Contingency Test Research Articles

Macroevolution of panicoid inflorescences: a history of contingency and order of trait acquisition.

Inflorescence forms of panicoid grasses (Panicoideae s.s.) are remarkably diverse and they look very labile to human eyes; however, when performing a close inspection one can identify just a small subset of inflorescence types among a huge morphospace of possibilities. Consequently, some evolutionary constraints have restricted, to some extent, the diversification of their inflorescence. Developmental and genetic mechanisms, the photosynthetic type and plant longevity have been postulated as candidate constraints for angiosperms and panicoids in particular; however, it is not clear how these factors operate and which of these have played a key role during the grass inflorescence evolution. To gain insight into this matter the macroevolutionary aspects of panicoid inflorescences are investigated. The inflorescence aspect (lax versus condensed), homogenization, truncation of the terminal spikelet, plant longevity and photosynthetic type were the traits selected for this study. Maximum likelihood and Bayesian Markov chain Monte Carlo methods were used to test different models of evolution and to evaluate the existence of evolutionary correlation among the traits. Both, models and evolutionary correlation were tested and analysed in a phylogenetic context by plotting the characters on a series of trees. For those cases in which the correlation was confirmed, test of contingency and order of trait acquisition were preformed to explore further the patterns of such co-evolution. The data reject the independent model of inflorescence trait evolution and confirmed the existence of evolutionary contingency. The results support the general trend of homogenization being a prerequisite for the loss of the terminal spikelet of the main axis. There was no evidence for temporal order in the gain of homogenization and condensation; consequently, the homogenization and condensation could occur simultaneously. The correlation between inflorescence traits with plant longevity and photosynthetic type is not confirmed. The findings indicate that the lability of the panicoid inflorescence is apparent, not real. The results indicate that the history of the panicoids inflorescence is a combination of inflorescence trait contingency and order of character acquisition. These indicate that developmental and genetic mechanisms may be important constraints that have limited the diversification of the inflorescence form in panicoid grasses.

Genetic mapping of two genes conferring resistance to powdery mildew in common bean (Phaseolus vulgaris L.)

Powdery mildew (PM) is a serious disease in many legume species, including the common bean (Phaseolus vulgaris L.). This study investigated the genetic control behind resistance reaction to PM in the bean genotype, Cornell 49242. The results revealed evidence supporting a qualitative mode of inheritance for resistance and the involvement of two independent genes in the resistance reaction. The location of these resistance genes was investigated in a linkage genetic map developed for the XC RIL population. Contingency tests revealed significant associations for 28 loci out of a total of 329 mapped loci. Fifteen were isolated or formed groups with less than two loci. The thirteen remaining loci were located at three regions in linkage groups Pv04, Pv09, and Pv11. The involvement of Pv09 was discarded due to the observed segregation in the subpopulation obtained from the Xana genotype for the loci located in this region. In contrast, the two subpopulations obtained from the Xana genotype for the BM161 locus, linked to the Co-3/9 anthracnose resistance gene (Pv04), and from the Xana genotype for the SCAReoli locus, linked to the Co-2 anthracnose resistance gene (Pv11), exhibited monogenic segregations, suggesting that both regions were involved in the genetic control of resistance. A genetic dissection was carried out to verify the involvement of both regions in the reaction to PM. Two resistant recombinant lines were selected, according to their genotypes, for the block of loci included in the Co-2 and Co-3/9 regions, and they were crossed with the susceptible parent, Xana. Linkage analysis in the respective F2 populations supported the hypothesis that a dominant gene (Pm1) was located in the linkage group Pv11 and another gene (Pm2) was located in the linkage group Pv04. This is the first report showing the localization of resistance genes against powdery mildew in Phaseolus vulgaris and the results offer the opportunity to increase the efficiency of breeding programs by means of marker-assisted selection.

