NNT mediates redox-dependent pigmentation via a UVB- and MITF-independent mechanism.

Ultraviolet (UV) light and incompletely understood genetic and epigenetic variations determine skin color. Here we describe an UV- and microphthalmia-associated transcription factor (MITF)-independent mechanism of skin pigmentation. Targeting the mitochondrial redox-regulating enzyme nicotinamide nucleotide transhydrogenase (NNT) resulted in cellular redox changes that affect tyrosinase degradation. These changes regulate melanosome maturation and, consequently, eumelanin levels and pigmentation. Topical application of small-molecule inhibitors yielded skin darkening in human skin, and mice with decreased NNT function displayed increased pigmentation. Additionally, genetic modification of NNT in zebrafish alters melanocytic pigmentation. Analysis of four diverse human cohorts revealed significant associations of skin color, tanning, and sun protection use with various single-nucleotide polymorphisms within NNT. NNT levels were independent of UVB irradiation and redox modulation. Individuals with postinflammatory hyperpigmentation or lentigines displayed decreased skin NNT levels, suggesting an NNT-driven, redox-dependent pigmentation mechanism that can be targeted with NNT-modifying topical drugs for medical and cosmetic purposes.

Combined genome-wide association study of 136 quantitative ear morphology traits in multiple populations reveal 8 novel loci.

Human ear morphology, a complex anatomical structure represented by a multidimensional set of correlated and heritable phenotypes, has a poorly understood genetic architecture. In this study, we quantitatively assessed 136 ear morphology traits using deep learning analysis of digital face images in 14,921 individuals from five different cohorts in Europe, Asia, and Latin America. Through GWAS meta-analysis and C-GWASs, a recently introduced method to effectively combine GWASs of many traits, we identified 16 genetic loci involved in various ear phenotypes, eight of which have not been previously associated with human ear features. Our findings suggest that ear morphology shares genetic determinants with other surface ectoderm-derived traits such as facial variation, mono eyebrow, and male pattern baldness. Our results enhance the genetic understanding of human ear morphology and shed light on the shared genetic contributors of different surface ectoderm-derived phenotypes. Additionally, gene editing experiments in mice have demonstrated that knocking out the newly ear-associated gene (Intu) and a previously ear-associated gene (Tbx15) causes deviating mouse ear morphology.

Clotting factor genes are associated with preeclampsia in high-altitude pregnant women in the Peruvian Andes.

Preeclampsia is a multi-organ complication of pregnancy characterized by sudden hypertension and proteinuria that is among the leading causes of preterm delivery and maternal morbidity and mortality worldwide. The heterogeneity of preeclampsia poses a challenge for understanding its etiology and molecular basis. Intriguingly, risk for the condition increases in high-altitude regions such as the Peruvian Andes. To investigate the genetic basis of preeclampsia in a population living at high altitude, we characterized genome-wide variation in a cohort of preeclamptic and healthy Andean families (n = 883) from Puno, Peru, a city located above 3,800 meters of altitude. Our study collected genomic DNA and medical records from case-control trios and duos in local hospital settings. We generated genotype data for 439,314 SNPs, determined global ancestry patterns, and mapped associations between genetic variants and preeclampsia phenotypes. A transmission disequilibrium test (TDT) revealed variants near genes of biological importance for placental and blood vessel function. The top candidate region was found on chromosome 13 of the fetal genome and contains clotting factor genes PROZ, F7, and F10. These findings provide supporting evidence that common genetic variants within coagulation genes play an important role in preeclampsia. A selection scan revealed a potential adaptive signal around the ADAM12 locus on chromosome 10, implicated in pregnancy disorders. Our discovery of an association in a functional pathway relevant to pregnancy physiology in an understudied population of Native American origin demonstrates the increased power of family-based study design and underscores the importance of conducting genetic research in diverse populations.

Inbreeding, Native American ancestry and child mortality: linking human selection and paediatric medicine.

