Fine-scale population structure in five rural populations from the Spanish Eastern Pyrenees using high-coverage...

Area of Science:

• Population genetics
• Human evolutionary studies
• Genomics

Background:

• The Spanish Pyrenees presents unique demographic dynamics due to its orography and rural population.
• Previous genetic studies indicated a West-East gradient but missed finer population substructure.
• High-throughput sequencing and spatial methods can reveal micro-level genetic variations.

Purpose of the Study:

• To investigate fine-scale population substructure within the Spanish Eastern Pyrenees (SEP).
• To analyze genome-wide data for demographic histories and population differentiation.
• To understand the evolutionary trajectories of isolated rural populations.

Main Methods:

• Genome sequencing of 30 individuals from five SEP valleys at 40x coverage.
• Haplotype-based methods and spatial analyses to detect micro-population substructure.
• Linkage disequilibrium, autozygosity, and Approximate Bayesian Computation with Deep Learning (ABC-DL) for demographic modeling.

Main Results:

• Detected significant micro-population substructure within the SEP, not evident in prior studies.
• Identified diverse demographic histories and heterogeneity in effective population sizes among closely located valleys.
• Demographic modeling suggests the emergence of this substructure approximately 2500 years ago.

Conclusions:

• Each rural population in the Pyrenees may represent a distinct genetic entity.
• Geographic proximity does not preclude significant genetic differentiation in isolated populations.
• The study highlights the importance of high-resolution genomic data for understanding fine-scale population genetics.