may be associated with mental and functional deterioration as well as severe self‐injurious behaviour, commencing in early childhood.
Staff strategies and explanations for intervening with challenging behaviours: a replication in a community sample
Authors: Watts M. J. , Reed T. S. , Hastings R. P.
Published: December 2004

Carers' beliefs about challenging behaviours may partially determine their behavioural responses to them. The present study replicated previous work on the beliefs of institution staff and their explanations about interventions for challenging behaviours (Hastings 1996) with a sample of 56 community staff. Many immediate intervention strategies, and the staff motivation for these choices, were in conflict with behavioural approaches to challenging behaviour and would be considered counter‐habilitative from this perspective. Staff were able to describe appropriate longer‐term interventions. These basic findings confirmed those of previous research with institution staff. However, tentative comparisons suggested that community staff were more likely than institution staff (from previous research) to describe interventions involving the building of relationships with service users and the identification of the underlying causes of the behaviours.
Microalbuminuria and oxidative stress in essential hypertension
Authors: Giner V. , Tormos C. , Chaves F. J. , Sáez G. , Redón J.
Published: December 2004

Objective.  To assess the relationship between microalbuminuria and oxidative stress in mononuclear peripherals cells in essential hypertension.

Methods.  A total of 123 hypertensive patients in absence of antihypertensive treatment were included. A 24‐h ambulatory blood pressure (BP) monitoring was performed using a Spacelabs 90207 monitor, and microalbuminuria was measured in 24‐h urine collections. Oxidized/reduced glutathione ratio and the content of malondialdehide and damaged base 8‐oxo‐2′‐deoxyguanosine in genomic and mitochondrial DNA were measured in peripheral mononuclear cells.

Results.  In the 29 (24%) microalbuminuric subjects, the amount of reduced glutathione was significantly lower and the ratio oxidized/reduced glutathione was significantly higher than in the normoalbuminuric subjects. In contrast, the simultaneous measurement of the levels of malondialdehide and 8‐oxo‐2′‐deoxyguanosine from both genomic and mitochondrial DNA oxidation did not achieve statistical significance between the two groups. Subjects with the highest oxidized/reduced glutathione ratio tertile showed the highest urinary albumin excretion (UAE) (P = 0.04 for trend). In a stepwise multiple regression analysis, oxidized/reduced glutathione ratio was the main significant determinant of UAE accounting for the 9% of the variance when 24‐h mean BP, age, sex, body mass index, glucose and total cholesterol were included in the model.

Conclusions.  Oxidative stress seems to be a determinant of UAE independent of BP levels even in hypertensive subjects.
Hybridization between the fire‐bellied toads Bombina bombina and Bombina variegata in the karst regions of Slovakia and Hungary: morphological and allozyme evidence
Authors: Gollmann Günter , Roth Petr , Hödl Walter
Published: December 2004

Geographic variability and genetic interactions in the contact zone between the fire‐bellied toads, Bombina bombina and B. variegata, were studied using analysis of morphological and genetic variation in sixteen samples from the Slovak Karst and Aggtelek Karst regions. Genotype frequencies at four marker loci (Ldh‐1, Mdh‐1, Adk, Hem) demonstrate the existence of a hybrid zone with highly variable population structures. While some samples appear to represent panmictic hybrid populations, other samples are very heterogeneous. Pure individuals of both species occurred together with hybrids at one site. Habitat segregation among genetically differentiated demes probably causes this heterogeneity of population structures. Increased frequencies of the allele Ldh‐1M, which is present in low proportion in B. bombina south of the contact zone, were found in some hybrid populations.
Molecular analysis of heterochronic changes in the evolution of direct developing sea urchins
Authors: Parks Annette L. , Parr Brian A. , Chin Jia‐En , Leaf David S. , Raff Rudolf A.
Published: December 2004

