Subterranean Fishes of the World

4281

2019

AIM 2019

33

Low oxygen content is a well-known feature of numerous cave systems around the globe, including caves of the Sierra de El Abra region. Many studies have shown that differences in oxygen content have driven physiological adaptations in the circulatory systems of hypogean teleosts. Some of these changes impact oxygen metabolism, gill surface area and oxygen binding affinity, which likely play significant roles in survivability. However, few studies have examined these putative adaptations in Astyanax cavefish. Prior genetic studies suggest possible avenues of adaptation to the extreme cave environment. Genome-wide sequence analyses have revealed in-frame indel mutations in two genes associated with blood physiology: myeloid leukemia factor 1 (mlf1) and plasminogen (plg). Additionally, transcriptomic studies reveal expression level differences in several blood-related genes between cave and surface forms. These findings have led us to explore hemoglobin concentrations in isolated blood samples from surface- and cavedwelling forms. Preliminary analyses suggest cavefish may harbor elevated hemoglobin (Hb) concentrations compared to surface fish, however cavefish appear to demonstrate higher variability in Hb readings. Thus, important changes in blood physiology may contribute to survivability in the extreme cave environment through more efficient cellular respiration. This work will enable a better understanding of how cave animals adapt to the diminished oxygen content of the subterranean environment. By exploring other cave systems across the El Abra region, we hope to gain insight into whether geographically distinct populations adapt to reduced oxygen through convergent or parallel genetic mechanisms.

1

Astyanax Interrnational Meeting