bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosurgery supports granulation and debridement in chronic wounds – clinical data and remittance spectroscopy measurement
Authors: Wollina Uwe , Liebold Kristin , Schmidt Wolf‐Dieter , Hartmann Michael , Fassler Dieter
Published: March 2003

Background Maggot therapy (biosurgery) has received increasing interest for the debridement of chronic wounds and for the improvement of wound healing. The purpose of this study was to investigate the clinical effects, side‐effects, and possible mechanisms of action of biosurgery.

Methods Biosurgery was used for debridement in 30 patients with chronic leg ulcers of mixed origin. The effect of a single application of maggots for 1–4 days was evaluated by a clinical wound score and contact‐free spectroscopy. Side‐effects were recorded.

Results Debridement was rapid and selective. The wound secretion was temporarily increased. We observed a significant improvement of the wound score with a decrease from 13.5 ± 1.8 to 6.3 ± 2.7 (P < 0.001). The treatment was well tolerated in most patients. Twelve out of 30 patients reported temporary pain, but only two needed analgesic treatment. Other side‐effects included venous bleeding in one patient. The remittance spectra showed an improvement of tissue oxygenation as revealed by the characteristic oxygen doublet peak (548 and 575 nm).

Conclusions Biosurgery is an effective and rapid treatment for the debridement of chronic wounds and the improvement of wound healing. A possible mode of action is the increase in tissue oxygenation. More studies are needed.
Bullous lesions in scleroderma
Authors: Rencic Adrienne , Goyal Supriya , Mofid Mona , Wigley Frederick , Nousari H. Carlos
Published: March 2003

Background The occurrence of bullous lesions in localized or systemic scleroderma is rare. Three histologic patterns have been reported: lichen sclerosus et atrophicus‐like, lymphangiectatic blisters and autoimmune blistering diseases.

Objective  To investigate the frequency, clinical, and immunopathologic features of patients with scleroderma and bullous eruptions and to review the literature regarding this rare condition.

Methods  A retrospective study of 53 cases of scleroderma (localized, generalized, and systemic) in the dermatology and rheumatology clinics at one institution over an 8‐year span. Clinical, serologic, and immunopathologic findings were analyzed in four cases.

Results Four of 53 patients exhibited bullous lesions in association with scleroderma. The first case illustrates lymphangioma‐like clinical and pathologic presentation. The second case demonstrates bullous lichen sclerosus et atrophicus‐like pattern. The other two cases exemplify a superimposed autoimmune skin disease, epidermolysis bullosa acquisita and penicillamine induced pemphigus foliaceus after treatment for systemic scleroderma.

Conclusions  Of the 53 original patients, we have described four cases of bullous scleroderma (7.5%) Illustrating several pathogenetic mechanisms of bulla formation. inflammatory (lichen sclerosus et atrophicus), fibrotic/obstructive (lymphangiomatous), autoimmune (epidermolysis bullosa acquisita), and pemphigus foliaceus.

The final case illustrates bullae as a complication of therapy for the underlying scleroderma.
HLA‐class 1 and class 2 antigens in Turkish patients with pemphigus
Authors: Birol Ahu , Anadolu Rana Yavuzer , Tutkak Hüseyin , Gürgey Erbak
Published: March 2003

Background Pemphigus is an autoimmune disease which is more frequently seen in certain ethnic groups such as Jews. It is thought that exogenous factors may induce pemphigus in genetically predisposed individuals. Recent reports on HLA antigens indicate an increased frequency of HLA‐class II antigens particularly HLA‐DR4 among Jewish patients. Herein we investigated the antigen frequencies of HLA‐A, B, C, HLA‐DR and DQ in Turkish patients with pemphigus.

Methods HLA class I and II antigens were typed by microdroplet lymphocyte cytotoxicity test in 33 patients with pemphigus and 100 healthy individuals.

Results HLA‐B35, B44, CW4, DR4, DR14, DQ8 and DQ4 antigens were significantly high in the study group whereas HLA‐DR11, DQ7 and DQ2 antigens were high among the controls. The most striking differences were observed in HLA class II antigens. HLA DR14‐DQ8 and HLA B35‐DR14 haplotypes were the most frequently observed ones in the study group.

Conclusions We postulate that HLA‐B35, B44, CW4, DR4, DR14, DQ4 and DQ8 antigens may be responsible for susceptibility to pemphigus while HLA‐DR11, DQ7 and DQ2 antigens may have a protective role in the Turkish population.
Pathergic pyoderma gangrenosum in a venous ulcer
Authors: Rosina Paolo , Cunego Stefano , Zambelli Franz Cristina , Saverio D’Onghia Francesco , Chieregato Giancarlo
Published: March 2003

A 74‐year‐old woman was referred to our department in December 1999 for a pyoderma gangrenosum (PG) arising at the edges of chronic leg ulcer. The history was positive for benign monoclonal gammopathy, ischemic hypertensive cardiopathy, polyarthrosis and venous lower leg deficiency. Monoclonal gammopathy of IgA Kappa type was diagnosed 10 years before with a continued benign nature. In 1990 a post traumatic PG of the left leg was diagnosed and a therapy with Cyclosporine A was started with healing of the lesion.

