People from Ibiza: an unexpected isolate in the Western Mediterranean

Abstract

In this study, we seek to understand and to correlate the genetic patterns observed in the population of the island of Ibiza in the Western Mediterranean basin with past events.Genome-wide genotypes of 189 samples representing 13 of 17 regions in Spain have been analyzed, in addition to 105 samples from the Levant, 157 samples from North Africa, and one ancient sample from the Phoenician Cas Molí site in Ibiza. Before the Catalans conquered the island in 1235 CE, Ibiza (Eivissa) had already been influenced by several cultures, starting with the Phoenicians, then the Carthaginians, followed by the Umayyads. The impact of these various cultures on the genetic structure of the islanders is still unexplored. Our results show a clear distinction between Ibiza and the rest of Spain. To investigate whether this was due to the Phoenician colonization or to more recent events, we compared the genomes of current Ibizans to that of an ancient Phoenician sample from Ibiza and to both modern Levantine and North African genomes. We did not identify any trace of Phoenician ancestry in the current Ibizans.Interestingly, the analysis of runs of homozygosity and changes in the effective population size through time support the idea that drift has shaped the genetic structure of current Ibizans. In addition to the small carrying capacity of the island, Ibiza experienced a series of dramatic demographic changes due to several instances of famine, war, malaria and plague that could have significantly contributed to its current genetic differentiation.

Genetic origins, singularity, and heterogeneity of Basques

“…The PCA shows a remarkable micro-geographical genetic structure and clustering of the Basque groups. To obtain an external reference of similar size and sampling density at a microgeographical scale, such as the present study, the Catalan samples from Biagini et al 28 were compared to our dataset. The PCA of Catalans does not show any geographical structure comparable to that of Basques and Peri-Basques (Figure S5), which may imply that the clustering observed in Basques is specific to them and unrelated to the sample strategy.…”

“…Our Franco-Cantabrian samples were merged with public available data genotyped with the same array: samples from Catalonia, Valencia, and Balearic Islands; 28 plus modern and ancient North African and Western Eurasian samples. 19,26,27,44 Modern Basque samples from Lazaridis et al 27 were included in the analyses in the Basque category as general ''Spanish'' and ''French'' Basques due to the lack of information about their microgeographical origin.…”

The effect of diet and sociopolitical change on physiological stress and behavior in lateRoman‐EarlyByzantine (300–700AD) and Islamic (902–1,235AD) populations from Ibiza, Spain

“…As Ibiza has been repeatedly colonized throughout its history, the contribution of migration to Ibiza's genetic history makes this an especially important consideration. The origin of migrants to Ibiza and the extent of their genetic contribution to contemporary Ibiza remain much debated, and a full consideration falls beyond the scope of this analysis (Biagini et al, 2019; Tomàs, Jiménez, Picornell, Castro, & Ramon, 2006; Zalloua et al, 2018). Craniometrics may give support to some migration from North and Sub‐Saharan Africa since at least the Punic colonization (sixth century BC onwards) (Márquez‐Grant, 2005, 2006) and genetic discontinuity through time is also supported by recent DNA studies (Biagini et al, 2019).…”

“…The origin of migrants to Ibiza and the extent of their genetic contribution to contemporary Ibiza remain much debated, and a full consideration falls beyond the scope of this analysis (Biagini et al, 2019; Tomàs, Jiménez, Picornell, Castro, & Ramon, 2006; Zalloua et al, 2018). Craniometrics may give support to some migration from North and Sub‐Saharan Africa since at least the Punic colonization (sixth century BC onwards) (Márquez‐Grant, 2005, 2006) and genetic discontinuity through time is also supported by recent DNA studies (Biagini et al, 2019). Migration, whether primarily from mainland Spain as well as North and Sub‐Saharan Africa seems to be the scenario for most of Ibiza's archeological past, as documented not only through biology but also material culture (Ferrer, 2019; Kaufman, 2000; Márquez‐Grant, 2006).…”

Reshaping theHexagone: the genetic landscape of modern France

“…Thus, the complete dataset included 256 newly genotyped samples, plus 139 additional ones, for a final group of 395 samples distributed among 20 different French departments (see Figure 1 for the geographical distribution). For the allele frequency analyses, as comparison with external populations, 218 samples among Germany, Norway, Spain, Italy, England, Ireland, and Scotland were used from public data (Lazaridis et al, 2016a), together with 107 samples from the Spanish autonomous communities of Catalonia, Valencian Community, and Balearic islands from public data (Biagini et al, 2019), and 8 additional samples from South Italy (Naples) newly genotyped with Axiom ® Genome-Wide Human Origins Arrays (~629 K SNPs) and presented in this study for the first time. A further 797 samples from external populations (Lazaridis, Nadel, Rollefson, Merrett, et al, 2016) were added to the previous ones when applying haplotype-based methods (see Supplementary Figure 2 for the external samples distribution, and Supplementary table 1 for a summary of the dataset composition).…”