bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of the BRAF V600E mutation in melanocytic lesions using the ligase detection reaction
Authors: Turner Daniel J. , Zirvi Monib A. , Barany Francis , Elenitsas Rosalie , Seykora John
Published: April 2005

Background:  BRAF is a member of the RAF kinase family, and it promotes signaling through the RAS‐MAP kinase signal transduction cascade. Research has shown that a majority of melanomas and nevi exhibit an activating V600E (T1799A) mutation in BRAF exon 15. Additional studies of BRAF have demonstrated that the T1799A mutation is absent in uveal melanomas and Spitz nevi.

Methods:  The ligase detection reaction (LDR) is a sensitive technique that can identify specific DNA mutations occurring at very low frequency within heterogeneous clinical samples, and it has previously been used to analyze mutations in paraffin‐embedded tissue specimens.

Results:  The LDR can readily detect mutations in DNA extracted from non‐microdissected paraffin‐embedded sections of common nevi, dysplastic nevi, and melanomas. In addition, this method demonstrated the absence of the V600E (T1799A) mutation within Spitz nevi.

Conclusion:  The LDR is a highly sensitive and specific test for detecting mutations in formalin‐fixed tissue. The LDR can be easily adapted to detect any mutation associated with a cutaneous disorder. The absence of the BRAF V600E mutation in Spitz's nevi may serve as a molecular signature to distinguish these lesions from common nevi, dysplastic nevi, and some types of malignant melanoma.
Peroxisome proliferator‐activated receptors in squamous cell carcinoma and its precursors
Authors: Nijsten Tamar , Geluyckens Elke , Colpaert Cecile , Lambert Julien
Published: April 2005

Background:  Peroxisome proliferator‐activated receptors (PPARs) mediate several functions that are of interest in carcinogenesis. Although PPARα, PPARβ, and PPARγ are expressed in multiple human, their expression has not been investigated in non‐melanoma skin cancer.

Methods:  We performed a retrospective paired immunohistochemical analysis of normal skin, actinic keratosis (AK), and squamous cell carcinoma (SCC) among 35 individuals. Specimens were considered PPAR immunoreactive when 1% or more of the tumor cells showed clear evidence of immunostaining. Cyclooxygenase‐2 (COX‐2) expression, the fraction of proliferating endothelial cells, and microvessel density were also evaluated in these samples.

Results:  PPARα immunoreactivity was significantly less likely to occur in SCC and AK than in normal skin of each individual. In contrast to PPARα, PPARβ appeared to be upregulated in (pre)malignant skin lesions. For each individual, the likelihood that normal skin, AK, or SCC was immunoreactive against PPARγ was comparable. COX‐2 immunopositivity was significantly associated with PPARβ and PPARγ immunoreactivity. No statistical differences were noted for the angiogenesis parameters and PPARα, PPARβ, or PPARγ expression, except that the microvessel density was significantly higher among PPARβ‐immunoreactive SCCs compared to that among immunonegative SCCs.

Conclusion:  Although further research is warranted, these results suggest that PPAR ligands such as fibrates and thiazolidinediones may have chemoprophylactic properties in skin carcinogenesis.
Design Inertia: Designing for Life‐Cycle Flexibility in Internet‐Based Services*
Authors: Verganti Roberto , Buganza Tommaso
Published: April 2005

Managing innovation in rapidly moving environments, such as Internet‐based services, is a major challenge in theory and in practice. Most of the existing literature focuses on the development process as the main area in which innovation takes place. However, in environments where the pace of change of technology and market needs is extremely high, managing service innovations means not only being able to design a good service but also, more importantly, continuously redesigning and adapting the service in order to deal with frequent exogenous changes and opportunities. A high number of innovations therefore must be introduced throughout the entire life cycle of a service. This capability of introducing incremental and radical innovations during the service life cycle (i.e., to adapt a service to contextual changes and opportunities after it has been first released onto the market) at low costs and in the shortest possible time is what is defined here as service life‐cycle flexibility. This process of service adaptation and upgrading implies significant challenges that can be traced back to when a service is first conceived and designed. In fact, many decisions made during the first design process (i.e., the choice of a given database environment) involve a low reversibility rate and may reduce the possibility of taking advantage of future unpredictable opportunities, creating what is called inertia toward innovation. In other words, service life‐cycle flexibility largely depends on how a service has been first designed. This article analyzes two in‐depth case studies of Italian online newspapers and identifies five possible inertia factors that may influence service life‐cycle flexibility, namely (1) technological inertia; (2) internal organizational inertia; (3) external organizational inertia; (4) customer inertia toward changes in the service package; and (5) customer inertia toward changes in the service interaction design. These inertia factors are traced back to the service development process in order to suggest design practices that may increase the service life‐cycle flexibility.
Managing External Information in Manufacturing Firms: The Impact on Innovation Performance*
Authors: Frishammar Johan , Åke Hörte Sven
Published: April 2005