In June 1999, 6 months before the hospitalization, a typical venous ulcer of the right leg appeared and was treated with bed‐rest, compression bandaging and topical desloughing therapy. In the last month, after a minor surgical debridement of the wound, the lesion developed pustules evolving into a painful, necrotic ulcer with ragged, purple‐red, undetermined borders (Fig. 1). A relapse of PG was suspected.

Pyoderma gangrenosum involving the leg. An arrow indicates the site of the original chronic venous ulcer

image

Histological examination was consistent with pyoderma gangrenosum and showed massive neutrophilic infiltration, hemorrhage and necrosis of the overlying epidermis. Wound culture was negative. Other laboratory examinations only showed IgA = 8.15 g/L. Investigation of other underlying medical conditions were normal or negative.

The venous leg ulcer gradually healed with antiseptic and compression‐bandage therapy. After a 4‐month course of topical steroid therapy with good results, the PG recurred also involving the proximal area of the leg. Metilprednisolone 50 mg/day was started. Healing began 10 days later and 2 months later the wound healed and epithelialized. Steroid was reduce to 5 mg daily for 4 months. No recurrence was seen when the drug was stopped.
Prevalence of skin disease among nursing home patients in southern Taiwan
Authors: Derek Richard Smith , Hamm‐Ming Sheu , Fu‐Sen Hsieh , Yung‐Ling Lee , Suh‐Jen Chang , Yueliang Leon Guo
Published: March 2003

Background Continuing advances in medical care and nutrition have prolonged the lifespan and expanded the elderly demographic world‐wide. Despite increasing elderly populations within Taiwanese nursing homes, there has been a lack of dermatologic surveys, and the prevalence of skin conditions within this group is unknown.

Methods To establish the prevalence of skin disease within nursing homes in southern Taiwan, we undertook a dermatologic and epidemiologic investigation of 398 patients in Tainan City, southern Taiwan, between November 1999 and February 2000.

Results This study revealed that more than half of all nursing home patients suffered from fungus (61.6%) and xerosis (58.3%), while other pruritic skin diseases, such as dermatitis and scabies, were less prevalent at 7.3% and 3.3%, respectively. Risk factors for fungal infection included bedridden status (risk ratio (RR), 1.2; 95% confidence interval (CI), 1.1–1.4) and male gender (RR, 1.2; 95% CI, 1.0–1.3). Xerosis was statistically correlated with an age range of 80–90 years (RR, 1.2; 95% CI, 1.0–1.4) when compared to other age ranges. Current scabies diagnosis was strongly associated with a previous history of scabies (RR, 8.9; 95% CI, 1.7–21.1).

Conclusions Our study provides clinically relevant data regarding the prevalence of skin diseases in institutionalized Taiwanese patients for the first time. The results suggest that scabies persists within some nursing homes despite treatment, and that some patients remain undiagnosed. The dermatologic needs of these Taiwanese patients are not currently being satisfied.
Increase in total blood antioxidant status and selenium levels in black patients with active vitiligo
Authors: Boisseau‐Garsaud Anne‐Marie , Garsaud Philippe , Lejoly‐Boisseau Hélène , Robert Michel , Quist Danielle , Arveiler Benoît
Published: March 2003

Background Oxidative stress could be an important phenomenon leading to melanocyte death in vitiligo. The accumulation of hydrogen peroxide (H2O2) and low catalase levels have recently been demonstrated in the epidermis of vitiligo patients. Few abnormalities of antioxidants have been found in the blood of patients with vitiligo, except for an elevation of selenium. No studies on oxidative stress have been performed so far on patients with skin phototype VI (Fitzpatrick classification).

Aim To study the blood antioxidant status of black patients with active generalized vitiligo.

Methods Randox total antioxidant status, selenium, ferritin, transferrin, ceruloplasmin, tocopherol, and retinol levels were evaluated in blood samples obtained from 11 dark‐skinned patients from the French West Indies (Isle of Martinique) with recent active lesions of vitiligo and from 11 age‐ and sex‐matched healthy volunteers.

Results Total blood antioxidant status and selenium levels were significantly increased in vitiligo patients, compared to those in sex‐ and age‐matched controls (P  <  0.01 and P  <  0.02, respectively). Blood levels of ferritin, transferrin, ceruloplasmin, retinol, and tocopherol were not significantly modified.

Conclusions This is the first report on the global blood antioxidant status in vitiligo. The increase in total blood antioxidant status observed in black patients was an unexpected result that needs to be confirmed and explained by further studies. The spontaneous increase in selenium levels could be of interest, as it has been recommended in the treatment of vitiligo.
A human placental extract: in vivo and in vitro assessments of its melanocyte growth and pigment‐inducing activities
Authors: Pal Prajnamoy , Mallick Shampa , Mandal Samir Kr. , Das Madhusudan , Dutta Ajit Kr. , Datta Pijush K. , Bera Rabindranath , Bhadra Ranjan
Published: March 2003

Background The authenticity of various prototype human placental extracts with biological activity, such as that inducing vitiligo repigmentation, is under serious criticism, mainly due to a lack of demonstration at the cellular level. Considering the present worldwide scenario with regard to the occurrence and treatment of vitiligo, a thorough scientific exploration of such extracts should be undertaken.

