114 research outputs found
Sexual Dimorphism in Melanin Pigmentation, Feather Coloration and Its Heritability in the Barn Swallow (Hirundo rustica)
Melanin is the main pigment in animal coloration and considerable variation in the concentrations of the two melanin forms (pheo- and eumlanin) in pigmented tissues exists among populations and individuals. Melanin-based coloration is receiving increasing attention particularly in socio-sexual communication contexts because the melanocortin system has been hypothesized to provide a mechanistic basis for covariation between coloration and fitness traits. However, with few notable exceptions, little detailed information is available on inter-individual and inter-population variation in melanin pigmentation and on its environmental, genetic and ontogenetic components. Here, we investigate melanin-based coloration in an Italian population of a passerine bird, the barn swallow (Hirundo rustica rustica), its sex-and age-related variation, and heritability. The concentrations of eu- and pheomelanin in the throat (brown) and belly (white-to-brownish) feathers differed between sexes but not according to age. The relative concentration of either melanin (Pheo:Eu) differed between sexes in throat but not in belly feathers, and the concentrations in males compared to females were larger in belly than in throat feathers. There were weak correlations between the concentrations of melanins within as well as among plumage regions. Coloration of belly feathers was predicted by the concentration of both melanins whereas coloration of throat feathers was only predicted by pheomelanin in females. In addition, Pheo: Eu predicted coloration of throat feathers in females and that of belly feathers in males. Finally, we found high heritability of color of throat feathers. Melanization was found to differ from that recorded in Hirundo rustica rustica from Scotland or from H. r. erythrogaster from North America. Hence, present results show that pigmentation strategies vary in a complex manner according to sex and plumage region, and also among geographical populations, potentially reflecting adaptation to different natural and sexual selection regimes, and that some coloration components seem to be highly heritable
Impact of Tumor Regional Involvement on Active Surveillance Outcomes: Validation of the Cumulative Cancer Location Metric in a US Population.
BACKGROUND: Treatment progression for men on active surveillance (AS) for prostate cancer (PCa) is driven primarily by grade and volume progression on isolated prostate biopsies (PBx). As PCa is a multifocal disease, regional disease progression over time should be accounted for.
OBJECTIVE: To validate the utility of the cumulative cancer location (CCLO) metric, which assesses regional core involvement, as described by Erickson et al (Cumulative cancer locations is a novel metric for predicting active surveillance outcomes: a multicenter study. Eur Urol Oncol 2018;1:268-75), in predicting AS outcomes in a North American cohort.
DESIGN, SETTING, AND PARTICIPANTS: A single-institutional retrospective chart review of all AS patients evaluated between 2015 and 2017.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: CCLO defined as the total number of cancer-positive sextant locations among all PBx to that point in time (range 1-6). Baseline demographics and clinical characteristics of the entire cohort were stratified by CCLOÎ, defined as the difference between the first and the last CCLO. CCLOÎ then correlated with progression to treatment and treatment outcomes.
RESULTS AND LIMITATIONS: A total of 261 men met the inclusion criteria. Though the mean number of biopsies was slightly higher in the CCLOÎ 3-5 cohort than in the CCLOÎ 0-2 cohort (pâ=â 0.006), mean AS follow-up time (3.3 yr) was not significantly different (pâ=â 0.327). As CCLOÎ increased, the proportion of men remaining on AS decreased, while the proportion of men receiving treatment increased (pâ\u3câ 0.001). In men undergoing radical prostatectomy, a higher CCLOÎ was not associated with higher rates of Gleason 7-10 (pâ=â 0.38) or pT3 (pâ=â 0.52) disease. However, as CCLOÎ increased, upgrading from final PBx to RP pathology increased, while downgrading decreased (pâ=â 0.12). In Kaplan-Meier analyses, lower CCLOÎ and lower initial cancer location scores were associated with the highest 5-yr treatment-free survival rates (pâ\u3câ 0.001).
CONCLUSIONS: Higher regional cancer core involvement is associated with higher rates of progression to treatment in AS patients. The CCLO metric is a potentially useful modality in stratifying AS patients among the North American cohort for treatment, while not compromising disease outcomes.
PATIENT SUMMARY: In the North American population, cumulative cancer-positive locations among biopsies can be used to predict active surveillance outcomes in men with prostate cancer
Assessing Multivariate Constraints to Evolution across Ten Long-Term Avian Studies
Background
In a rapidly changing world, it is of fundamental importance to understand processes constraining or facilitating adaptation through microevolution. As different traits of an organism covary, genetic correlations are expected to affect evolutionary trajectories. However, only limited empirical data are available.