Drawing upon a sample of 206 medium‐sized manufacturing firms, this article investigates the extent to which management of external information is associated with innovation performance. The overall purpose of the article is to examine whether or not those organizations that are better at managing external information are also those that are the better innovators. The research strategy used was a survey, and data were collected by means of mail questionnaires (with a 62.4% response rate). A multiple regression analysis was used for hypothesis testing. The results show that scanning the technological sector of the environment was positively associated with innovation performance, while scanning customers, suppliers, and competitors proved to be negatively correlated with innovation performance. Cross‐functional integration in the form of collaboration also proved significantly correlated with innovation performance, while interaction showed no such relationship. Further, decision‐making based on information from the industry environment correlated significantly with innovation performance. Research and managerial implications of these findings are presented and are discussed.
The Moderating Effect of Environmental Uncertainty on New Product Development and Time Efficiency*
Authors: Bstieler Ludwig
Published: April 2005

This empirical study examines the influence of environmental uncertainty on industrial product innovation. The present study addresses what is believed to be a shortcoming in the new product development literature and explores potential effects of environmental uncertainty on the development process, project organization, and on project timeliness with a sample of development projects in two countries, Canada and Australia. When looking at the combined sample of 182 completed projects, this study finds that the perceived market‐related project environment has a direct and positive impact on time efficiency. Further, this research finds that a higher degree of technological uncertainty moderates the relationship between development process, project organization and time efficiency. Consequently, innovating companies may benefit by adapting some of their development approaches to different environmental conditions and to varying degrees of uncertainty. However, when examining country‐specific effects, the results change quite significantly. In particular, the findings indicate that environmental uncertainty in the Canadian sample neither directly impacts time efficiency, nor does it have any moderating effect. Instead, technical proficiency in the development process, project team organization, and process compression appear to be viable strategies to increase time‐efficient development. In contrast, the results of the Australian study suggest that perceived market and technological uncertainty impact time efficiency. In particular, under conditions of technological unpredictability, project team organization increases time efficiency, whereas process compression appears to decrease time‐efficient product development. However, process compression seems to be a viable strategy in environments characterized by lower technological uncertainty. The results also point to the importance of disaggregating data when studying product development processes across countries.
A multivariate approach to the feeding habits of small fishes in the Guadalquivir Estuary
Authors: Baldoa F. , Drake P.
Published: April 2005

In the analysis of the feeding habits of the 11 most abundant fish species in the Guadalquivir Estuary, collected monthly (February 1998 to January 1999) at two different sampling sites, a total of 46 prey taxa were identified. Classifications (based on Bray–Curtis similarities derived from occurrence, number and mass data) of the different fish categories (postlarvae and juvenile–adults of each species) revealed two main trophic guilds, whose preferential prey (SIMPER analysis) were mysids and copepods, respectively. The similarity matrices derived from occurrence, number and mass data were always significantly correlated (RELATE: r>0.636; P<0.01), indicating that a good agreement in feeding patterns emerged from these variables. The seasonal coincidence of maximal fish and key‐prey species densities suggests that food availability may be a principal factor influencing the nursery function of the Guadalquivir Estuary.
Biological, technical and socioeconomic aspects of the fishing activity in a Brazilian estuary
Authors: Chaves P. , Pichler H. , Robert M.
Published: April 2005

Technical, biological and socioeconomic factors act as obstacles in the development of fishing activity in the Guaratuba Bay, southern Brazil. Amongst the difficulties registered, the following stand out: there was little variety of fishing gear; the purchasing power of the fishermen was low; there was a lack of regularity in the presence of the target species in the estuary; legislation restricted the use of certain gear at particular times; the size of the individual fish was small when compared to those from the continental shelf. Aquaculture could offer an alternative to the revenue of the fishermen, but cultural tradition and the lack of financial resources make it difficult to introduce aquaculture as an activity for the fishermen. The pessimism encountered in the community indicates that the future of artisanal fishing in this estuary is uncertain.
Biomass and production estimates of a fish community in a small South African estuary
Authors: Cowley P. D. , Whitfield A. K.
Published: April 2005

The fish community of the small (17·5 ha) intermittently open East Kleinemonde estuary was sampled between 1994 and 1997 to estimate population size, standing stock, growth and productivity. The estuarine‐spawning species were numerically more abundant (n c. 750 000) but due to their small size contributed only 11·7% to the total biomass. The total annual productivity of all fishes in the estuary (n c. 890 000), with a standing stock of 28·44 g m −2, was calculated at 55·89 g m−2 year−1. The small sparid Rhabdosargus holubi with a production estimate of 41·35 g m−2 year−1 accounted for <74% of the total fish production in this estuary.
Abundance and reproduction of Nilsson's pipefish on tidal flats
Authors: Hiddink J. G. , Jager Z.
Published: April 2005

Nilsson's pipefish Syngnathus rostellatus were found on tidal flats in the Dollard (Ems estuary, Wadden Sea) in high numbers in May and June (20 to 150 1000 m‐2) and August and September (150 to 300 1000m‐2). Low numbers were found in April, July, November and December. Nilsson's pipefish with eggs and larvae in their brood pouch were most numerous in May and August and September. Both the fraction of Nilsson's pipefish with a brood pouch and the fraction of brood pouches with eggs and larvae increased with fish length. Analysis of length‐frequency distributions suggests that two cohorts live in the Dollard (spring cohort, April–August; summer cohort, July–December). Reproducing animals were found in both cohorts. It was assumed that the spring cohort was the previous year's summer cohort, which migrate to the tidal flats in spring, reproduced and then disappeared. The summer cohort was their offspring (0 group) which leave the tidal flats during November and December.
Lack of consistency between the trophic interrelationships of five sparid species in two adjacent central Mediterranean coastal lagoons
Authors: Marian S. , Maccaroni A. , Massa F. , Rampacci M. , Tancioni L.
Published: April 2005