The children of related parents show increased risk of early mortality. The Native American genome typically exhibits long stretches of homozygosity, and Latin Americans are highly heterogeneous regarding the individual burden of homozygosity, the proportion and the type of Native American ancestry. We analysed nationwide mortality and genome-wide genotype data from admixed Chileans to investigate the relationship between common causes of child mortality, homozygosity and Native American ancestry. Results from two-stage linear-Poisson regression revealed a strong association between the sum length of runs of homozygosity (SROH) above 1.5 Megabases (Mb) in each genome and mortality due to intracranial non-traumatic haemorrhage of foetus and newborn (5% increased risk of death per Mb in SROH, P = 1 × 10-3) and disorders related to short gestation and low birth weight (P = 3 × 10-4). The major indigenous populations in Chile are Aymara-Quechua in the north of the country and the Mapuche-Huilliche in the south. The individual proportion of Aymara-Quechua ancestry was associated with an increased risk of death due to anencephaly and similar malformations (P = 4 × 10-5), and the risk of death due to Edwards and Patau trisomy syndromes decreased 4% per 1% Aymara-Quechua ancestry proportion (P = 4 × 10-4) and 5% per 1% Mapuche-Huilliche ancestry proportion (P = 2 × 10-3). The present results suggest that short gestation, low birth weight and intracranial non-traumatic haemorrhage mediate the negative effect of inbreeding on human selection. Independent validation of the identified associations between common causes of child death, homozygosity and fine-scale ancestry proportions may inform paediatric medicine.

Development and internal validation of a multifactorial risk prediction model for gallbladder cancer in a high-incidence country.

Since 2006, Chile has been implementing a gallbladder cancer (GBC) prevention program based on prophylactic cholecystectomy for gallstone patients aged 35 to 49 years. The effectiveness of this prevention program has not yet been comprehensively evaluated. We conducted a retrospective study of 473 Chilean GBC patients and 2137 population-based controls to develop and internally validate three GBC risk prediction models. The Baseline Model accounted for gallstones while adjusting for sex and birth year. Enhanced Model I also included the non-genetic risk factors: body mass index, educational level, Mapuche surnames, number of children and family history of GBC. Enhanced Model II further included Mapuche ancestry and the genotype for rs17209837. Multiple Cox regression was applied to assess the predictive performance, quantified by the area under the precision-recall curve (AUC-PRC) and the number of cholecystectomies needed (NCN) to prevent one case of GBC at age 70 years. The AUC-PRC for the Baseline Model (0.44%, 95%CI 0.42-0.46) increased by 0.22 (95%CI 0.15-0.29) when non-genetic factors were included, and by 0.25 (95%CI 0.20-0.30) when incorporating non-genetic and genetic factors. The overall NCN for Chileans with gallstones (115, 95%CI 104-131) decreased to 92 (95%CI 60-128) for Chileans with a higher risk than the median according to Enhanced Model I, and to 80 (95%CI 59-110) according to Enhanced Model II. In conclusion, age, sex and gallstones are strong risk factors for GBC, but consideration of other non-genetic factors and individual genotype data improves risk prediction and may optimize allocation of financial resources and surgical capacity.

Disentangling Signatures of Selection Before and After European Colonization in Latin Americans.

Throughout human evolutionary history, large-scale migrations have led to intermixing (i.e., admixture) between previously separated human groups. Although classical and recent work have shown that studying admixture can yield novel historical insights, the extent to which this process contributed to adaptation remains underexplored. Here, we introduce a novel statistical model, specific to admixed populations, that identifies loci under selection while determining whether the selection likely occurred post-admixture or prior to admixture in one of the ancestral source populations. Through extensive simulations, we show that this method is able to detect selection, even in recently formed admixed populations, and to accurately differentiate between selection occurring in the ancestral or admixed population. We apply this method to genome-wide SNP data of ∼4,000 individuals in five admixed Latin American cohorts from Brazil, Chile, Colombia, Mexico, and Peru. Our approach replicates previous reports of selection in the human leukocyte antigen region that are consistent with selection post-admixture. We also report novel signals of selection in genomic regions spanning 47 genes, reinforcing many of these signals with an alternative, commonly used local-ancestry-inference approach. These signals include several genes involved in immunity, which may reflect responses to endemic pathogens of the Americas and to the challenge of infectious disease brought by European contact. In addition, some of the strongest signals inferred to be under selection in the Native American ancestral groups of modern Latin Americans overlap with genes implicated in energy metabolism phenotypes, plausibly reflecting adaptations to novel dietary sources available in the Americas.

