Phylogeographical convergence between Astyanax cavefish and mysid shrimps in the Sierra de El Abra, Mexico

Joseph Kopp,Luis Espinasa,Shristhi Avasthi

doi:10.3897/subtbiol.26.27097

Abstract

The Sierra de El Abra is a long (120 km) and narrow (10 km) karstic area in northeastern Mexico. Some studies have suggested independent evolutionary histories for the multiple populations of blind cavefish Astyanaxmexicanus that inhabit this mountain range, despite the hydrological connections that may exist across the Sierra. Barriers between caves could have prevented stygobitic populations to migrate across caves, creating evolutionary significant units localized in discrete biogeographical areas of the Sierra de El Abra. The goal of the present study was to evaluate if there is a correspondence in phylogeographical patterns between Astyanax cavefish and the stygobitic mysid shrimp Spelaeomysisquinterensis. Astyanax mtDNA and mysid histone H3 DNA sequences showed that in both species, cave populations in central El Abra, such as Tinaja cave, are broadly different from other cave populations. This phylogeographical convergence supports the notion that the central Sierra de El Abra is a biogeographical zone with effective barriers for either cave to cave or surface to cave gene flow, which have modulated the evolutionary history across species of its aquatic stygobitic community.

Highlights

The teleost Astyanax mexicanus has become one of the most influential models for studying regressive evolution and cave adapted organisms
The surfacedwelling forms inhabit a high variety of hydrological systems throughout Mesoamerica region, while the stygobitic forms inhabit a series of subterranean systems in the Sierra de El Abra, Sierra de Guatemala, and Micos area, in Northeast Mexico
Despite its success as a model organism for study in the field of evolutionary development, there is still considerable controversy regarding its phylogeography (e.g. Ornelas-García et al 2008; Bradic et al 2012, Strecker et al 2012). Central to this discussion has been the question of how many times have the surface populations independently colonized the cave environment and how much underground dispersal has occurred to establish the current cave populations

Summary

Introduction

The teleost Astyanax mexicanus has become one of the most influential models for studying regressive evolution and cave adapted organisms. The Sierra de El Abra, where the largest abundance of caves with cavefish populations are located, (i.e. 21 populations currently discovered), is a long (120 km) and narrow (10 km) limestone ridge. Despite its success as a model organism for study in the field of evolutionary development, there is still considerable controversy regarding its phylogeography (e.g. Ornelas-García et al 2008; Bradic et al 2012, Strecker et al 2012). Central to this discussion has been the question of how many times have the surface populations independently colonized the cave environment and how much underground dispersal has occurred to establish the current cave populations. A plethora of publications have accumulated over time with terms such as phylogenetically old/new populations, lineages A/B, phylogenetically old/new clusters, and old/new epigean stocks, with individual cavefish populations assigned contradictorily to one or to another set (Gross 2012)

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