The sea urchin Heliocidaris erythrogramma is a direct developer; it progresses directly from the gastrula to the juvenile adult without forming a pluteus larva. No larval skeleton is formed by mesenchyme cells, but formation of the juvenile skeleton is accelerated. We have examined two alterations in mesenchyme cell behavior that accompany this striking change in developmental pattern. 1) Rapid cell proliferation produces 1700–2200 mesenchyme cells by mid‐gastrula, compared to 30–60 primary mesenchyme cells in species with typical larval development. This change may reflect the accelerated production of adult structures in H. erythrogramma. 2) B2C2 is a monoclonal antibody that recognizes primary (Anstrom et al., 1987) and adult mesenchyme cells associated with skeleton formation in typical developers. The altered pattern of B2C2 staining in H. erythrogramma (e.g., a later initial appearance of the B2C2 antigen) suggests that H. erythrogramma has deleted part of a larval program of development and accelerated its adult program of development. These results indicate that cellular and molecular heterochronies accompany the morphological changes in H. erythrogramma development.
Natural and artificial selection on a deviant character of the anal papillae in Drosophila melanogaster and their significance for salt adaptation
Authors: Te Velde J. H. , Scharloo W.
Published: December 2004

Artificial selection was carried out on a deviant character of remnants of the anal papillae in pupae of Drosophila melanogaster, i. e. stretched (S) instead of the normal retracted (R) papillae. A chromosomal interchange between the R‐ and S‐selection lines revealed the polygenic determination of the S‐character. A comparison of lines with a different number of chromosomes of the S‐line shows the importance of properties of the anal papillae for salt adaptation. By a comparison of populations obtained by artificial selection for anal papillae and by natural selection for salt adaptation we could analyse the significance of the deviant character under natural selection on media with increasing percentages of salt.

Our results shows that taking into account only one character in natural selection is often a simplification. However, applying artificial selection on components of the phenotype contributing to the adaptation make an important contribution to the analysis of adaptive processes.
The evolution of food‐producing glands in eusocial bees (Apoidea, Hymenoptera)1
Authors: Webster Thomas C. , Peng Ying‐Shin
Published: December 2004

A food‐producing role for cephalic exocrine glands has arisen independently in both taxa of highly eusocial bees, Apis and Meliponini. With several exceptions, there is little evidence that food is produced by glands of solitary bees or by most bees at lower levels of sociality. We suggest that this association with sociality is due to four adaptive features of these glands: (1) food from the glands allows feces from queens and larvae to have a small volume, (2) the queen's fecundity can be increased, (3) nutrient recovery via cannibalism can be facilitated, and (4) rearing of emergency replacement queens is accelerated. Acceleration of the rearing of other castes and of queens in the normal process of colony fission is not clearly an advantage ascribed to these glands. Trophic eggs produced by meliponine colony workers are analogous to the secretions from food‐producing glands in Meliponini and Apis workers.
Suspending disbelief—of Wynne‐Edwards and his reception
Authors: Pollock Gregory B.
Published: December 2004

Critique of Wynne‐Edwards' views on population regulation and sociality suppose a population of discrete, mutually exclusive groups essential to his thought. Yet both his past and present work focus on continually distributed, philopatric populations; his critics have argued the untenability of a position never his own. Wynne‐Edwardsian ‘group selection’ focuses on local population productivity under philopatry. A ‘group’ is a local confluence of genotypes which need not be reified, and group selection consists of the differential replication (hence heritability) of the local social environment in which a genotype is embedded. Differential productivity contingent on social environment can eliminate some relational structures on genotypes in favor of others, creating an expanding wave of population productivity as in Wright's shifting balance metaphor. Such a process is inherent in the evolution of reciprocity, where cooperators must cluster to successfully invade a population of defectors. Regulation of resource exploitation in continuously distributed populations may be modeled as overlapping n‐person Prisoner's Dilemmas, where each individual participates in several distinct commons and defection represents local over‐exploitation of resources.
Morphological clines across a karyotypic zone of house mice in Central Italy
Authors: Corti Marco , Thorpe Roger S.
Published: December 2004

