Biology subjects

Yüncü, E.

Publications and source records attributed to Yüncü, E..

7 recordsLinked to original sources

bioRxiv2024

An age-specific burial practice reflected in ancient DNA preservation in Neolithic Catalhöyük

Selective funerary practices can inform about social relationships in prehistoric societies but are often difficult to discern. Here we present evidence for an age-specific practice at the Neolithic site of Catalhoyuk in Anatolia, dating to the 7th millennium BCE. Among ancient DNA libraries produced from 362 petrous bone samples, those of subadults contained three times higher average human DNA than those of adults. This difference in organic preservation was also confirmed by FTIR analysis. Studying similar datasets from seven prehistoric and historical sites, we found a similar age-related difference in only one cemetery. We propose that the organic preservation difference with age was caused by the special treatment of chosen corpses before interment, such as defleshing or drying, which was more frequently applied to Catalhoyuk adults and promoted organic decay.

evolutionary biology↗

bioRxiv2023

Population genomic history of the endangered Anatolian and Cyprian mouflons in relation to worldwide wild, feral and domestic sheep lineages

Once widespread in their homelands, Anatolian mouflon (Ovis gmelini anatolica) and Cyprian mouflon (Ovis gmelini ophion) were driven to near extinction during the 20th century and are currently listed as endangered populations by the IUCN. While the exact origins of these lineages remain unclear, they have been suggested to be close relatives of domestic sheep or remnants of proto-domestic sheep groups. Here, we study whole genome sequences of n=5 Anatolian mouflons and n=10 Cyprian mouflons in terms of population history and diversity, relative to eight other extant sheep lineages. We find reciprocal genetic affinity between Anatolian and Cyprian mouflons and domestic sheep, higher than all other studied wild sheep genomes, including the Iranian mouflon (Ovis gmelini). Despite similar recent population dynamics, Anatolian and Cyprian mouflons exhibit disparate diversity levels, which can potentially be attributed to founder effects, island isolation, introgression from domestic lineages, or different bottleneck dynamics. The lower relative mutation load found in Cyprian compared to Anatolian mouflons suggests the purging of recessive deleterious variants in the former. This agrees with estimates of a long-term small effective population size in the Cyprian mouflon. Both subspecies harbor considerable numbers of runs of homozygosity (ROH) blocks <2 Mb, which reflects the effect of small population size. Expanding our analyses to worldwide wild and feral Ovis genomes, we observe varying viability metrics among different lineages, and a limited consistency between viability metrics and conservation status. Factors such as recent inbreeding, introgression, and unique population dynamics may contribute to the observed disparities.

evolutionary biology↗

bioRxiv2023

The first complete genome of the extinct European wild ass (Equus hemionus hydruntinus)

We present paleogenomes of three morphologically-unidentified Anatolian equids dating to the 1st millennium BCE, sequenced to coverages of 0.6-6.4X. Mitochondrial DNA haplotypes of the Anatolian individuals clustered with those of Equus hydruntinus (or Equus hemionus hydruntinus), the extinct European wild ass. The Anatolian wild ass whole genome profiles fall outside the genomic diversity of other extant and past Asiatic wild ass (E.hemionus) lineages. These observations strongly suggest that the three Anatolian wild asses represent E.hydruntinus, making them the latest recorded survivors of this lineage, about a millennium later than the latest observations in the zooarchaeological record. Comparative genomic analyses suggest that E.hydruntinus was a sister clade to all ancient and present-day E.hemionus lineages, representing an early split. We also find indication of gene flow between hydruntines and Middle Eastern wild asses. Analyses of genome-wide heterozygosity and runs of homozygosity reveal that the Anatolian wild ass population had severely lost genetic diversity by the mid-1st millennium BCE, a likely omen of its eventual demise.

genomics↗

bioRxiv2023

False discovery rates of qpAdm-based screens for genetic admixture

qpAdm is a statistical tool that is often used for testing large sets of alternative admixture models for a target population. Despite its popularity, qpAdm remains untested on two-dimensional stepping-stone landscapes and in situations with low pre-study odds (low ratio of true to false models). We tested high-throughput qpAdm protocols with typical properties such as number of source combinations per target, model complexity, model feasibility criteria, etc. Those protocols were applied to admixture-graph-shaped and stepping-stone simulated histories sampled randomly or systematically. We demonstrate that false discovery rates of high-throughput qpAdm protocols exceed 50% for many parameter combinations since: 1) pre-study odds are low and fall rapidly with increasing model complexity; 2) complex migration networks violate the assumptions of the method, hence there is poor correlation between qpAdm p-values and model optimality, contributing to low but non-zero false positive rate and low power; 3) although admixture fraction estimates between 0 and 1 are largely restricted to symmetric configurations of sources around a target, a small fraction of asymmetric highly non-optimal models have estimates in the same interval, contributing to the false positive rate. We also re-interpret large sets of qpAdm models from two studies in terms of source-target distance and symmetry and suggest improvements to qpAdm protocols: 1) temporal stratification of targets and proxy sources in the case of admixture-graph-shaped histories; 2) focused exploration of few models for increasing pre-study odds; dense landscape sampling for increasing power and stringent conditions on estimated admixture fractions for decreasing the false positive rate. Article SummaryProliferation in the archaeogenetic literature of protocols for detection of admixed groups based a so-called qpAdm algorithm became disconnected from performance testing: the only extensive study of qpAdm on simulated data showed that it performs well under an unrealistically simple demographic scenario. We found that false discoveries of gene flows by qpAdm on a collection of random admixture-graph-shaped histories and on complex stepping-stone landscapes are very common and provide guidelines for design of qpAdm protocols in archaeogenetic studies.