Both interspecific and intraspecific inter‐lagoon differences, between the central Mediterranean coastal lakes of Fogliano and Caprolace, in the trophic patterns of the examined species Diplodus annularis, Diplodus puntazza, Diplodus sargus, Lithognathus mormyrus and Sparus aurata were revealed by means of correspondence analysis. The most evident inter‐lagoon qualitative and quantitative diet changes were observed in S. aurata. Feeding similarities among species were synthesized for each lake by means of multidimensional scaling. Trophic interrelationships among sparid fish were different in the two lagoons, as a direct consequence of diet variations in each species. Such differences are interpreted as possibly reflecting differences in the overall structure of the benthic communities. Different feeding models could be identified, each corresponding to a peculiar adaptive strategy for the consumption of lagoon benthic resources. The use of benthophagous fish feeding habits as a tool for the monitoring of the structure and the dynamics of coastal lagoon communities is discussed.
Fish communities in two environmentally different estuarine systems of Mexico
Authors: Raz‐Guzman A. , Huidobro L.
Published: April 2005

Mexico has two main types of coasts, an Amero‐trailing‐edge coast along the Gulf of Mexico and a collision coast along the Pacific, each of which determine the characteristics of their coastal lagoons. The lagoons along the Gulf of Mexico are extensive, tropical and rich in seagrass beds and mangroves, and among these Laguna Madre has 84 species of fishes. In contrast, the lagoons along the Pacific are small, closed, mostly oligohaline and usually lack seagrass beds, and among these Laguna Salinas del Padre has 19 species of fishes. This marked difference in species richness, in turn, has a direct effect on the size and value of the fisheries, as these are regional in the first case and local and seasonal in the second.
Reproduction of Micropogonias funieri in a shallow temperate coastal lagoon in the southern Atlantic
Authors: Vizziano D. , Forni F. , Saona G. , Norbis W.
Published: April 2005

The white croaker Micropogonias furnieri, in the coastal Rocha Lagoon, spawned during 5 months, in late spring and summer. It was eurythermic (gonad growth at 12·5 to 25·5° C, spawning at 20 to 27° C) and mesoxic (living at 5·2 to 9·1 mg l‐1). The spawning occurred in brackish (8–18 salinity), basic (c. 8 pH) and oxygenated (c. 8·0 mg l‐1) waters. The temperature appeared to be an important environmental factor affecting the timing of reproduction. The size at first maturity (19–20 cm) was 11–12 cm lower than the reported for the Río de la Plata spawning area (Uruguay). Juveniles were observed throughout most of the year suggesting that the lagoon is also a nursery area. In Brazil, M. furnieri spawns in marine areas while in Uruguay it spawns in estuaries. This is the first time that a coastal lagoon of the subtropical and temperate western coast of the South Atlantic Ocean has been shown to be a spawning area of a marine species.
Fish feeding guilds in shallow rocky and soft bottom areas on the Swedish west coast
Authors: Wennhage H. , Pihl L.
Published: April 2005

Multivariate analyses of the diet relationships within fish assemblages resulted in the recognition of five major feeding guilds in shallow (0‐9 m) rocky‐ and soft‐bottom habitats on the Swedish west coast. The two habitats had similar guilds that could be broadly described as piscivores, decapod feeders, copepod feeders and amphipod and mollusc feeders. The last guild on the rocky bottom was more strictly one of amphipod feeders, whereas the last guild on soft bottoms consisted of infauna feeders (mainly polychaetes and bivalves). A comparison of the diet of the entire fish assemblages showed that amphipods and gastropods were more prevalent as prey taxa on rocky bottoms, whereas bivalves and teleosts were more common on soft bottoms. A large proportion (12 out of 27 species) of the fish species investigated was found in both habitats. These fish species generally seemed to rely on the same major prey groups in the two habitats, but also included prey taxa characteristic for the habitat in which they resided. Sea trout Salmo trutta, mackerel Scombrus scombrus, saithe Pollachius virens, whiting Merlangius merlangus and cod Gadus morhua were found to be the major piscivores in both the investigated habitats. Herring Clupea harengus and members of the family gobiidae were the most prevalent prey species for piscivores within the rocky‐ as well as the soft‐bottom fish assemblage. A comparison of feeding modes suggested that the fish assemblage on rocky bottoms predominantly (60% of the food items) relied on food found in vegetation. On soft bottoms, the average distribution of food categories among fish species was 44% benthic, 35% pelagic and 21% vegetation‐associated food items.
Long‐term acid suppression by omeprazole in gastro‐oesophageal reflux disease patients does not lead to anti‐gastric autoantibody production
Authors: Bergman M. P. , Klinkenberg‐Knol E. C. , Faller G. , van der Aar A. , Lakhai W. , Vandenbroucke‐Grauls C. M. J. E. , Kuipers E. J. , Appelmelk B. J.
Published: April 2005

Background : Helicobacter pylori‐associated atrophy of the gastric corpus is associated with the presence of anti‐canalicular autoantibodies. Also, long‐term profound acid suppression in H. pylori‐infected subjects may cause atrophic corpus gastritis.