Multivariate morphometric differentiation between chromosomal races of the mouse Mus domesticus in Central Italy was investigated using a population of 2n = 22 “CB” karyotype, three populations of standard 2n = 40 karyotype, five populations of 2n = 22 “CD” karyotype and three populations from the hybrid zone between the latter two karyotypes. Whilst populations of different karyotype generally have significantly different morphometry, canonical analysis does not reveal that the populations ordinate into distinct aggregations based on karyotype, largely because the 2n = 22 “CD” populations are so diverse. Nevertheless, canonical analysis does reveal a significant cline in morphology across the contact zone between the 2n = 40 and 2n = 22 “CD” mice. The nature of this transition, i. e. a cline 1. within the 2n = 40 range, 2. within the hybrid range (but unrelated to chromosome number) and 3. within the 2n = 22 “CD” range, tends to indicate that the morphometric divergence is due to adaptation to the different ecological regimes across which these mice are distributed rather than the phylogenetic divergence of the karyotypic races.
Timing of diapause in relation to temporally variable catastrophes
Authors: Taylor Fritz , Spalding John B.
Published: December 2004

This paper analyses the response of the distribution of diapause switching times in an arthropod population with respect to variation in a catastrophe, which kills nondiapause individuals. For concreteness, the catastrophe will be taken to the onset of winter. The relationship between an individual's switching time and the decision whether to diapause is defined as follows: If she passes through the end of the sensitive period, during which the diapause decision is made, before her switching time, she will complete development and reproduce rather than diapause. If she passes through the sensitive period on or after her switching time, she will diapause. The model follows the evolution of the distribution of switching times for a population over a sequence of years. Random variation in the end of the season is created by sampling from a normal distribution of times at the end of the growing season. The model is for a haploid population in which the distribution of switching times that a female passes to her offspring is normally distributed having her switching time as its mean. This approximates a sexual population with strong positive assortative mating and heritability near 1. This mode of inheritance permits a rapid response to yearly changes in the end of the season as a contrast to earlier models, which incorporated a slow response. Patterns of temporal change in the median switching time are analyzed. The influences of three parameters are considered: the mean and standard deviation of the end of the season, and standard deviation of the offspring distribution.

The main conclusion differs from the results of earlier models in that the end of the season must be extremely variable before the median of the distribution of switching times displays conservative behavior, i. e., before it becomes significantly earlier than the median expected when the end of the season is constant and equal to the mean of the normal distribution for the end of the season used in the simulation. Previous models predicted a conservative response even in moderately variable environments.
Genetics of sexual Ostracoda from a low Arctic site
Authors: Havel John E. , Hebert Paul D. N. , Delorme L. Denis
Published: December 2004

Members of the crustacean subclass Ostracoda show a high incidence of transitions from sexual to asexual reproduction. The cause of these shifts remains uncertain, perhaps because there have been few genetic studies on the group. The present study examined sex ratios and allozyme variation in 7 sexual species of ostracodes from ponds at a low Arctic site. Sex ratios in most species were strongly female‐biased. Detailed study of Cyprinotus glaucus indicated that sex ratios were heterogeneous among populations, but stable during juvenile‐adult development. Among 6 species, the proportion of polymorphic loci ranged from 0–33 %, and individual heterozygosities 0–14 %. Genotypic frequencies at polymorphic loci conformed to Hardy‐Weinberg expectations in all species, but gene frequency differences among local populations of C. glaucus suggest restricted gene flow for this passively‐dispersed species. Averaged over 5 species, approximately 27 % of the polymorphic loci were sex‐linked. Linkage relationships were variable, with an individual locus being sex‐linked in some species and autosomal in others.
Cytogenetic studies of Hynobiidae (Urodela). X Morphological variation of chromosome 10 in ten pond‐type Hynobius from Korea and Japan, with comments on phylogenetic relationships
Authors: Ikebe Chikako , Kuro‐o Masaki , Yamada Hiroyuki , Kohno Sei‐ichi
Published: December 2004

