Abstract Hominin evolution is characterized by adaptive solutions often rooted in behavioral and cognitive changes. If balancing selection had an important and long-lasting impact on the evolution of these traits, it can be hypothesized that genes associated with them should carry an excess of shared polymorphisms (trans- SNPs) across recent Homo species. In this study, we investigate the role of balancing selection in human evolution using available exomes from modern (Homo sapiens) and archaic humans (H. neanderthalensis and Denisovan) for an excess of trans-SNP in two gene sets: one associated with the immune system (IMMS) and another one with behavioral system (BEHS). We identified a significant excess of trans-SNPs in IMMS (N=547), of which six of these located within genes previously associated with schizophrenia. No excess of trans-SNPs was found in BEHS, but five genes in this system harbor potential signals for balancing selection and are associated with psychiatric or neurodevelopmental disorders. Our approach evidenced recent Homo trans-SNPs that have been previously implicated in psychiatric diseases such as schizophrenia, suggesting that a genetic repertoire common to the immune and behavioral systems could have been maintained by balancing selection starting before the split between archaic and modern humans.
Abstract In spite of many genetic studies that contributed for a deep knowledge about the peopling of the Americas, no consensus has emerged about important parameters such as the effective size of the Native Americans founder population. Previous estimates based on genomic datasets may have been biased by the use of admixed individuals from Latino populations, while other recent studies using samples from Native American individuals relied on approximated analytical approaches. In this study we use resequencing data for nine independent regions in a set of Native American and Siberian individuals and a full-likelihood approach based on isolation-with-migration scenarios accounting for recent flow between Asian and Native American populations. Our results suggest that, in agreement with previous studies, the effective size of the Native American population was small, most likely in the order of a few hundred individuals, with point estimates close to 250 individuals, even though credible intervals include a number as large as ~4,000 individuals. Recognizing the size of the genetic bottleneck during the peopling of the Americas is important for determining the extent of genetic markers needed to characterize Native American populations in genome-wide studies and to evaluate the adaptive potential of genetic variants in this population.
Abstract Alcohol dehydrogenases belong to the large superfamily of medium-chain dehydrogenases/reductases, which occur throughout the biological world and are involved with many important metabolic routes. We considered the phylogeny of 190 ADH sequences of animals, fungi, and plants. Non-class III Caenorhabditis elegans ADHs were seen closely related to tetrameric fungal ADHs. ADH3 forms a sister group to amphibian, reptilian, avian and mammalian non-class III ADHs. In fishes, two main forms are identified: ADH1 and ADH3, whereas in amphibians there is a new ADH form (ADH8). ADH2 is found in Mammalia and Aves, and they formed a monophyletic group. Additionally, mammalian ADH4 seems to result from an ADH1 duplication, while in Fungi, ADH formed clusters based on types and genera. The plant ADH isoforms constitute a basal clade in relation to ADHs from animals. We identified amino acid residues responsible for functional divergence between ADH types in fungi, mammals, and fishes. In mammals, these differences occur mainly between ADH1/ADH4 and ADH3/ADH5, whereas functional divergence occurred in fungi between ADH1/ADH5, ADH5/ADH4, and ADH5/ADH3. In fishes, the forms also seem to be functionally divergent. The ADH family expansion exemplifies a neofunctionalization process where reiterative duplication events are related to new activities.
Abstract After a brief introduction about the factors that are involved in science development, and world and Brazilian evolutionary genetics, the studies developed in Porto Alegre in this area were reviewed. Four periods in the development of this group were distinguished: (a) Origins and first expansion (1949-1961); (b) Second expansion (1962-1988); (c) Third expansion (1989-2001); and (d) The last 15 years (2002-present). The international Porto Alegre Biological Evolution Workshops (PABEWs), with five biannual events from 2007 o 2015, were also mentioned. The final message stressed the importance of the maintenance of this and other Brazilian groups of research through adequate finance and recognition.
Abstract The FOXP subfamily is probably the most extensively characterized subfamily of the forkhead superfamily, playing important roles in development and homeostasis in vertebrates. Intrinsically disorder protein regions (IDRs) are protein segments that exhibit multiple physical interactions and play critical roles in various biological processes, including regulation and signaling. IDRs in proteins may play an important role in the evolvability of genetic systems. In this study, we analyzed 77 orthologous FOXP genes/proteins from Tetrapoda, regarding protein disorder content and evolutionary rate. We also predicted the number and type of short linear motifs (SLIMs) in the IDRs. Similar levels of protein disorder (approximately 70%) were found for FOXP1, FOXP2, and FOXP4. However, for FOXP3, which is shorter in length and has a more specific function, the disordered content was lower (30%). Mammals showed higher protein disorders for FOXP1 and FOXP4 than non-mammals. Specific analyses related to linear motifs in the four genes showed also a clear differentiation between FOXPs in mammals and non-mammals. We predicted for the first time the role of IDRs and SLIMs in the FOXP gene family associated with possible adaptive novelties within Tetrapoda. For instance, we found gain and loss of important phosphorylation sites in the Homo sapiens FOXP2 IDR regions, with possible implication for the evolution of human speech.