Aim : To investigate whether long‐term acid suppression by omeprazole leads to antigastric autoantibodies.

Methods : Fifty patients, of which 34 H. pylori‐positive on entry of the study, were treated with omeprazole (20–40 mg once daily) for reflux oesophagitis, and were evaluated for anti‐gastric autoantibody responses by immunohistochemistry before and after treatment. H. pylori was not eradicated and patients were followed for an average of 6.6 years (range 3–14.1 years). In addition to immunohistochemistry, anti‐H+, K+‐ATPase reactivity was assessed by Western blot in paired sera of 41 patients (26 H. pylori‐positive and 15 uninfected) and results are critically evaluated.

Results : In immunohistochemistry, all patients were negative for anti‐canalicular autoantibodies when omeprazole therapy started, except for two patients with corpus‐predominant gastritis in the presence of H. pylori. One patient, who was H. pylori‐negative, newly developed an anti‐canalicular antibody response during therapy.

Conclusions : Our results indicate that, as compared with non‐infected patients, long‐term profound acid suppression therapy in H. pylori‐infected gastro‐oesophageal reflux disease patients does not increase or accelerate gastric autoimmunity.
Absorbable vs. non‐absorbable antibiotics in the treatment of small intestine bacterial overgrowth in patients with blind‐loop syndrome
Authors: Di Stefano M. , Miceli E. , Missanelli A. , Mazzocchi S. , Corazza G. R.
Published: April 2005

Background : Small intestine bacterial overgrowth is associated with the presence of predisposing conditions, acting through different mechanisms. Therefore, the failure to define a standardized therapy may be due to a methodological bias: to treat a condition characterized by different pathophysiological mechanisms with the same pharmacological approach. Non‐absorbable antibiotics could have a lower efficacy than absorbable drugs in patients with blind loops which exclude a portion of the intestine from the transit.

Aim : To evaluate the efficacy of absorbable vs. non‐absorbable antibiotics in this subgroup of patients.

Methods : A group of small intestine bacterial overgrowth patients with total gastrectomy or gastrojejunostomy and blind loop underwent a therapeutic trial comparing rifaximin to metronidazole. Seven patients underwent a course of rifaximin followed by a course of metronidazole on recurrence of symptoms. To compare the effect of the drugs, another two groups of patients underwent two consecutive courses of rifaximin or metronidazole. Hydrogen breath test after glucose administration and symptom severity measurement were performed.

Results : Both drugs reduced breath H2 excretion but a much better improvement was achieved after metronidazole. Symptom improvement was higher after metronidazole.

Conclusion : Metronidazole is more effective than rifaximin for the treatment of small intestine bacterial overgrowth associated with the presence of a blind loop.
Normalization of oesophageal pH does not guarantee control of duodenogastro‐oesophageal reflux in Barrett's oesophagus
Authors: Todd J. A. , Basu K. K. , De Caestecker J. S.
Published: April 2005

Background : Proton‐pump inhibitors are effective at preventing the acid component of gastro‐oesophageal refluxate from entering the oesophagus. It is not clear whether proton‐pump inhibitors prevent duodenogastro‐oesophageal reflux.

Aim : To measure oesophageal exposure to duodenogastro‐oesophageal refluxate while on proton‐pump inhibitors in patients with Barrett's oesophagus.

Methods : Twenty‐five patients (23 male) with Barrett's oesophagus underwent 24 h oesophageal pH and Bilitec 2000 monitoring while on omeprazole 40 mg/day (n = 19) or omeprazole 60 mg/day (n = 6). All patients were undergoing argon plasma ablation of their Barrett's epithelium as part of a clinical trial and the Bilitec measurements were only carried out after the ablation had been completed.

Results : 20 of 25 (80%) patients had a normal oesophageal pH profile. Fifteen of the 25 (60%) had abnormal oesophageal exposure to bile as measured by Bilitec 2000. Of the 20 patients who had a normal 24 h oesophageal pH profile, 11 (55%) had pathological exposure to bile in their oesophagus.

Conclusion : Complete acid suppression does not guarantee elimination of duodenogastro‐oesophageal reflux.
Mucosa‐associated bacteria in ulcerative colitis before and after antibiotic combination therapy
Authors: Nomura T. , Ohkusa T. , Okayasu I. , Yoshida T. , Sakamoto M. , Hayashi H. , Benno Y. , Hirai S. , Hojo M. , Kobayashi O. , Terai T. , Miwa H. , Takei Y. , Ogihara T. , Sato N.
Published: April 2005

Background : We proposed that Fusobacterium varium is one of the causative agents in ulcerative colitis.

Aim : To examine the efficacy of antibiotic combination therapy against F. varium and to investigate the mucosa‐associated bacteria before and after the therapy using a new molecular approach.