Methodology/Principal Findings
We investigate the extent to which multivariate constraints affect the rate of adaptation, focusing on four morphological traits often shown to harbour large amounts of genetic variance and considered to be subject to limited evolutionary constraints. Our data set includes unique long-term data for seven bird species and a total of 10 populations. We estimate population-specific matrices of genetic correlations and multivariate selection coefficients to predict evolutionary responses to selection. Using Bayesian methods that facilitate the propagation of errors in estimates, we compare (1) the rate of adaptation based on predicted response to selection when including genetic correlations with predictions from models where these genetic correlations were set to zero and (2) the multivariate evolvability in the direction of current selection to the average evolvability in random directions of the phenotypic space. We show that genetic correlations on average decrease the predicted rate of adaptation by 28%. Multivariate evolvability in the direction of current selection was systematically lower than average evolvability in random directions of space. These significant reductions in the rate of adaptation and reduced evolvability were due to a general nonalignment of selection and genetic variance, notably orthogonality of directional selection with the size axis along which most (60%) of the genetic variance is found.
Conclusions
These results suggest that genetic correlations can impose significant constraints on the evolution of avian morphology in wild populations. This could have important impacts on evolutionary dynamics and hence population persistence in the face of rapid environmental change
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Incorporating mpMRI biopsy data into established pre-RP nomograms: potential impact of an increasingly common clinical scenario
Background: We examine the practical application of multiparametric MRI (mpMRI) prostate biopsy data using established pre-RP nomograms and its potential implications on RP intraoperative decision-making. We hypothesize that current nomograms are suboptimal in predicting outcomes with mpMRI targeted biopsy (TBx) data.
Materials and methods: Patients who underwent mpMRI-based TBx prior to RP were assessed using the MSKCC and Briganti nomograms with the following iterations: (1) Targeted (T) (targeted only), (2) Targeted and Systematic (TS) and (3) Targeted Augmented (TA) (targeted core data; assumed negative systematic cores for 12 total cores). Nomogram outcomes, lymph node involvement (LNI), extracapsular extension (ECE), organ-confined disease (OCD), seminal vesicle invasion (SVI), were compared across iterations. Clinically significant impact on management was defined as a change in LNI risk above or below 2% (Î2) or 5% (Î5).
Results: A total of 217 men met inclusion criteria. Overall, the TA iteration had more conservative nomogram outcomes than the T. Moreover, TA better predicted RP pathology for all four outcomes when compared with the T. In the entire cohort, Î2 and Î5 were 16.6â25.8% and 20.3â39.2%, respectively. In the subset of 190 patients with targeted and systematic cores, TA was a better approximation of TS outcomes than T in 71% (MSKCC) and 82% (Briganti) of patients.
Conclusion: In established pre-RP nomograms, mpMRI-based TBx often yield variable and discordant results when compared with systematic biopsies. Future nomograms must better incorporate mpMRI TBx core data. In the interim, augmenting TBx data may serve to bridge the gap
Setting the Standards: Examining Research Productivity Among Academic Urologists in the USA and Canada in 2019.
BACKGROUND: Research productivity among academic urologists is strongly encouraged, but little data are available on productivity metrics within the field.
OBJECTIVE: To provide the first comprehensive survey of research productivity among academic urologists in the USA and Canada.
DESIGN, SETTING, AND PARTICIPANTS: Using the Accreditation Council for Graduate Medical Education, the Canadian Resident Matching Service, and individual program websites, all active accredited urology faculties were identified. For each individual, we collected data on American Urological Association section, title, gender, fellowship training, Scopus H-index, and citations. Comprehensive searches were completed during March-May 2019.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Descriptive statistics for demographic comparisons were performed using analysis of variance for continuous variables and chi-square test for categorical variables. Multivariable logistic regressions were used to identify the predictors of H-index greater than the median.
RESULTS AND LIMITATIONS: A total of 2214 academic urology faculties (2015 in USA and 199 in Canada) were identified. The median and mean H-indices for the entire cohort of physicians were 11 and 16.1, respectively. On multivariable analysis, physicians in the North Central and Western Sections (vs mid-Atlantic), who were fellowship trained (vs no fellowship training), and of higher academic rank (professor and associate professor vs clinical instructor) were more likely to have H-index values greater than the median. Additionally, female physicians (vs male) were more likely to have H-index values less than the median.