Mapping spatial morbidity patterns for bronchiolitis related to socioeconomic estimators: A spatial epidemiology approach to identify health disparities in Puerto Madryn, Argentina.

OBJECTIVES: To describe the frequency of hospitalizations of infants under 1 year of age with bronchiolitis in Puerto Madryn, Argentina, and to study the spatial distribution of cases throughout the city in relation to socioeconomic indicators. To visualize and better understand the underlying processes behind the local manifestation of the disease by creating a vulnerability map of the city. METHODS: We performed a cross-sectional study of all patients discharged for bronchiolitis from the local public Hospital in 2017, considering length of hospital stay, readmission rate, patient age, home address and socioeconomic indicators (household overcrowding). To understand the local spatial distribution of the disease and its relationship to overcrowding, we used GIS and Moran's global and local spatial autocorrelation indices. RESULTS: The spatial distribution of bronchiolitis cases was not random, but significantly aggregated. Of the 120 hospitalized children, 100 infants (83.33%) live in areas identified as having at least one unsatisfied basic need (UBN). We found a positive and statistically significant relationship between frequency of cases and percentage of overcrowded housing by census radius. CONCLUSIONS: A clear association was found between bronchiolitis and neighborhoods with UBNs, and overcrowding is likely to be a particularly important explanatory factor in this association. By combining GIS tools, spatial statistics, geo-referenced epidemiological data, and population-level information, vulnerability maps can be created to facilitate visualization of priority areas for development and implementation of more effective health interventions. Incorporating the spatial and syndemic perspective into health studies makes important contributions to the understanding of local health-disease processes.

Gallstones, Body Mass Index, C-Reactive Protein, and Gallbladder Cancer: Mendelian Randomization Analysis of Chilean and European Genotype Data.

BACKGROUND AND AIMS: Gallbladder cancer (GBC) is a neglected disease with substantial geographical variability: Chile shows the highest incidence worldwide, while GBC is relatively rare in Europe. Here, we investigate the causal effects of risk factors considered in current GBC prevention programs as well as C-reactive protein (CRP) level as a marker of chronic inflammation. APPROACH AND RESULTS: We applied two-sample Mendelian randomization (MR) using publicly available data and our own data from a retrospective Chilean and a prospective European study. Causality was assessed by inverse variance weighted (IVW), MR-Egger regression, and weighted median estimates complemented with sensitivity analyses on potential heterogeneity and pleiotropy, two-step MR, and mediation analysis. We found evidence for a causal effect of gallstone disease on GBC risk in Chileans (P = 9 × 10-5 ) and Europeans (P = 9 × 10-5 ). A genetically elevated body mass index (BMI) increased GBC risk in Chileans (P = 0.03), while higher CRP concentrations increased GBC risk in Europeans (P = 4.1 × 10-6 ). European results suggest causal effects of BMI on gallstone disease (P = 0.008); public Chilean data were not, however, available to enable assessment of the mediation effects among causal GBC risk factors. CONCLUSIONS: Two risk factors considered in the current Chilean program for GBC prevention are causally linked to GBC risk: gallstones and BMI. For Europeans, BMI showed a causal effect on gallstone risk, which was itself causally linked to GBC risk.

Genome-wide association studies and CRISPR/Cas9-mediated gene editing identify regulatory variants influencing eyebrow thickness in humans.

