Biology subjects

Oteo-Garcia, G.

Publications and source records attributed to Oteo-Garcia, G..

4 recordsLinked to original sources

bioRxiv2026

Hic sunt dracones: ancient DNA from the extinct palaeofauna of the tiny Mediterranean archipelago of Columbretes and its implications for human visitation

The Columbretes archipelago in the Mediterranean is an example of deep isolation and sporadic human interaction during the Holocene. We recovered ancient DNA from 2,600-year-old microfauna and historical museum specimens to investigate the island's extinct fauna. Despite challenging preservation conditions, we successfully recovered mitogenomes from historical Vipera latastei specimens, and partial mitogenomes from snake, skink, and lizard subfossils. Phylogenetic analyses confirm the extinct Columbretes snake as Vipera latastei, sharing a haplotype with the historical specimen and clustering with modern populations from northeastern Iberia, validating its provenance and suggesting a single mitochondrial lineage since isolation. The extinct skink, Chalcides bedriagai, also shows affinities with eastern Iberia. These results point to a vicariant origin for the herpetofauna, likely isolated on the island following sea level rise after the Last Glacial Maximum. Conversely, a 2,600-year-old mouse incisor yielded a Mus musculus mitogenome, indicating Iron Age human-mediated introduction. Additionally, genomic analysis of a 11th-century CE human burial revealed an individual with genetic affinities to the Central Mediterranean and Balkans, highlighting medieval maritime mobility. This study resolves the long-debated Columbretes snake identity, traces biogeographic origins and illustrates the interplay of natural isolation and anthropogenic influence on the island biodiversity.

ecology↗

bioRxiv2024

Medieval genomes from eastern Iberia illuminate the role of Morisco mass deportations in dismantling a long-standing genetic bridge with North Africa

BackgroundThe Islamic influence on the Iberian Peninsula left an enduring legacy culturally and linguistically, however the demographic impact is less well understood. This study aims to explore the dynamics of gene flow and population structure in eastern Iberia from the early to late Medieval period through ancient DNA. ResultsOur comprehensive genomic analysis uncovered gene flow from various Mediterranean regions into Iberia before the Islamic period, supporting a pre-existing pan-Mediterranean homogenization phenomenon during the Roman Empire. North African ancestry is present but sporadic in late antiquity genomes but becomes consolidated during the Islamic period. We uncovered one of the earliest dated Islamic burials in Spain, which showed high levels of inbreeding. For the first time we also prove the persistence of North African ancestry in a Christian cemetery until the 17th century, in addition to evidence of slave traffick from the Maghreb. ConclusionsThis study reveals the complex interaction between political events and cultural shifts that influenced the population of eastern Iberia. It highlights the existence of a slave trade and underscores the lasting impact of historical events, such as the Expulsion of the Moriscos in 1609 CE, on the regions genetic and cultural landscape through mass population displacement and replacement.

evolutionary biology↗

bioRxiv2023

The geometry of admixture in population genetics: the blessing of dimensionality

We present a geometry-based interpretation of the f-statistics framework, commonly used to determine phylogenetic relationships from genetic data. The focus is on the determination of the mixing coefficients in population admixture events subject to post-admixture drift. The interpretation takes advantage of the high dimension of the dataset and analyzes the problem as a dimensional reduction issue. We show that it is possible to think of the f-statistics technique as an implicit transformation of the genetic data from a phase space into a subspace where the mapped data structure is more similar to the ancestral admixture configuration. The positive effect of the map can be explicitly assessed. The overarching geometric framework provides slightly more general formulas than the f-formalism by using a different rationale as a starting point. Explicitly addressed are two- and three-way admixtures. The mixture proportions are provided by suitable linear fits in two or three dimensions that can be easily visualized. The developments and findings are illustrated with numerical simulations from real world datasets.

evolutionary biology↗

bioRxiv2020

A geometrical framework for f-statistics

A detailed derivation of the f-statistics formalism is made from a geometrical framework. It is shown that the f-statistics appear when a genetic distance matrix is constrained to describe a four population phylogenetic tree. The choice of genetic metric is crucial and plays an outstanding role as regards the tree-like-ness criterion. The case of lack of treeness is interpreted in the formalism as presence of population admixture. In this respect, four formulas are given to estimate the admixture proportions. One of them is the so-called f4-ratio estimate and we show that a second one is related to a known result developed in terms of the fixation index FST. An illustrative numerical simulation of admixture proportion estimates is included. Relationships of the formalism with coalescence times and pairwise sequence differences are also provided.

evolutionary biology↗