Method One such prototype placental preparation was prepared, and was evaluated with regard to its melanogenic action in C57BL/6J mice in vivo and its mitogenic and melanogenic activity on B16F10 mouse melanoma cells and normal human melanocytes in vitro. The extract was applied topically to mice with age‐induced prolonged telogenic phase of hair growth (grey body coat hair). Standard 3H‐thymidine incorporation and spectrophotometric methods were followed to illustrate mitogenic and melanogenic effects at the cellular level.

Results The resurgence of blue skin, followed by shiny black hair, at the regions of application of the extract demonstrated the reversal of the age‐induced prolonged telogenic phase of hair growth to the anagenic phase after topical application of the extract on C57BL/6J mice. Further support was obtained from histology where, at the extract‐treated sites, the development of new melanogenic centers and hair follicles was observed. During in vitro studies, the vehicle‐free extract constituents stimulated both mitogenesis and melanogenesis of B16F10 mouse melanoma cells in a concentration‐dependent manner. The cell morphology and extent of melanogenesis also showed significant changes. In addition, two known melanocyte activity‐modulating peptides, endothelin‐1 (ET‐1) and adrenocorticotropic hormone (ACTH), were determined in the extract, chiefly in the total lipid fraction, indicating their effective cutaneous permeation.

Conclusions The extract was found to be a potent mitogen in the in vitro condition and a potent melanogen in both the in vitro and in vivo situations. This strongly suggests its therapeutic potential for the repigmentation of vitiligo patches.
Rapid response to infliximab in severe pustular psoriasis, von Zumbusch type
Authors: Newland Meggan R. , Weinstein Andrew , Kerdel Francisco
Published: March 2003

Tumor necrosis factor‐alpha (TNF‐α) is a chemokine secreted by T cells which is thought to play a critical role in the pathophysiology of psoriasis. The monoclonal antibody, infliximab, complexes with TNF‐α, rendering it inactive. A recent clinical trial has reported the clinical benefit and safety of infliximab in moderate to severe plaque psoriasis. We report a case of rapid response and clinical benefit using infliximab in severe pustular psoriasis of von Zumbusch.
Presence of Leishmania organisms in specific and non‐specific skin lesions in HIV‐infected individuals with visceral leishmaniasis
Authors: Bosch Ricardo J. , Rodrigo Ana B. , Sánchez Purificación , De Gálvez María V. , Herrera Enrique
Published: March 2003

Background Leishmania coinfection is frequently seen in human immunodeficiency virus (HIV)‐infected patients in endemic areas, and from time to time the protozoan is detected in cutaneous biopsies.

Objective To establish the characteristics and possible ethiologic role of the presence of Leishmania in these lesions.

Methods We studied 12 cutaneous biopsies with Leishmania organisms from nine HIV‐infected patients (seven men and two women) with visceral leishmaniasis, diagnosed by bone marrow examination, seen over a period of 9 years.

Results Based on clinical characteristics, evolution and response to anti‐leishmanial treatment, cutaneous alterations were found to be related to the presence of the protozoan in six cases, whereas in the other six cases it was not considered responsible for the dermatological lesions (dermatofibroma, and lesions of psoriasis, Reiter's syndrome, bacillary angiomatosis, cryptococcosis and oral aphthae). Of note was the high prevalence of specific mucocutaneous manifestations, usually accompanied by intense pruritus, great variability, and a tendency to relapse after treatment stopped. On two occasions, detection of the protozoa in skin biopsies led to the diagnosis of a previously unsuspected visceral leishmaniasis.

Conclusions Cutaneous detection of Leishmania is frequent in HIV‐infected individuals with visceral leishmaniasis. Sometimes Leishmania is associated with changes attributable to other dermatological processes, and its presence does not imply a causative role. A clear relationship between the systemic process and the therapeutic response is necessary to demonstrate an ethiologic role.
Clinicopathologic reassessment of non‐mycosis fungoides primary cutaneous lymphomas during 17 years
Authors: Bergman Reuven , Marcus‐Farber Bat‐Sheva , Manov Lena , Nerodinisky Ina , Epelbaum Ron , Sahar Dvorah , Schein‐Goldschmid Rinat , Ramon Michal , Ben‐Arieh Yehudith
Published: March 2003

Background  New classification systems have recently been proposed for primary cutaneous lymphomas (PCLs). The aim of our study was to evaluate the applicability and significance of the new classification systems to the diagnosis and management of non‐mycosis fungoides (non‐MF) PCL.

Methods  Immunohistochemical restaining, histological reclassification, and clinical follow‐up of all new non‐MF PCL cases during 17 consecutive years were performed. The histological reclassification was performed according to the Revised European–American Lymphoma (REAL) classification, except for lymphomatoid papulosis (Lyp), which was included as an indolent lymphoma, according to the European Organization for the Research and Treatment of Cancer (EORTC) classification.