Hair plays an important role in primates and is clearly subject to adaptive selection. While humans have lost most facial hair, eyebrows are a notable exception. Eyebrow thickness is heritable and widely believed to be subject to sexual selection. Nevertheless, few genomic studies have explored its genetic basis. Here, we performed a genome-wide scan for eyebrow thickness in 2961 Han Chinese. We identified two new loci of genome-wide significance, at 3q26.33 near SOX2 (rs1345417: P = 6.51×10(-10)) and at 5q13.2 near FOXD1 (rs12651896: P = 1.73×10(-8)). We further replicated our findings in the Uyghurs, a population from China characterized by East Asian-European admixture (N = 721), the CANDELA cohort from five Latin American countries (N = 2301), and the Rotterdam Study cohort of Dutch Europeans (N = 4411). A meta-analysis combining the full GWAS results from the three cohorts of full or partial Asian descent (Han Chinese, Uyghur and Latin Americans, N = 5983) highlighted a third signal of genome-wide significance at 2q12.3 (rs1866188: P = 5.81×10(-11)) near EDAR. We performed fine-mapping and prioritized four variants for further experimental verification. CRISPR/Cas9-mediated gene editing provided evidence that rs1345417 and rs12651896 affect the transcriptional activity of the nearby SOX2 and FOXD1 genes, which are both involved in hair development. Finally, suitable statistical analyses revealed that none of the associated variants showed clear signals of selection in any of the populations tested. Contrary to popular speculation, we found no evidence that eyebrow thickness is subject to strong selective pressure.

Religion and fertility patterns: comparison of life history traits in Catholics and Protestants, Hallstatt (Austria) 1733-1908.

Catholicism and Protestantism have different ways of promoting the family unit that could influence survival and fertility at a population level. Parish records in the Austrian village of Hallstatt allowed the reconstruction of Catholic and Protestant genealogies over a period of 175 years (1733-1908) to evaluate how religion and social changes affected reproduction and survival. Life history traits such as lifespan beyond 15 years, number of offspring, reproductive span, children born out of wedlock and child mortality were estimated in 5678 Catholic and 3282 Protestant individuals. The interaction of sex, time and religion was checked through non-parametric factorial ANOVAs. Religion and time showed statistically significant interactions with lifespan >15 years, number of offspring and age at birth of first child. Protestants lived longer, had a larger reproductive span and an earlier age at birth of first child. Before the famine crisis of 1845-1850, Protestants showed lower values of childhood mortality than Catholics. Comparison of the number of children born out of wedlock revealed small differences between the two religions. Religion influenced reproduction and survival, as significant differences were found between Catholics and Protestants. This influence could be explained in part by differential socioeconomic characteristics, since Protestants may have enjoyed better living and sanitary conditions in Hallstatt.

Meta-analysis of genome-wide association studies identifies 8 novel loci involved in shape variation of human head hair.

Shape variation of human head hair shows striking variation within and between human populations, while its genetic basis is far from being understood. We performed a series of genome-wide association studies (GWASs) and replication studies in a total of 28 964 subjects from 9 cohorts from multiple geographic origins. A meta-analysis of three European GWASs identified 8 novel loci (1p36.23 ERRFI1/SLC45A1, 1p36.22 PEX14, 1p36.13 PADI3, 2p13.3 TGFA, 11p14.1 LGR4, 12q13.13 HOXC13, 17q21.2 KRTAP, and 20q13.33 PTK6), and confirmed 4 previously known ones (1q21.3 TCHH/TCHHL1/LCE3E, 2q35 WNT10A, 4q21.21 FRAS1, and 10p14 LINC00708/GATA3), all showing genome-wide significant association with hair shape (P < 5e-8). All except one (1p36.22 PEX14) were replicated with nominal significance in at least one of the 6 additional cohorts of European, Native American and East Asian origins. Three additional previously known genes (EDAR, OFCC1, and PRSS53) were confirmed at the nominal significance level. A multivariable regression model revealed that 14 SNPs from different genes significantly and independently contribute to hair shape variation, reaching a cross-validated AUC value of 0.66 (95% CI: 0.62-0.70) and an AUC value of 0.64 in an independent validation cohort, providing an improved accuracy compared with a previous model. Prediction outcomes of 2504 individuals from a multiethnic sample were largely consistent with general knowledge on the global distribution of hair shape variation. Our study thus delivers target genes and DNA variants for future functional studies to further evaluate the molecular basis of hair shape in humans.

Multiethnic GWAS Reveals Polygenic Architecture of Earlobe Attachment.