Methods : Twenty patients with ulcerative colitis were randomly assigned into the antibiotic treatment group (amoxicillin, tetracycline and metronidazole for 2 weeks) and no‐antibiotics group. Clinical assessment, colonoscopic and histological evaluations were performed at 0 and 3–5 months after the treatment. DNA from mucosal bacteria was isolated from biopsy specimens. We investigated the mucosa‐associated bacterial components by terminal restriction fragment length polymorphism with the restriction enzyme HhaI and MspI, and quantified the change in the number of bacteria by real‐time polymerase chain reaction. Immunohistochemical detection of F. varium in biopsy specimens was also performed.

Results : After the treatment, the clinical assessment, colonoscopic and histological scores improved in the antibiotic group compared with the control group. Three peaks of terminal restriction fragment length polymorphism decreased after treatment only in the antibiotic group. Eubacterium rectale, Dorea formicigenerans, Clostridium clostridioforme and F. varium were included in these peaks. Based on the real‐time polymerase chain reaction study, only F. varium was significantly reduced after treatment. In the immunostaining, post‐treatment scores in treatment group were significantly lower than that in control group.

Conclusions : Antibiotics combination therapy was effective for ulcerative colitis. The number of mucosa‐associated F. varium significantly decreased after the treatment.
A multilocus population genetic survey of the greater sage‐grouse across their range
Authors: OYLER‐MCCANCE S. J. , TAYLOR S. E. , QUINN T. W.
Published: April 2005

The distribution and abundance of the greater sage‐grouse (Centrocercus urophasianus) have declined dramatically, and as a result the species has become the focus of conservation efforts. We conducted a range‐wide genetic survey of the species which included 46 populations and over 1000 individuals using both mitochondrial sequence data and data from seven nuclear microsatellites. Nested clade andstructureanalyses revealed that, in general, the greater sage‐grouse populations follow an isolation‐by‐distance model of restricted gene flow. This suggests that movements of the greater sage‐grouse are typically among neighbouring populations and not across the species, range. This may have important implications if management is considering translocations as they should involve neighbouring rather than distant populations to preserve any effects of local adaptation. We identified two populations in Washington with low levels of genetic variation that reflect severe habitat loss and dramatic population decline. Managers of these populations may consider augmentation from geographically close populations. One population (Lyon/Mono) on the southwestern edge of the species’ range appears to have been isolated from all other greater sage‐grouse populations. This population is sufficiently genetically distinct that it warrants protection and management as a separate unit. The genetic data presented here, in conjunction with large‐scale demographic and habitat data, will provide an integrated approach to conservation efforts for the greater sage‐grouse.
Genetic continuity of brood‐parasitic indigobird species
Authors: SEFC KRISTINA M. , PAYNE ROBERT B. , SORENSON MICHAEL D.
Published: April 2005

Speciation in brood‐parasitic indigobirds (genus Vidua) is a consequence of behavioural imprinting in both males and females. Mimicry of host song by males and host fidelity in female egg laying result in reproductive isolation of indigobirds associated with a given host species. Colonization of new hosts and subsequent speciation require that females occasionally lay eggs in the nests of novel hosts but the same behaviour may lead to hybridization when females parasitize hosts already associated with other indigobird species. Thus, retained ancestral polymorphism and ongoing hybridization are two alternative explanations for the limited genetic differentiation among indigobird species. We tested for genetic continuity of indigobird species using mitochondrial sequences and nuclear microsatellite data. Within West Africa and southern Africa, allopatric populations of the same species are generally more similar to each other than to sympatric populations of different species. Likewise, a larger proportion of genetic variation is explained by differences between species than by differences between locations in alternative hierarchical amovas, suggesting that the rate of hybridization is not high enough to homogenize sympatric populations of different species or prevent genetic differentiation between species. Broad sharing of genetic polymorphisms among species, however, suggests that some indigobird species trace to multiple host colonization events in space and time, each contributing to the formation of a single interbreeding population bound together by songs acquired from the host species.
Northwestern song sparrow populations show genetic effects of sequential colonization
Authors: PRUETT CHRISTIN L. , WINKER KEVIN
Published: April 2005

Two genetic consequences are often considered evidence of a founder effect: substantial loss in genetic diversity and rapid divergence between source and founder populations. Single‐step founder events have been studied for these effects, but with mixed results, causing continued controversy over the role of founder events in divergence. Experiments of serial bottlenecks have shown losses of diversity, increased divergence, and rapid behavioural changes possibly leading to reproductive isolation between source and final populations. The few studies conducted on natural, sequentially founded systems show some evidence of these effects. We examined a natural vertebrate system of sequential colonization among northwestern song sparrows (Melospiza melodia). This system has an effectively linear distribution, it was probably colonized within the last 10 000 years, there are morphological and behavioural differences among populations, and the westernmost populations occur in atypical habitats for the species. Eight microsatellite loci from eight populations in Alaska and British Columbia (n = 205) showed stepwise loss of genetic diversity, genetic evidence for strong population bottlenecks, and increased population divergence. The endpoint population on Attu Island has extremely low diversity (HE = 0.18). Our study shows that sequential bottlenecks or founder events can have powerful genetic effects in reducing diversity, possibly leading to rapid evolutionary divergence.
Transposable element polymorphism of Wolbachia in the mosquito Culex pipiens: evidence of genetic diversity, superinfection and recombination
Authors: DURON OLIVIER , LAGNEL JACQUES , RAYMOND MICHEL , BOURTZIS KOSTAS , FORT PHILIPPE , WEILL MYLÈNE
Published: April 2005