Role of second‐trimester ultrasound in screening for Down syndrome

Role of second‐trimester ultrasound in screening for Down syndrome

Involvement of IL-1 and Oncostatin M in Acanthosis Associated With Hypertensive Leg Ulcer

Hypertensive leg ulcer (HLU) is an inflammatory disease characterized by intense pain, alteration of vascularization, and skin necrosis. The optimal treatment relies on surgical removal of necrotic tissues covered by a split-skin graft. We studied the histomorphology of the lesions and investigated the involvement of inflammatory cells and cytokines to further define the physiopathology of HLU. We report epidermis acanthosis and a preferential occlusion of the precapillary arterioles with infiltration of neutrophils, macrophages, and T lymphocytes in the dermis. OSM, IL-1β, and IL-6 were overexpressed in the ulcer, whereas the Th17-derived cytokines were not. In vitro, the addition of IL-1β and OSM promoted acanthosis and destructuring of reconstructed epidermis. Exogenous IL-1β and OSM synergistically induced epidermal acanthosis in mice. These data show that OSM and IL-1β are not only a biological characteristic signature of HLU, but these cytokines reflect a specific inflammatory state, directly involved in the pathogenesis. We suggest that anti-cytokine biotherapies could be an alternative strategy to surgery to treat HLU.

Clinical and Nutritional characterization of patients with massive intestinal resection in Ribeirão Preto, SP, Brazil

ABSTRACT Background: Short bowel syndrome (SBS) is a clinical situation due to extensive intestinal resection or dysfunction of the absorptive system of the small intestine. When these patints are not submitted to nutritional therapy their maximum survival is six months. In Brazil there are few reference centers for the treatment and follow-up of these patients and information about their characterization is scarce. Objective: To describe enterectomized patients attended during the period from 1996 to 2007. Methods: All medical records of the patients attended at the Nutrology service of HCFMRP-USP were analyzed retrospectively. Data were collected and analyzed descriptively using the contingency test and the Wilcoxon- Mann-Whitney test for independent samples. Results: Thirty-eight patients with a mean age of 52 years at the time of enterectomy were analyzed, 47% of them males and 53% females. The main etiology of SBS was mesenteric ischemia (73%). Of these patients, 67% had some risk factor associated with atherosclerosis. No significant differences in eating habits were detected between the period before and after surgery. After surgery, 39% of the patients developed a significant weight loss and 79% developed some type of complication, surgical in 34%, infectious in 66% and of both types in 21%. Survival was 9.5 years. Conclusion: Extensive resections of the small bowel may be associated with atherosclerosis and represent an important nutritional risk, with a significant weight loss during the first year, which seems to be related to increased morbidity. Adequate nutritional therapy is associated with increased survival.

Correlates of monoicy and dioicy in hornworts, the apparent sister group to vascular plants

BackgroundWhether male and female gametes are produced by single or separate individuals shapes plant mating and hence patterns of genetic diversity among and within populations. Haploid-dominant plants (“bryophytes”: liverworts, mosses and hornworts) can have unisexual (dioicous) or bisexual (monoicous) gametophytes, and today, 68% of liverwort species, 57% of moss species, and 40% of hornwort species are dioicous. The transitions between the two sexual systems and possible correlations with other traits have been studied in liverworts and mosses, but not hornworts. Here we use a phylogeny for 98 of the 200 species of hornworts, the sister group to vascular plants, representing roughly equal proportions of all monoicous and all dioicous species, to test whether transitions in sexual systems are predominantly from monoicy to dioicy as might be expected based on studies of mosses. We further investigate possible correlations between sexual system and spore size, antheridium number, ploidy level, and diversification rate, with character selection partly based on findings in mosses and liverworts.ResultsHornworts underwent numerous transitions between monoicy and dioicy. The transition rate from dioicy to monoicy was 2× higher than in the opposite direction, but monoicous groups have higher extinction rates; diversification rates do not correlate with sexual system. A correlation important in mosses, that between monoicy and polyploidy, apparently plays a small role: of 20 species with chromosome counts, only one is polyploid, the monoicous Anthoceros punctatus. A contingency test revealed that transitions to dioicy were more likely in species with small spores, supporting the hypothesis that small but numerous spores may be advantageous for dioicous species that depend on dense carpets of gametophytes for reproductive assurance. However, we found no evidence for increased antheridium-per-chamber numbers in dioicous species.ConclusionsSexual systems in hornworts are labile, and the higher number of extant monoicous species (60%) may be largely due to frequent transitions to monoicy.