The genetic basis of earlobe attachment has been a matter of debate since the early 20th century, such that geneticists argue both for and against polygenic inheritance. Recent genetic studies have identified a few loci associated with the trait, but large-scale analyses are still lacking. Here, we performed a genome-wide association study of lobe attachment in a multiethnic sample of 74,660 individuals from four cohorts (three with the trait scored by an expert rater and one with the trait self-reported). Meta-analysis of the three expert-rater-scored cohorts revealed six associated loci harboring numerous candidate genes, including EDAR, SP5, MRPS22, ADGRG6 (GPR126), KIAA1217, and PAX9. The large self-reported 23andMe cohort recapitulated each of these six loci. Moreover, meta-analysis across all four cohorts revealed a total of 49 significant (p < 5 × 10-8) loci. Annotation and enrichment analyses of these 49 loci showed strong evidence of genes involved in ear development and syndromes with auricular phenotypes. RNA sequencing data from both human fetal ear and mouse second branchial arch tissue confirmed that genes located among associated loci showed evidence of expression. These results provide strong evidence for the polygenic nature of earlobe attachment and offer insights into the biological basis of normal and abnormal ear development.

Body shape: Implications in the study of obesity and related traits.

OBJECTIVES: The diagnosis and treatment of obesity are usually based on traditional anthropometric variables including weight, height, and several body perimeters. Here we present a three-dimensional (3D) image-based computational approach aimed to capture the distribution of abdominal adipose tissue as an aspect of shape rather than a relationship among classical anthropometric measures. METHODS: A morphometric approach based on landmarks and semilandmarks placed upon the 3D torso surface was performed in order to quantify abdominal adiposity shape variation and its relation to classical indices. Specifically, we analyzed sets of body cross-sectional circumferences, collectively defining each, along with anthropometric data taken on 112 volunteers. Principal Component Analysis (PCA) was performed on 250 circumferences located along the abdominal region of each volunteer. An analysis of covariance model was used to compare shape variables (PCs) against anthropometric data (weight, height, and waist and hip circumferences). RESULTS: The observed shape patterns were mainly related to nutritional status, followed by sexual dimorphism. PC1 (12.5%) and PC2 (7.5%) represented 20% of the total variation. In PCAs calculated independently by sex, linear regression analyses provide statistically significant associations between PC1 and the three classical indexes: body mass index, waist-to-height ratio, and waist-hip ratio. CONCLUSION: Shape indicators predict well the behavior of classical markers, but also evaluate 3D and geometric features with more accuracy as related to the body shape under study. This approach also facilitates diagnosis and follow-up of therapies by using accessible 3D technology.

Subtypes of Native American ancestry and leading causes of death: Mapuche ancestry-specific associations with gallbladder cancer risk in Chile.

Latin Americans are highly heterogeneous regarding the type of Native American ancestry. Consideration of specific associations with common diseases may lead to substantial advances in unraveling of disease etiology and disease prevention. Here we investigate possible associations between the type of Native American ancestry and leading causes of death. After an aggregate-data study based on genome-wide genotype data from 1805 admixed Chileans and 639,789 deaths, we validate an identified association with gallbladder cancer relying on individual data from 64 gallbladder cancer patients, with and without a family history, and 170 healthy controls. Native American proportions were markedly underestimated when the two main types of Native American ancestry in Chile, originated from the Mapuche and Aymara indigenous peoples, were combined together. Consideration of the type of Native American ancestry was crucial to identify disease associations. Native American ancestry showed no association with gallbladder cancer mortality (P = 0.26). By contrast, each 1% increase in the Mapuche proportion represented a 3.7% increased mortality risk by gallbladder cancer (95%CI 3.1-4.3%, P = 6×10-27). Individual-data results and extensive sensitivity analyses confirmed the association between Mapuche ancestry and gallbladder cancer. Increasing Mapuche proportions were also associated with an increased mortality due to asthma and, interestingly, with a decreased mortality by diabetes. The mortality due to skin, bladder, larynx, bronchus and lung cancers increased with increasing Aymara proportions. Described methods should be considered in future studies on human population genetics and human health. Complementary individual-based studies are needed to apportion the genetic and non-genetic components of associations identified relying on aggregate-data.

Describing the children's body shape by means of Geometric Morphometric techniques.