Results  During the period 1983–99, 251 new PCL cases were seen, 213 (85%) of which were MF and Sézary syndrome (eight cases), and 38 (15%) of which were non‐MF. Of the latter, 20 (53%) were B‐cell lymphomas, including eight (40%) follicle center lymphoma, follicular (FCLF), eight (40%) marginal zone lymphoma (MZL), two (10%) diffuse large cell lymphoma, and two (10%) unclassifiable cases. Most or all of the lesions did not stain for CD10, CD43, and bcl‐2 protein, and immunostaining for kappa and lambda immunoglobulin light chain restriction was much more useful diagnostically in MZL. Of the 18 primary non‐MF cutaneous T‐cell lymphomas, 13 (72%) were Lyp, all of which were type A, four (22%) were CD30+ anaplastic large cell lymphoma, and one (6%) was natural killer (NK)/T‐cell lymphoma. Except for the NK/T‐cell lymphoma, all the other non‐MF PCLs had an indolent course.

Conclusions  A minority of the routinely diagnosed PCLs are non‐MF, equally divided between B‐ and T‐cell lymphomas. The REAL classification is applicable to the majority, although it does not include entities such as Lyp; the clinical correlations are not as obvious because most of the non‐MF PCLs tend to have a relatively indolent course.
The genetics of phenotypic plasticity I. Heritability
Authors: Scheiner Samuel M. , Lyman Richard F.
Published: March 2003

Methods for estimating the genetic component of phenotypic plasticity are presented. In the general case of clonal replicates or full‐sibs raised in several environments, the heritability of plasticity can be measured as the ratio of the genotype‐environment interaction variance to the total phenotypic variance. In the special case of only two environments plasticity also can be measured as the difference among environments in genotype or family means. In that case, the heritability of plasticity can be measured as either a ratio of variance components or as the slope of a parent‐offspring regression. The general measure suffers because no least‐square standard errors have been developed, although they can be calculated by maximum‐likelihood or bootstrapping techniques. For the other two methods least‐square standard errors can be calculated but require very large experiments for statistical significance to be achieved. The heritability measures are compared using data on plasticity of thorax size in response to temperature in Drosophila melanogaster. The heritability estimates are all in close agreement. Models of the evolution of phenotypic plasticity have treated it as a trait in its own right and as a cross‐environment genetic correlation. Although the first approach is the one used here, neither one is preferred.
Parasites and sexual selection: Current status of the Hamilton and Zuk hypothesis
Authors: Møller Anders Pape
Published: March 2003

Hamilton and Zuk (1982) suggested that females could continuously base their choice of mates on heritable resistance to parasites, as generated in a process of coadaptational cycles of hosts and their parasites and advertized in terms of individual differences in plumage features or displays of the chosen sex. This hypothesis was based on three assumptions: (1) the full expression of secondary sexual traits of individual hosts is dependent on their overall health and vigour; (2) hosts are coevolving with their parasites, thereby continuously generating heritable resistance to parasites; and (3) parasites have negative effects on host viability. Given these assumptions one may then make the following intra‐ and interspecific predictions: (1) females will obtain mates with few or no parasites by choosing males with fully expressed sexual ornaments, (2) males with inferior ornaments will be less desirable partners and therefore take longer to become mated, (3) assortative mating occurs with respect to parasite loads, (4) females which mate with males with poorly developed secondary sexual characters will copulate outside their pair bond with males showing more fully expressed ornaments, and (5) in species especially vulnerable to parasite invasions, sexual selection will lead to more extreme development of health‐certifying traits, allowing females to more accurately assess the parasite load of a male. Here I shall evaluate the empirical evidence for these assumptions and predictions and discuss alternative hypotheses advanced, in order to explain the importance of parasites for the sexual selection theory. An open question not yet studied satisfactorily is whether, and how often, coadaptational cycles exist, and, if they exist, how they should affect mate choice.
Inter‐generational competition and selection for helping behaviour
Authors: Poiani Aldo
Published: March 2003

A model is presented which considers the effects of inter‐generational competition (IC) for breeding status on selection for helping behaviour. The model shows that for species with both high inter‐generational overlap and high frequency of breeding opportunities within the individual's lifespan, helping behaviour is selected if the relatives raised by the helper through helping (i.e. present indirect fitness gains) do not decrease the helper's future direct fitness as a breeder. This effect is dependent on the value of α, the coefficient of IC. The occurrence of high α values can explain those cases in which a non‐breeding member of a social group does not help. The effect of α can be reduced by means of establishing an age‐based queueing system to attain breeding status. The breeders' acceptance of a non‐helping individual within their territory may be explained as extended parental care or parental facilitation.
Variation in self-fertility, inbreeding depression and levels of inbreeding in four Cyclamen species
Authors: Affre  , Thompson
Published: March 2003