Is there Unity in Europe? First Survey of EUPSA Delegates on the Management of Gastroschisis

To report the first European survey on the current management of gastroschisis and ascertain the degree of variability between centers. A 10-question survey was administered at the 2011 European Paediatric Surgeons' Association (EUPSA) Congress. Questionnaires were completed by 205 delegates from 39 countries. A total of 21 responses (10%) were incomplete and voided. The remaining 184 were divided on the basis of following region of practice: Western Europe (WE, n = 102), Eastern Europe (EE, n = 59), and non-European countries (n = 23). Differences between WE and EE were analyzed using contingency tests. p < 0.05 was considered significant. A total of 15% WE and 2% EE responders work in centers where antenatal magnetic resonance imaging scans are routinely used. Nonplanned delivery is the most popular approach (WE 46%, EE 58%). Primary closure is the preferred choice (WE 92%, EE 86%), and it is achieved by operative fascial closure in the majority (WE 80%, EE 75%) rather than by Bianchi technique (WE 20%, EE 25%). Staged reduction and closure is less popular (WE 8%, EE 14%), and it is achieved by custom-made silo (WE 25%, EE 12.5%), preformed silo (PFS) followed by surgical closure (WE 63%, EE 75%), or PFS followed by sutureless closure (WE 12%, EE 12.5%). Objection to PFS in WE is mainly related to surgeons' lack of confidence in the technique (40%), whereas in EE it is due to unavailability and high cost (62%, p = 0.01). In case of associated intestinal atresia, immediate resection and anastomosis is preferred by 60% of WE surgeons versus 35% of EE surgeons (p = 0.03), who equally favor primary closure and delayed surgery (33%). Nutrition is preferably delivered by peripheral long line in WE (64%) and by central line inserted in the first week of life in EE (62%, p = 0.003). Primary fascial closure is currently the preferred method of gastroschisis closure across Europe. Aspects of care such as strategy for intestinal atresia and delivery of parenteral nutrition differ significantly between WE and EE. Economic considerations appear to influence management strategy particularly in EE. A Europe-wide audit appears warranted to identify whether this survey reflects actual practice.

Optimal cut‐offs for down syndrome contingent screening in a population of 10 156 pregnant women

A population of 10,156 pregnant women with singleton pregnancies were screened by the integrated test. Risks were retrospectively recalculated for contingent test strategies with first step intermediate risk groups defined by first trimester upper cut-offs of 1 : 10, 1 : 30, 1 : 50, and 1 : 70 and lower cut-offs 1 : 1500, 1 : 1200, 1 : 1100, and 1 : 900. The second trimester high risk group was based on a single cut-off of 1 : 250. In the first trimester, the detection rate (DR) ranged from 21% (6/29) to 52% (15/29) as the high risk first trimester cut-off was changed from 1 : 10 to 1 : 70. The corresponding first trimester false positive rate (FPR) increased from 0.2% to 1.4%. In the second trimester, an additional 21/29 (72%) to 12/29 (41%) affected pregnancies could be detected with an additional 1.6% to 2.7% false positives when lower first trimester cut-offs of 1 : 900 to 1 : 1500 were used. The best results were obtained with the upper first trimester cut-off of 1 : 30 and lower first trimester cut-off of 1 : 900, which yielded a rate of women requiring a second trimester test of only 12%, with overall DR and FPR of 93% and 2.8%, respectively. Although the study population was relatively small, the results confirm the advantage of using contingent screening and suggest optimal first trimester cut-offs of 1 : 30 (lower cut-off) and 1 : 900 (upper cut-off).