INTRODUCTION: Large shape variations take place during the growth process of children, including quantitative mass and size increase plus qualitative changes in their body shape. The aim of the present study is to apply Geometric Morphometric techniques in order to visualize and quantify such body shape differences in healthy children aged 6-59 months with optimal nutritional status. MATERIALS AND METHODS: Anthropometrical measurements of weight, height, and middle-upper arm circumference were used to assess nutritional status on a sample of 258 Senegalese (n = 154) and Spanish (n = 104) children. A set of 36 anatomical and/or osteologically-based landmarks were identified on the body of the children along with 108 semi-landmarks used to capture curvature attributes on the frontal view of the body image. A specific method was developed to place and photograph children, as well as to locate landmarks, treat images and calculate semi-landmarks. Shape differences among children were analyzed in terms of age, sex, and population origin, taking into consideration allometry effects. RESULTS: Our results indicate significant differences in shape and size for all the three factors under study before removing size effect (p < .0001), and in shape after the size correction (p < .01). Only the ontogenetic effect persisted in the size of studied individuals after size-effects correction (p < .0001). Morphometric significant differences were described regarding age for PC1 and population origin in PC2 before removing size effect. Between-population morphometric differences were sorted along PC1 after size correction. DISCUSSION: Geometric Morphometric techniques are useful to study morphometric changes in the anterior whole-body view of children under 5 years old, allowing a precise description of shape changes observed when age and population origin are considered.

Variation in dental morphology and inference of continental ancestry in admixed Latin Americans.

OBJECTIVES: To investigate the variation in dental nonmetric traits and to evaluate the utility of this variation for inferring genetic ancestry proportions in a sample of admixed Latin Americans. MATERIALS AND METHODS: We characterized a sample from Colombia (N = 477) for 34 dental traits and obtained estimates of individual Native American, European, and African ancestry using genome-wide SNP data. We tested for correlation between dental traits, genetic ancestry, age, and sex. We carried out a biodistance analysis between the Colombian sample and reference continental population samples using the mean measure of divergence statistic calculated from dental trait frequencies. We evaluated the inference of genetic ancestry from dental traits using a regression approach (with 10-fold cross-validation) as well as by testing the correlation between estimates of ancestry obtained from genetic and dental data. RESULTS: Latin Americans show intermediate dental trait frequencies when compared to Native Americans, Europeans, and Africans. Significant correlations were observed for several dental traits, genetic ancestry, age, and sex. The biodistance analysis displayed a closer relationship of Colombians to Europeans than to Native Americans and Africans. Mean ancestry estimates obtained from the dental data are similar to the genetic estimates (Native American: 32% vs. 28%, European: 59% vs. 63%, and African: 9% vs. 9%, respectively). However, dental features provided low predictive power for genetic ancestry of individuals in both approaches tested (R2 < 5% for all genetic ancestries across methods). DISCUSSION: The frequency of dental traits in Latin Americans reflects their admixed Native American, European and African ancestry and can provide reasonable average estimates of genetic ancestry. However, the accuracy of individual genetic ancestry estimates is relatively low, probably influenced by the continental differentiation of dental traits, their genetic architecture, and the distribution of genetic ancestry in the individuals examined.

Obesity, genomic ancestry, and socioeconomic variables in Latin American mestizos.

OBJECTIVES: This article aims to assess the contribution of genomic ancestry and socioeconomic status to obesity in a sample of admixed Latin Americans. METHODS: The study comprised 6776 adult volunteers from Brazil, Chile, Colombia, Mexico, and Peru. Each volunteer completed a questionnaire about socioeconomic variables. Anthropometric variables such as weight, height, waist, and hip circumference were measured to calculate body indices: body mass index, waist-to-hip ratio and waist-to-height ratio (WHtR). Genetic data were extracted from blood samples, and ancestry was estimated using chip genotypes. Multiple linear regression was used to evaluate the relationship between the indices and ancestry, educational level, and economic well-being. The body indices were dichotomized to obesity indices by using appropriate thresholds. Odds ratios were calculated for each obesity index. RESULTS: The sample showed high percentages of obesity by all measurements. However, indices did not overlap consistently when classifying obesity. WHtR resulted in the highest prevalence of obesity. Overall, women with low education level and men with high economic wellness were more likely to be obese. American ancestry was statistically associated with obesity indices, although to a lesser extent than socioeconomic variables. CONCLUSIONS: The proportion of obesity was heavily dependent on the index and the population. Genomic ancestry has a significant influence on the anthropometric measurements, especially on central adiposity. As a whole, we detected a large interpopulation variation that suggests that better approaches to overweight and obesity phenotypes are needed in order to obtain more precise reference values.

