Revista: Molecular Phylogenetics and Evolution

Enlace: https://doi.org/10.1016/j.ympev.2026.108675

Autores: Jorge L. Ramirez, Kiefer A. Bedoya, Rina Ramírez, Ricardo Britzke

Profesores de la FCB: Jorge L. Ramirez, Rina Ramírez, Ricardo Britzke

Abstract

This study presents the most comprehensive phylogenetic analysis to date of the high-Andean fish genus Orestias, a diverse and largely endemic group, using Genotype-by-Sequencing (GBS) and extensive sampling across the full range of the genus, from northern Peru to northern Chile. In particular, the evolutionary relationships and population structure within the O. agassii species complex were reconstructed. Phylogenetic analyses consistently recovered three major clades: a newly identified Northern clade, the Lake Titicaca radiation, and the O. agassii species complex. The genus originated around 4 Ma, with a deep divergence between clades (4–3 Ma) and more recent diversification within each clade (0.3–1.15 Ma). This pattern suggests historical extinctions linked to climatic shifts and the survival of lineages in large Andean lakes acting as refuges. The O. agassii species complex is the most widespread clade, with a dispersal route from north (Mantaro basin) to south (Chilean Altiplano). Population genomic analyses revealed strong geographic structuring within the O. agassii species complex, with nine distinct lineages, corresponding to major basins such as Chillon, Coastal Arequipa, Mantaro, Apurímac, Urubamba and Titicaca. The O. agassii populations show an isolation-by-distance pattern attributed to ecological preference and low vagility. Our results provide a robust phylogenetic framework and emphasize the need for further taxonomic and conservation efforts, as Orestias species are particularly vulnerable to anthropogenic pressures such as pollution, habitat loss, climate-driven lake shrinkage, and predation by introduced trout.