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Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity1–4. Sparse taxon sampling has previously been proposed to confound phylogenetic inference5, and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families—including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confdently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specifc variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will ofer new perspectives on evolutionary processes in cross-species comparative analyses and assist in eforts to conserve species.

\"Two leading scientists reveal how we became the amazing creatures we are--and help us understand the biology that makes human beings uniquely capable of choice.\"--Dust jacket flap.

An analysis of 16 health-related quantitative traits in approximately 350,000 individuals reveals statistically significant associations between genome-wide homozygosity and four complex traits (height, lung function, cognitive ability and educational attainment); in each case increased homozygosity associates with a decreased trait value, but no evidence was seen of an influence on blood pressure, cholesterol, or ten other cardio-metabolic traits. Parental relatedness link to height and intelligence This consortium meta-analysis of 102 cohorts and more than 350,000 individuals investigates the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity, ROH), which are inferred to be homozygous along their complete length. Focusing on 16 health-related quantitative traits, the authors find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in a second, general cognitive ability and educational attainment. In each case increased homozygosity associates with decreased trait value. No evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Homozygosity has long been associated with rare, often devastating, Mendelian disorders 1 , and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness 2 . However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power 3 , 4 . Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment ( P < 1 × 10 −300 , 2.1 × 10 −6 , 2.5 × 10 −10 and 1.8 × 10 −10 , respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months’ less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples 5 , 6 , no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection 7 , this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been.

Jeffries, D.L., Lavanchy, G., Sermier, R., Sredl, M.J., Miura, I., Borzée, A., Barrow, L.N., Canestrelli, D., Crochet, P.-A., Dufresnes, C., Fu, J., Ma, W.-J., Garcia, C.M., Ghali, K., Nicieza, A.G., O’Donnell, R.P., Rodrigues, N., Romano, A., Martínez-Solano, Í., Stepanyan, I., Zumbach, S., Brelsford, A., Perrin, N.

Arguing that the perfection of the human body is the result of improbable mutation, a prominent Darwinian uses the metaphor of climbing a mountain to illustrate how natural perfection is due to the unending journey of DNA through time.

Understanding the effects of landscape heterogeneity on spatial genetic variation is a primary goal of landscape genetics. Ecological and geographic variables can contribute to genetic structure through geographic isolation, in which geographic barriers and distances restrict gene flow, and ecological isolation, in which gene flow among populations inhabiting different environments is limited by selection against dispersers moving between them. Although methods have been developed to study geographic isolation in detail, ecological isolation has received much less attention, partly because disentangling the effects of these mechanisms is inherently difficult. Here, I describe a novel approach for quantifying the effects of geographic and ecological isolation using multiple matrix regression with randomization. I explored the parameter space over which this method is effective using a series of individual-based simulations and found that it accurately describes the effects of geographic and ecological isolation over a wide range of conditions. I also applied this method to a set of real-world datasets to show that ecological isolation is an often overlooked but important contributor to patterns of spatial genetic variation and to demonstrate how this analysis can provide new insights into how landscapes contribute to the evolution of genetic variation in nature.

Background The piwi -interacting RNAs (piRNAs) are small non-coding RNAs that specifically repress transposable elements (TEs) in the germline of Drosophila . Despite our expanding understanding of TE:piRNA interaction, whether there is an evolutionary arms race between TEs and piRNAs was unclear. Results Here, we studied the population genomics of TEs and piRNAs in the worldwide strains of D. melanogaster . By conducting a correlation analysis between TE contents and the abundance of piRNAs from ovaries of representative strains of D. melanogaster , we find positive correlations between TEs and piRNAs in six TE families. Our simulations further highlight that TE activities and the strength of purifying selection against TEs are important factors shaping the interactions between TEs and piRNAs. Our studies also suggest that the de novo generation of piRNAs is an important mechanism to repress the newly invaded TEs. Conclusions Our results revealed the existence of an evolutionary arms race between the copy numbers of TEs and the abundance of antisense piRNAs at the population level. Although the interactions between TEs and piRNAs are complex and many factors should be considered to impact their interaction dynamics, our results suggest the emergence, repression specificity and strength of piRNAs on TEs should be considered in studying the landscapes of TE insertions in Drosophila . These results deepen our understanding of the interactions between piRNAs and TEs, and also provide novel insights into the nature of genomic conflicts of other forms.