The ability to self in the absence of pollinators, i.e. reproductive assurance, and the detrimental consequences of inbreeding, i.e. inbreeding depression, are central factors influencing plant mating system evolution. The purpose of this study was to quantify whether self-fertility and inbreeding depression are related to levels of inbreeding in four Cyclamen species, namely C. balearicum (mean Fis = 0.930), C. creticum (mean Fis = 0.748), C. repandum (mean Fis = 0.658) and C. hederifolium (mean Fis = 0.329). C. balearicum showed a markedly greater capacity to autonomously self-fertilize than the three other species, which may have favoured inbreeding in this species. Levels of inbreeding depression were highest in C. creticum and C. hederifolium at the fruit maturation (δ = 0.18 and 0.20, respectively) and seed number (δ = 0.32 and 0.30, respectively) stages, and for C. repandum at the seed weight stage (δ = 0.23). Although C. balearicum showed inbreeding depression on seed germination (δ = 0.45), this may be an artefact of the generally low levels of seed germination in the experiment. Overall, we observed only limited evidence for the predicted negative relation between inbreeding coefficients and levels of inbreeding since C. creticum had high levels of inbreeding and inbreeding depression. Other factors may thus influence the relationship between inbreeding and inbreeding depression in these species.
Correlation between enzyme activities and routine metabolic rate in Drosophila
Authors: Berrigan  , Hoang
Published: March 2003

To determine whether enzyme activity is correlated with physiological performance, we analysed the relationship between routine metabolic rate and published data on activity of 12 enzymes from nine species of Drosophila. The enzymes are involved in several aspects of intermediary metabolism including glycolysis. Multiple regression on phylogenetically independent contrasts revealed significant and positive correlations between in vitro enzyme activity and routine metabolic rate. The regression analysis included body size and locomotor activity level as covariates. This result suggests that there may be energetic costs associated with increased enzyme capacity.
Is seasonal variation in leaf traits adaptive for the annual plant Dicerandra linearifolia?
Authors: Winn
Published: March 2003

Empirical studies of phenotypic plasticity have often relied on the plausibility that a plastic response to the environment would increase fitness in order to diagnose the response as adaptive. I conducted a test of the hypothesis that seasonal variation in leaf traits is an adaptive response to seasonal variation in environmental conditions faced by the annual plant Dicerandralinearifolia. This species exhibits variation in leaf morphology and anatomy in response to temperature that is consistent with the expectations for adaptive plasticity. I examined variation in the size, thickness and density of stomata of leaves that develop in summer and winter and used analysis of phenotypic selection during winter and summer seasons to test the hypothesis that seasonal variation in these traits is adaptive. Regression analyses of estimated dry mass (as a proxy for fitness) on leaf traits revealed no evidence supporting the adaptive hypothesis. Selection favoured individuals with large and thick leaves in both winter and summer, and density of stomata had little or no effect on estimated relative fitness in any season. Correspondence between seasonal variation in leaf thickness and density of stomata and expectations for adaptive plasticity appears to be purely fortuitous. Seasonal variation in leaf traits may persist simply because there is no selection against individuals in which these traits vary. My results underscore the importance of definitive tests of the hypothesis of adaptation to distinguish adaptive plasticity from neutral or nonadaptive phenotypic plasticity.
Major gene effects on phenotype and fitness: the relative roles of Pgm-3 and Gp-9 in introduced populations of the fire ant Solenopsis invicta
Authors: Keller  , Ross
Published: March 2003

The objective of this study was to disentangle the relative effects of Pgm-3 and Gp-9 and/or other closely linked genes on the phenotypes and reproductive success of queens in introduced (USA) populations of S. invicta. Gp-9 or a closely linked gene(s) was found to have major effects on queen weight, the likelihood that queens shed their wings (a behaviour associated with the onset of reproduction), and the probability that queens are accepted in polygyne (multiple-queen) colonies. Our analyses show that once the effect of Gp-9 genotype is taken into account, Pgm-3 genotype no longer is significantly associated with differences in queen phenotype or the probability of queens being accepted in polygyne colonies. This suggests that the associations of Pgm-3 genotype with weight, wing shedding rate and probability of acceptance by polygyne colonies previously reported in studies that did not control for the effects of Gp-9 are due to the strong linkage disequilibrium that exists between Pgm-3 and Gp-9, or to linkage disequilibria between these and other genes affecting queen phenotype and fitness. Several lines of evidence, including data from the native South American range, suggest that additional cryptic alleles at Gp-9, or additional genes in the same linkage group as Gp-9, must be involved in controlling queen phenotype and the large suite of traits important in determining social organization of S. invicta colonies.
Morphological evolution and genetic differentiation in Daphnia species complexes
Authors: Gießler  , Mader  , Schwenk
Published: March 2003

Despite many ecological and evolutionary studies, the history of several species complexes within the freshwater crustacean genus Daphnia (Branchiopoda, Anomopoda) is poorly understood. In particular, the Daphnia longispina group, comprising several large-lake species, is characterized by pronounced phenotypic plasticity, many hybridizing species and backcrossing. We studied clonal assemblages from lakes and ponds comprising daphnids from several species complexes. In order to reveal patterns of reticulate evolution and introgression among species, we analysed three data sets and compared nuclear, mtDNA and morphological divergence using animals from 158 newly established clonal cultures. By examining 15 nuclear and 11 mitochondrial (12S/16S rDNA) genetic characters (allozymes/restriction enzymes), and 48 morphological traits, we found high clonal diversity and discontinuities in genotypic and morphological space which allowed us to group clones by cytonuclear differentiation into seven units (outgroup D. pulex). In contrast to six groups emerging from nuclear divergence (related to three traditional species, D. cucullata, D. galeata, D. hyalina and three pairwise intermediate hybrids), a seventh group of clones was clearly resolved by morphological divergence: distinct mtDNA haplotypes within one nuclear defined cluster, ‘D. hyalina’, resembled traditional D. hyalina and D. rosea phenotypes, respectively. In other nuclear defined clusters, association between mtDNA haplotype and morphology was low, despite hybridization being bidirectional (reciprocal crosses). Morphological divergence was greatest between young sister species which are separated on the lake/pond level, suggesting a significant role for divergent selection during speciation along with habitat shifts. Phylogenetic analyses were restricted to four cytonuclear groups of clones related to species. mtDNA and nuclear phylogenies were consistent in low genetic divergence and monophyly of D. hyalina and D. rosea. Incongruent patterns of phylogenies and different levels of genetic differentiation between traditional species suggest reticulate evolutionary processes.
Experimental analysis of the evolutionary potential of hybridization in leopard frogs (Anura: Ranidae)
Authors: Parris  , Semlitsch  , Sage
Published: March 2003

