Subterranean Fishes of the World

3198

2013

AIM 2013

Extensive studies of microsatellite (mSat) and SNP variation among cave and surface populations in the Sierra de El Abra region clearly establish that the cave populations of the region evolved independently at least five times. They are derived from at least two distinct lineages of surface fish which occupied the area consecutively. The same patterns of genetic relationships among populations emerge from independent analyses of both mSats and SNPs. The population genetic signatures unambiguously establish the lineage identity of all nine studied cave populations. The ancient separation of the two lineages previously established (6.7 mya, Ornelas-Garcia, et al. 2008) suggests that they may represent different species. This hypothesis is strongly supported by studies of inter-population hybrids. Hybrids between lineages have sex ratios strongly skewed towards females. Those that do develop as males exhibit extreme transmission bias of parental alleles, with the biased loci organized into large blocks throughout the genome. In addition, sperm from inter-lineage hybrid males, in comparison to non-hybrid males, are abnormal in several ways, including lower percent motilities, swimming velocities and endurances. Hybrids between populations within lineages do not exhibit these abnormalities. These results argue for the resurrection of the species name, Astyanax jordani, for all cave populations of the Sierra de El Abra proper, from Cueva Chica in the south to Cueva de El Pachón in the north.

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