The genetic heritage of China: A genomic study of PR China based on nine representative ethnic populations

During the course of the last decade, genetic data have increasingly complemented linguistic, archaeological and palaeontological evidence in efforts to reconstruct human history. As technology has developed, studies have utilised genomic techniques in tracing the origins and migratory patterns of modem humans. East Asia is a particular hotspot of human migration, _especially Mainland China where a large number of human fossils have been unearthed and more than 20% of the wor1d\u27s population now resides. There are 56 officially recognised ethnic groups (minzu) within the population of PR China which totals 1,300 million. The majority Han population is distributed throughout the country and forms 90% of the total, whereas the other 55 minority populations mostly live in peripheral and boundary regions. To date, information on these minorities has been fragmentary and, from both evolutionary and historical perspectives, data on their genetic profiles would be of considerable value in identifying their founding populations and genetic inter-relationships. There are also strongly conflicting opinions on the origins of the Han and the degree to which they can be regarded as genetically homogenous. The current study measured the genetic diversity and ancestry of nine ethnic populations resident in PR China. In addition to the Han, these study populations comprised the Miao, Yao, Kucong and Tibetan communities from Yunnan province in the southwest of the country, and four Muslim populations, the Hui, Bo\u27an, Dongxiang and Sala from northern and central China. Both biparental and uniparental genetic influences on the populations were examined by the analysis of autosomal, mitochondrial and Y -chromosome markers. In general, it was found that the study populations displayed diverse paternal ancestries but more restricted maternal ancestries. From the Y-chromosome data in particular, major events such as the Neolithic population expansion and more recent historical events, such-as migration along the Silk Road, could be inferred. Through the use of autosomal markers, aspects of the internal structure of the study populations were uncovered, such as endogamy and/or consanguinity. These conclusions were made possible, in part, by experimental Likelihood-based stochastic coalescent modelling. Intriguingly. it was revealed that the Kucong of Yunnan, an ethnic group not previously surveyed for genetic diversity and not accorded official minority status within PR China. could possibly be representative of indigenous populations dating from the first migrations into East Asia. While other\u27 more recent events could be inferred from summary statistics and phylogenetic and coalescent-based genetic analyses of the study populations, the changing definition of the ethnic study populations themselves proved to be the most important factor. It is therefore recommended that future studies primarily utilize a community-by-community approach, and not rely on the official minzu category as an accurate indicator of genetic ancestry

Comparative genomics of Bistorta vivipara

High Northern latitudes are predicted to change considerably in forthcoming climate scenarios, and empirical evidence detailing a species\u27 capacity to cope with extreme variability is needed. Tundra plants make for an excellent study because their genetic histories were impacted by the dramatic transitions of historic glacial and interglacial ages. Here, thousands of restriction site-associated DNA (RAD) markers from geographically isolated Alaskan (Arctic) and Coloradan (Alpine) Bistorta vivipara (Polygonaceae) populations are compared in an investigation of evolutionary response to rapid climate change. Non-coding nuclear markers were analyzed in a coalescent framework to estimate an effective ancestral population size (Na) and divergence date (t) of the two populations of ~23 000 individuals and ~140 000 years before present. Nucleotide substitutions per synonymous site (dS) and nonsynonymous site (dN) were calculated for putative orthologous protein-coding sequences to determine the form of selection acting on the subsampled genome in the context of t. Most sequences were either 100% conserved or exhibited dS \u3e dN, suggesting purifying selection. The few sequences suggesting positive selection (dS \u3c dN) were identified as retroelements, which are expected to escape purifying selection. There were two exceptions: a putative protein phosphatase and a kinase involved with steroid signaling. The results suggest genetic adaptation is not a readily apparent option for B. vivipara’s response to climate change. This, and other organisms whose habitats will shift quickly or disappear, may depend on demographic and plastic responses as alternatives to extinction

2022 - The Third Annual Fall Symposium of Student Scholars

The full program book from the Fall 2022 Symposium of Student Scholars, held on November 17, 2022. Includes abstracts from the presentations and posters.https://digitalcommons.kennesaw.edu/sssprograms/1026/thumbnail.jp

Ramifications génétiques et démographiques de l'effet fondateur québécois

Les événements fondateurs et les expansions territoriales peuvent promouvoir une cascade de changements génétiques et ont ainsi pu jouer un rôle important au cours de l’histoire évolutive de l’Homme moderne. Or, chez les populations humaines, les conséquences évolutives et la dynamique démographique des processus de colonisation demeurent largement méconnues et difficiles à étudier. Dans cette thèse, nous avons utilisé les généalogies de la population fondatrice canadienne-française ainsi que des données génomiques pour étudier ces questions. Les analyses génomiques et généalogiques, remarquablement concordantes, ont dévoilé un nouveau portrait détaillé de la structure de la population du Québec, incluant un continuum de diversité génétique dans l’axe ouest/est et des sous-populations significativement différenciées. L’analyse de l’immigration fondatrice a montré que virtuellement tous les Canadiens français sont métissés. Allant à l’encontre d’une prétendue homogénéité génétique de la population, nos résultats démontrent que le peuplement des régions a engendré une rapide différentiation génétique et expliquent certaines signatures régionales de l’effet fondateur. De plus, en suivant les changements évolutifs dans les généalogies, nous avons montré que les caractéristiques des peuplements fondateurs peuvent affecter les traits liés à la fécondité et au succès reproducteur. Cette thèse offre une meilleure compréhension du patrimoine génétique du Québec et apporte des éléments de réponse sur les conséquences évolutives des événements fondateurs.Founding events and range expansions can promote a cascade of genetic changes and may have played an important role in the evolutionary history of modern humans. Yet the evolutionary consequences and demographic dynamics of these colonization processes remain poorly documented and challenging to study in human populations. In this thesis, we used deep-rooted genealogies from the French Canadian founder population in addition to genomic data to address these questions. Genomic and genealogical analyses were remarkably concordant and revealed a new portrait of Quebec fine-scale population structure, including a continuum of genetic diversity in the west/east axis and sub-populations significantly differentiated. The analysis of the founding immigration showed that virtually all French Canadians are admixed. Contrary to the idea of homogeneity of the population, our results demonstrate that the regional settlement histories led to a rapid genetic differentiation and explain some regional signatures of the founder effect. By monitoring evolutionary changes in real genealogies, we show that founding events impact fertility traits and reproductive success. This thesis leads to a better understanding of the genetic heritage of Quebec and provides insights on how peopling of new territories shaped human evolution

Random covering of an interval and a variation of Kingman's coalescent

We consider the covering of [0, 1] by a large number of small random intervals. We show that a simple variation of Kingman's coalescent describes the emergence of macroscopic connected components. © 2004 Wiley Periodicals, Inc. Random Struct. Alg. 200