Wolbachia is a group of maternally inherited endosymbiotic bacteria that infect and induce cytoplasmic incompatibility (CI) in a wide range of arthropods. In contrast to other species, the mosquito Culex pipiens displays an extremely high number of CI types suggesting differential infection by multiple Wolbachia strains. Attempts so far failed to detect Wolbachia polymorphism that might explain this high level of CI diversity found in C. pipiens populations. Here, we establish that Wolbachia infection is near to or at fixation in worldwide populations of the C. pipiens complex. Wolbachia polymorphism was addressed by sequence analysis of the Tr1 gene, a unique transposable element of the IS5 family, which allowed the identification of five C. pipiens Wolbachia strains, differing either by nucleotide substitution, presence or absence pattern, or insertion site. Sequence analysis also showed that recombination, transposition and superinfection occurred at very low frequencies. Analysis of the geographical distributions of each Wolbachia strain among C. pipiens populations indicated a strong worldwide differentiation independent from mosquito subspecies type, except in the UK. The availability of this polymorphic marker now opens the way to investigate evolution of Wolbachia populations and CI dynamics, in particular in regions where multiple crossing types coexist among C. pipiens populations.
Similar mating and sperm displacement patterns in two highly divergent D. simulans populations from Africa and Europe
Authors: SCHLÖTTERER CHRISTIAN , REISS MARTINA , SCHNEIDER ANGELIKA , IMHOF MARIANNE
Published: April 2005

The frequency of remating in Drosophila melanogaster is affected by both genetic and ecological factors. We studied the remating behaviour in one European (Italy) and one African (Uganda) Drosophila simulans population using six highly polymorphic microsatellite markers. Despite that the populations were genetically distinct (FST = 0.18) and originated from very dissimilar ecological settings with different population densities, we inferred a very similar mating pattern. The remating parameter α was similar in both populations  (ā = 1.3–1.4). No more than two distinct paternal genotypes per family were detected in each population.
Geographic variation of multiple paternity in the American lobster, Homarus americanus
Authors: GOSSELIN THIERRY , SAINTE‐MARIE BERNARD , BERNATCHEZ LOUIS
Published: April 2005

We studied the frequency of multiple paternity for American lobster (Homarus americanus) at three Canadian sites differing in exploitation rate and mean adult size. The probability of detecting multiple paternity using four microsatellite loci and 100 eggs per female was in excess of 99% under various scenarios of paternal contribution. Overall, 13% of the 108 examined females carried a clutch sired by two or three males. Multiple paternity was observed at the two most exploited sites (11% at Magdalen Islands and 28% at Grand Manan Island), whereas single paternity only was observed at the least exploited site (Anticosti Island). Within populations females with a clutch sired by more than one male tended to be smaller than females with a clutch sired by a single male. Based on these and other findings, we postulate a link between female promiscuity and sperm limitation in the American lobster.
Postglacial expansion of the southern red‐backed vole (Clethrionomys gapperi) in North America
Authors: RUNCK AMY M. , COOK JOSEPH A.
Published: April 2005

Dynamic climatic oscillations of the Pleistocene dramatically changed the distributions of high latitude species. Molecular investigations of a variety of organisms show that processes of postglacial colonization of boreal regions were more complex than initially thought. Phylogeographical and coalescent analyses were conducted on partial sequences of the cytochrome b gene (600 bp) from 64 individuals of Clethrionomys gapperi from North Carolina, Pennsylvania, Minnesota, Idaho, Washington, British Columbia, Northwest Territories, and Alaska to test hypotheses relating to Pleistocene refugia and postglacial colonization routes. Three divergent clades (east, west, central) were identified with highest net divergence (dA = 5.2%) between the eastern and western clades. Populations from the recently deglaciated higher latitudes of Canada and Alaska are closely related to lower latitude populations of the central clade (dA = 1.2%) suggesting recent expansion from this midwestern region. No representatives from the east or west clade were found at latitudes higher than 50°N, indicating that postglacial colonization occurred through a midcontinental route. The high latitude population from the Northwest Territories exhibited demographic patterns and genetic diversity consistent with a stable noncolonizing population. This population is found near the Mackenzie range, where the two continental ice sheets were believed to have coalesced. Molecular variation observed in this population may be the result of leading edge population diversifying in the continental corridor or may reflect the signal of a high latitude refugial population.
Spatial structure of genetic variation and primary succession in the pioneer tree species Antirhea borbonica on La Réunion
Authors: LITRICO I. , RONFORT J. , VERLAQUE R. , THOMPSON J. D.
Published: April 2005