OP23.02: Contingent testing, an alternative for regions lacking first trimester screening for Down's syndrome

late samples. Age standardised detection and false positive rates for different screening protocols were produced. Results: We collected two blood samples in 27 pregnancies affected by trisomy 21 and in 3891 control pregnancies. The early samples were taken between gestational week 8+0 up to week 13+6, and the late samples between week 11+3 up to week 14+6. The median interval between the samples was 17 days (range 1–40 days). We found a significantly better (P 0.05). Conclusions: Using early sampling with measurement of PAPPA and free β-hCG in the combined first trimester screening can optimise screening performance for trisomy 21. Using a double set of the maternal serum markers has the potential to further improve screening performance.

Tell Me Who You Think You Are and I Tell You How You Travel. Exploring the Viability of Market Segmentation by Means of Travelers' Stated Personality: Insights from a Mature Market (Switzerland)

People travel to different destinations for different reasons. In this study, we investigate the viability of market segmentation by personal traits (based on and exemplified by Jungian's MBTI variables) of travelers from Switzerland, by performing a data-driven a posteriori segmentation by means of k-means clustering. To identify the segmentation power of personal traits, this analysis is complemented with a multiple discriminant analysis as well as a number of contingency tests to identify differences between the segments. We identified four clearly definable segments, which differ in terms of the psychographic traits of the segment members but also in terms of some sociodemographic characteristics as well as travel profiles. Despite a growing body of work on classical market segmentation, there is a growing but still limited number of works on potentialities of psychographic approaches relating to a traveler's traits and/or personality as a segmentation basis in tourism.

First trimester contingent test as a screening method for Down’s syndrome. A prospective study in the general population

Objectives: To evaluate the possibility of implementing a contingent test as a screening method for Down’s syndrome (DS) in the first trimester of pregnancy, and assess its sensitivity (Sen) and false positive rate (FPR). Methods: Prospective study covering a 4-year study period (July 2006–June 2010). Pregnant women were offered a combined test (CT) as the first step of a contingent test. An intermediate risk group is identified in the CT (1/101 and 1/1000) and offered an ultrasound assessment of secondary s (nasal bone, ductus venosus, tricuspid regurgitation). Results: CTs were performed on 10,452 pregnant women (24 cases of DS). In the intermediate risk group, which had 7 cases of DS, we performed secondary ultrasound marker assessment on 98.1% (1,017/1,036). The CT and the contingent test had a Sen of 83% (95% CI; 67.9–98) (20/24) and 70.8% (95% CI; 52.6–88.9) (17/24) with an FPR of 3% (95% CI; 2.7–3.3) (316/10,430) and 2% (95% CI; 1.7–2.3) (220/10,408), respectively. Conclusions: With the contingent test, we managed to reduce the FPR, but the Sen was too low for use as a screening method for DS.

Group contingency test for two or several independent samples

This paper proposes a new and distribution-free test called “Group Contingency” test (GC, for short) for testing two or several independent samples. Compared with traditional nonparametric tests, GC test tends to explore more information based on samples, and it’s location-, scale-, and shapesensitive. The authors conduct some simulation studies comparing GC test with Wilcoxon rank sum test (W), Kolmogorov-Smirnov test (KS) and Wald-Wolfowitz runs test (WW) for two sample case, and with Kruskal-Wallis (KW) for testing several samples. Simulation results reveal that GC test usually outperforms other methods.

