Biology subjects

Brunelli, A.

Publications and source records attributed to Brunelli, A..

4 recordsLinked to original sources

bioRxiv2019

Contrasting paternal and maternal genetic histories of Thai and Lao populations

The human demographic history of Mainland Southeast Asia (MSEA) has not been well-studied; in particular there have been very few sequence-based studies of variation in the male-specific portions of the Y chromosome (MSY). Here, we report new MSY sequences of [~]2.3 mB from 914 males, and combine these with previous data for a total of 928 MSY sequences belonging to 59 populations from Thailand and Laos who speak languages belonging to three major MSEA families: Austroasiatic (AA), Tai-Kadai (TK) and Sino-Tibetan (ST). Among the 92 MSY haplogroups, two main MSY lineages (O1b1a1a* (O-M95*) and O2a* (O-M324*)) contribute substantially to the paternal genetic makeup of Thailand and Laos. We also analyse complete mtDNA genome sequences published previously from the same groups, and find contrasting pattern of male and female genetic variation and demographic expansions, especially for the hill tribes, Mon, and some major Thai groups. In particular, we detect an effect of post-marital residence pattern on genetic diversity in patrilocal vs. matrilocal groups. Additionally, both male and female demographic expansions were observed during the early Mesolithic ([~]10 kya), with two later major male-specific expansions during the Neolithic period ([~]4-5 kya) and the Bronze/Iron Age ([~]2.0-2.5 kya). These two later expansions are characteristic of the modern AA and TK groups, respectively, consistent with recent ancient DNA studies. We simulate MSY data based on three demographic models (continuous migration, demic diffusion and cultural diffusion) of major Thai groups and find different results from mtDNA simulations, supporting contrasting male and female genetic histories.

genetics↗

bioRxiv2018

Genetic structure in the wood mouse and the bank vole: contrasting patterns in a human-modified and highly fragmented landscape

Habitat fragmentation related to human activities modifies the distribution and the demographic trajectory of a species, often leading to genetic erosion and increased extinction risks. Understanding the impact of fragmentation on different species that co-exist in the same area becomes extremely important. Here we estimated the impact produced by different natural and anthropic landscape features on gene flow patterns in two sympatric species sampled in the same locations. Our main goal was to identify shared and private factors in the comparison among species. 199 bank voles and 194 wood mice were collected in 15 woodlands in a fragmented landscape, and genotyped at 8 and 7 microsatellites, respectively. Genetic variation and structure were analysed with standard approaches. Effective migration surfaces, isolation by resistance analysis, and regression with randomization were used to study isolation by distance and to estimate the relative importance of land cover elements on gene flow. Genetic structure was similarly affected by isolation by distance in these species, but the isolation-by-resistance analysis suggests that i) the wood mouse has constrained patterns of dispersal across woodland patches and facilitated connectivity in cultivated areas; ii) the bank vole connectivity is hindered by urban areas, while permeability is facilitated by the presence of woodlands, and cultivated terrains. Habitat loss and fragmentation can therefore influence genetic structure of small sympatric mammal species in different ways, and predicting the genetic consequences of these events using only one species may be misleading.

genetics↗

bioRxiv2018

A genetic perspective on Longobard-Era migrations

From the first century AD, Europe has been interested by population movements, commonly known as Barbarian migrations. Among these processes, the one involving the Longobard culture interested a vast region, but its dynamics and demographic impact remains largely unknown. Here we report 87 new complete mitochondrial sequences coming from nine early-medieval cemeteries located along the area interested by the Longobard migration (Czech Republic, Hungary and Italy). From the same locations, we sampled necropolises characterized by cultural markers associated with the Longobard culture (LC) and coeval burials where no such markers were found (NLC). Population genetics analysis and ABC modeling highlighted a similarity between LC individuals, as reflected by a certain degree of genetic continuity between these groups, that reached 70% among Hungary and Italy. Models postulating a contact between LC and NLC communities received also high support, indicating a complex dynamics of admixture in medieval Europe.

genetics↗

bioRxiv2017

New insights from Thailand into the maternal genetic history of Mainland Southeast Asia

Tai-Kadai (TK) is one of the major language families in Mainland Southeast Asia (MSEA), with a concentration in the area of Thailand and Laos. Our previous study of 1,234 mtDNA genome sequences supported a demic diffusion scenario in the spread of TK languages from southern China to Laos as well as northern and northeastern Thailand. Here we add an additional 560 mtDNA sequences from 22 groups, with a focus on the TK-speaking central Thai people and the Sino-Tibetan speaking Karen. We find extensive diversity, including 62 haplogroups not reported previously from this region. Demic diffusion is still a preferable scenario for central Thais, emphasizing the extension and expansion of TK people through MSEA, although there is also some support for an admixture model. We also tested competing models concerning the genetic relationships of groups from the major MSEA languages, and found support for an ancestral relationship of TK and Austronesian-speaking groups.

genetics↗