Subterranean Fishes of the World

3275

2017

AIM 2017

Sierra de El Abra cave populations of Astyanax lack aggressive behavior, territorial behavior, and have increased food searching behavior compared to surface populations. This docile nature of El Abra cave populations compared to their aggressive surface counterparts is part of a “cavefish behavioral syndrome” and is thought to be evolutionarily advantageous in low-nutrient cave environments. However, we report here that Astyanax cave fish from the Sierra de Guatemala region have aggression levels and territoriality comparable to surface fish, yet retain enhanced feeding behavior. In our behavioral studies, El Abra cave fish (4 Pachon cave specimens) only exhibited an average of 0.83 (+/- 0.98 SD; N=6) aggressive attacking behaviors during a 5 min period, while Molino and Caballo Moro cave populations, from Sierra de Guatemala, and surface fish exhibited respectively 22.1 (+/- 7.9 SD; N=6), 26.5 (+/- 14.4 SD; N=6) and 52.1 (+/-34.8 SD; N=6) attacks. Sierra de El Abra cavefish did not form territoriality, which was evident in both Sierra de Guatemala cave fish and in surface fish. Feeding behavior studies showed that contrary to the above, Sierra de Guatemala were more similar to El Abra cavefish: Surface fish were satiated after being fed 1.8% (+/- 0.6%; N=13) of their body weight, Pachon cave fish after 3.6% (+/- 0.4%; N=8), and Sierra de Guatemala cave fish after 6.5% (±1.6%; N=10). Sequencing data revealed a P106L mutation in the MAO gene in El Abra cave fish that is not present in surface fish or Sierra de Guatemala cavefish. MAO is a neurotransmitter degrading enzyme, thus it may enhance food searching behavior while reducing aggression and territoriality. Tests with deprenyl, a MAO inhibitor, reduced aggression in Molino (58.4% ± 70.9) and Caballo Moro specimens (74.8% ± 21.0) as well as in their territoriality and food satiation. This evidence suggests divergent evolutionary pathways of the cavefish behavioral syndrome.

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