Abstract 5246: Genomic determinants of aggressive phenotype in oral SCC

Abstract Background: Oral squamous cell carcinoma (OSCC), the common form of HNSCC, affects over 600,000 cases worldwide per annum. We reviewed 561 consecutive cases in Liverpool1 finding that the most predictive marker for death was extra-capsular spread (ECS) from cervical lymph nodes (p&amp;lt;0.001). Overall survival at 5 years was 56% for all 561 cases, but only 24% in the ECS group independently of its site, extent or the stage of the primary tumour2. The presence of ECS predicted for recurrence, usually at the primary site, even when surgical margins were generous indicating that this aggressive phenotype is likely to be expressed in the primary tumour as much as in the metastatic cells. Hypothesis: We hypothesised that molecular pathways represented by global gene expression signatures would be detected in the samples associated with ECS. Methods: High density exon array expression analysis was performed on fresh frozen samples comprising T2 and T4 stage OSCC cases having no nodal involvement; positive nodes without ECS or positive nodes plus ECS picked longitudinally from a single centre series (n&amp;gt;200) with bias towards increasing the numbers with ECS. Contingency tests were performed to assess the significance of ECS associated pathways. Results and Discussion: Power analysis showed that 90% of all ≥ twofold differences in gene expression between node negative &amp; ECS cases were significant. Affected pathways included: keratinocyte differentiation, ECM remodelling, chemokines &amp; adhesion, TGF &amp; WNT: cytoskeletal remodelling, regulation of actin cytoskeleton by rho GTPases &amp; cell adhesion/ histamine H1 receptor signalling/loss of cell barrier (p values:7.7×10−15 – 1.9×10−6). A 29 gene signature able to discriminate the ECS from the non-ECS cases with 78% sensitivity and 86% specificity was found. Blocked differentiation of keratinocytes at an early (“stem cell”/ EMT) stage was suggested by the genes which included keratin 15, keratinocyte differentiation-associated protein, retinol binding protein 1, cellular serine peptidase inhibitor (Kazal type 6), and stratifin implicated in mesenchymal stem cells, basal, suprabasal expression and keratinocyte activation and differentiation. The signature may be connected with these tumours having poor prognosis. Conclusion: This is a significant and novel finding suggesting that the pattern of metastasis in regional lymph nodes can be predicted by molecular pathways prevalent in a small oral biopsy. 1. Rogers et al. Oral Oncol 2009;45(3):201-211 2. Shaw et.al. Head Neck 2010;32(6):714-722 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5246. doi:10.1158/1538-7445.AM2011-5246

Reward economics and organisation: The issue of effectiveness

The paper sets out to assess the relationship that exists between reward in an organization and organizational effectiveness. Organizational effectiveness is defined in terms of profitability. Guinness Nigeria Plc was taken as the case study. An instrument of questionnaire containing both open and close ended questions was used to elicit information from both the management staff and employees of Guinness Plc, Benin city, Nigeria on their perceived impact of reward structure on organizational effectiveness. The study tested three main hypotheses with the use of chi-square technique. Our study revealed that organizational effectiveness can be achieved to a great extent with solid reward structure and that corporate reward policy influences individual employees’ behaviour. It was also found that non-financial rewards, such as training and development, seminars, symposia and workshops can enhance organizational effectiveness. However, the application of the coefficient of contingency test on one of our chi-square analysis result indicated that there is a weak correlation between the effectiveness and salary structure under investigation. This phenomenon results in a major break through in our study in that it pin-points that organizational effectiveness can not be achieved only by the organization’s reward structure. Thus, effectiveness is a variable of so many factors and individual needs and goals are not always the same. This study therefore recommends that a piece rate system of reward can be adopted to mechanically link pay to job performance. Key words: Reward, economics, organization, effectiveness, human behaviour.

Motivation Techniques Used By Heads Of Higher Educational Institutions In Pakistan

The study was aimed to investigate the Motivation techniques used by Heads Higher Educational Institutions in Pakistan. The population of this study comprised all the heads of degree colleges of Pakistan. For choosing the sample from this population, random sampling type was used. The sample constituted of 200 heads of degree colleges and colleges and 1000 teachers of degree colleges. A questionnaire was used as research instruments for collection of data. Collected data were tabulated, analyzed and interpreted in the light of objectives of the study by applying statistical tools of research such as chi-square as a contingency test and percentage were used. Chi-square as contingency test was used to compare the frequencies of principals/teachers. In the light of the conclusions it is recommended that a special training course may be arranged for educational managers, administrators and supervisors for achieving competency in motivation techniques.