Artificial crossing using Rana blairi and R. sphenocephala frogs produced conspecific, interspecific and F1 backcross hybrid genotypes. Although hybrid males used in the crosses were sterile, crosses using hybrid females produced viable larvae. The larval performance of resultant parental and hybrid genotypes was measured in experimental ponds at two densities. Density significantly affected survival, body mass at metamorphosis, larval period length and metamorphosis for all genotypes. Survival was the same among genotypes, but decreased with increasing density. Body mass at metamorphosis was the same among genotypes, but decreased with increasing density. Larval period increased with increasing density. Among genotypes, larvae from the conspecific R. sphenocephala cross had the shortest larval period while larvae from the conspecific R. blairi cross had the longest larval period. All hybrid genotypes had larval periods longer than R. sphenocephala, but shorter than R. blairi. The percentage of individuals metamorphosing was highest for R. sphenocephala ponds and lowest for R. blairi ponds across densities. Ponds with hybrid larvae produced a greater proportion of metamorphs than those with R. blairi larvae, but a smaller proportion than R. sphenocephala ponds. Equivalent or increased relative larval performance of hybrid genotypes under the conditions of our experiment suggests that hybrid genotypes may possess similar or higher fitnesses relative to their progenitors in some environments. Reduced fertility of adult hybrid males is a powerful selective force against natural hybridization. Nevertheless, because of the successful reproduction by female hybrids, natural hybridization has the potential to serve as a mechanism for the introgression of novel genetic variation that can benefit both R. blairi and R. sphenocephala in fluctuating and unpredictable larval environments. Experimental determination of the fitness of parental and hybrid genotypes is crucial for a comprehensive understanding of the effects of hybridization on organismal evolution.
Mariner-like sequences are present in the genome of the fruitfly, Drosophila melanogaster
Authors: Augé-Gouillou  , Bigot  , Periquet
Published: March 2003

No mariner-like elements (MLEs) have been described until now in the genome of Drosophila melanogaster despite many experiments using molecular methods. However, analyses of sequence data from the Berkeley Drosophila Genome Project show that there are DNA sequences corresponding to pieces of MLE in the genome of D. melanogaster. The sequences of these elements have diverged considerably (about 40%) from any other sequences observed elsewhere. Moreover, the putative amino acid sequences encoded by the best conserved regions reveal that these sequences are clearly homologous to MLEs transposase.
Variation in thermal sensitivity of performance among colour morphs of a pygmy grasshopper
Authors: Forsman A.
Published: March 2003

Populations of pygmy grasshoppers, Tetrix subulata, display genetically coded discrete variation in colour pattern and there are differences among morphs in the capacity to achieve body heating. To determine whether colour morphs differ in thermal physiology, I assessed reaction distance and jumping performance of individuals belonging to different morphs at two different temperatures. Individuals allowed a potential predator to approach less closely and jumped longer distances at high than at low temperature. My analyses also uncovered variation among morphs in average reaction distance and jumping capacity, as well as in thermal sensitivity of these two traits. Matrix correlation analysis further revealed that pair-wise differences between morphs in thermal sensitivity of jumping performance (but not reaction distance) could be accurately predicted by differences in body temperatures preferred in a laboratory thermal gradient. These results support the view that morphology, behaviour and thermal physiology of ectotherms may evolve in concert. The relationship between reaction distance and jumping performance varied among colour morphs at high temperature, and the common within-morph relationship between these two traits deviated from the corresponding among-morph relationship. This suggests that the variation among morphs has partially arisen through active divergence, with selection having influenced both traits and modifications having occurred to different degrees in different morphs. My data further suggest that pale colour morphs, with a limited capacity to attain high body temperatures, may not necessarily be at a selective disadvantage, because their physiology may be adapted to lower body temperatures.
Patterns of evolution in Graomys griseoflavus (Rodentia, Muridae). IV. A case of rapid speciation
Authors: Theiler G. R. , Gardenal C. N. , Blanco A.
Published: March 2003