We have studied karyotypes of ten pond‐type Hynobius collected from 51 localities: H. leechii from Korea, and H. tsuensis, H. dunni, H. nebulosus, H. abei, H. tokyoensis, H. takedai, H. lichenatus, H. nigrescens and H. retardatus from Japan. C‐banding analyses have been performed on the specimens from 38 out of the 51 localities. Among the karyological variations observed, chromosome 10 showed intra‐ and interspecific variations in many species, which we considered suitable for phylogenetic analysis. Our phylogenetic inferences concerning the morphological variation of chromosome 10 in ten pond‐type Hynobius are summarized as follows: 1) similarity in the morphology and the amount of heterochromatin of chromosome 10 in species found in close geographic proximity to each other indicates a close phylogenetic relationship; 2) species distributed in widely separated geographic areas and yet with similar amounts of heterochromatin on chromosome 10 have conserved this chromosomal pattern from a common ancestor; 3) the main evolutionary changes of chromosome 10 are decreases in the C‐positive region and transformation of the biarmed type of this chromosome to the uniarmed type by a pericentric inversion involving the C‐positive region.
Genetic analysis of ecologically relevant morphological variability in Plantago lanceolata L. VI The relation between allozyme heterozygosity and some fitness components*
Authors: Wolff Kirsten , Haeck Jaap
Published: December 2004

Demographic characters and allozyme variability were studied in a hayfield population of P. lanceolata. From 1978 until 1987 all plants present in 15 permanent quadrats of 40 × 30 cm were observed with regard to year of origin and number of leaves, scapes and rosettes. In 1986 small parts of the leaves were sampled and used for electrophoresis. The genotypes for 10 allozyme loci were determined and correlations of heterozygosity and demographic characters were calculated. It appeared that the presence of scapes and the total number of scapes had significant positive correlations with heterozygosity. In some cases there was a positive correlation between number of leaves and heterozygosity, whereas there was no correlation between age and heterozygosity. In separate analyses of each allozyme locus, superiority of the heterozygote allozyme genotype was found in a number of cases. Therefore the overdominance hypothesis cannot be rejected.
Microevolution in predominantly clonal populations of pelagic Daphnia (Crustacea: Phyllopoda): Selection, exchange, and sex
Authors: Jacobs Jürgen
Published: December 2004

The study addresses the problem of gene pools and units of microevolution in mainly apomictic species. The genetic variation of Daphnia cucullata at the phosphoglucose‐isomerase locus was studied in 6 lakes for 3–6 consecutive years. The two most distant lakes were 12 km apart. All lakes were sampled once a year; in one of the lakes (Klostersee), the main basin (WT) and the largest bay (WB, volume 1/7 of WT) were sampled every month for 2½ years.

Three alleles and all six expected genotypes were found. Spatial differentiation was substantial, indicating lake‐specific selection. There was a geographic gradient of allele frequencies without an apparent environmental gradient, suggesting exchange processes. Genotype frequencies in WB and WT showed marked fluctuations. They differed consistently between the two parts of the lake yet were highly correlated. The correlation was best if the WB frequencies were allowed to lag about one month behind the WT frequencies. This is to be expected if bay and basin experience different selection pressures but exchange parts of their populations, which requires some time. No parallel time lags were observed in environmental or demographic parameters. There was a significant correlation between fecundity (eggs/female) and genotype frequency, suggesting clone‐specific differences in fitness.

Biparental reproduction was very rare and superimposed on a continuum of parthenogenesis. Deviations from Hardy‐Weinberg proportions were common and significant unless one allele was predominant. The direction of deviation of a given genotype frequency was usually the same in all lakes, suggesting overall differences in fitness between genotypes apart from lake‐specific conditions of selection.