In habitats where colonization and extinction are recurrent, the distribution of gene frequencies among patches of suitable habitat may reflect the age structure of different populations. In this study, we quantify population genetic structure for a pioneer tree species, Antirhea borbonica, in a chrono‐sequence of primary succession on the lava flows of the Piton de La Fournaise volcano (La Réunion). Using microsatellite loci and amplified fragment length polymorphism (AFLP) markers, we quantified genetic variation within and among populations for early‐ and late‐succession populations in a landscape where extinction and recolonization are recurrent (the ‘Grand Brûlé’) and for late‐succession populations in a more stable landscape. This study produced three main results. First, we detected no evidence that founder events increase genetic differentiation among colonizing populations; FST values among early‐ and among late‐succession populations were similar. Second, we found no evidence for isolation by distance; genetic distance was not correlated with spatial distance within and among populations. Third, FIS values are consistently high in all populations, despite the fact that A. borbonica populations are functionally close to dioecy and thus expected to have an outcrossing mating system. Multiple colonization events from different sources may limit differentiation among young populations and spatial isolation may enhance differentiation among late‐succession populations. Ecological processes acting during colonization may create the conditions for spatial aggregation within pioneer populations, and thus contribute to the high FIS values.
On the origins of extreme mycorrhizal specificity in the Monotropoideae (Ericaceae): performance trade‐offs during seed germination and seedling development
Authors: BIDARTONDO M. I. , BRUNS T. D.
Published: April 2005

Fungal‐induced seed germination is a phenomenon characteristic of mycorrhizal plants that produce dust‐like seeds with only minimal nutritional reserves. In such systems, fungi trigger germination and/or subsidize development. We studied mycorrhizal germination in relation to mycorrhizal specificity in the Monotropoideae, a lineage of dust‐seeded nonphotosynthetic plants that are dependent upon ectomycorrhizal fungi of forest trees. A total of 1695 seed packets, each containing two to five compartments with seeds from different sources, were buried for up to 2 years near known ectomycorrhizal fungi in six different native forest locations. Upon harvest, seedlings were analysed by cultivation‐independent molecular methods to identify their mycorrhizal fungi. We report that (i) germination is only induced by the same fungus that associates with mature plants or by closely related congeners; (ii) seedlings associated with the latter fungi develop less than those associated with maternal fungal species in most settings; and (iii) exceptions to this pattern occur in allopatric settings, where novel plant–fungal associations can result in the greatest seedling development. We interpret these results as evidence of performance trade‐offs between breadth of host range and rate of development. We propose that in conjunction with host‐derived germination cues, performace trade‐offs can explain the extreme mycorrhizal specificity observed at maturity. The allopatric exceptions support the idea that performance trade‐offs may be based on a coevolutionary arms race and that host range can be broadened most readily when naïve fungal hosts are encountered in novel settings.
Genetic analysis of the breeding system of an invasive subterranean termite, Reticulitermes santonensis, in urban and natural habitats
Authors: DRONNET STÉPHANIE , CHAPUISAT MICHEL , VARGO EDWARD L. ,   CAROLINE LOHOU, BAGNÈRES ANNE‐GENEVIÈVE
Published: April 2005

Reticulitermes santonensis is a subterranean termite that invades urban areas in France and elsewhere where it causes damage to human‐built structures. We investigated the breeding system, colony and population genetic structure, and mode of dispersal of two French populations of R. santonensis. Termite workers were sampled from 43 and 31 collection points, respectively, from a natural population in west–central France (in and around the island of Oléron) and an urban population (Paris). Ten to 20 workers per collection point were genotyped at nine variable microsatellite loci to determine colony identity and to infer colony breeding structure. There was a total of 26 colonies, some of which were spatially expansive, extending up to 320 linear metres. Altogether, the analysis of genotype distribution, F‐statistics and relatedness coefficients suggested that all colonies were extended families headed by numerous neotenics (nonwinged precocious reproductives) probably descended from pairs of primary (winged) reproductives. Isolation by distance among collection points within two large colonies from both populations suggested spatially separated reproductive centres with restricted movement of workers and neotenics. There was a moderate level of genetic differentiation (FST = 0.10) between the Oléron and Paris populations, and the number of alleles was significantly higher in Oléron than in Paris, as expected if the Paris population went through bottlenecks when it was introduced from western France. We hypothesize that the diverse and flexible breeding systems found in subterranean termites pre‐adapt them to invade new or marginal habitats. Considering that R. santonensis may be an introduced population of the North American species R. flavipes, a breeding system consisting primarily of extended family colonies containing many neotenic reproductives may facilitate human‐mediated spread and establishment of R. santonensis in urban areas with harsh climates.
Allopatric origins of sympatric brook charr populations: colonization history and admixture
Authors: FRASER D. J. , BERNATCHEZ L.
Published: April 2005

