Skip to main content
Dryad

Astyanax cavefish body shape coordinates from: Phylogeographic relationships and morphological evolution between cave and surface Astyanax mexicanus populations (De Fillipi 1853) (Actinopterygii, Characidae)

Data files

Jun 27, 2023 version files 103.82 KB
Jun 28, 2023 version files 103.99 KB

Abstract

The Astyanax mexicanus complex includes two different morphs, a surface and a cave-adapted ecotype, found at three mountain ranges in Northeastern Mexico: Sierra de El Abra, Sierra de Guatemala, and Sierra de la Colmena (Micos). Since their discovery, multiple studies have attempted to characterize the timing and the number of events that gave rise to the evolution of these cave-adapted ecotypes. Here, using RAD-seq and genome-wide sequencing, we assessed the phylogenetic relationships, genetic structure, and gene flow events between the cave and surface Astyanax mexicanus populations, to estimate the time and mode of evolution of the cave-adapted ecotypes. We also evaluated the body shape evolution across different cave lineages using geometric morphometrics to examine the role of phylogenetic signal vs. environmental pressures. We found strong evidence of parallel evolution of cave-adapted ecotypes derived from two separate lineages of surface fish and hypothesize that there may be up to four independent invasions of caves from surface fish. Moreover, a strong congruence between the genetic structure and geographic distribution was observed across the cave populations, with the Sierra de Guatemala the region exhibiting most genetic drift among the cave populations analyzed. Interestingly, we found no evidence of phylogenetic signal in body shape evolution, but we found support for parallel evolution in body shape across independent cave lineages, with cavefish from the Sierra de El Abra reflecting the most divergent morphology relative to surface and other cavefish populations.