Heterozygote excess dominated. Biparental reproduction appears to be unimportant for the observed changes in genotype frequencies. The populations behave as if they are composed of independent clones. The main function of biparental reproduction may be the occasional replenishment of genotypic diversity and dispersal via resting eggs. The smallest local entities with distinct selection characteristics seem to be sections of lakes, but microevolution may involve several lakes because of exchange processes.
The genetics of phenotypic plasticity. III. Genetic correlations and fluctuating asymmetries
Authors: Scheiner Samuel M. , Caplan Roberta L. , Lyman Richard F.
Published: December 2004

We examined the relationship of three aspects of development, phenotypic plasticity, genetic correlations among traits, and developmental noise, for thorax length, wing length, and number of sternopleural bristles in Drosophila melanogaster. We used 14 lines which had previously been selected on either thorax length or plasticity of thorax length in response to temperature. A half‐sib mating design was used and offspring were raised at 19° C or 25° C. We found that genetic correlations were stable across temperatures despite the large levels of plasticity of these traits. Plasticities were correlated among developmentally related traits, thorax and wing length, but not among unrelated traits, lengths and bristle counts. Amount of developmental noise, measured as fluctuating asymmetry and within‐environmental variation, was positively correlated with amount of plasticity only for some traits, thorax length and bristle number, and only at one temperature, 25° C.
Cytoplasmic incompatibilities in the mosquito Culex pipiens: How to explain a cytotype polymorphism?*
Authors: Rousset François , Raymond Michel , Kjellberg Finn
Published: December 2004

Although cytoplasmic incompatibilities have been used as a means of eradicating the mosquito Culex pipiens, the population dynamics of these sterilities in relation to the coexistence of multiple incompatible cytotypes in a single area has not been investigated, except in the case of two unidirectionally incompatible cytotypes. An analytical model of the evolution of n cytotypes in an infinite panmictic population has been developed in order to investigate polymorphic equilibrium. A necessary criterion for the stability of such an equilibrium is established; it is shown that a stable polymorphism cannot exist between incompatible cytotypes. This result is discussed in the light of population dynamics and genetics of Culex pipiens, and of our present knowledge on incompatibilities. The consequences of a geographic structuring and of homogamy are considered. A careful reconsideration of previous experimental results disclosed probable nuclear effects and a serious experimental weakness: with the common procedure of backcrossing hybrid females to males of constant genotype it is not possible to rule out probable nuclear effects with paternal expression. It is concluded that incompatibilities in Culex pipiens may have a nuclear‐cytoplasmic determinism.
Resource allocation to growth, reproduction and survival in Gladiolus : The cost of male function
Authors: Rameau Catherine , Gouyon Pierre‐Henri
Published: December 2004

Theoretical models of life‐history evolution assume trade‐offs between present and future reproduction and/or survival. Models of the evolution of sex assume trade‐offs between male function and female function. Generally, experiments designed to evaluate the cost of reproduction on other functions tend to ignore male function. The present work on Gladiolus takes into account simultaneously the different primary functions of the plant and separates sexual reproduction into one male component (pollen production) and one female component (seed production).

The study of environmental (within‐clone), between‐clone and genetic correlations using strains of Gladiolus and principal component analysis show that trade‐offs exist between male function, female function and survival, including both characters of plant vigour, perennation (corm production) and vegetative propagation (cormel production). Phenotypic correlations, using different species and species‐hybrids, have been obtained which confirm these results. In particular, these results underline the importance of the impact of pollen production on the other functions.
Developmental pathways, homology and homonomy in metameric animals
Authors: Minelli Alessandro , Peruffo Beatrice
Published: December 2004

Following Wagner's (1989) distinction between historical and biological concepts of homology, we analyze homology problems of metameric animals in the light of a biological concept. In identifying homology, we refer to the common informational background which two structures share. Therefore, homology relationships are matters of degree; they are ‘perfect’ only when there is full identity of informational background between the structures under comparison. Homonomy (serial homology) is not fundamentally different from other kinds of homology. We regard the differences between epimorphically and anamorphically developed segments as minor; therefore, the two kinds of segments are largely homologous. The morphogenetic processes giving rise to segmental structures are regarded as not necessarily hierarchical. We contrast the phylogenetic pattern of hierarchically nested homologies with a largely non‐hierarchical pattern of homologous structures within the individual organism. This topological difference adds to heterochrony in generating the widespread mismatch of ontogeny and phylogeny.
Sex‐linked altruism: A stepping‐stone in the evolution of social behavior?
Authors: Kawecki Tadeusz J.
Published: December 2004