The South American group of rodents known as Graomys griseoflavus comprises two sibling species differing only in diploid chromosomal complement: G. griseoflavus (2n = 36, 37 and 38) and G. centralis (2n=42). Reproductive barriers comprising postzygotic as well as precopulatory mechanisms prevent gene exchange between these species. We have studied genetic polymorphism in two populations of G. centralis and four of G. griseoflavus by means of gel electrophoresis of enzymes and other proteins giving information on a total of 30 loci. Values of interspecific genetic identity were similar to those obtained for conspecific populations, suggesting that fixation of Robertsonian fusions would have occurred without significant bottlenecks. It would also indicate that the cladogenetic process must be relatively recent. FIS values showed no evidence of inbreeding. Fixation indices (FST) for the ancestral species showed a tendency to form demes with very low gene flow among them, while in the derived species such tendency was not shown. However, because of the characteristics of the region they occupy, populations are of moderate size, and genic flow is low. Lack of correlation between gene flow levels and geographical distance between population pairs would indicate a recent and fast colonization of its distribution areas by the derived species. It is possible that fixation of Robertsonian fusions occurred in a marginal deme of the ancestral species, e.g. in a parapatric geographical context.
Unpredictable selection in a structured population leads to local genetic differentiation in evolved reaction norms
Authors: De Jong G.
Published: March 2003

Unpredictability during development of the optimum phenotype under future selection leads to a compromise reaction norm with a slope that is shallower than the slope of the optimum reaction norm. Unpredictability of selection can lead to an evolved curved reaction norm when genetic variation for curvature is available even if the optimum reaction norm is linear. This requires asymmetry in the frequency distribution of the habitats of selection; at small population size, stochasticity in the number of individuals per selection habitat is sufficient to generate such asymmetry.

Unpredictability of selection in structured populations leads to local genetic differentiation of reaction norms. The mean habitat of a subpopulation is defined as the subpopulation's focal habitat. The evolved mean reaction norm of each subpopulation is anchored at the optimum genotypic value in its focal habitat. Linear reaction norms are parallel if the conditional distribution of adults around the focal habitats is the same for each subpopulation.

Adult migration and absence of zygote dispersal represents the ultimate structured population, each habitat playing the role of focal habitat. Absence of zygote dispersal requires that the flow of individuals through the habitats is used instead of the habitats’ frequencies in the prediction of the evolved reaction norm. Adult migration in absence of zygote dispersal leads to an evolved pattern of locally differentiated reaction norms with optimum genotypic value anchored in the focal habitat and, for linear reaction norms, parallel slopes.
Natural selection on body size traits in a long-lived bird, the snow petrel Pagodroma nivea
Authors: Barbraud
Published: March 2003

I consider the possibility of selection favouring large body size in a population of snow petrels (Pagodroma nivea), a long-lived seabird species. I measured natural selection on body size traits in a population from 1987 to 1998. There was evidence of selection on body size associated with fecundity and survival. Directional selection on bill length and stabilizing selection on tarsus length associated with reproductive success were detected among males. Selection associated with survival favoured males with longer bills. However, selection was weak in all cases. No evidence of selection acting on female body size traits was detected. Offspring–parents regression suggested that bill length and tarsus length were heritable. Although I was able to identify the targets of selection in this population, I could not demonstrate the ecological implications of both tarsus length and bill length variation. The selection on male, but not on female, body size traits suggests factors such as intrasexual competition for nests and/or mates rather than factors such as feeding efficiency as mechanisms of selection on bill size.
Rapid evolution and specialization following host colonization in a yucca moth
Authors: Groman  , Pellmyr
Published: March 2003

Host shifts followed by specialization can result in sympatric genetic differentiation, and may have fuelled the diversification of phytophagous insects. This study examines a recent colonization of a non-native host by Prodoxus quinquepunctellus (Lepidoptera: Prodoxidae). Allozyme differentiation was detected among different host feeding populations, yet was nearly absent among similar host feeding populations in sympatry. Geographical patterns of allozyme variation showed a much higher level of population structure among populations feeding on the derived host. Conversely, mtDNA haplotype frequencies were nearly homogeneous in the derived populations compared to the ancestral populations, suggesting a bottleneck and/or rapid fixation of haplotypes following host colonization. Moth emergence coincided with host plant flowering, and phenological differences between host species translated into allochronic isolation between populations feeding on different hosts. Derived moth populations also differed significantly in three ovipositor characters from ancestral populations. These findings suggest rapid host-specific genetic differentiation, and specialization of moth emergence time and ovipositor morphology following host colonization.
Individual variation in growth trajectories: phenotypic and genetic correlations in ontogeny of the house finch (Carpodacus mexicanus)
Authors: Badyaev  , Martin
Published: March 2003

We studied patterns of growth in a recently established natural population of the house finch (Carpodacus mexicanus) to examine whether phenotypic and genetic covariation among age-specific trait values is likely to constrain morphological change favoured by selection acting on adults. We found variable patterns of allometric relationships during ontogeny, and documented relatively weak covariations among ages or among traits in individual growth trajectories. Frequent compensatory growth largely cancelled out the initial differences among nestlings, potentially enabling house finches to raise offspring under diverse and unpredictable environmental conditions. Moderate levels of additive genetic variance in morphological traits throughout ontogeny, and relatively low and fluctuating phenotypic and genetic covariation among ages imply strong potential for evolutionary change in morphological traits under selection. This conclusion is consistent with the profound population-level divergence in morphological patterns that accompanied very successful colonization of most of North America by the house finch over the last 50 years.
Inbreeding and outbreeding effects on pollen fitness and zygote survival in Silene nutans (Caryophyllaceae)
Authors: Hauser  , Siegismund
Published: March 2003

