Subterranean Fishes of the World

3096

2015

AIM 2015

Even though a human can survive equally well in both fifty degree weather and seventy degree weather, why is it that most would prefer to be in the latter? Everybody has preferences, but not much is known about the genetics of preferences or how they evolve. We have been studying temperature preference of Astyanax mexicanus populations from different caves and of surface population living in adjacent rivers. In principle, the temperature in the caves differs from, and is more stable than, the temperature in rivers, and we hope to measure this during our time in Mexico, which could lead to selection for different preferences. It would make sense that the caves have different temperatures, as we have indeed found that the cave populations have different temperature preferences. In particular, the fish from the Molino cave like warmer temperatures, the Pachon fish like cooler temperatures, and the Tinaja fish and river fish both seemed to like moderate temperatures. Genetic analysis indicates that these are inherited traits. For example, when we crossed the Molino and Pachon fish, the hybrids overwhelmingly went to the warmer temperatures like the Molino fish. We are now analysing F2s to determine if the trait is Mendelian or if it is more complex.

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