A verbal model is presented for a mechanism that enhances the probability of the evolution of altruism in diploids if the gene for altruism arises on the X chromosome. If the altruism takes place between sibs of the homogametic sex, the condition for spread of a sex‐linked gene for altruism is less stringent than for an autosomal gene. Then, with altruistic behavior present, selection for increased efficiency (benefit/cost ratio) may raise the efficiency above the autosomal threshold before autosomal modifiers are widespread enough to eliminate the behavior. The results of computer simulations confirms that, if the initial benefit/cost ratio is lower than 2, sex‐linkage can make the evolution of altruism more likely.
Inference of selection and recombination from nucleotide sequence data*
Authors: Hartl Daniel L. , Sawyer Stanley A.
Published: December 2004

Two techniques for obtaining information about population structure from nucleotide sequences in DNA are summarized. The first focuses on the selection or neutrality of enzyme polymorphisms, the second on the detection of recombination. Neither method requires phylogeny estimation.
Environmentally induced morphological variation in the Barnacle Goose, Branta leucopsis
Authors: Larsson Kjell , Forslund Pär
Published: December 2004

The environmental conditions to which juvenile barnacle geese (Branta leucopsis) were exposed during growth were found to affect their body size at fledging as well as their final adult body size. Small juveniles showed compensatory growth from the time of fledging up to one year of age, but this did not fully compensate the differences in body size that were established before fledging. The variation in protein content in plants eaten during growth could probably explain the observed body size differences, sometimes of more than 10%, between different categories of adult geese. Our results imply that one cannot infer selection on morphological characters from differences between samples of adult birds from different localities or from different cohorts within a population, without first showing that environmental conditions during growth do not affect the development of the characters under study.
An experimental study of geographic variation in avian growth and development
Authors: Rhymer Judith M.
Published: December 2004

Reciprocal transplant and “common garden” experiments were done to distinguish the genetic and environmental components of geographic variation in growth, development and morphological characters of Mallard Ducks (Anas platyrhynchos) from California, USA and Manitoba, Canada. Most of the variation in growth and development could be attributed to differences in nesting phenology and local environmental conditions. Differences in morphological characters typical of birds in the two wild populations could be induced by transplanting young between localities. All differences between populations disappeared in the F1 offspring from captive breeding crosses, reared in a common environment. These results suggest that population‐level variation in growth, development and morphology of Mallards in the wild is environmentally induced.
Optimum body size: effects of food quality and temperature, when reproductive growth rate is restricted, with examples from aphids
Authors: Kindlmann Pavel , Dixon Anthony F. G.
Published: December 2004

Most models of optimum energy partitioning predict variability in adult size, although not always explicitly. Increase in size is usually attributed to an increase in the growth rate or decline in mortality. The model presented shows that this may not always be the case. Even when mortality is kept constant in organisms with overlapping generations, a constraint on the maximum reproductive growth rate may lead, when the rate of overall growth increases, to either an increase or a decline in the optimum adult body size.

It is shown that adult size could be a consequence of the differential responses of life history traits to changes in temperature and food quality. This is clearly advantageous for short lived organisms, like aphids, each generation of which only experience a very small part of the great seasonal range in conditions. This hypothesis complements Iwasa's (1991) explanation of the phenotypic plasticity observed in long lived organisms.

The predictions are illustrated with empirical data from aphids. The model presented, which has been verified against a very large data set, indicates that for aphids the adult weight observed at a particular combination of temperature and food quality is that at which the population growth rate, rm, is maximized.