Surface‐ and deep‐level dissimilarity effects on social integration and individual effectiveness related outcomes in work groups: A meta‐analytic integration

Prior research linking demographic (e.g., age, ethnicity/race, gender, and tenure) and underlying psychological (e.g., personality, attitudes, and values) dissimilarity variables to individual group member's work‐related outcomes produced mixed and contradictory results. To account for these findings, this study develops a contingency framework and tests it using meta‐analytic and structural equation modelling techniques. In line with this framework, results showed different effects of surface‐level (i.e., demographic) dissimilarity and deep‐level (i.e., underlying psychological) dissimilarity on social integration, and ultimately on individual effectiveness related outcomes (i.e., turnover, task, and contextual performance). Specifically, surface‐level dissimilarity had a negative effect on social integration under low but not under high team interdependence. In return, social integration fully mediated the negative relationship between surface‐level dissimilarity and individual effectiveness related outcomes under low interdependence. In contrast, deep‐level dissimilarity had a negative effect on social integration, which was stronger under high and weaker under low team interdependence. Contrary to our predictions, social integration did not mediate the negative relationship between deep‐level dissimilarity and individual effectiveness related outcomes but suppressed positive direct effects of deep‐level dissimilarity on individual effectiveness related outcomes. Possible explanations for these counterintuitive findings are discussed.

Evaluative Study Of M.A. Education Programmes Of Teacher Education At Higher Education Level In Pakistan

The study was aimed at evaluating the MA Education Programme of teacher education in Pakistan. Post-graduate teacher’s training institutes in Pakistan grant the Master of Education (MA/M.Ed.), Master of Philosophy (M.Phil) and Doctor of Philosophy (Ph D) post-graduate degrees in the field of education to enhance the careers and accelerate the professional development of educators. The population of the study was all heads and teachers of education departments of public sector universities and government colleges of education and prospective teachers enrolled in public sector universities and government colleges where the Master degree of Education (MA Education) programme was offered. The sample of 20 heads of public sector universities and government colleges of education, 56 teacher educators of 10 public sector universities and 10 government colleges of education, and 200 prospective teachers enrolled in public sector universities and government colleges of education departments, where the Master degree of Education (M.A./M.Ed.) was offered in Pakistan, was selected through cluster random sampling. For the collection of data, three questionnaires - one each for heads of institutions, teacher educators and prospective teachers - were developed. For analysis, chi-square as the contingency test, was applied for identifying the trends from the frequency of responses of each questionnaire item. It was concluded that the teaching faculty of the MA education programme was using a variety of teaching methods according to the nature of objectives, content and students. Evaluation systems for students of the MA education programme were found satisfactory. It is recommended that required changes be introduced in admission criteria, curriculum, duration of degree programme, teaching-practice, research work, rewards and incentives of existing MA Education Programme in Pakistan.

A prevalência do uso de sonda nasogástrica em bebês portadores de fissura de lábio e/ou palato

OBJETIVO: Investigar a prevalência do uso de sonda nasogástrica em bebês com fissura labiopalatina, sua correlação com tipo de fissura, maternidade e cidade de origem, e a idade na primeira consulta. MÉTODOS: A amostra constituiu-se de 137 bebês de ambos os gêneros, com fissura de lábio e/ou palato, sem outros comprometimentos, nascidos a termo, e que chegaram para primeira consulta em um centro especializado em fissura entre zero e 12 meses (mediana=33 dias). Realizou-se análise estatística pelo teste de coeficiente de contingência (p&lt;0,05). RESULTADOS: Da amostra total, 61% eram do gênero masculino e 39% do feminino, 51% apresentavam fissura de lábio e palato, 35% de palato e 14% de lábio. Quanto ao nascimento, 36% nasceram em maternidades particulares e 64% em públicas, 60% em Belo Horizonte, 15% em outras cidades da região metropolitana e 25% no interior do estado. O uso de sonda ocorreu em 23% dos casos. Não houve associação entre tipo de fissura ou de maternidade e o uso de sonda, mas este foi mais frequente na região metropolitana (p=0,007). CONCLUSÃO: A prevalência do uso de sonda em bebês com fissura foi considerada alta, visto que nasceram a termo e não apresentavam comprometimentos associados que indicassem o uso da mesma. O uso de sonda é mais frequente em bebês nascidos em maternidades da região metropolitana de Belo Horizonte, quando comparados a outras cidades do estado de Minas Gerais.