CONCLUSIONS: This study represents the first comprehensive assessment of research productivity metrics among academic urologists. These represent key benchmarks for trainees considering careers in academics and for practicing physicians gauging their own productivity in relation to their peers.
PATIENT SUMMARY: In this study, we provide the first comprehensive assessment of research productivity among academic urologists in the USA and Canada. Our results help provide key benchmarks for trainees considering careers in academics and for practicing physicians gauging their own productivity in relation to peers
Climate change drives microevolution in a wild bird
To ensure long-term persistence, organisms must adapt to climate change, but an evolutionary response to a quantified selection pressure driven by climate change has not been empirically demonstrated in a wild population. Here, we show that pheomelanin-based plumage colouration in tawny owls is a highly heritable trait, consistent with a simple Mendelian pattern of brown (dark) dominance over grey (pale). We show that strong viability selection against the brown morph occurs, but only under snow-rich winters. As winter conditions became milder in the last decades, selection against the brown morph diminished. Concurrent with this reduced selection, the frequency of brown morphs increased rapidly in our study population during the last 28 years and nationwide during the last 48 years. Hence, we show the first evidence that recent climate change alters natural selection in a wild population leading to a microevolutionary response, which demonstrates the ability of wild populations to evolve in response to climate change
Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals
Funding: Hoge Veluwe great tits: the NIOO-KNAW, ERC, and numerous funding agencies; Wytham great tits: Biotechnology and Biological Sciences Research Council, ERC, and the UK Natural Environment Research Council (NERC).The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change.PostprintPeer reviewe
Costs of Inducible Defence along a Resource Gradient
In addition to having constitutive defence traits, many organisms also respond to predation by phenotypic plasticity. In order for plasticity to be adaptive, induced defences should incur a benefit to the organism in, for example, decreased risk of predation. However, the production of defence traits may include costs in fitness components such as growth, time to reproduction, or fecundity. To test the hypothesis that the expression of phenotypic plasticity incurs costs, we performed a common garden experiment with a freshwater snail, Radix balthica, a species known to change morphology in the presence of molluscivorous fish. We measured a number of predator-induced morphological and behavioural defence traits in snails that we reared in the presence or absence of chemical cues from fish. Further, we quantified the costs of plasticity in fitness characters related to fecundity and growth. Since plastic responses may be inhibited under limited resource conditions, we reared snails in different densities and thereby levels of competition. Snails exposed to predator cues grew rounder and thicker shells, traits confirmed to be adaptive in environments with fish. Defence traits were consistently expressed independent of density, suggesting strong selection from predatory molluscivorous fish. However, the expression of defence traits resulted in reduced growth rate and fecundity, particularly with limited resources. Our results suggest full defence in predator related traits regardless of resource availability, and costs of defence consequently paid in traits related to fitness
Archiving primary data: solutions for long-term studies
The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers
The Long Term Response of Birds to Climate Change: New Results from a Cold Stage Avifauna in Northern England
The early MIS 3 (55â40 Kyr BP associated with Middle Palaeolithic archaeology) bird remains from Pin Hole, Creswell Crags, Derbyshire, England are analysed in the context of the new dating of the siteâs stratigraphy. The analysis is restricted to the material from the early MIS 3 level of the cave because the upper fauna is now known to include Holocene material as well as that from the Late Glacial. The results of the analysis confirm the presence of the taxa, possibly unexpected for a Late Pleistocene glacial deposit including records such as Alpine swift, demoiselle crane and long-legged buzzard with southern and/or eastern distributions today. These taxa are accompanied by more expected ones such as willow ptarmigan /red grouse and rock ptarmigan living today in northern and montane areas. Finally, there are temperate taxa normally requiring trees for nesting such as wood pigeon and grey heron. Therefore, the result of the analysis is that the avifauna of early MIS 3 in England included taxa whose ranges today do not overlap making it a non-analogue community similar to the many steppe-tundra mammalian faunas of the time. The inclusion of more temperate and woodland taxa is discussed in the light that parts of northern Europe may have acted as cryptic northern refugia for some such taxa during the last glacial. These records showing former ranges of taxa are considered in the light of modern phylogeographic studies as these often assume former ranges without considering the fossil record of those taxa. In addition to the anomalous combination of taxa during MIS 3 living in Derbyshire, the individuals of a number of the taxa are different in size and shape to members of the species today probably due to the high carrying capacity of the steppe-tundra
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