We conclude that predictions about adult size from models based on the partitioning of energy are more likely to apply to organisms that scramble for resources, i.e., “r” selected species. The size of organisms that contest for resources is more likely to be determined by competitive status and avoidance of natural enemies.
The genetics of phenotypic plasticity. V. Evolution of reaction norm shape
Authors: Gavrilets Sergey , Scheiner Samuel M.
Published: December 2004

We present a general quantitative genetic model for the evolution of reaction norms. This model goes beyond previous models by simultaneously permitting any shaped reaction norm and allowing for the imposition of genetic constraints. Earlier models are shown to be special cases of our general model; we discuss in detail models involving just two macroenvironments, linear reaction norms, and quadratic reaction norms. The model predicts that, for the case of a temporally varying environment, a population will converge on (1) the genotype with the maximum mean geometric fitness over all environments, (2) a linear reaction norm whose slope is proportional to the covariance between the environment of development and the environment of selection, and (3) a linear reaction norm even if nonlinear reaction norms are possible. An examination of experimental studies finds some limited support for these predictions. We discuss the limitations of our model and the need for more realistic gametic models and additional data on the genetic and developmental bases of plasticity.
An unusual histone H4 gene from Tilapia nilotica exhibiting characteristics of both a replication‐dependent histone and a basal‐expression histone: evolutionary considerations
Authors: Englander E. , Moav B. , Tabachnik M. , Shuali Y. , Graur D.
Published: December 2004

The nucleotide sequence of a histone H4 gene from the fish Tilapia nilotica was determined. The deduced amino acid sequence is identical to that of H4 from the trout, Salmo gairdnerii. The 3′ untranslated region of the Tilapia gene exhibits a unique combination of structural features each of which is usually associated with either a replication‐dependent histone or a basal‐expression histone, but not with both. The direction of nucleotide substitutions in the Tilapia and Salmo lineages was inferred. The Tilapia gene was found to evolve faster and to exhibit a more biased pattern of substitution and codon usage than its Salmo homologue. This combination of features cannot be explained by either mutation or purifying selection. The rapid embryonic development of Tilapia prompts us to suggest that the molecular evolution of the histone H4 gene is driven by fixation of advantageous synonymous mutations.
Encephalization and the evolution of longevity in mammals
Authors: Hofman Michel A.
Published: December 2004

Allometric principles account for most of the observed variation in maximum life span among mammals. When body‐size effects are controlled for, most of the residual variance in mammalian life span can be explained by variations in brain size, metabolic rate and body temperature. It is shown that species with large brains for a given body size and metabolic rate, such as anthropoid primates, also have long maximum life spans. Conversely, mammals with relatively high metabolic rates and low levels of encephalization, as in most insectivores and rodents, tend to have short life spans. The hypothesis is put forward that encephalization and metabolic rate, which may govern other life history traits, such as growth and reproduction, are the primary determinants directing the evolution of mammalian longevity.
How can a character be developmentally constrained despite variation in developmental pathways?
Authors: Wagner G. P. , Misof B. Y.
Published: December 2004

A fundamental riddle of evolutionary developmental biology is the conservation of adult morphological patterns (Hall, 1992). Conservative patterns are either called body plans if they concern overall body design, or homologues if they concern parts of the body (Riedl, 1978; Roth, 1982; Sattler, 1984; Van Valen, 1982; Wagner, 1989a, 1989b). An adult pattern is considered conservative if it remains unchanged in spite of changes in function, as indicated by the original definition of homology by Owen, as a similarity of organs regardless of form and function (Owen, 1848). Conservation of anatomical features despite different adaptive pressures is naturally explained by developmental constraints (Wagner, 1986). However, this approach to explain the biological basis of homology is plagued by the fact that developmental pathways are often more variable than the characters that they produce (see Tab. 1) (Hall, 1992; Roth, 1988, 1991; Spemann, 1915; Wagner, 1989b). This is also true for any other application of the concept of developmental constraints. The widely held opinion that early stages of development are conservative because any early perturbation is likely to interfere with later development, is far from absolute, since a vast amount of data in comparative developmental biology speaks to developmental variation (see e.g. the examples in Tab. 1). The question then is, how can developmental constraints on adult variation be reconciled with the fact of developmental variation?
Genotypic variation in propensity for host alternation within a population of Pemphigus betae (Homoptera: Aphididae)
Authors: Moran Nancy , Seminoff Jeffrey , Johnstone Laurel
Published: December 2004