Leaf shape variation as a potential biomarker of soil pollution.

Halophytic plants play a fundamental role in salt marshes, influencing their structure, dynamics, and cycling of nutrients and minerals. These plants have the ability to retain metals in the soil, or absorb and retain them in underground structures, or transport them to their aerial structures. Here we aim to study shape variation in the leaves of Cressa truxillensis inhabiting the salt marsh of San Antonio Oeste, according to their proximity to a source of metals in the soil. A gradient of bioavailability of metal was observed in the soil, decreasing from the site closest to the source to the most distant point, where Zn was the most abundant metal followed by Pb and Cu. We used landmark-based geometric morphometric tools to study leaf shape variation. We observed more oval leaf growth on the farthest point of the pollutant's source, and lanceolate shape close to it. No significant among-site size differences were found. Collectively, these results suggest that the stress conditions associated with the soil metals' concentration generate changes in the leaf shape of Cressa truxilensis. Considering that this species has not been extensively analyzed, this study establishes a baseline and supports the use of the leaf as an early biomarker of stress by contamination in plants associated with marshes.

Measuring fitness heritability: Life history traits versus morphological traits in humans.

OBJECTIVES: Traditional interpretation of Fisher's Fundamental Theorem of Natural Selection is that life history traits (LHT), which are closely related with fitness, show lower heritabilities, whereas morphological traits (MT) are less related with fitness and they are expected to show higher heritabilities. In humans, although few studies have examined the heritability of LHT and MT, none of them have analyzed the same sample for comparative purposes. Here we assessed, for the first time, the heritability, additive genetic variance (VA ), residual variance (VR ) and coefficient of genetic additive variation (CVA ) values of LHT and MT in a singular collection of identified skulls with associated demographic records from Hallstatt (Austria). MATERIALS AND METHODS: LHT, such as lifespan, number of offspring, age at birth of first and last child, reproductive span, and lifetime reproductive success, were estimated from 18,134 individuals from the Hallstatt Catholic parish records, which represent seven generations and correspond to a time span of 400 years. MT were assessed through 17 craniofacial indices and 7 angles obtained from 355 adult crania from the same population. Heritability, VA , VR , and CVA values of LHT and MT were calculated using restricted maximum likelihood methods. RESULTS: LHT heritabilities ranged from 2.3 to 34% for the whole sample, with men showing higher heritabilities (4-45%) than women (0-23.7%). Overall, MT presented higher heritability values than most of LHT, ranging from 0 to 40.5% in craniofacial indices, and from 13.8 to 32.4% in craniofacial angles. LHT showed considerable additive genetic variance values, similar to MT, but also high environmental variance values, and most of them presenting a higher evolutionary potential than MT. DISCUSSION: Our results demonstrate that, with the exception of lifespan, LHT show lower heritability values, than MT. The lower heritability of LHT is explained by a higher influence of environmental and cultural factors.

Admixture in Latin America: geographic structure, phenotypic diversity and self-perception of ancestry based on 7,342 individuals.

The current genetic makeup of Latin America has been shaped by a history of extensive admixture between Africans, Europeans and Native Americans, a process taking place within the context of extensive geographic and social stratification. We estimated individual ancestry proportions in a sample of 7,342 subjects ascertained in five countries (Brazil, Chile, Colombia, México and Perú). These individuals were also characterized for a range of physical appearance traits and for self-perception of ancestry. The geographic distribution of admixture proportions in this sample reveals extensive population structure, illustrating the continuing impact of demographic history on the genetic diversity of Latin America. Significant ancestry effects were detected for most phenotypes studied. However, ancestry generally explains only a modest proportion of total phenotypic variation. Genetically estimated and self-perceived ancestry correlate significantly, but certain physical attributes have a strong impact on self-perception and bias self-perception of ancestry relative to genetically estimated ancestry.