engleski

Anesthesia Tolerance in Cave Adapted and Surface Conspecific Populations of Astyanax mexicanus

The cave adapted fish Astyanax mexicanus has numerous morphological, physiological and behavioral changes in comparison to its surface conspecifics. It is not clear how they evolved and whether they are linked to some of the other features via pleiotrophy. The purpose of this research is to test the hypothesis that anesthesia tolerance is negatively correlated with pigmentation in this species. The study groups include albino cave and pigmented surface populations. Anesthesia tolerance was initially tested by exposing the fry to ice water and calculating average time to unconsciousness ; it was determined the albino population remained conscious significantly longer than the surface population. The hypothesis was re-tested using chemical anesthetic MS-222. It was determined that the populations from two different caves, Pachon and Tinaja, remained conscious significantly longer. Additionally, it was discovered that the difference in tolerance does not arise until 4 days post fertilization and persists through adulthood in Pachon. In addition, the length and mass of the adult fish were measured and compared to their respective times to unconsciousness. It was determined that there is no significant correlation between body mass or length and time to unconsciousness. Genetic results showed linkage between anesthesia tolerance and the loss of pigmentation which together segregated independently of eye loss. Future experiments will aim to understand the relationship between this phenomenon and the development of the nervous system in Astyanax.

anesthesia tolerance, loss of pigmentation, cave adapted animal, Astyanax mexicanus

nije evidentirano