In a Utah canyon, the aphid Pemphigus betae shows both a complex life cycle, with alternation between a gall‐forming phase on cottonwood leaves and a root‐feeding phase on herbs, and a simple life cycle, with year‐round residence on roots. In order to determine the extent of clonal variation in life cycle, experiments using multiple sublines of individual clones were carried out in the laboratory and in the field. Previous studies suggested that both genetic and environmental factors underlie life cycle differences among subpopulations of aphids from different sites and different life cycle phases. The current study is the first assessment of clonal variation in propensity for host alternation within a natural population of aphids. In the laboratory experiment, clones showed highly significant differences in reproductive rates and in production of the host‐alternating migrants. In agreement with previous findings, clones originating from lineages that had alternated to cotton‐wood hosts in the previous year had lower average density and produced more migrants than clones originating from lineages that had remained on roots during the previous year.

In order to ascertain how clonal variation and site‐specific environmental factors affect life cycle variation under natural conditions, clones from laboratory cultures were used to establish experimental colonies at two elevational sites within the canyon. Production of the host‐alternating migrants was affected strongly by clone‐x‐site interaction and was affected slightly by site.

Results from both experiments indicate that loss of host alternation in P. betae could be effected through genetic change, environmental change, or both.
Molecular phylogeny of the Canary Island lacertids (Gallotia): mitochondrial DNA restriction fragment divergence in relation to sequence divergence and geological time
Authors: Thorpe Roger S. , McGregor Duncan P. , Cumming Alistair M.
Published: December 2004

Restriction fragment length polymorphisms of 6 base pair recognising endonucleases are used to reconstruct the phylogeny of the endemic Canary Island lacertid, Gallotia. The division into conventional species is upheld by this molecular analysis and the western Canary Island lizard (G. galloti) and eastern Canary Island lizard (G. atlantica) are hypothesized to be sister species. A more comprehensive study of the intraspecific relationships of G. galloti, based on nineteen restriction enzymes, indicates that there are distinct southern and northern lineages within this species. The phylogenetic analysis does not uphold the conventional subspecies, but suggests an alternative arrangement with one northern (La Palma, Tenerife) and one southern (Gomera, Hierro) subspecies. The inferred timing of molecular divergence of populations of G. galloti, based on RFLP analysis, is compatible with the geological timing for island origin and fossil data. Mantel tests show that mitochondrial RFLP divergence is correlated with mitrochondrial 12s rRNA and cytochrome oxidase I sequence divergence and highly correlated with mitochondrial cytochrome b sequence divergence.
Genetic variation in a phylogenetic context: Responses of two specialized leaf beetles (Coleoptera: Chrysomelidae) to host plants of their congeners
Authors: Futuyma Douglas J. , Walsh Joseph S. , Morton Timothy , Funk Daniel J. , Keese Mark C.
Published: December 2004

This work explores the possibility that constraints on genetic variation guide host shifts and are responsible for the evolutionary conservatism of host affiliation in phytophagous insects. To this end, we used full‐ and half‐sib breeding designs to screen two species of the North American bettle genus Ophraella for genetic variation in larval and adult feeding responses to several host plants of other species of Ophraella. All the plants are in the family Asteraceae. In O. conferta, we observed effectively no feeding response, and hence no genetic variation in response, to three of five test plant species; only those plants related to the species' natural hosts evoked genetically variable responses. In O. artemisiae, adults displayed genetic variation in response to a congener of the natural host, but not to two distantly related plants. However, significant variation among full‐sib broods in larval feeding suggests the existence of nonadditive genetic variance in feeding response to all five species of test plants—although survival was very low on most of them. The results suggest that patterns of presence versus apparent absence of detectable genetic variation may be related to the chemical similarity of plants to the insects' natural hosts, but not evidently to the phylogenetic history of host affiliation within the genus. Almost all genetic correlations in responses to host plants were not significantly different from zero; the few significant correlations were positive, and negative correlations that might explain host specificity were not found. Our data do not explain why exclusive shifts to new hosts should occur, but the apparent lack of genetic variation in responses to some plants suggests that the direction of host shifts is genetically constrained.