Southern crossroads of the Western Palaearctic during the Late Pleistocene and their imprints on current patterns of genetic diversity: insights from the mosquito Aedes caspius

Aim Climatic changes have strongly reshaped the Western Palaearctic biota throughout the Late Pleistocene. For animals, most studies so far have focused on species having low to moderate dispersal abilities, while strong dispersers have remained understudied, despite their abundance. With the aim of contributing to filling this gap, we here investigate the Late Pleistocene evolutionary history of one such species, the mosquito Aedes caspius. Location Western Palaearctic. Methods Sequences of the cytochrome c oxidase subunits I and II mitochondrial DNA genes were analysed in individuals from 16 sampling localities. The phylogeographic structure was investigated using phylogenetic network analysis, permutational contingency tests, spatial analysis of molecular variance, and correlation of genetic and geographic distances between populations. Historical demographic changes were investigated by analysing the mismatch distributions, the Bayesian skyline plot method and Fu’s FS statistic. Results We observed 67 haplotypes over all 112 individuals analysed (haplotype diversity = 0.971; nucleotide diversity = 0.0067). Despite the substantial genetic diversity, we found neither strong phylogenetic divergence among haplotypes (uncorrected mean sequence divergence 0.8%) nor any phylogeographic structure across the study area. The historical demographic analyses suggested that the species maintained a stable population size until roughly 25,000 years ago, when it underwent a sudden demographic expansion. Main conclusions Our data suggest that during the last glacial stage, A. caspius did not undergo dramatic range fragmentation in separate glacial refugia. Rather, the species is likely to have persisted in largely interconnected populations throughout most of the region, in areas with suitable environmental conditions. This scenario adds to similar patterns emerging for other temperate regions of the world, suggesting that an important component of the evolutionary history of temperate biotas has hitherto been largely overlooked.

Evidence of Panmixia between Sympatric Life History Forms of Coastal Cutthroat Trout in Two Lower Columbia River Tributaries

AbstractCoastal cutthroat trout Oncorhynchus clarkii clarkii exhibit resident and migratory life history strategies that often occur sympatrically, but the relationship between these forms within a population is poorly characterized. Through use of passive integrated transponder technology, migratory and resident coastal cutthroat trout were identified in two lower Columbia River tributaries (Abernathy Creek and the Chinook River) separated by more than 80 km. Genetic data from 17 highly variable microsatellite loci were used to ascertain the genetic population structure of these life history forms within and between streams. No distinct genetic separation was observed between the life history forms within a stream, as assessed by four different statistical approaches: permutation tests based on the genetic differentiation index FST, principal components analysis of individuals, analysis of molecular variance, and contingency tests of allele frequency heterogeneity. Genetic differences were an order of magnitude higher between stream samples (FST &gt; 0.03) than between life history forms within a stream (FST &lt; 0.003). The contingency test detected allele frequency differences between migratory and resident life history forms in Abernathy Creek (P = 0.001), but this result was influenced more by age‐class structure than by reproductive isolation between life history forms. Results are consistent with a single, randomly mating population in each stream producing both migratory and resident life history forms. These data suggest that individual life history strategy in coastal cutthroat trout is predominantly determined by phenotypic plasticity rather than genotype.