Natural selection is presumed to be the driving force behind the occurrence of phenotypically and genetically divergent populations in sympatry within many north temperate freshwater fishes. If, however, these populations have different ancestral origins, history could also contribute to their divergence. We previously found evidence for the role of selection in the evolution of divergent outflow and inflow breeding populations of migratory brook charr (Salvelinus fontinalis) inhabiting postglacial Mistassini Lake (Québec, Canada). Here, we show that these populations do not have a common origin, through the use of admixture and spatial analyses with seven microsatellite loci. Divergent populations clustered into two different population groups when compared to samples from surrounding drainages, although inflow populations appeared to be more admixed between the two population groups than the outflow population. These results are noteworthy since outflow and inflow populations were monomorphic at mitochondrial DNA (338‐bp sequence of the control region) and are only moderately differentiated (meanFST = 0.10). Colonization by two ancestral populations was also consistent with known outflow direction changes throughout lake formation. In addition to providing insight into how phenotypic divergence in sympatry may have been affected by the nature (i.e. timing and direction) of colonization of ancestral populations, our results also suggest that ancestral populations may have differed in their ability to colonize certain lake habitats.
Phylogeographic analysis of mitochondrial gene flow and introgression in the salamander,Plethodon shermani
Authors: WEISROCK D. W. , KOZAK K. H. , LARSON A.
Published: April 2005

Plethodon shermanicomprises a series of geographically disjunct populations occupying high‐elevation mountain isolates. These populations hybridize at their borders with salamanders of thePlethodon glutinosusspecies complex, and past range expansions inferred from Pleistocene climatic cycles may have increased the possible genetic interactions betweenP. shermaniand species of theP. glutinosuscomplex. Because mitochondrial DNA haplotypes often show introgression across species borders, we survey mtDNA variation for evidence of past and ongoing genetic interactions betweenP. shermani,its close relativePlethodon cheoah,and species of theP. glutinosuscomplex. Ongoing hybridization with theP. glutinosus‐complex speciesPlethodon teyahaleeis accompanied by extensive mitochondrial introgression in some Unicoi populations ofP. shermani,but it has little genetic impact onP. shermanipopulations outside hybrid zones at three other isolates (Tusquitee, Wayah Bald, Standing Indian). Some Unicoi populations ofP. shermaniexhibit mtDNA evidence of past hybridization with diverse lineages fromP. aureolusandP. glutinosus. The Tusquitee isolate ofP. shermaniis also characterized by mtDNA haplotypes most closely related toPlethodon aureolusandP. glutinosus, presumably introduced by past genetic contact with these species or with introgressed populations of UnicoiP. shermani. The mtDNA variation in sampled populations of the Wayah Bald and Standing Indian isolates ofP. shermaniappears largely unaffected by ongoing hybridization. Principal components analyses of allozymic data indicate thatP. shermaniisolates collectively form a genetically homogeneous unit clearly demarcated from species with which they have had current or past genetic interactions. Rapid mtDNA introgression associated with transient contacts betweenP. shermaniand other species permits a fine‐level resolution of evolutionary lineages not evident from allozymic data.
Monitoring coyote population dynamics by genotyping faeces
Authors: PRUGH L. R. , RITLAND C. E. , ARTHUR S. M. , KREBS C. J.
Published: April 2005

Reliable population estimates are necessary for effective conservation and management, and faecal genotyping has been used successfully to estimate the population size of several elusive mammalian species. Information such as changes in population size over time and survival rates, however, are often more useful for conservation biology than single population estimates. We evaluated the use of faecal genotyping as a tool for monitoring long‐term population dynamics, using coyotes (Canis latrans) in the Alaska Range as a case study. We obtained 544 genotypes from 56 coyotes over 3 years (2000–2002). Tissue samples from all 15 radio‐collared coyotes in our study area had ≥ 1 matching faecal genotypes. We used flexible maximum‐likelihood models to study coyote population dynamics, and we tested model performance against radio telemetry data. The staple prey of coyotes, snowshoe hares (Lepus americanus), dramatically declined during this study, and the coyote population declined nearly two‐fold with a 11/2‐year time lag. Survival rates declined the year after hares crashed but recovered the following year. We conclude that long‐term monitoring of elusive species using faecal genotyping is feasible and can provide data that are useful for wildlife conservation and management. We highlight some drawbacks of standard open‐population models, such as low precision and the requirement of discrete sampling intervals, and we suggest that the development of open models designed for continuously collected data would enhance the utility of faecal genotyping as a monitoring tool.
Genetic structure in the coral‐reef‐associated Banggai cardinalfish, Pterapogon kauderni
Authors: HOFFMAN ERIC A. , KOLM NICLAS , BERGLUND ANDERS , ARGUELLO J. ROMAN , JONES ADAM G.
Published: April 2005

In this study, we used 11 polymorphic microsatellite loci to show that oceanic distances as small as 2–5 km are sufficient to produce high levels of population genetic structure (multilocus FST as high as 0.22) in the Banggai cardinalfish (Pterapogon kauderni), a heavily exploited reef fish lacking a pelagic larval dispersal phase. Global FST among all populations, separated by a maximum distance of 203 km, was 0.18 (RST = 0.35). Moreover, two lines of evidence suggest that estimates of FST may actually underestimate the true level of genetic structure. First, within‐locus FST values were consistently close to the theoretical maximum set by the average within‐population heterozygosity. Second, the allele size permutation test showed that RST values were significantly larger than FST values, indicating that populations have been isolated long enough for mutation to have played a role in generating allelic variation among populations. The high level of microspatial structure observed in this marine fish indicates that life history traits such as lack of pelagic larval phase and a good homing ability do indeed play a role in shaping population genetic structure in the marine realm.