Abstract Oxytocin receptor (OXTR) and arginine vasopressin receptors (AVPR1a, AVPR1b, and AVPR2) are paralogous genes that emerged through duplication events; along the evolutionary timeline, owing to speciation, numerous orthologues emerged as well. In order to elucidate the evolutionary forces that shaped these four genes in placental mammals and to reveal specific aspects of their protein structures, 35 species were selected. Specifically, we investigated their molecular evolutionary history and intrinsic protein disorder content, and identified the presence of short linear interaction motifs. OXTR seems to be under evolutionary constraint in placental mammals, whereas AVPR1a, AVPR1b, and AVPR2 exhibit higher evolutionary rates, suggesting that they have been under relaxed or experienced positive selection. In addition, we describe here, for the first time, that the OXTR, AVPR1a, AVPR1b, and AVPR2 mammalian orthologues preserve their disorder content, while this condition varies among the paralogues. Finally, our results reveal the presence of short linear interaction motifs, indicating possible functional adaptations related to physiological and/or behavioral taxa-specific traits.
Abstract A brief introduction considering Darwin's work, the evolutionary synthesis, and the scientific biological field around the 1970s and subsequently, with the molecular revolution, was followed by selected examples of recent investigations dealing with the selection-drift controversy. The studies surveyed included the comparison between essential genes in humans and mice, selection in Africa and Europe, and the possible reasons why females in humans remain healthy and productive after menopause, in contrast with what happens in the great apes. At the end, selected examples of investigations performed in Latin America, related to the action of selection for muscle performance, acetylation of xenobiotics, high altitude and tropical forest adaptations were considered. Despite dissenting views, the influence of positive selection in a considerable portion of the human genome cannot presently be dismissed.
The population of Argentina has already been studied with regard to several genetic markers, but much more data are needed for the appropriate definition of its genetic profile. This study aimed at investigating the admixture patterns and genetic structure in Central Argentina, using biparental markers and comparing the results with those previously obtained by us with mitochondrial DNA (mtDNA) in the same samples. A total of 521 healthy unrelated individuals living in 13 villages of the Córdoba and San Luis provinces were tested. The individuals were genotyped for ten autosomal ancestry informative markers (AIMs). Allele frequencies were compared with those of African, European and Native American populations, chosen to represent parental contributions. The AIM estimates indicated a greater influence of the Native American ancestry as compared to previous studies in the same or other Argentinean regions, but smaller than that observed with the mtDNA tests. These differences can be explained, respectively, by different genetic contributions between rural and urban areas, and asymmetric gene flow occurred in the past. But a most unexpected finding was the marked interpopulation genetic homogeneity found in villages located in diverse geographic environments across a wide territory, suggesting considerable gene flow.
A general introduction to the origins and history of Latin American populations is followed by a systematic review of the data from molecular autosomal assessments of the ethnic/continental (European, African, Amerindian) ancestries for 24 Latin American countries or territories. The data surveyed are of varying quality but provide a general picture of the present constitution of these populations. A brief discussion about the applications of these results (admixture mapping) is also provided. Latin American populations can be viewed as natural experiments for the investigation of unique anthropological and epidemiological issues.
The world view in the Dark (Middle Ages) could not be more monotonous. The world would have been created by a divine entity in a fixed version, and divergent opinions would be considered a heresy and subjected to strong opposition by the church. Everything changed with the publication in 1859 of Charles Darwin's seminal work The Origin of Species. Nature was not created to serve us; instead, the human species was just one in a multitude of other biological entities. To this Darwinian revolution others followed in the ensuing one and a half century, involving: a) The Modern synthesis, b) elucidation of the structure of the genetic material, c) techniques of DNA manipulation, and d) bioinformatics and nanotechnology. The half-a-century investigations of our group followed these changes, and examples of some of the most recent will be described, involving: 1. comparisons between archaic and modern genomes, 2. genomic approaches to Amerindian history, and 3. gene-culture interactions involving specific traits. Molecular and bioinformatic techniques are allowing us to have a detailed view of our past, better understanding of our present, and conditions to better predict our future.
La visión del mundo en el oscurantismo (Edad Media) no podría ser más monótona. La versión establecida era que el mundo había sido creado por una entidad divina y las opiniones divergentes se consideraban una herejía y enfrentaban la fuerte oposición de la Iglesia. Todo cambió con la publicación, en 1859, de la obra precursora de Charles Darwin, El origen de las especies. La naturaleza no fue creada para servirnos; la especie humana, más bien, fue sólo una más en una multitud de otras entidades biológicas. A esta revolución darwiniana le siguieron otras en el siglo subsiguiente y el siguiente medio siglo, las cuales implicaron: a) la síntesis evolutiva moderna, b) la dilucidación de la estructura del material genético; c) las técnicas de manipulación del ADN y d) la bioinformática y la nanotecnología. El medio siglo de investigaciones de nuestro grupo continuó con estos cambios, entre los más recientes se incluyen algunos de los ejemplos que se describen a continuación: 1. comparaciones entre los genomas arcaicos y modernos, 2. enfoques genómicos para la historia amerindia y 3. interacciones entre los genes y la cultura con rasgos específicos. La técnica molecular y la bioinformática nos permiten tener una vista detallada de nuestro pasado así como una mejor comprensión de nuestro presente y de las condiciones que predicen mejor nuestro futuro.
The questions of the title have been considered in several ways. First, indications of the traits which make us humans were considered. Then the behavior and culture concepts were examined, and the biology and culture interactions discussed, with an emphasis on the similarities and differences between the genetic and cultural transmissions. Next diverse types of selective pressures were reviewed, and finally pessimistic and optimistic views of our future contrasted. Vigorous action against acts which lead to exclusion and discriminatory policies against human subjects is needed.