416 research outputs found
Third Indus Basin Knowledge Forum (IBKF) âManaging Systems Under Stress: Science for Solutions in the Indus Basin
The âalgebra of evolutionâ: the RobertsonâPrice identity and viability selection for body mass in a wild bird population
By the RobertsonâPrice identity, the change in a quantitative trait owing to
selection, is equal to the traitâs covariance with relative fitness. In this study,
we applied the identity to long-term data on superb fairy-wrens Malurus cyaneus, to estimate phenotypic and genetic change owing to juvenile viability
selection. Mortality in the four-week period between fledging and independence was 40%, and heavier nestlings were more likely to survive, but why?
There was additive genetic variance for both nestling mass and survival, and
a positive phenotypic covariance between the traits, but no evidence of additive genetic covariance. Comparing standardized gradients, the phenotypic
selection gradient was positive, βP = 0.108 (0.036, 0.187 95% CI), whereas the
genetic gradient was not different from zero, βA = â0.025 (â0.19, 0.107 95%
CI). This suggests that factors other than nestling mass were the cause of variation in survival. In particular, there were temporal correlations between mass
and survival both within and between years. We suggest that use of the Price
equation to describe cross-generational change in the wild may be challenging,
but a more modest aim of estimating its first term, the RobertsonâPrice identity,
to assess within-generation change can provide valuable insights into the
processes shaping phenotypic diversity in natural populations.
This article is part of the theme issue âFifty years of the Price equationâG.K.H. was supported by the U.K. Natural Environment
Research Council (grant no. NE/L002558/1) through the University
of Edinburghâs E3 Doctoral Training Partnership, and L.E.B.K. was
funded by an ARC Future Fellowship FT110100453. The long-term
superb fairy-wren study research has been facilitated by a series of
Discovery Project grants from the Australian Research Council to
A.C. and L.E.B.K., most recently DP150100298
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Embracing uncertainty flexibility: harnessing a supervised tree kernel to empower ensemble modelling for 2D echocardiography-based prediction of right ventricular volume
The right ventricular (RV) function deterioration strongly predicts clinical outcomes in numerous circumstances. To boost the clinical deployment of ensemble regression methods that quantify RV volumes using tabular data from the widely available two-dimensional echocardiography (2DE), we propose to complement the volume predictions with uncertainty scores. To this end, we employ an instance-based method which uses the learned tree structure to identify the nearest training samples to a target instance and then uses a number of distribution types to more flexibly model the output. The probabilistic and point-prediction performances of the proposed framework are evaluated on a relatively small-scale dataset, comprising 100 end-diastolic and end-systolic RV volumes. The reference values for point performance were obtained from MRI. The results demonstrate that our flexible approach yields improved probabilistic and point performances over other state-of-the art methods. The appropriateness of the proposed framework is showcased by providing exemplar cases. The estimated uncertainty embodies both aleatoric and epistemic types. This work aligns with trustworthy artificial intelligence since it can be used to enhance the decision-making process and reduce risks. The feature importance scores of our framework can be exploited to reduce the number of required 2DE views which could enhance the proposed pipelineâs clinical application
Environmental and Parental Influences on Offspring Health and Growth in Great Tits (Parus major)
PMCID: PMC3728352This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Estimating Heritabilities and Genetic Correlations: Comparing the âAnimal Modelâ with Parent-Offspring Regression Using Data from a Natural Population
Quantitative genetic parameters are nowadays more frequently estimated with restricted maximum likelihood using the âanimal modelâ than with traditional methods such as parent-offspring regressions. These methods have however rarely been evaluated using equivalent data sets. We compare heritabilities and genetic correlations from animal model and parent-offspring analyses, respectively, using data on eight morphological traits in the great reed warbler (Acrocephalus arundinaceus). Animal models were run using either mean trait values or individual repeated measurements to be able to separate between effects of including more extended pedigree information and effects of replicated sampling from the same individuals. We show that the inclusion of more pedigree information by the use of mean traits animal models had limited effect on the standard error and magnitude of heritabilities. In contrast, the use of repeated measures animal model generally had a positive effect on the sampling accuracy and resulted in lower heritabilities; the latter due to lower additive variance and higher phenotypic variance. For most trait combinations, both animal model methods gave genetic correlations that were lower than the parent-offspring estimates, whereas the standard errors were lower only for the mean traits animal model. We conclude that differences in heritabilities between the animal model and parent-offspring regressions were mostly due to the inclusion of individual replicates to the animal model rather than the inclusion of more extended pedigree information. Genetic correlations were, on the other hand, primarily affected by the inclusion of more pedigree information. This study is to our knowledge the most comprehensive empirical evaluation of the performance of the animal model in relation to parent-offspring regressions in a wild population. Our conclusions should be valuable for reconciliation of data obtained in earlier studies as well as for future meta-analyses utilizing estimates from both traditional methods and the animal model
Correction for de Villemereuil et al., Fluctuating optimum and temporally variable selection on breeding date in birds and mammals
Characterisation of the transcriptome of a wild great tit Parus major population by next generation sequencing
Background: The recent development of next generation sequencing technologies has made it possible to generate very large amounts of sequence data in species with little or no genome information. Combined with the large phenotypic databases available for wild and non-model species, these data will provide an unprecedented opportunity to "genomicise" ecological model organisms and establish the genetic basis of quantitative traits in natural populations
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