In plants, selfing and outcrossing may be affected by maternal mate choice and competition among pollen and zygotes. To evaluate this in Silene nutans, we pollinated plants with mixtures of (1) self- and outcross pollen and (2) pollen from within a population and from another population. Pollen fitness and zygote survival was estimated from the zygote survival and paternity of seeds. Self pollen had a lower fitness than outcross pollen, and selfed zygotes were less likely, or as likely, to develop into seeds. Hybrid zygotes survived as frequently or more than local zygotes, and pollen from one of the populations fertilized most ovules in both populations. Our results thus indicate strong maternal discrimination against selfing, whereas the success of outbreeding seems mostly affected by divergent pollen performance. The implications for the evolution of maternal mate choice are discussed.
Neutral genetic differentiation in an island model with cyclical parthenogenesis
Authors: Berg  , Lascoux
Published: March 2003

Unusually high levels of genetic differentiation are often observed between populations of Daphnia (Crustacea: Cladocera) and other cladocerans. Selection and departure from migration–mutation–drift equilibrium have been invoked to explain this fact. However, the null model of neutral genes at equilibrium has not been explicitly stated. Using a simple island model that takes into account the main characteristics of the cyclical parthenogenetic life-cycle, we show that a high level of differentiation can be obtained for neutral genes at equilibrium if the migration rate during the asexual phase is low and the effective size over the season is reduced, or if mating within clones is common. Recurrent population bottlenecks have a large effect on differentiation and the time to reach equilibrium. Such fluctuating clonal dynamics could be brought about by limitations in the number of clones that hatch and establish themselves each season, or by random associations between neutral and selected genes, as previously suggested in the literature.
Using path analysis to measure natural selection
Authors: Scheiner  , Mitchell  , Callahan
Published: March 2003

We expand current methods for calculating selection coefficients using path analysis and demonstrate how to analyse nonlinear selection. While this incorporation is a straightforward extension of current procedures, the rules for combining these traits to calculate selection coefficients can be complex. We demonstrate our method with an analysis of selection in an experimental population of Arabidopsis thaliana consisting of 289 individuals. Multiple regression analyses found positive directional selection and positive nonlinear selection only for inflorescence height. In contrast, the path analyses also revealed positive directional selection for number of rosette leaves and positive nonlinear selection for leaf number and time of inflorescence initiation. These changes in conclusions came about because indirect selection was converted into direct selection with the change in causal structure. Path analysis has great promise for improving our understanding of natural selection but must be used with caution since coefficient estimates depend on the assumed causal structure.
Comparison of genetic (co)variance matrices within and between Scabiosa canescens and S. columbaria
Authors: Waldmann  , Andersson
Published: March 2003

In the current study, we used bootstrap analyses and the common principal component (CPC) method of Flury (1988) to estimate and compare the G-matrix of Scabiosa columbaria and S. canescens populations. We found three major patterns in the G-matrices: (i) the magnitude of the (co)variances was more variable among characters than among populations, (ii) different populations showed high (co)variance for different characters, and (iii) there was a tendency for S. canescens to have higher genetic (co)variances than S. columbaria. The hypothesis of equal G-matrices was rejected in all comparisons and there was no evidence that the matrices differed by a proportional constant in any of the analyses. The two ‘species matrices’ were found to be unrelated, both for raw data and data standardized over populations, and there was significant between-population variation in the G-matrix in both species. Populations of S. canescens showed conservation of structure (principal components) in their G-matrices, contrasting with the lack of common structure among the S. columbaria matrices. Given these observations and the results from previous studies, we propose that selection may be responsible for some of the variation between the G-matrices, at least in S. columbaria and at the between-species level.
Testing hypotheses on the dispersal and evolutionary history of freshwater mussels (Mollusca: Bivalvia: Unionidae)
Authors: Nagel
Published: March 2003

The relationship between dispersal and differentiation of the European freshwater mussel Unio pictorum (Linnaeus, 1758) was studied with molecular genetic methods. Forty-two populations from France, Italy and central Europe were analysed. Genetic relationships were assessed from the geographical distribution of allele frequencies at 17 enzyme loci. Neighbouring groups of populations show small to moderate mean genetic distances (0.020 < Dmean < 0.263). With a few exceptions the genetic affinities of the populations are the closest within the same drainage basin. In central Europe and Northern Italy genetic differences between drainage systems are relatively large. Populations from north-eastern Italy are genetically similar to Danubian populations. Mussels from the islands of Corsica and Sardinia are more closely related to populations from the Italian peninsula than to French populations from the Rhône drainage system. Genetic relationships within U. pictorum from central Europe reflect palaeogeographical relationships between river systems during the Pliocene and Pleistocene. Literature data on two North American unionid species and one European fish species show the same relationship between genetic diversity and the history of drainage systems, although the correlations are less strong. In France and Italy this correspondence is much less evident. Population dynamic processes and human activities leading to populational bottlenecks might have obscured it.