genetics↗

bioRxiv2023

Modeling of African population history using f-statistics can be highly biased and is not addressed by previously suggested SNP ascertainment schemes

f-statistics have emerged as a first line of analysis for making inferences about demographic history from genome-wide data. These statistics can provide strong evidence for either admixture or cladality, which can be robust to substantial rates of errors or missing data. f-statistics are guaranteed to be unbiased under "SNP ascertainment" (analyzing non-randomly chosen subsets of single nucleotide polymorphisms) only if it relies on a population that is an outgroup for all groups analyzed. However, ascertainment on a true outgroup that is not co-analyzed with other populations is often impractical and uncommon in the literature. In this study focused on practical rather than theoretical aspects of SNP ascertainment, we show that many non-outgroup ascertainment schemes lead to false rejection of true demographic histories, as well as to failure to reject incorrect models. But the bias introduced by common ascertainments such as the 1240K panel is mostly limited to situations when more than one sub-Saharan African and/or archaic human groups (Neanderthals and Denisovans) or non-human outgroups are co-modelled, for example, f4-statistics involving one non-African group, two African groups, and one archaic group. Analyzing panels of SNPs polymorphic in archaic humans, which has been suggested as a solution for the ascertainment problem, cannot fix all these problems since for some classes of f-statistics it is not a clean outgroup ascertainment, and in other cases it demonstrates relatively low power to reject incorrect demographic models since it provides a relatively small number of variants common in anatomically modern humans. And due to the paucity of high-coverage archaic genomes, archaic individuals used for ascertainment often act as sole representatives of the respective groups in an analysis, and we show that this approach is highly problematic. By carrying out large numbers of simulations of diverse demographic histories, we find that bias in inferences based on f-statistics introduced by non-outgroup ascertainment can be minimized if the derived allele frequency spectrum in the population used for ascertainment approaches the spectrum that existed at the root of all groups being co-analyzed. Ascertaining on sites with variants common in a diverse group of African individuals provides a good approximation to such a set of SNPs, addressing the great majority of biases and also retaining high statistical power for studying population history. Such a "pan-African" ascertainment, although not completely problem-free, allows unbiased exploration of demographic models for the widest set of archaic and modern human populations, as compared to the other ascertainment schemes we explored.

genetics↗

bioRxiv2021

Indian genetic heritage in Southeast Asian populations

The great ethnolinguistic diversity found today in mainland Southeast Asia (MSEA) reflects multiple migration waves of people in the past. Deeply divergent East Eurasian hunter-gatherers were the first anatomically modern human population known to migrate to the region. Agriculturalists from South China migrated to the region and admixed with the local hunter-gatherers during the Neolithic period. During the Bronze and Iron Ages, the genetic makeup of people in MSEA changed again, indicating an additional influx of populations from South China. Maritime trading between MSEA and India was established at the latest 300 BCE, and the formation of early states in Southeast Asia during the first millennium CE was strongly influenced by Indian culture, and this cultural influence is still prominent today. Several ancient Indian-influenced states were located in present-day Thailand, and various populations in the country are likely to be descendants of people from those states. To systematically explore Indian genetic heritage in MSEA, we generated genome-wide SNP data (the HumanOrigins array) for 119 present-day individuals belonging to 10 ethnic groups from Thailand and co-analyzed them with published data from MSEA using the PCA, ADMIXTURE, f3-statistics, qpAdm, and qpGraph methods. We found South Asian low-level admixture in various MSEA populations which are probably descendants of people from the ancient Indian-influenced states, but failed to find a South Asian genetic component in present-day hunter-gatherer groups and relatively isolated groups from highlands in Northern Thailand. Our results also support close genetic affinity between Kra-Dai-speaking (also known as Tai-Kadai) and Austronesian-speaking populations, which fits a linguistic hypothesis suggesting cladality of the two language families. Author SummaryMainland Southeast Asia is a region with great ethnolinguistic diversity and complex population history. We studied genetic population history of present-day mainland Southeast Asian populations using genome-wide SNP data (the HumanOrigins array). We generated new data for 10 present-day ethnic groups from Thailand, which we further combined with published data from mainland and island Southeast Asians and worldwide populations. We revealed South Asian genetic admixture in various mainland Southeast Asian ethnic groups which are highly influenced by Indian culture, but failed to find it in groups who remained culturally isolated until recently. Our finding suggests that a massive migration of Indian people in the past was responsible for the spread of Indian culture in mainland Southeast Asia. We also found support for a close genetic affinity between Kra-Dai- and Austronesianspeaking populations, which fits a linguistic hypothesis suggesting cladality of the two language families.

genetics↗

bioRxiv2020

Archaeogenetic analysis of Neolithic sheep from Anatolia suggests a complex demographic history since domestication

Sheep was among the first domesticated animals, but its demographic history is little understood. Here we present combined analyses of mitochondrial and nuclear polymorphism data from ancient central and west Anatolian sheep dating to the Late Glacial and early Holocene. We observe loss of mitochondrial haplotype diversity around 7500 BCE during the early Neolithic, consistent with a domestication-related bottleneck. Post-7000 BCE, mitochondrial haplogroup diversity increases, compatible with admixture from other domestication centres and/or from wild populations. Analysing archaeogenomic data, we further find that Anatolian Neolithic sheep (ANS) are genetically closest to present-day European breeds, and especially those from central and north Europe. Our results indicate that Asian contribution to south European breeds in the post-Neolithic era, possibly during the Bronze Age, may explain this pattern.

evolutionary biology↗