Presentation Details
Evidence for repeated evolution of cave traits in the Mexican tetra Astyanax mexicanus

Maya S.Enriquez1, Stefan Choy2, Johanna E.Kowalko2, Suzanne E.McGaugh1.

1University of Minnesota - Twin Cities, Saint Paul, Minnesota, USA.2Lehigh University, Bethlehem, Pennsylvania, USA

Abstract


Mexican tetra fish exhibit two distinct phenotypes: the surface form which live in freshwater rivers, and the cave form which live in underground caves. Cave fish exhibit traits such as eye loss, increased sensitivity in sensory systems besides vision, and significantly reduced sleep compared to surface fish. Lineage reconstruction suggests several independent cave colonization events from ancestral surface fish, yet it is unknown whether cave traits appeared through similar or divergent mechanisms across cave populations. We aim to characterize the parallel evolutionary trajectory of complex cave traits across three different cave populations using quantitative trait locus (QTL) mapping of sleep reduction, increased neuromast density, and the interaction between starvation and sleep. We estimated sleep under different feeding regimes to examine the plasticity of sleep response in response to nutrient availability and counted neuromasts within an anatomical region strongly associated with cave behaviors. Preliminary results suggest neuromast quantity correlates with sleep in some populations but not others, suggesting a different genetic basis and evidence for parallel evolution.  

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